    Maritime Security: Public Safety Consequences of a Terrorist
    Attack on a Tanker Carrying Liquefied Natural Gas Need
    Clarification (22-FEB-07, GAO-07-316).

    The United States imports natural gas by pipeline from Canada and
    by tanker as liquefied natural gas (LNG) from overseas. LNG--a
    supercooled form of natural gas--currently accounts for about 3
    percent of total U.S. natural gas supply, with an expected
    increase to about 17 percent by 2030, according to the Department
    of Energy (DOE). With this projected increase, many more LNG
    import terminals have been proposed. However, concerns have been
    raised about whether LNG tankers could become terrorist targets,
    causing the LNG cargo to spill and catch on fire, and potentially
    explode. DOE has recently funded a study to consider these
    effects; completion is expected in 2008. GAO was asked to (1)
    describe the results of recent studies on the consequences of an
    LNG spill and (2) identify the areas of agreement and
    disagreement among experts concerning the consequences of a
    terrorist attack on an LNG tanker. To address these objectives,
    GAO, among other things, convened an expert panel to discuss the
    consequences of an attack on an LNG tanker.
    -------------------------Indexing Terms-------------------------
    REPORTNUM:   GAO-07-316
        ACCNO:   A66105
      TITLE:     Maritime Security: Public Safety Consequences of a
    Terrorist Attack on a Tanker Carrying Liquefied Natural Gas Need
    Clarification
         DATE:   02/22/2007
      SUBJECT:   Emergency preparedness
    	     Hazardous substances
    	     Homeland security
    	     Importing
    	     Liquefied natural gas
    	     Maritime security
    	     Natural gas
    	     Port security
    	     Research reports
    	     Ships
    	     Tanks (containers)
    	     Terrorism
    	     Transportation terminals
    	     Water transportation
    	     Public safety

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    GAO-07-316

         * [1]Results in Brief
         * [2]Background
         * [3]Studies Identified Different Distances for the Heat Effects

              * [4]Studies Identified Various Distances That the Heat Effects o
              * [5]Some Studies Examined Other Potential Hazards and Identified

         * [6]Experts Generally Agreed That the Most Likely Public Safety

              * [7]Experts Agreed That the Heat from an LNG Fire Was Most Likel
              * [8]Experts Disagreed with a Few Key Conclusions of the Sandia N
              * [9]Experts Suggest Future Research Priorities to Determine the

         * [10]Conclusions
         * [11]Recommendation for Executive Action
         * [12]Agency Comments and Our Evaluation

              * [13]Introduction
              * [14]LNG Hazards

                   * [15]Overall Hazards
                   * [16]LNG Hazards-Freeze Burns
                   * [17]LNG Hazards-Asphyxiation
                   * [18]LNG Hazards-Vapor Cloud: Wind Effect
                   * [19]LNG Hazards-Fire Hazard
                   * [20]LNG Hazards-Fire Hazard: Thermal Hazard End Point
                   * [21]LNG Hazards-Fire Hazard: Pool Fire
                   * [22]LNG Hazards-Vapor Cloud Fire
                   * [23]LNG Hazards-Vapor Cloud Fire: Burn Back Speed
                   * [24]Explosions-RPT
                   * [25]Explosions-Deflagrations and Detonations
                   * [26]Explosions--Deflagrations, Detonations, and BLEVEs
                   * [27]LNG Hazards-Is BLEVE the Worst?

              * [28]Questions About the 2004 Sandia National Laboratories Study
              * [29]Commodity Comparison
              * [30]Future Research

         * [31]GAO Contact
         * [32]Staff Acknowledgments
         * [33]GAO's Mission
         * [34]Obtaining Copies of GAO Reports and Testimony

              * [35]Order by Mail or Phone

         * [36]To Report Fraud, Waste, and Abuse in Federal Programs
         * [37]Congressional Relations
         * [38]Public Affairs

    Report to Congressional Requesters

    United States Government Accountability Office

    GAO

    February 2007

    MARITIME SECURITY

    Public Safety Consequences of a Terrorist Attack on a Tanker Carrying
    Liquefied Natural Gas Need Clarification

    GAO-07-316

    Contents

    Letter 1

    Results in Brief 7
    Background 8
    Studies Identified Different Distances for the Heat Effects of an LNG Fire
    11
    Experts Generally Agreed That the Most Likely Public Safety Impact of an
    LNG Spill Is Fire's Heat Effect, but That Further Study Is Needed to
    Clarify the Extent of This Effect 17
    Conclusions 22
    Recommendation for Executive Action 23
    Agency Comments and Our Evaluation 23
    Appendix I Scope and Methodology 24
    Appendix II Names and Affiliations of Members of GAO's Expert Panel on LNG
    Hazards 26
    Appendix III Summary of Expert Panel Results 27
    Appendix IV GAO Contact and Staff Acknowledgments 41

    Tables

    Table 1: Key Assumptions and Results of the LNG Spill Consequence Studies
    13
    Table 2: Expert Panel's Ranking of Need for Research on LNG 21

    Figures

    Figure 1: Existing, Approved, and Proposed LNG Terminals in the United
    States, as of October 2006 3
    Figure 2: LNG Membrane Tanker 11

    This is a work of the U.S. government and is not subject to copyright
    protection in the United States. It may be reproduced and distributed in
    its entirety without further permission from GAO. However, because this
    work may contain copyrighted images or other material, permission from the
    copyright holder may be necessary if you wish to reproduce this material
    separately.

    Abbreviations

    BLEVE boiling liquid expanding vapor explosion
    DOE Department of Energy
    DOT Department of Transportation
    FERC Federal Energy Regulatory Commission
    kW/m^2 kilowatts per square meter
    LNG liquefied natural gas
    LPG liquefied petroleum gas
    m^2 square meters
    m^3 cubic meters
    m/s meters per second
    RPT rapid phase transition
    WSA Waterway Suitability Assessment

    United States Government Accountability Office

    Washington, DC 20548

    February 22, 2007

    The Honorable John D. Dingell
    Chairman
    The Honorable Joe Barton
    Ranking Member
    Committee on Energy and Commerce
    House of Representatives

    The Honorable Bennie G. Thompson
    Chairman
    The Honorable Peter King
    Ranking Member
    Committee on Homeland Security
    House of Representatives

    The Honorable Edward J. Markey
    House of Representatives

    Worldwide, over 40,000 tanker cargos of liquefied natural gas (LNG) have
    been shipped since 1959, and imports of LNG are projected to increase over
    the next 10 years. LNG is a supercooled liquid form of natural gas--a
    crucial source of energy for the United States. Natural gas is used in
    homes for cooking and heating and as fuel for generating electricity, and
    it accounts for about one-fourth of all energy consumed in the United
    States each year. Prices for natural gas in the United States have risen
    over the past 5 years as demand for natural gas has increased faster than
    domestic production. To make up for the domestic shortfall, the United
    States imports some natural gas in pipelines from Canada. However, most
    reserves of natural gas are overseas and cannot be transported through
    pipelines. Natural gas from these reserves has to be transported to the
    United States as LNG in tankers. Because of the projected increase in LNG
    tankers arriving at U.S. ports, concerns have been raised about whether
    the tankers could become terrorist targets. Worldwide, over 40,000 tanker
    cargos of liquefied natural gas (LNG) have been shipped since 1959, and
    imports of LNG are projected to increase over the next 10 years. LNG is a
    supercooled liquid form of natural gas--a crucial source of energy for the
    United States. Natural gas is used in homes for cooking and heating and as
    fuel for generating electricity, and it accounts for about one-fourth of
    all energy consumed in the United States each year. Prices for natural gas
    in the United States have risen over the past 5 years as demand for
    natural gas has increased faster than domestic production. To make up for
    the domestic shortfall, the United States imports some natural gas in
    pipelines from Canada. However, most reserves of natural gas are overseas
    and cannot be transported through pipelines. Natural gas from these
    reserves has to be transported to the United States as LNG in tankers.
    Because of the projected increase in LNG tankers arriving at U.S. ports,
    concerns have been raised about whether the tankers could become terrorist
    targets.

    LNG--primarily composed of methane--is odorless and nontoxic. It is
    produced by supercooling natural gas to minus 260 degrees Fahrenheit at
    atmospheric pressure, thus reducing its volume by more than 600 times.
    This process makes transport by tankers feasible. The tankers are
    double-hulled, with each tanker containing between four and six adjacent
    tanks heavily insulated to maintain the LNG's supercool temperature.
    Generally, LNG--primarily composed of methane--is odorless and nontoxic.
    It is produced by supercooling natural gas to minus 260 degrees Fahrenheit
    at atmospheric pressure, thus reducing its volume by more than 600 times.
    This process makes transport by tankers feasible. The tankers are
    double-hulled, with each tanker containing between four and six adjacent
    tanks heavily insulated to maintain the LNG's supercool temperature.
    Generally, these ships can carry enough LNG to supply the daily energy
    needs of over 10 million homes. Importing LNG requires specialized
    facilities--called regasification terminals--at ports of entry. At these
    terminals, the liquid is reconverted into natural gas and then injected
    into the pipeline system for consumers. Currently, the United States has a
    total of five LNG import terminals--four are considered onshore terminals,
    that is, they are located within 3 miles of the shore; one is an offshore
    terminal located 116 miles off the Louisiana coast in the Gulf of
    Mexico.^1

    The United States imports about 3 percent of its total natural gas supply
    as LNG in recent years, but by 2030, LNG imports are projected to account
    for about 17 percent of the U.S. natural gas supply, according to the
    Department of Energy's (DOE) Energy Information Administration. To meet
    this increased demand, energy companies have submitted 32 applications to
    build new terminals for importing LNG in 10 states and five offshore
    areas. Figure 1 shows the locations of LNG terminals that are operational,
    approved, and proposed.

    ^1The onshore facilities are near Boston, Massachusetts; Cove Point,
    Maryland; Savannah, Georgia; and Lake Charles, Louisiana. The United
    States also has one LNG export facility in Kenai, Alaska, that ships LNG
    to Japan.

    Figure 1: Existing, Approved, and Proposed LNG Terminals in the United
    States, as of October 2006

    As of October 2006, the Federal Energy Regulatory Commission
    (FERC)^2--responsible for approving onshore LNG terminal siting
    applications--and the U.S. Coast Guard^3--responsible for approving
    offshore LNG terminal siting applications--had together approved 13 of
    these applications. In addition, the Coast Guard contributes to FERC's
    review of onshore LNG facilities by reviewing and validating an
    applicant's Waterway Suitability Assessment (WSA) and reaching a
    preliminary conclusion as to whether the waterway is suitable for LNG
    operations with regard to navigational safety and security considerations.
    The WSA includes a security risk assessment to evaluate the public safety
    risk of an LNG spill from a tanker following an attack. The security risk
    assessment analyzes potential types of attacks, their probability, and the
    potential consequences. The WSA also identifies appropriate strategies
    that can be used to reduce the risk posed by a terrorist attack on an LNG
    tanker, either by reducing the probability of an attack, or by reducing
    its consequences. If the WSA deems the waterway suitable for LNG tanker
    traffic, the Coast Guard provides FERC with a "Letter of Recommendation,"
    which describes the overall risk reduction strategies that will be used on
    LNG tankers traveling to the proposed terminal. The Coast Guard is the
    lead federal agency for ensuring the security of active LNG import
    terminals and tankers traveling within U.S. ports.

    As figure 1 shows, six new facilities have been proposed for the
    northeastern United States, a region that faces gas supply challenges. The
    Northeast has limited indigenous supplies of natural gas, and receives
    most of its natural gas either through pipelines from the U.S. Gulf Coast
    or Canada, or from overseas via tanker as LNG. The pipelines into the
    Northeast currently run at or near capacity for much of the winter, and
    demand is projected to significantly increase over the next 5 years,
    exceeding available supply by 2010. To meet the increasing demand, new
    supplies of natural gas must reach the Northeast by expanding existing
    pipeline capacity, constructing new pipelines, or constructing new LNG
    terminals--all of which have risk associated with them. Difficulties
    siting LNG facilities in the Northeast could lead to higher natural gas
    prices unless additional supply can be brought into the region via new, or
    expansion of old, pipelines.

    ^2Under the Natural Gas Act, as amended, FERC has exclusive authority to
    approve or deny an application for the siting, construction, or operation
    of onshore LNG terminals, including pipelines, and offshore facilities in
    state waters--that is, generally within 3 miles of shore.

    ^3The Coast Guard, along with the Department of Transportation's Maritime
    Administration, has jurisdiction under the Deep Water Port Act of 1974, as
    amended, to approve the siting and operation of offshore LNG facilities in
    federal waters.

    Scientists and the public have raised concerns about the potential hazards
    that an LNG spill could pose. When LNG is spilled from a tanker, it forms
    a pool of liquid on the water. Individuals who come into contact with LNG
    could experience freeze burns. As the liquid warms and changes into
    natural gas, it forms a visible, foglike vapor cloud close to the water.
    The cloud mixes with ambient air as it continues to warm up and eventually
    the natural gas disperses into the atmosphere. Under certain atmospheric
    conditions, however, this cloud could drift into populated areas before
    completely dispersing. Because an LNG vapor cloud displaces the oxygen in
    the air, it could potentially asphyxiate people who come into contact with
    it. Furthermore, like all natural gas, LNG vapors can be flammable,
    depending on conditions.^4 If the LNG vapor cloud ignites, the resulting
    fire will burn back through the vapor cloud toward the initial spill. It
    will continue to burn above the LNG that has pooled on the surface--this
    is known as a pool fire. Experiments to date have shown that LNG fires
    burn hotter than oil fires of the same size. Both the cold temperatures of
    spilled LNG and the high temperatures of an LNG fire have the potential to
    significantly damage the tanker, causing multiple tanks on the ship to
    fail in sequence--called a cascading failure. Such a failure could
    increase the severity of the incident. Finally, concerns have been raised
    about whether an explosion could result from an LNG spill.

    Although LNG tankers have carried over 40,000 shipments worldwide since
    1959, there have been no LNG spills resulting from a cargo tank rupture.
    Some safety incidents, such as groundings or collisions, have resulted in
    small LNG spills that did not affect public safety. In the 1970s and
    1980s, experiments to determine the consequences of a spill examined small
    LNG spills of up to 35 meters in diameter. Following the terrorist attacks
    of September 11, 2001, however, many experts recognized that an attack on
    an LNG tanker could result in a large spill--a volume of LNG up to 100
    times greater than studied in past experiments. Since then, a number of
    studies have reevaluated safety hazards of LNG tankers in light of a
    potential terrorist threat. Because a major LNG spill has never occurred,
    studies examining LNG hazards rely on computer models to predict the
    effects of hypothetical accidents, often focusing on the properties of LNG
    vapor fires. The Coast Guard uses one of these studies, conducted in 2004
    by Sandia National Laboratories,^5 as a basis for conducting the security
    risk assessment required in the WSA for proposed onshore LNG facilities.^6
    Access to accurate information about the consequences of LNG spills is
    crucial for developing accurate risk assessments for LNG siting decisions.
    While an underestimation of the consequences could expose the public to
    additional risk in the event of an LNG spill, an overestimation of
    consequences could result in the use of inappropriate and costly risk
    mitigation strategies. DOE recently funded a new study--to be completed by
    Sandia National Laboratories in 2008--that will conduct small- and
    large-scale LNG fire experiments to refine and validate existing models
    (such as the one used by Sandia National Laboratories in their 2004 study)
    that calculate the heat hazards of large LNG fires.

    ^4LNG vapors only ignite when they are in a 5 percent to 15 percent
    concentration in the air. If the LNG concentration is higher, there is not
    enough oxygen available for fire. If the concentration is lower, there is
    likewise not enough fuel for fire.

    In this context, you asked us to (1) describe the results of recent
    unclassified studies on the consequences of an LNG spill and (2) identify
    the areas of agreement and disagreement among experts concerning the
    consequences of a terrorist attack on an LNG tanker.

    To address the first objective, we identified eight unclassified,
    completed studies of LNG hazards and reviewed the six studies that
    included new, original research (either experimental or modeling) and
    clearly described the methodology used. While we have not verified the
    scientific modeling or results of these studies, the methods used seem
    appropriate for the work conducted. We also interviewed agencies
    responsible for LNG regulations and visited all four onshore LNG import
    facilities and one export facility. To address the second objective, we
    identified 19 recognized experts in LNG hazard analysis and convened a
    Web-based expert panel to obtain their views on LNG hazards and to get
    agreement on as many issues as possible. In selecting experts for the
    panel, we sought individuals who are widely recognized as having
    experience with one or more key aspects of LNG hazard analysis. We sought
    to achieve balance in representation from government, academia,
    consulting, research organizations, and industry. Additionally, we ensured
    that our expert panel included at least one author from each of the six
    unclassified studies of LNG hazards. Because some of the studies conducted
    are classified, this public version of our findings supplements a more
    comprehensive classified report produced under separate cover. A more
    detailed description of our scope and methodology is presented in appendix
    I. We conducted our work from January 2006 through January 2007 in
    accordance with generally accepted government auditing standards.

    ^5Sandia National Laboratories. Guidance on Risk Analysis and Safety
    Implications of a Large Liquefied Natural Gas (LNG) Spill Over Water.
    Albuquerque: 2004.

    ^6DOE is also sponsoring additional research that applies the 2004 Sandia
    National Laboratories' methodology to LNG tankers larger than those
    previously studied, which is expected to be completed in July 2007.

    Results in Brief

    The six unclassified studies we reviewed all examined the heat impact of
    an LNG pool fire but produced varying results; some studies also examined
    other potential hazards of a large LNG spill and reached consistent
    conclusions on explosions. Specifically, the studies' conclusions about
    the distance at which 30 seconds of exposure to the heat could burn people
    ranged from about 500 meters (less than 1/3 of a mile) to more than 2,000
    meters (about 1-1/4 miles). The Sandia National Laboratories' study
    concluded that the most likely distance for a burn is about 1,600 meters
    (1 mile). These variations occurred because researchers had to make
    numerous modeling assumptions to scale-up the existing experimental data
    for large LNG spills since there are no large spill data from actual
    events. These assumptions involved the size of the hole in the tanker, the
    number of tanks that fail, the volume of LNG spilled, key LNG fire
    properties, and environmental conditions, such as wind and waves. Three of
    the studies also examined other potential hazards of an LNG spill,
    including LNG vapor explosions, asphyxiation, and cascading failure. All
    three studies considered LNG vapor explosions unlikely unless the LNG
    vapors were in a confined space. Only the Sandia National Laboratories'
    study examined asphyxiation, and it concluded that asphyxiation did not
    pose a hazard to the general public. Finally, only the Sandia National
    Laboratories' study examined the potential for cascading failure of LNG
    tanks and concluded that only three of the five tanks would be involved in
    such an event and that this number of tanks would increase the duration of
    the LNG fire.

    Our panel of 19 experts generally agreed on the public safety impact of an
    LNG spill, disagreed with a few conclusions reached by the Sandia National
    Laboratories' study, and suggested priorities for research to clarify the
    impact of heat and cascading tank failures. Experts agreed that (1) the
    most likely public safety impact of an LNG spill is the heat impact of a
    fire; (2) explosions are not likely to occur in the wake of an LNG spill,
    unless the LNG vapors are in confined spaces; and (3) some hazards, such
    as freeze burns and asphyxiation, do not pose a hazard to the public.
    Experts disagreed with the heat impact and cascading tank failure
    conclusions reached by the Sandia National Laboratories' study, which the
    Coast Guard uses to prepare WSAs. Specifically, all experts did not agree
    with the heat impact distance of 1,600 meters. Seven of 15 experts thought
    Sandia's distance was "about right," and the remaining eight experts were
    evenly split as to whether the distance was "too conservative" or "not
    conservative enough" (the other 4 experts did not answer this question).
    Experts also did not agree with the Sandia National Laboratories'
    conclusion that only three of the five LNG tanks on a tanker would be
    involved in a cascading failure. Finally, experts suggested priorities to
    guide future research aimed at clarifying uncertainties about heat impact
    distances and cascading failure, including large-scale fire experiments,
    large-scale LNG spill experiments on water, the potential for cascading
    failure of multiple LNG tanks, and improved modeling techniques. DOE's
    recently funded study involving large-scale LNG fire experiments addresses
    some, but not all, of the research priorities identified by the expert
    panel.

    We are recommending that DOE incorporate into its current LNG study the
    key issues identified by the expert panel. We particularly recommend that
    DOE examine the potential for cascading failure of LNG tanks.

    Background

    Natural gas is primarily composed of methane, with small percentages of
    other hydrocarbons, including propane and butane. When natural gas is
    cooled to minus 260 degrees Fahrenheit at atmospheric pressure, the gas
    becomes a liquid, known as LNG, and it occupies only about 1/600th of the
    volume of its gaseous state. Since LNG is maintained in an extremely
    cooled state--reducing its volume--there is no need to store it under
    pressure. This liquefaction process allows natural gas to be transported
    by trucks or tanker vessels. LNG is not explosive or flammable in its
    liquid state. When LNG is warmed, either at a regasification terminal or
    from exposure to air as a result of a spill, it becomes a gas. As this gas
    mixes with the surrounding air, a visible, low-lying vapor cloud results.
    This vapor cloud can be ignited and burned only within a minimum and
    maximum concentration of air and vapor (percentage by volume). For
    methane, the dominant component of this vapor cloud, this flammability
    range is between 5 percent and 15 percent by volume. When fuel
    concentrations exceed the cloud's upper flammability limit, the cloud
    cannot burn because too little oxygen is present. When fuel concentrations
    are below the lower flammability limit, the cloud cannot burn because too
    little methane is present. As the cloud vapors continue to warm, above
    minus 160 degrees Fahrenheit, they become lighter than air and will rise
    and disperse rather than collect near the ground.

    If the cloud vapors ignite, the resulting fire will burn back through the
    vapor cloud toward the initial spill and will continue to burn above the
    LNG that has pooled on the surface. This fire burns at an extremely high
    temperature--hotter than oil fires of the same size. LNG fires burn hotter
    because the flame burns very cleanly and with little smoke. In oil fires,
    the smoke emitted by the fire absorbs some of the heat from the fire and
    reduces the amount of heat emitted. Scientists measure the amount of heat
    given off by a fire by looking at the amount of heat energy emitted per
    unit area as a function of time. This is called the surface emissive power
    of a fire and is measured in kilowatts per square meter (kW/m^2).
    Generally, the heat given off by an LNG fire is reported to be more than
    200 kW/m^2. By comparison, the surface emissive power of a very smoky oil
    fire can be as little as 20 kW/m^2. The heat from fire can be felt far
    away from the fire itself. Scientists use heat flux--also measured in
    kW/m^2--to quantify the amount of heat felt at a distance from a fire. For
    instance, a heat flux of 5 kW/m^2 can cause second degree burns after
    about 30 seconds of exposure to bare skin. This heat flux can be compared
    with the heat from a candle--if a hand is held about 8 to 9 inches above
    the candle, second degree burns could result in about 30 seconds. A heat
    flux of about 12.5 kW/m^2, over an exposure time of 10 minutes, will
    ignite wood, and a heat flux of about 37.5 kW/m^2 can damage steel
    structures.

    Four types of explosions could potentially occur after an LNG spill: rapid
    phase transitions (RPT), deflagrations, detonations, and
    boiling-liquid-expanding-vapor-explosions (BLEVE).^7 More specifically:

               o An RPT occurs when LNG is warmed and changes into natural gas
               nearly instantaneously. An RPT generates a pressure wave that can
               range from very small to large enough to damage lightweight
               structures. RPTs strong enough to damage test equipment have
               occurred in past LNG spill experiments on water, although their
               effects have been localized at the site of the RPT.
               o Deflagrations and detonations are explosions that involve
               combustion (fire). They differ on the basis of the speed and
               strength of the pressure wave generated: deflagrations move at
               subsonic velocities and can result in pressures (overpressures) up
               to 8 times higher than the original pressure; detonations travel
               faster--at supersonic velocities--and can result in larger
               overpressures--up to 20 times the original pressure. Methane does
               not detonate as readily as other hydrocarbons; it requires a
               larger explosion to initiate a detonation in a methane cloud.
               o A BLEVE occurs when a liquefied gas is heated to above its
               boiling point while contained within a tank. For instance, if a
               hot fire outside an LNG tanker sufficiently heated the liquid
               inside, a percentage of the LNG within the tank could "flash" into
               a vapor state virtually instantaneously, causing the pressure
               within the tank to increase. LNG tanks do have pressure relief
               valves, but if these were inadequate or failed, the pressure
               inside the tank could rupture the tank. The escaping gas would be
               ignited by the fire burning outside the tank, and a fireball would
               ensue. The rupture of the tank could create an explosion and
               flying debris (portions of the tank).

               World natural gas reserves are abundant, estimated at about 6,300
               trillion cubic feet, or 65 times the volume of natural gas used in
               2005. Much of this gas is considered "stranded" because it is
               located in regions far from consuming markets. Russia, Iran, and
               Qatar combined hold natural gas reserves that represent more than
               half of the world total. Many countries have imported LNG for
               years. In 2005, 13 countries shipped natural gas to 14
               LNG-importing countries. LNG imports, as a percentage of a
               country's total gas supply, for each of the importing countries
               ranged from 3 percent in the United States to nearly 95 percent in
               Japan. In 2005, LNG imports to the United States originated
               primarily in Trinidad and Tobago (70 percent), Algeria (15
               percent), and Egypt (11 percent). The remaining 4 percent of U.S.
               LNG imports came from Oman, Malaysia, Nigeria, and Qatar.

               LNG tankers primarily have two basic designs, called membrane or
               Moss (see fig. 2). Both designs consist of an outer hull, inner
               hull, and cargo containment system. In membrane tank designs, the
               cargo is contained by an Invar, or stainless steel double-walled
               liner, that is structurally supported by the vessel's inner hull.
               The Moss tank design uses structurally independent spherical or
               prismatic shaped tanks. These tanks, usually five located one
               behind the other, are constructed of either stainless steel or an
               aluminum alloy. LNG tankers ships are required to meet
               international maritime construction and operating standards, as
               well as U.S. Coast Guard safety and security regulations.

               Figure 2: LNG Membrane Tanker

    			  Studies Identified Different Distances for the Heat Effects of an
    			  LNG Fire

               The six studies we examined identified various distances at which
               the heat effects of an LNG fire could be hazardous to people. The
               studies' variations in heat effects result from the assumptions
               made in the studies' models. Some studies also examined other
               potential hazards such as LNG vapor explosions, other types of
               explosions, and asphyxiation, and identified their potential
               impacts on public safety.

    			  Studies Identified Various Distances That the Heat Effects of an
    			  LNG Fire Could Be Hazardous to People because of Assumptions Made

               The studies' conclusions about the distance at which 30 seconds of
               exposure to the heat could burn people ranged from about 500
               meters (less than 1/3 mile) to more than 2,000 meters (about 1-1/4
               miles). The results--size of the LNG pool, the duration of the
               fire, and the heat hazard distance for skin burn--varied in part
               because the studies made different assumptions about key
               parameters of LNG spills and also because they were designed and
               conducted for different purposes. Key assumptions made included
               the following:

               o Hole size and cascading failure. Hole size is an important
               parameter for modeling LNG spills because of its relationship to
               the duration of the event--larger holes allow LNG to spill from
               the tanker more quickly, resulting in larger LNG pools and shorter
               duration fires. Conversely, small holes could create
               longer-duration fires. Cascading failure is important because it
               increases the overall spill volume and the duration of the spill.
               o Waves and wind. These conditions can affect the size of both the
               LNG pool and the heat hazard zone. One study indicated that waves
               can inhibit the spread of an LNG pool, keeping the pool size much
               smaller than it would be on a smooth surface, and thereby reducing
               the size of the LNG pool fire. Wind will tend to tilt the fire
               downwind (like a candle flame blowing in the wind), increasing the
               heat hazard zone in that direction (and decreasing it upwind).
               o Volume of LNG spilled. The amount of LNG spilled is one of the
               factors that can affect the size of the pool.
               o Surface emissive power of the fire. While the amount of heat
               given off by a large LNG fire is unknown, assumptions about it
               directly affect the results for the heat hazard zone. It is
               expected that the surface emissive power of LNG fires will be
               lower for large fires because oxygen will not circulate
               efficiently within a very large fire. Lack of oxygen in the middle
               of a large fire would lead to more smoke production, which would
               block some of the heat from the fire.

               The LNG spill consequence studies' key assumptions and results are
               shown in table 1.

    ^7Generally, an explosion is an energy release associated with a pressure
    wave. Some explosions are large enough that the pressure wave can break
    windows or damage structures, while others are much smaller.

    Table 1: Key Assumptions and Results of the LNG Spill Consequence Studies

                                        Key assumptions                              Key results
                                        Environmental
                                         conditions
                                          modeled:
                                                   Wind
                                                  speed
                                                    and                               Distance
                           Number of                its                Fire             to the
                          tanks that  Wind speed effect             surface            5kw/m^2
                     Hole    rupture     and its     on      Spill emissive      Pool     heat
                     size (cascading   effect on   fire     volume    power  diameter    level  Duration
                    (m^2)    failure  waves(m/s)  (m/s)      (m^3) (kW/m^2)  (meters) (meters) (minutes)
    Quest            19.6          1         1.5    1.5     12,500        b       156      497      14.3
    Consultants     19.6           1    5.0      5.0      12,500          b       146                531    16.6
    Inc. (Quest)^a  19.6           1    9.0      9.0      12,500          b       110                493    28.6
    Sandia              2          3           c      c     37,500      220       209      784        20
    National           5           3      c        c      37,500        220       572              2,118     8.1
    Laboratories       5           1      c        c      12,500        350       330              1,652     8.1
    (Sandia)         5^d           1      c        c      12,500        220   330-405        1,305-1,579 5.4-8.1
                      12           1      c        c      12,500        220       512              1,920     3.4
    Pitblado, et
    al.
    (Pitblado)^e     1.77          1           c    3.0     17,250        b       171      750        32
    ABS Consulting   0.79          1           c    8.9     12,500      265     200^g      650        51
    (ABSC)^f        19.6           1      c      8.9      12,500        265     620^g              1,500     4.2
    Fay (Fay)^h        20          1           c      c     14,300        b         b    1,900       3.3
    Lehr and
    Simecek-Beatty
    (Lehr)^i            b          b           c      c        500      200         b      500       2-3

    Source: GAO analysis of spill consequence studies.

    a"Modeling LNG Spills in Boston Harbor." Copyright(c) 2003 Quest
    Consultants, Inc., Norman, OK 73609; Letter from Quest Consultants to DOE
    (October 2, 2001); Letter from Quest Consultants to DOE (October 3, 2001).

    bInformation not available.

    cNot included in the model.

    dThe study examined multiple scenarios of 5m^2. The ranges listed
    summarize the highest and lowest values for those scenarios.

    eR. M. Pitblado, J. Baik, G. J. Hughes, C. Ferro, and S. J. Shaw.
    "Consequences of Liquefied Natural Gas Marine Incidents." Process Safety
    Progress 24 no. 2 (June 2005).

    fABS Consulting Inc. Consequence Assessment Methods for Incidents
    Involving Releases from Liquefied Natural Gas Carriers. May 13, 2004. FERC
    "Staff's Responses to Comments on the Consequence Assessment Methods for
    Incidents Involving Releases from Liquefied Natural Gas Carriers," June
    18, 2004.

    gABS Consulting modeled pool size as a semicircle and reported the radius
    of that semicircle in the study. The reported radii were used to calculate
    the diameter of the semicircle so the study results could be compared with
    the other studies.

    hJ.A. Fay. "Model of Spills and Fires from LNG and Oil tankers." Journal
    of Hazardous Materials B96 (2003): 171-188.

    IWilliam Lehr and Debra Simecek-Beatty. "Comparison of Hypothetical LNG
    and Fuel Oil Fires on Water." Journal of Hazardous Materials 107 (2004):
    3-9.

    In terms of the studies' results, we identified the following three key
    results:

               o Pool size describes the extent of the burning pool--and can help
               people understand how large the LNG fire itself will be.
               o Heat hazard distance describes the distance at which 30 seconds
               of exposure could cause second degree burns.
               o Fire duration of the incident describes how long people and
               infrastructure will be exposed to the heat from the fire. The
               longer the fire, the greater potential for damage to the tanker
               and for cascading failure.

               Although all the studies considered the consequences of an LNG
               spill, they were conducted for different purposes. Three of the
               six studies--Quest, Sandia, and Pitblado--specifically addressed
               the consequences of LNG spills caused by terrorist attacks. Two of
               these three studies--Quest and Sandia--were commissioned by DOE.
               The Quest study, begun in response to the September 11, 2001,
               attacks, was designed to quantify the heat hazard zones for LNG
               tanker spills in Boston Harbor. Only the Quest study examined how
               wind and waves would affect the spreading of the LNG on the water
               and the size of the resulting LNG pool. The Quest study based its
               wind and wave assumptions on weather data from buoys near Boston
               Harbor. The Quest study found that, while the waves would help
               reduce the size of the LNG pool, the winds that created the waves
               would tend to increase the heat hazard distance downwind. To
               simplify the modeling of the waves, the Quest study considered
               "standing" waves (rather than moving waves) of various heights
               and, therefore, did not consider the impact of wave movement on
               LNG pool spreading. The ABSC study expressed concern that Quest's
               standing wave assumption resulted in pool sizes that were too
               small because wave movement might help spread the LNG.

               The 2004 Sandia study was intended to develop guidance on a
               risk-based analysis approach to assess potential threats to an LNG
               tanker, determine the potential consequences of a large spill, and
               review techniques that could be used to mitigate the consequences
               of an LNG spill. The assumptions and results in table 1 for the
               Sandia study refer to the scenarios Sandia examined that had
               terrorist causes. According to Sandia, the study used available
               intelligence and historical data to develop credible and possible
               scenarios for the kinds of attacks that could breach an LNG
               tanker. Sandia then modeled how large a hole each of the weapon
               scenarios could create in an LNG tanker.^8 Two of these
               intentional breach scenarios included cascading failure of three
               tanks on an LNG tanker. In these cases, the LNG spill from one
               tank, as well as the subsequent fire, causes the neighboring two
               tanks to fail on the LNG tanker, resulting in LNG spills from
               three of the five tanks on the tanker. After considering all of
               its scenarios, Sandia concluded that, as a rule-of-thumb, 1,600
               meters is a good approximation of the heat hazard distance for
               terrorist-induced spills. However, as the table shows, one of
               Sandia's scenarios--for a large spill with cascading failure of
               three LNG tanks--found that the distance could exceed more than
               2,000 meters and that the cascading failure would increase the
               duration of the incident.

               Finally, the stated purpose of industry's Pitblado study was to
               develop credible threat scenarios for attacks on LNG tankers and
               predict hazard zones for LNG spills from those types of attacks.
               The study identified a hole size smaller than the other studies
               that specifically considered terrorist attacks.

               The other studies we reviewed examined LNG spills regardless of
               cause. FERC commissioned the ABS Consulting study to develop
               appropriate methods for estimating heat hazard zones from LNG
               spills. FERC uses these methods, in conjunction with the Sandia
               study, to examine the public safety consequences of tankers
               traveling to proposed onshore LNG facilities before granting
               siting approval. The two scenarios in the ABSC study illustrate
               how small holes could result in longer fires, which have a higher
               potential to damage the tanker itself. One scenario used a hole
               size of 0.79 square meters and the other a hole size of about 20
               square meters. The difference in duration is striking--it takes 51
               minutes and 4.2 minutes, respectively, for the fire to consume all
               the spilled LNG.

               Finally, the Lehr and Fay studies compared the fire consequences
               of LNG spills with known information about oil spills and fires.
               Although most studies made similar assumptions about the volume of
               LNG spilled from any single LNG tank, Lehr examined a much smaller
               spill volume--just 500 cubic meters of LNG, compared with a range
               of 12,500 to 17,250 cubic meters.

    ^8Please note that the information used to develop Sandia's terrorist
    scenarios is classified and will be discussed in GAO's classified report.

    			  Some Studies Examined Other Potential Hazards and Identified Their
    			  Impact on Public Safety

               Three of the studies also examined other potential hazards of an
               LNG spill, including LNG vapor explosions, other types of
               explosions, and asphyxiation.

               LNG vapor explosions. Three studies--Sandia, ABSC, and
               Pitblado--examined LNG vapor explosions, and all agreed that it is
               unlikely that LNG vapors could explode and create a pressure wave
               if the vapors are in an unconfined space. Although the three
               studies agreed that LNG vapors could explode only in confined
               areas, they did not conduct modeling or describe the likelihood of
               such confinement after an LNG spill from a tanker. The Sandia
               study stated that fire will generally progress through the vapor
               cloud slowly and without producing an explosion with damaging
               pressure waves. The study did suggest, however, that if the LNG
               vapor cloud is confined (e.g., between the inner and outer hull of
               an LNG carrier), it could explode but would only affect the
               immediate surrounding area. The ABSC study and the Pitblado study
               agreed that a confined LNG vapor cloud could result in an
               explosion.

               Other types of explosions. Three studies--Sandia, ABSC, and
               Pitblado--examined the potential for RPTs. The Sandia study
               concluded that, while RPTs have generated energy releases
               equivalent to several pounds of explosives, RPT impacts will be
               localized near the spill. Sandia also noted that RPTs are not
               likely to cause structural damage to the vessel. The ABSC study
               noted that their literature search suggested that damage from RPT
               overpressures would be limited to the immediate vicinity, though
               it noted that the literature did not include large spills like
               those that could be caused by a terrorist attack. Only one study,
               Pitblado, discussed the possibility of a BLEVE. According to our
               discussions with Dr. Pitblado, an LNG ship with membrane tanks
               could not result in a BLEVE, but he said that Moss spherical tanks
               could potentially result in a BLEVE. A BLEVE could result because
               it is possible for pressure to build up in a Moss tanker. A 2002
               LNG tanker truck incident in Spain resulted in an explosion that
               some scientists have characterized as a BLEVE of an LNG truck.
               Portions of the tanker truck were found 250 meters from the
               accident itself, propelled by the strength of the blast.

               Asphyxiation. Only the Sandia study examined the potential for
               asphyxiation following an LNG spill if the vapors displace the
               oxygen in the air. It concluded that fire hazards would be the
               greatest problem in most locations, but that asphyxiation could
               threaten the ship's crew, pilot boat crews, and emergency response
               personnel.

    			  Experts Generally Agreed That the Most Likely Public Safety Impact
    			  of an LNG Spill Is Fire�s Heat Effect, but That Further Study Is
    			  Needed to Clarify the Extent of This Effect

               Our panel of 19 experts generally agreed on the public safety
               impact of an LNG spill and disagreed with a few of the conclusions
               of the Sandia study.^9 The experts also suggested priorities for
               future research--some of which are not fully addressed in DOE's
               ongoing LNG research--to clarify uncertainties about heat impact
               distances and cascading failure. These priorities include
               large-scale fire experiments, large-scale LNG spill experiments on
               water, the potential for cascading failure of multiple LNG tanks,
               and improved modeling techniques.

    			  Experts Agreed That the Heat from an LNG Fire Was Most Likely to
    			  Affect Public Safety, but That Explosions from an LNG Spill Are
    			  Unlikely

               Experts discussed two types of fires: vapor cloud fires and pool
               fires. Eighteen of 19 experts agreed that the ignition of a vapor
               cloud over a populated area could burn people and property in the
               immediate vicinity of the fire. While the initial vapor cloud fire
               would be of short duration as the flames burned back toward the
               LNG carrier, any flammable object enveloped by the vapor cloud
               fire could ignite nearby objects, creating secondary fires that
               present hazards to the public. Three experts emphasized in their
               comments that the vapor cloud is unlikely to penetrate very far
               into a populated area before igniting. Expanding on this point,
               one expert noted that any injuries from a vapor cloud fire would
               occur only at the edges of a populated area, for example, along
               beaches. One expert disagreed, arguing that a vapor cloud fire is
               unlikely to cause significant secondary fires because it would not
               last long enough to ignite other materials.

               Experts agreed that the main hazard to the public from a pool fire
               is the heat from the fire but emphasized that the exact hazard
               distance depends on site-specific and scenario-specific factors.
               Furthermore, a large, unconfined pool fire is very difficult to
               extinguish; generally almost all the LNG must be consumed before
               the fire goes out. Experts agreed that three of the main factors
               that affect the amount of heat from an LNG fire are the following:

               o Site-specific weather conditions. Weather conditions, such as
               wind and humidity, can influence the heat hazard distances. For
               example, more humid conditions allow heat to be absorbed by the
               moisture in the air, reducing heat hazard distances.
               o Composition of the LNG. The composition of the LNG can also
               affect the distance at which heat from the fire is felt by the
               public. In small fires, methane, which comprises between 84
               percent and 97 percent of LNG, burns cleanly, with little smoke.
               Other LNG components--propane and butane--produce more smoke when
               burned, absorbing some of the fire's heat and reducing the hazard
               distance. As the fire grows larger, the influence of the
               composition of LNG is hypothesized to be less pronounced because
               large fires do not burn efficiently.
               o Size of the fire. The size of the fire has a major impact on its
               surface emissive power; the heat hazard distance increases with
               pool size up to a point but is expected to decrease for very large
               pools, like those caused by a terrorist attack.

               Experts also discussed the following hazards related to an LNG
               spill:

               o RPTs. Experts agreed that RPTs could occur after an LNG spill
               but that the overpressures generated would be unlikely to directly
               affect the public.
               o Detonations and deflagrations. Experts made a key distinction
               between these types of explosions in confined spaces as opposed to
               unconfined spaces. For confined spaces, they agreed that it is
               possible, under controlled experimental conditions, to induce both
               types of explosions of LNG vapors; however, a detonation of
               confined LNG vapors is unlikely following an LNG spill caused by a
               terrorist attack. Experts were split on the likelihood of a
               confined deflagration occurring after a terrorist attack: eight
               thought it was unlikely, four thought it likely, and five thought
               neither likely nor unlikely.^10 For unconfined spaces, experts
               were split on whether it is possible to induce such explosions;
               however, even experts who thought such explosions were possible
               agreed that deflagrations and detonations in unconfined spaces are
               unlikely to occur following an LNG spill caused by a terrorist
               attack.

               o BLEVE. Experts were split on whether a BLEVE is theoretically
               possible in an LNG tanker. Of the ten experts who agreed it was
               theoretically possible, six thought that a BLEVE is unlikely to
               occur following an LNG spill caused by a terrorist attack on a
               tanker.^11
               o Freeze burns and asphyxiation. Experts agreed that freeze burns
               do not present a hazard to the public because only people in close
               proximity to LNG spill, such as personnel on the tanker or nearby
               vessels, might come into contact with LNG or very cold LNG vapor.
               For asphyxiation, experts agreed that it is unlikely that an LNG
               vapor cloud could reach a populated area while still sufficiently
               concentrated to pose an asphyxiation threat.

    			  Experts Disagreed with a Few Key Conclusions of the Sandia
    			  National Laboratories Study

               Experts disagreed with heat hazard and cascading failure
               conclusions of the Sandia study. Specifically, 7 of 15 experts
               thought Sandia's heat hazard distance was "about right," and the
               remaining 8 experts were evenly split as to whether the distance
               was "too conservative" (i.e., larger than needed to protect the
               public) or "not conservative enough" (i.e., too small to protect
               the public). Experts who thought the distance was too conservative
               generally listed one of two reasons. First, the assumptions about
               the surface emissive power of large fires were incorrect because
               the surface emissive power of large fires would be lower than
               Sandia assumed. Second, Sandia's hazard distances are based on the
               maximum size of a pool fire. However, these experts pointed out
               that once a pool fire ignites, its diameter will begin to shrink,
               which will also reduce the heat hazard distance. Experts who
               thought Sandia's heat hazard distance was not conservative enough
               listed a number of concerns. For example, Sandia's distances do
               not take into consideration the effects of cascading failure. One
               expert suggested that a 1-meter hole in the center tank of an LNG
               tanker that resulted in a pool fire could cause the near
               simultaneous failure of the other four tanks, leading to a larger
               heat hazard zone.

               Officials at Sandia National Laboratories and our panel of experts
               cautioned that the hazard distances presented cannot be applied to
               all sites. According to the Sandia study authors, their goal was
               to provide guidance to federal agencies on the order of magnitude
               of the hazards of an LNG spill on water. As they pointed out in
               interviews and in their original study, further analysis for
               specific sites is needed to understand hazards in a particular
               location. Six experts on our panel also emphasized the importance
               of site-specific and scenario-specific factors. For instance, one
               expert explained that the 5kW/m^2 hazard distance depends on the
               size of the tanker and the spill scenario, including factors such
               as wind speed, timing of ignition, and the location of the hole.
               Other experts suggested that key factors are spill volume and the
               impact of waves. Additionally, two experts explained that there is
               no "bright line" for hazards--that is, 1,599 meters is not
               necessarily "dangerous," and 1,601 meters is not necessarily
               "safe."

               Only 9 of 15 experts agreed with Sandia's conclusion that only
               three of the five LNG tanks on a tanker would be involved in
               cascading failure. Five experts noted that the Sandia study did
               not explain how it concluded that only three tanks would be
               involved in cascading failure. Three experts said that an LNG
               spill and subsequent fire could potentially result in the loss of
               all tanks on board the tanker.

               Twelve of 16 experts agreed, however, with Sandia's conclusion
               that cascading failure events are not likely to greatly increase
               (by more than 20 to 30 percent) the overall fire size or heat
               hazard ranges. The four experts who disagreed with Sandia's
               conclusion about the public safety impact of cascading failure
               cited two main reasons: (1) Sandia did not clearly explain how it
               reached that conclusion and (2) the impact of cascading failure
               will partly depend on how the incident unfolds. For instance, one
               expert suggested that cascading failure could include a tank
               rupture, fireball, or BLEVE, any of which could have direct
               impacts on the public (from the explosive force) and which would
               change the heat hazard zones that Sandia identified.

               Finally, experts agreed with Sandia's conclusion that consequence
               studies should be used to support comprehensive, risk-based
               management and planning approaches for identifying, preventing,
               and mitigating hazards from potential LNG spills.

    			  Experts Suggest Future Research Priorities to Determine the Public
    			  Safety Impact of an LNG Spill

               In the second iteration of the Web-based panel, we asked the
               experts to identify the five areas related to the consequences of
               LNG spills that need further research. Then, in the final
               iteration of the Web-based panel, we provided the experts with a
               list of 19 areas--generated by their suggestions and comments from
               the second iteration--and asked them to rank these in order of
               importance. Table 2 presents the results of that ranking for the
               top 10 areas identified and indicates those areas that are funded
               in the DOE study discussed earlier.

               Table 2: Expert Panel's Ranking of Need for Research on LNG

                                                                       Funded in
    Rank Research area                                             DOE's study
    1    Large fire phenomena                                         X
    2    Cascading failure
    3    Large-scale spill testing on water                           X
    4    Large-scale fire testing                                     X
    5    Comprehensive modeling: interaction of physical processes
    6    Risk tolerability assessments
    7    Vulnerability of containment systems (hole size)
    8    Mitigation techniques
    9    Effect of sea water coming in as LNG flows out
    10   Impact of wind, weather, and waves

               Source: GAO.

               Note: A rank of 1 is the highest rank, and a rank of 10 is the
               lowest. Panel members ranked 19 areas of research from 1 to 19; a
               score was calculated for each area based on this ranking. Only the
               10 areas with the highest scores are presented in this table.

               As the table shows, two of the top five research areas identified
               are related to large LNG fires--large fire phenomena and
               large-scale fire testing. Experts believe this research is needed
               to establish the relationship between large pool fires and the
               surface emissive power of the fire. Experts recommended new LNG
               tests for fires between 15 meters and 1,000 meters. The median
               suggested test size was 100 meters. Some experts also raised the
               issue of whether large LNG fires will stop behaving like one
               single flame but instead break up into several smaller, shorter
               flames. Sandia noted in its study that this behavior could reduce
               heat hazard distances by a factor of two to three.

               Experts also ranked research into cascading failure of LNG tanks
               second in the list of priorities. Concerning cascading failure,
               one expert noted that, although the consequences could be serious,
               there are virtually no data looking at the hull damage caused by
               exposure to extreme cold or heat.

               As table 2 shows, DOE's recently funded study involving
               large-scale LNG fire experiments addresses some, but not all, of
               the research priorities identified by the expert panel. For DOE,
               Sandia National Laboratories plans to conduct large-scale LNG pool
               fire tests beginning with a pool size of 35 meters--the same size
               as the largest test conducted to date. Sandia will validate the
               existing 35-meter data and then conduct similar tests for pool
               sizes up to 100 meters. The goal of this fire testing is to
               document the impact of smoke on large LNG pool fires. Sandia
               suggests that these tests will create a higher degree of knowledge
               of large-scale pool fire behavior and significantly lower the
               current uncertainty in predicting heat hazard distances.

               According to researchers at Sandia National Laboratories, some of
               the research our panel of experts suggested may not be
               appropriate. Sandia indicated that comprehensive modeling, which
               allows various complex processes to interact, would be very
               difficult to do because of the uncertainty surrounding each
               individual process of the model. One expert on our panel agreed,
               noting that while comprehensive modeling of all LNG phenomena is
               important, combining those phenomena into one model should wait
               for experiments that lead to better understanding of each
               individual phenomenon.

    ^9We considered experts "in agreement" if more than 75 percent of experts
    indicated that they completely agreed or generally agreed with a given
    statement. Not all experts commented on every issue discussed.

    ^10Two experts did not comment.

    ^11Three experts said that BLEVEs were "neither likely nor unlikely," and
    one expert thought that BLEVEs were likely.

    			  Conclusions

               It is likely that the United States will increasingly depend on
               the importation of LNG to meet the nation's demand for natural
               gas. Understanding and resolving the uncertainties surrounding LNG
               spills is critical, especially in deciding on where to locate LNG
               facilities. Because there have been no large-scale LNG spills or
               spill experiments, past studies have developed modeling
               assumptions based on small-scale spill data. While there is
               general agreement on the types of effects from an LNG spill, the
               results of these models have created what appears to be
               conflicting assessments of the specific consequences of an LNG
               spill, creating uncertainty for regulators and the public.
               Additional research to resolve some key areas of uncertainty could
               benefit federal agencies responsible for making informed decisions
               when approving LNG terminals and protecting existing terminals and
               tankers, as well as providing reliable information to citizens
               concerned about public safety. Although DOE has recently funded a
               study that will address large-scale LNG fires, this study will
               address only 3 of the top 10 issues--and not the second-highest
               ranked issue--that our panel of experts identified as potentially
               affecting public safety.

    			  Recommendation for Executive Action

               To provide the most comprehensive and accurate information for
               assessing the public safety risks posed by tankers transiting to
               proposed LNG facilities, we recommend that the Secretary of Energy
               ensure that DOE incorporates the key issues identified by the
               expert panel into its current LNG study. We particularly recommend
               that DOE examine the potential for cascading failure of LNG tanks
               in order to understand the damage to the hull that could be caused
               by exposure to extreme cold or heat.

    			  Agency Comments and Our Evaluation

               We requested comments on a draft of this report from the Secretary
               of Energy (DOE). DOE agreed with our findings and recommendation.
               In addition, DOE included technical and clarifying comments, which
               we included in our report as appropriate.

               As agreed with your offices, unless you publicly announce the
               contents of this report earlier, we plan no further distribution
               until 30 days from the report date. At that time, we will send
               copies to interested congressional committees, the Secretary of
               Energy, and other interested parties. We also will make copies
               available to others upon request. In addition, the report will be
               available at no charge on the GAO Web site at http://
               www.gao.gov .

               If you or your staff have any questions regarding this report,
               please contact me at (202) 512-3841 or wellsj@gao.gov. Contact
               points for our Offices of Congressional Relations and Public
               Affairs may be found on the last page of this report. Key
               contributors to this report are listed in appendix IV.

               Jim Wells
    			  Director, Natural Resources and Environment

    			  Appendix I: Scope and Methodology

               To address the first objective, we identified eight unclassified,
               completed studies of liquefied natural gas (LNG) hazards and
               reviewed the six studies that included new, original research
               (either experimental or modeling) and clearly described the
               methodology used. While we have not verified the scientific
               modeling or results of these studies, the methods used seem
               appropriate for the work conducted based on conversations with
               experts in the field and our assessment. We also discussed these
               studies with their authors and visited all four onshore LNG import
               facilities and one export facility. We attended a presentation on
               LNG safety and received specific training on LNG properties and
               safety. We also conducted interviews with officials from Sandia
               National Laboratories, Federal Energy Regulatory Commission,
               Department of Transportation, Department of Energy, and the U. S.
               Coast Guard. During our interviews, we asked officials to provide
               information on past LNG studies and plans for future LNG spill
               consequences work.

               To obtain information on experts' opinions of the public safety
               consequences of an LNG spill from a tanker, we conducted a
               three-phase, Web-based survey of 19 experts on LNG spill
               consequences. We identified these experts from a list of 51
               individuals who had expertise in one or more key aspects of LNG
               spill consequence analysis. In compiling this initial list, we
               sought to achieve balance in terms of area of expertise (i.e., LNG
               experiments, modeling LNG dispersion, LNG vaporization, fire
               modeling, and explosion modeling). In addition, we included at
               least one author of each of the six major LNG studies we reviewed,
               that is, studies by Sandia National Laboratories; ABS Consulting;
               Quest Consultants Inc.; Pitblado, et al.; James Fay (MIT); and
               William Lehr (National Oceanic and Atmospheric Administration). We
               gathered resumes, publication lists, and major LNG-related
               publications from the experts identified on the initial list.

               We selected 19 individuals for the panel. One or more of the
               following selection criteria were used: (1) has broad experience
               in all facets of LNG spill consequence modeling (LNG spill from
               hole, LNG dispersion, vaporization and pool formation, vapor cloud
               modeling, fire modeling, and explosion modeling); (2) has
               conducted physical LNG experiments; or (3) has specific experience
               with areas of particular importance, such as LNG explosion
               research. In addition, we included: (1) at least one author from
               each of the major LNG studies and (2) representatives from private
               industry, consulting, academia, and government. All 19 experts
               selected for the panel agreed to participate. The names and
               affiliations of panel members are included in appendix II.

               To obtain consensus concerning public safety issues, we used an
               iterative Web-based process. We used this method, in part, to
               eliminate the potential bias associated with group discussions.
               These biasing effects include the potential dominance of
               individuals and group pressure for conformity. Moreover, by
               creating a virtual panel, we were able to include more experts
               than possible with a live panel.

               For each phase in the process, we posted a questionnaire on GAO's
               survey Web site. Panel members were notified of the availability
               of the questionnaire with an e-mail message. The e-mail message
               contained a unique user name and password that allowed each
               respondent to log on and fill out a questionnaire but did not
               allow respondents access to the questionnaires of others.

               In the questionnaires, we asked the experts to agree or disagree
               with a set of statements about LNG hazards derived from GAO's
               synthesis of major LNG spill consequence studies. Prior to the
               first iteration, we had an LNG spill consequence expert who was
               not a part of the panel review each statement and provide comments
               about technical accuracy and tone. Experts were asked to indicate
               agreement on a 3-point scale (completely agree, generally agree,
               do not agree) and to provide comments about how the statements
               could be changed to better reflect their understanding of the
               consequences of LNG spills.

               If most experts agreed with a statement during the first
               iteration, we did not include it in the second iteration. If there
               was not agreement, we used the experts' comments to revise the
               statements for the second iteration. The second iteration was
               posted on the Web site, using the same protocol as used for the
               first. Again, panel members were asked to agree or disagree and
               provide narrative comments. We revised the statements where there
               was disagreement and posted them on the Web site again for the
               third iteration. At the end of the third iteration, at least 75
               percent of the experts agreed or generally agreed with most of the
               ideas presented.

               Because some of the studies conducted are classified, this public
               version of our findings supplements a more comprehensive
               classified report produced under separate cover. We conducted our
               work from January 2006 through January 2007 in accordance with
               generally accepted government auditing standards.

    			  Appendix II: Names and Affiliations of Members of GAO�s Expert
    			  Panel on LNG Hazards

    Myron Casada   ABS Consulting
    T.Y. Chu       Sandia National Laboratories
    Philip Cleaver Advantica
    Bob Corbin     U.S. Department of Energy
    John Cornwell  Quest Consultants, Inc.
    James Fay      Massachusetts Institute of Technology
    Louis Gritzo   FM Global
    Jerry Havens   University of Arkansas
    Benedict Ho    BP
    Greg Jackson   University of Maryland
    Ron Koopman    Hazard Analysis Consulting
    Bill Lehr      National Oceanic and Atmospheric Administration
    Georges Melhem ioMosaic Corporation
    Gordon Milne   Lloyd's Register
    Robin Pitblado Det Norske Veritas
    Phani Raj      Technology and Management Systems, Inc.
    Velisa Vesovic Imperial College
    Harry West     Texas A&M University
    John Woodward  Baker Engineering and Risk Consultants, Inc.

    			  Appendix III: Summary of Expert Panel Results

               For each question below, we show only those responses that were
               selected by at least one expert. The number of responses adds up
               to 19--the total number of experts on the panel. Percentages may
               not add to 100% due to rounding.

    			  Introduction

               Large LNG spills from a vessel could be caused by an accident,
               such as collision or grounding, or by an intentional attack. While
               large accidental LNG spills are highly unlikely given current LNG
               carrier designs and operational safety policies and practices,
               these spills do pose a hazard to the public if they occur in or
               near a populated area. What is your level of agreement with this
               paragraph? (Finalized in the second iteration.)

    Count Percentage  Label
    8         42.11%  Completely agree
    11        57.89%  Generally agree

    			  LNG Hazards

    			  Overall Hazards

               LNG is a cryogenic liquid composed primarily of methane with low
               concentrations of heavier hydrocarbons, such as ethane, propane,
               and butane. LNG is colorless, odorless, and nontoxic. When LNG is
               spilled, it boils and forms LNG vapor (natural gas). The LNG vapor
               is initially denser than ambient air and visible; LNG vapor will
               stay close to the surface as it mixes with air and disperses. LNG
               and LNG vapor pose four possible hazards: freeze burns,
               asphyxiation, fire hazard, and explosions. What is your level of
               agreement with this paragraph? (Finalized in the second
               iteration.)

    Count Percentage  Label
    5         26.32%  Completely agree
    12        63.16%  Generally agree
    2         10.53%  Do not agree

    			  LNG Hazards-Freeze Burns

               LNG poses a threat of freeze burns to people who come into contact
               with the liquid or with very cold LNG vapor. Since LNG boils
               immediately and vaporizes after it leaves an LNG tank and LNG
               vapor warms as it mixes with air, only people in close proximity
               to the release, such as personnel on the tanker or nearby escort
               vessels, might come into contact with LNG or LNG vapor while it is
               still cold enough to result in freeze burns. Freeze burns do not
               present a direct hazard to the public. What is your level of
               agreement with this paragraph? (Finalized in the second
               iteration.)

    Count Percentage  Label
    14        73.68%  Completely agree
    5         26.32%  Generally agree

    			  LNG Hazards-Asphyxiation

               After an LNG spill, LNG vapor forms a dense, visible vapor cloud
               that is initially heavier than air and remains close to the
               surface. The cloud warms as it mixes with air and as portions of
               the cloud reach ambient air temperatures, they begin to rise and
               disperse. Asphyxiation occurs when LNG vapor displaces oxygen in
               the air. Asphyxiation is a threat primarily to personnel on the
               LNG tanker or to people aboard vessels escorting the tanker at
               close range. An LNG vapor cloud could move away from the tanker as
               it mixes with air and begins to disperse. However, it is unlikely
               that the vapor cloud could reach a populated area while still
               sufficiently concentrated to pose an asphyxiation threat to the
               public. What is your level of agreement with this paragraph?
               (Finalized in the second iteration.)

    Count Percentage  Label
    8         42.11%  Completely agree
    10        52.63%  Generally agree
    1          5.26%  Do not agree

    			  LNG Hazards-Vapor Cloud: Wind Effect

               The effect of wind on an LNG vapor cloud varies with wind speed.
               The most hazardous wind conditions, however, are low winds, which
               can push a vapor cloud downwind without accelerating the LNG vapor
               dispersion into the atmosphere. Low wind conditions have the
               highest potential of allowing an LNG vapor cloud to move a
               significant distance downwind. What is your level of agreement
               with this paragraph? (Finalized in the third iteration.)

    Count Percentage  Label
    8         42.11%  Completely agree
    10        52.63%  Generally agree
    1          5.26%  Do not agree

    			  LNG Hazards-Fire Hazard

               Because LNG vapor in an approximately 5 to 15 percent mixture with
               air is flammable, LNG vapor within this flammability range is
               likely to ignite if it encounters a sufficiently strong ignition
               source such as a cigarette lighter or strong static charge. What
               is your level of agreement with this paragraph? (Finalized in the
               third iteration.)

    Count Percentage  Label
    13        68.42%  Completely agree
    6         31.58%  Generally agree

    			  LNG Hazards-Fire Hazard: Thermal Hazard End Point

               The main hazard to the public from a pool fire is the thermal
               radiation, or heat, that is generated by the fire rather than the
               flames themselves. Often this heat is felt at considerable
               distance from the fire. Scientific papers have used two different
               thresholds as end points to describe the impact of thermal
               radiation on the public: 5 kilowatts per square meter and 1.6
               kilowatts per square meter. Which level do you think is the
               appropriate end point to use to define thermal hazard zones in
               order to protect the public? (Please indicate your response, then
               provide an explanation in the textbox below your answer.)

    Count Percentage  Label
    8         42.11%  5 kilowatts per square meter
    2         10.53%  1.6 kilowatts per square meter
    6         31.58%  Other
    3         15.79%  I do not have the expertise necessary to respond to this
                         question.

               Of the six experts who answered "other," two experts indicated
               that 5kW/m^2 is a useful or appropriate level for measuring the
               impact on people. One expert suggested that dosage (a measure that
               combines thermal radiation and duration of exposure) is most
               appropriate. Another expert suggested that both thresholds are
               appropriate, depending on the circumstances of the analysis.
               (Finalized in the first iteration.)

    			  LNG Hazards-Fire Hazard: Pool Fire

               A pool fire could form in the wake of a vapor cloud fire burning
               back to the source or just after an LNG spill, if there is
               immediate ignition of the LNG vapor. A pool fire burns the vapor
               above a liquid LNG pool as the liquid boils from the pool. A
               large, unconfined pool fire is very difficult to extinguish;
               generally almost all the LNG must be consumed before the fire goes
               out. What is your level of agreement with this paragraph?
               (Finalized in the second iteration.)

    Count Percentage  Label
    13        68.42%  Completely agree
    5         26.32%  Generally agree
    1          5.26%  Do not agree

               The main hazard to the public from a pool fire is the thermal
               radiation, or heat, from the fire. This heat can be felt at a
               considerable distance from the flames themselves. Numerous factors
               can impact the amount of thermal radiation that could affect the
               public: site-specific weather conditions, including humidity and
               wind speed and direction, the composition of the LNG, and the size
               of the fire. What is your level of agreement with this paragraph?
               (Finalized in the second iteration.)

    Count Percentage  Label
    13        68.42%  Completely agree
    6         31.58%  Generally agree

               The wind speed and direction also affect the distance at which
               thermal radiation from the fire is felt by the public. In high
               winds, the flames will tilt downwind, increasing the amount of
               heat felt downwind of the fire and decreasing the amount of heat
               felt upwind. More humid conditions allow heat to be absorbed by
               the moisture in the air reducing the heat felt by the public. What
               is your level of agreement with the above paragraph? (Finalized in
               the second iteration.)

    Count Percentage  Label
    6         31.58%  Completely agree
    11        57.89%  Generally agree but suggest the following clarification.
    2         10.53%  I do not have the expertise necessary to respond to this
                         section.

               The composition of the LNG can also affect the distance at which
               thermal radiation from the fire is felt by the public. In small
               fires, methane, which comprises between 84 percent and 97 percent
               of LNG, burns cleanly, with little smoke. Cleaner-burning LNG
               fires, particularly those burning LNG with higher methane content,
               result in higher levels of thermal radiation than oil or gasoline
               fires of the same size because the smoke generated by oil and
               gasoline fires acts as a shield, reducing the amount of thermal
               radiation emitted by the fire. While LNG composition can have a
               large impact on the thermal radiation from small LNG fires, as LNG
               fires get larger, these effects are hypothesized to be less
               pronounced. What is your level of agreement with this paragraph?
               (Finalized in the third iteration.)

    Count Percentage  Label
    5         26.32%  Completely agree
    10        52.63%  Generally agree
    3         15.79%  Do not agree
    1          5.26%  I do not have the expertise necessary to respond to this
                         section.

               The size of the fire has a major impact on the thermal radiation
               from an LNG pool fire. Thermal radiation increases with pool size
               up to a point but is expected to decrease for very large pools,
               like those caused by a terrorist attack. What is your level of
               agreement with this paragraph? (Finalized in the second
               iteration.)

    Count Percentage  Label
    4         21.05%  Completely agree
    10        52.63%  Generally agree
    4         21.05%  Do not agree
    1          5.26%  I do not have the expertise necessary to respond to this
                         section.

    			  LNG Hazards�Vapor Cloud Fire

               If an LNG vapor cloud formed in the wake of an LNG spill and
               drifted away from the tanker as it warmed and dispersed, the vapor
               cloud could enter a populated area while areas of the cloud had
               LNG vapor/air mixtures within the flammability range. Since
               populated areas have numerous ignition sources, those portions of
               the cloud would likely ignite. The fire would then burn back
               through the cloud toward the tanker and continue to burn as a pool
               fire near the ship, assuming that liquid LNG still remains in the
               spill area. Ignition of a vapor cloud over a populated area could
               burn people and property in the immediate vicinity of the fire.
               While the initial fire would be of short duration as the flames
               burned back toward the LNG carrier, secondary fires could continue
               to present a hazard to the public. What is your level of agreement
               with the above paragraph? (Finalized in the second iteration.)

    Count Percentage  Label
    7         36.84%  Completely agree
    11        57.89%  Generally agree but suggest the following clarification
    1          5.26%  Do not agree

               LNG Hazards�Vapor Cloud Fire: Burn Back Speed

               After ignition of a vapor cloud that drifted away from an LNG
               tanker spill, how fast could the flame front travel back toward
               the spill site if it was unconfined or confined? (Finalized in the
               second iteration.)

    Count Percentage  Label
    15        78.95%  Not checked
    2         10.53%  I do not have the expertise necessary to respond to this
                         section.
    2         10.53%  No answer

               Experts did not agree on the speed of a flame front traveling
               through an LNG vapor cloud in either a confined or unconfined
               state. Responses varied from less than 5 meters per second up to
               50 meters per second in unconfined settings and from 0 meters per
               second to 2,000 meters per second in confined settings.

    			  Explosions-RPT

               A rapid phase transition (RPT) can occur when LNG spilled onto
               water changes from liquid to gas virtually instantaneously due to
               the rapid absorption of ambient environmental heat. While the
               rapid expansion from a liquid to vapor state can cause locally
               large overpressures, an RPT does not involve combustion. RPTs have
               been observed during LNG test spills onto water. In some cases,
               the overpressures generated were strong enough to damage test
               equipment in the immediate vicinity. Overpressures generated from
               RPTs would be very unlikely to have a direct affect on the public.
               What is your level of agreement with this paragraph? (Finalized in
               the second iteration.)

    Count Percentage  Label
    15        78.95%  Completely agree
    4         21.05%  Generally agree

    			  Explosions-Deflagrations and Detonations

               Deflagrations and detonations are rapid combustion processes that
               move through an unburned fuel-air mixture. Deflagrations move at
               subsonic velocities and can result in overpressures up to eight
               times the original pressure, particularly in congested/confined
               areas. Detonations move at supersonic velocities and can result in
               overpressures up to 20 times the original pressure. What is your
               level of agreement with this paragraph? (Finalized in the third
               iteration.)

    Count Percentage  Label
    1          5.26%  Not checked
    7         36.84%  Completely agree
    10        52.63%  Generally agree
    1          5.26%  Do not agree

    			  Explosions�Deflagrations, Detonations, and BLEVEs

               Please choose the response that best describes your opinion about
               each type of explosion of LNG vapors in each setting described.
               (Finalized in the third iteration.)

                 Deflagration Deflagration
                         with         with
                 overpressure overpressure Detonation Detonation
                        in an         in a      in an       in a
                   unconfined     confined unconfined   confined Boiling-liquid-expanding-vapor-explosion
    Answer            setting      setting    setting    setting                                  (BLEVE)
    Under
    controlled
    experimental
    conditions,
    it is
    possible to
    induce this
    type of
    explosion in
    this type of
    setting.                7           18          4         15                                       11
    This type of
    setting
    cannot
    support this
    type of
    explosion.              8            0         11          2                                        7
    More
    research is
    necessary to
    answer this
    question.               3            0          3          0                                        0
    I don't have
    the
    expertise
    necessary to
    answer this
    question.               0            0          0          1                                        0
    No
    answer/not
    checked                 1            1          1          1                                        1

               If experts answered that "under controlled experimental
               conditions, it is possible to induce this type of explosion in
               this type of setting," they were asked to answer the following
               question:

               What is the likelihood of a each type of explosion of LNG vapors
               in each setting described occurring following an LNG spill caused
               by a terrorist attack on a tanker? (Finalized in the third
               iteration.)

             Deflagration Deflagration
                     with         with
             overpressure overpressure Detonation Detonation
                    in an         in a      in an       in a
               unconfined     confined unconfined   confined Boiling-liquid-expanding-vapor-explosion
    Answer        setting      setting    setting    setting                                  (BLEVE)
    Highly              3            6          1          7                                        4
    unlikely
    Unlikely            2            2          3          3                                        2
    Neither             1            5          0          3                                        3
    likely
    nor
    unlikely
    Likely              1            4          0          2                                        1
    Highly              0            0          0          0                                        0
    likely
    No                  0            1          0          0                                        1
    answer/
    not
    checked

    			  LNG Hazards�Is BLEVE the Worst?

               A BLEVE is the worst potential hazard of an LNG spill. It would
               result in the rupture of one or more LNG tanks, perhaps
               simultaneously, on the ship, with potential rocketing debris and
               damaging pressure waves. What is your level of agreement with the
               above paragraph? (Finalized in the first iteration.)

    Count Percentage  Label
    2         10.53%  Completely agree
    16        84.21%  Do not agree (Please explain in the textbox below.)
    1          5.26%  No answer

    			  Questions About the 2004 Sandia National Laboratories Study1

               The Sandia report concluded that the most significant impacts to
               public safety exist within 500 meters of a spill, with much lower
               impacts at distances beyond 1,600 meters even for very large
               spills. Please choose the response that best describes your
               opinion about these hazard distances. (Finalized in the third
               iteration.)

    Count Percentage  Label
    4         23.54%  They are too conservative (i.e., should be smaller)
    7         41.18%  They are about right
    4         23.53%  They are not conservative enough (i.e., should be
                         larger)
    2         11.76%  No answer

    1Since two of the experts were authors of the Sandia study, their
    responses to ALL the questions related to the study below have been
    excluded. For the questions related to the Sandia study, there are 17
    experts responding.

               The Sandia report concluded that large, unignited LNG vapor clouds
               could spread over distances greater than 1,600 meters from a
               spill. For a nominal intentional spill, the hazard range could
               extend to 2,500 meters. The actual hazard distances will depend on
               breach and spill size, site-specific conditions, and environmental
               conditions. Please choose the response that best describes your
               opinion about these hazard distances. (Finalized in the third
               iteration.)

    Count Percentage  Label
    4         23.53%  They are too conservative (i.e., should be smaller)
    6         35.29%  They are about right
    4         23.53%  They are not conservative enough (i.e., should be
                         larger)
    1          5.88%  Do not have the expertise to answer
    2         11.76%  No answer

               The Sandia report concluded that cascading damage (multiple cargo
               tank failure) due to brittle fracture from exposure to cryogenic
               liquid or fire-induced damage to foam insulation is possible under
               certain conditions but is not likely to involve more than two or
               three cargo tanks for any single incident. What is your level of
               agreement with this paragraph? (Finalized in the third iteration.)

    Count Percentage  Label
    3         17.65%  Completely agree
    6         35.29%  Generally agree
    6         35.29%  Do not agree
    2         11.76%  I do not have the expertise necessary to respond to this
                         section.

               The Sandia report concluded that cascading events are not expected
               to greatly increase (not more than 20-30 percent) the overall fire
               size or hazard ranges (500 meters for severe impacts, much lower
               impacts beyond 1,600 meters) but will increase the expected fire
               duration. What is your level of agreement with this paragraph?
               (Finalized in the third iteration.)

               The Sandia report suggested that consequence studies should be
               used to support comprehensive, risk-based management and planning
               approaches for identifying, preventing, and mitigating hazards to
               public safety and property from potential LNG spills. What is your
               level of agreement with this paragraph? (Finalized in the third
               iteration.)

    			  Commodity Comparison

               In your opinion, what is the risk to public safety posed by an
               attack on tankers carrying each of the following energy
               commodities? (Finalized in the first iteration.)

                      Liquefied Crude                 Heating  Jet      Liquefied
    Answer       natural gas   oil Diesel Gasoline     oil fuel  petroleum gas
    Little to
    None                   1     2      1        0       1    1              0
    Little                 3    10     11        5      11    6              1
    Medium                 6     3      3        8       3    6              4
    Large                  3     0      0        2       0    2              5
    Very Large             2     0      0        0       0    0              5
    No expertise
    to answer              1     1      1        1       1    1              1
    No answer              3     3      3        3       3    3              3

    			  Future Research

               In the first and second survey iterations, you noted areas related
               to LNG spill consequences that need further research. We are
               interested in your thoughts on the relative level of need for
               research in these areas, and also the five areas you think should
               be of highest priority in future research.

               Please indicate the degree to which further research is needed in
               each of the areas listed below. (Finalized in the third
               iteration.)

               Responses to each part of this question are in the table below,
               which is sorted by mean score so that the highest-ranked research
               priorities appear first.

                                                                 Do not
                              Very                     Little  have the
                             great Great          Some  to no expertise     No
                              need  need Moderate need   need to answer answer  Mean
     Type of research          (1)   (2)  need(3)  (4)    (5)       (6)    (7) score
     Large fire phenomena
     (impact of smoke
     shielding, large flame
     versus smaller
     flamelets)                  9     5        3    0      1         1      0  4.17
     Cascading failure           5     9        4    1      0         0      0  3.95
     Large-scale LNG spill
     testing on water^a          7     7        2    1      2         0      0  3.84
     Large-scale fire
     testing^b                   7     6        3    2      1         0      0  3.84
     Comprehensive modeling
     allowing different
     physical processes to
     interact                    2    10        3    4      0         0      0  3.53
     Risk tolerability
     assessments                 5     4        3    1      3         1      2  3.44
     Vulnerability of LNG
     containment systems,
     including validating
     hole size predictions
     for the double hull
     ship structure              5     4        3    5      2         0      0  3.26
     Mitigation techniques       3     5        6    3      2         0      0  3.21
     Effect of sea water
     pouring into a hole as
     LNG flows out               2     6        5    3      2         0      1  3.17
     Impact of wind,
     weather, and waves (on
     pool spread size,
     evaporation rate, pool
     formation, etc.)            3     4        6    3      3         0      0  3.05
     Improvements to 3-D
     computational fluid
     dynamics dispersion
     modeling                    0     4        6    6      2         1      0  2.67
     Effects of different
     LNG compositions (on
     vaporization rates,
     thermal radiation,
     explosive behavior,
     etc.)                       2     2        4    8      3         0      0  2.58
     Whether an explosive
     attack will result in
     immediate vapor cloud
     ignition                    0     5        4    5      4         1      0  2.56
     Rapid phase
     transitions: likelihood
     in various scenarios
     and impact                  1     2        6    6      4         0      0  2.47
     Effects of igniting LNG
     vapors in containment
     or ballast tanks            0     5        3    5      6         0      0  2.37
     BLEVE properties of
     tanks on LNG ships          1     4        3    4      7         0      0  2.37
     Deflagration/detonation
     of LNG                      1     0        5    8      5         0      0  2.16
     Effects of a large,
     unignited vapor cloud
     drifting from the
     incident site               0     0        7    5      7         0      0  2.00
     Effect of clothing and
     obstructions on the
     radiant heat level
     received by the public      1     1        2    6      9         0      0  1.89
     Other^c                    12     2        0    0      0         0      5     d

               aExperts suggested pool sizes of 15 meters up to 1,000 meters,
               though the median response was 100 meters.

               bExperts suggested pool sizes of 15 meters up to 1,000 meters,
               though the median response was 100 meters.

               cExperts suggested frequency modeling, determination of acceptable
               risk to society, analysis of foam on LNG tankers, risk analysis
               for larger LNG tankers, CFD modeling for pool spreading and
               evaporation, and improvement to existing techniques used for
               fighting LNG fires.

               dNot applicable.

    			  Appendix IV: GAO Contact and Staff Acknowledgments

    			  GAO Contact

               Jim Wells, (202) 512-3841, or wellsj@gao.gov

    			  Staff Acknowledgments

               In addition to the individual named above, Mark Gaffigan, Amy
               Higgins, Lynn Musser, Janice Poling, Rebecca Shea, Carol
               Herrnstadt Shulman, and James W. Turkett made key contributions to
               this report.

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    (360675)

    www.gao.gov/cgi-bin/getrpt?GAO-07-316 .

    To view the full product, including the scope
    and methodology, click on the link above.

    For more information, contact Jim Wells at (202) 512-3841 or
    wellsj@gao.gov.

    Highlights of [48]GAO-07-316 , a report to congressional requesters

    February 2007

    MARITIME SECURITY

    Public Safety Consequences of a Terrorist Attack on a Tanker Carrying
    Liquefied Natural Gas Need Clarification

    The United States imports natural gas by pipeline from Canada and by
    tanker as liquefied natural gas (LNG) from overseas. LNG--a supercooled
    form of natural gas--currently accounts for about 3 percent of total U.S.
    natural gas supply, with an expected increase to about 17 percent by 2030,
    according to the Department of Energy (DOE). With this projected increase,
    many more LNG import terminals have been proposed. However, concerns have
    been raised about whether LNG tankers could become terrorist targets,
    causing the LNG cargo to spill and catch on fire, and potentially explode.
    DOE has recently funded a study to consider these effects; completion is
    expected in 2008.

    GAO was asked to (1) describe the results of recent studies on the
    consequences of an LNG spill and (2) identify the areas of agreement and
    disagreement among experts concerning the consequences of a terrorist
    attack on an LNG tanker. To address these objectives, GAO, among other
    things, convened an expert panel to discuss the consequences of an attack
    on an LNG tanker.

    [49]What GAO Recommends

    GAO recommends that the Secretary of Energy ensure that DOE incorporates
    into its LNG study the key issues identified by the expert panel.

    In reviewing our draft report, DOE agreed with our recommendation.

    The six unclassified completed studies GAO reviewed examined the effect of
    a fire resulting from an LNG spill but produced varying results; some
    studies also examined other potential hazards of a large LNG spill. The
    studies' conclusions about the distance at which 30 seconds of exposure to
    the heat (heat hazard) could burn people ranged from less than 1/3 of a
    mile to about 1-1/4 miles. Sandia National Laboratories (Sandia) conducted
    one of the studies and concluded, based on its analysis of multiple attack
    scenarios, that a good estimate of the heat hazard distance would be about
    1 mile. Federal agencies use this conclusion to assess proposals for new
    LNG import terminals. The variations among the studies occurred because
    researchers had to make modeling assumptions since there are no data for
    large LNG spills, either from accidental spills or spill experiments.
    These assumptions involved the size of the hole in the tanker; the volume
    of the LNG spilled; and environmental conditions, such as wind and waves.
    The three studies that considered LNG explosions concluded explosions were
    unlikely unless the LNG vapors were in a confined space. Only the Sandia
    study examined the potential for sequential failure of LNG cargo tanks
    (cascading failure) and concluded that up to three of the ship's five
    tanks could be involved in such an event and that this number of tanks
    would increase the duration of the LNG fire.

    GAO's expert panel generally agreed on the public safety impact of an LNG
    spill, but believed further study was needed to clarify the extent of
    these effects, and suggested priorities for this additional research.
    Experts agreed that the most likely public safety impact of an LNG spill
    is the heat hazard of a fire and that explosions are not likely to occur
    in the wake of an LNG spill. However, experts disagreed on the specific
    heat hazard and cascading failure conclusions reached by the Sandia study.
    DOE's recently funded study involving large-scale LNG fire experiments
    addresses some, but not all, of the research priorities identified by the
    expert panel. The leading unaddressed priority the panel cited was the
    potential for cascading failure of LNG tanks.

    LNG Tanker Passing Downtown Boston on Its Way to Port

    References

    Visible links
      48. http://www.gao.gov/cgi-bin/getrpt?GAO-07-316
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