[Federal Register Volume 77, Number 243 (Tuesday, December 18, 2012)]
[Proposed Rules]
[Pages 74788-74798]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-30452]



10 CFR Part 50

[Docket No. PRM-50-96; NRC-2011-0069]

Long-Term Cooling and Unattended Water Makeup of Spent Fuel Pools

AGENCY: Nuclear Regulatory Commission.

ACTION: Petition for rulemaking; consideration in the rulemaking 


SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) will consider in 
the NRC rulemaking process the issues raised in a petition for 
rulemaking (PRM) submitted by Thomas Popik (the petitioner) on behalf 
of the Foundation for Resilient Societies. The petition was dated March 
14, 2011, and was docketed as PRM-50-96. The petitioner requests that 
the NRC amend its regulations to require facilities licensed by the NRC 
to assure long-term cooling and unattended water makeup of spent fuel 
pools (SFP).

DATES: The docket for the petition for rulemaking, PRM-50-96, is closed 
on December 18, 2012.

ADDRESSES: Further NRC action on the issues raised by this petition can 
be found on the Federal Rulemaking Web site at http://www.regulations.gov by searching on Docket ID NRC-2011-0069.
    You can access publicly available documents related to the 
petition, which the NRC possesses and are publicly available, using any 
one of the following methods:
     Federal Rulemaking Web site: Public comments and 
supporting materials related to this petition can be found at http://www.regulations.gov by searching on the petition Docket ID NRC-2011-
0069. Address questions about NRC dockets to Carol Gallagher; telephone 
301-492-3668; email: [email protected].
     NRC's Agencywide Documents Access and Management System 
(ADAMS): You may access publicly available documents online in the NRC 
Library at http://www.nrc.gov/reading-rm/adams.html. To begin the 
search, select ``ADAMS Public Documents'' and then select ``Begin Web-
based ADAMS Search.'' For problems with ADAMS, please contact the NRC's 
Public Document Room (PDR) reference staff at 1-800-397-4209, 301-415-
4737, or by email to [email protected]. The ADAMS accession number 
for each document referenced in this notice (if that document is 
available in ADAMS) is provided the first time that a document is 
     NRC's PDR: You may examine and purchase copies of public 
documents at the NRC's PDR, O1-F21, One White Flint North, 11555 
Rockville Pike, Rockville, Maryland 20852.

FOR FURTHER INFORMATION CONTACT: Manash Bagchi or Richard Dudley, 
Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory 
Commission, Washington, DC 20555-0001; telephone 301-415-2905 or 301-
415-1116, email: [email protected].


I. The Petition
II. Regulatory Oversight of Electric Power Systems
III. Analysis of Public Comments
IV. NRC Evaluation
    A. NRC Requirements for Governing Spent Fuel Pool Cooling and 
Provision of Electric Power for Accidents
    B. Geomagnetic Storms and Effects on the Earth
    C. Frequency of Geomagnetic Storms With Potential Adverse 
Effects on the Electrical Grid
    D. Experience With Geomagnetic Storms' Effects on the Electrical 
    E. Federal Government Coordination and Emergency Response
V. Conclusion
VI. Resolution of the Petition

I. The Petition

    The petitioner submitted a PRM (ADAMS Accession No. ML110750145), 
dated March 14, 2011, to the NRC. The petitioner requests that the NRC 
amend its regulations to require facilities licensed by the NRC under 
part 50 of Title 10 of the Code of Federal Regulations (10 CFR) to 
assure long-term cooling and unattended water makeup of SFPs. The 
petitioner asserts that the North American commercial electric power 
grids are vulnerable to prolonged outage caused by extreme space 
weather, such as coronal mass ejections and associated geomagnetic 
disturbances and therefore cannot be relied on to provide continual 
power for active cooling and/or water makeup of SFPs. Moreover, 
existing means for providing onsite backup power are designed to 
operate for only a few days, while spent fuel requires active cooling 
for several years after removal of the fuel rods from the reactor core. 
The petitioner suggested rule language with the following requirements:

    Licensees shall provide reliable emergency systems to provide 
long-term cooling and water makeup for spent fuel pools using only 
on-site power sources. These emergency systems shall be able to 
operate for a period of two years without human operator 
intervention and without offsite fuel resupply. Backup power systems 
for spent fuel pools shall be electrically isolated from other plant 
electrical systems during normal and emergency operation. If 
weather-dependent power sources are to be used, sufficient water or 
power storage must be provided to maintain continual cooling during 
weather conditions which may temporarily constrict power generation.

    On May 6, 2011 (76 FR 26223), the NRC published a notice of receipt 
and request for public comment for this petition in the Federal 
Register (FR). The public comment period closed on July 20, 2011, and 
the NRC received 97 public comments. After reviewing public comments 
and evaluating other ongoing activities, the NRC performed a 
preliminary review and analysis to ascertain the validity, accuracy, 
and efficacy of the petitioner's technical

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assertions and proposed amendment of 10 CFR part 50.

II. Regulatory Oversight of Electric Power Systems

    The issues raised in this petition span the regulatory domains and 
oversight of several government agencies and an industry organization. 
A discussion of the regulatory domains and oversight of the NRC, the 
Federal Energy Regulatory Commission (FERC), and the North American 
Electric Reliability Corporation (NERC) is provided to illustrate the 
complexity and depth of the issues raised in this PRM.
    The mission of the NRC is to license and regulate civilian nuclear 
power facilities and civilian use of nuclear materials in order to 
protect public health and safety, promote the common defense and 
security, and protect the environment. An important part of that 
mission is to ensure public health and safety with respect to the 
design, construction, and operation of nuclear power plants (NPP).
    Commercial NPPs rely on electric power transmission networks to 
export power and normally use electrical power from the transmission 
network to safely shut down the plant when required. The NRC's existing 
regulations consider the historically high reliability of an electric 
power transmission system in the vicinity of the plants in maintaining 
the safety of the reactor and fuel stored in SFPs. However, if power 
from the electrical transmission system is not available, then safety-
related backup power systems, typically powered by emergency diesel 
generators (EDG), are relied on for essential power to safely shutdown 
the reactor, mitigate accidents, and provide long-term cooling for the 
reactor core and fuel in the SFPs. These safety-related onsite EDGs are 
typically maintained with at least a 3 to 7-day supply of fuel and 
lubricating oil. In addition, NRC regulations require capabilities to 
withstand a station blackout (10 CFR 50.63, ``Loss of all alternating 
current power'') and development and implementation of strategies to 
maintain or restore core-cooling, containment, and SFP cooling 
capabilities under the circumstances associated with loss of large 
areas of the plant due to explosions or fire (10 CFR 50.54(hh)(2)). 
These requirements are satisfied by equipment typically independent of 
the electric power transmission network.
    The FERC is an independent agency that regulates the interstate 
transmission of electricity, natural gas, and oil. The FERC's main 
authority in electric power transmission includes the following:
     Regulation of wholesale sales of electricity and 
transmission of electricity in interstate commerce;
     Oversight of mandatory reliability standards for the bulk-
power system;
     Promotion of a strong national energy infrastructure, 
including adequate transmission facilities; and
     Regulation of jurisdictional issuances of stock and debt 
securities, assumptions of obligations and liabilities, and mergers.
    The NERC's mission is to ensure the reliability of the North 
American bulk-power system. The NERC is the electric reliability 
organization certified by the FERC to establish and enforce reliability 
standards for the bulk-power system. The NERC develops and enforces 
reliability standards; assesses adequacy of capacity annually via a 10-
year forecast, summer forecasts, and winter forecasts; monitors the 
bulk-power system; and educates, trains, and certifies industry 
    The NRC does not have direct regulatory authority over electric 
transmission systems, but the NRC collaborates closely with FERC and 
NERC on electric grid reliability, cyber security issues, 
electromagnetic pulse issues, geomagnetically-induced current (GIC) 
research, and related activities to the extent that these issues may 
have impacts on NPPs.

III. Analysis of Public Comments

    The NRC received 97 comment submissions on PRM-50-96. Comments both 
favoring and opposing this PRM were received, and all comments were 
considered during the NRC staff's evaluation of the PRM. Comments 
recommending denial of this petition were submitted by the Nuclear 
Energy Institute (NEI) and are evaluated in the following paragraphs. 
The majority of comments supporting the petition were in form letter 
format and did not provided additional technical information. However, 
one commenter in favor of the PRM did provide technical arguments to 
support the petition. All of the comments supporting the petition are 
not discussed here, because it would be premature to discuss these 
comments in advance of the NRC's decision whether to actually adopt a 
final rule addressing the issues raised in the PRM. Therefore, comments 
supporting the petition will be discussed in any proposed rule that 
addresses one or more of the issues raised in this PRM. If the NRC 
ultimately determines not to address, by rulemaking, one or more issues 
raised in this PRM, then the NRC will explain, in a Federal Register 
notice (FRN), why the petitioner's requested rulemaking changes were 
not adopted by the NRC and addresses comments received in favor of the 

Comment NEI-1

    The NRC is separately addressing the long-term spent fuel pool 
cooling issue raised by this Petition through its near-term task force 
review of insights from the March 11, 2011 Fukushima Dai-ichi accident. 
On July 12, 2011, the task force issued recommendations that are 
currently being considered by the Commission. Several of these 
recommendations address the topic of long-term spent fuel pool cooling. 
The Petition raises no unique issues in this area requiring action 
separate from, or in addition to, those already being taken in response 
to the task force recommendations. The Commission's ongoing 
consideration of these recommendations provides ample opportunity to 
examine the NRC's regulations with respect to long-term spent fuel pool 
cooling and bolster assurances that the pools remain safe if an extreme 
event were to challenge cooling capabilities.
    The Commission is already conducting a thorough evaluation of the 
adequacy of these measures in response to the July 12, 2011 
recommendations of its near-term Task Force review of insights from the 
March 11, 2011 Fukushima Dai-ichi accident. This evaluation will 
further assure that adequate measures are in place to mitigate any 
potential severe event, not just space weather.

NRC Response

    The NRC agrees with the comment that the ongoing review of the 
Fukushima accident will separately address some safety issues related 
to the adequacy of long-term SFP cooling at NPPs. These actions are now 
being evaluated under five different Fukushima Near-Term Task Force 
(NTTF) report activities like EA Order-12-049, NTTF Recommendations 
4.1, 7.2, 8, and 9. They are discussed in further detail in Section V, 
``Conclusion,'' of this document.
    However, no new mitigating measures have been developed or defined; 
accordingly, the NRC does not have a sufficient basis at this time to 
conclude what future actions would be required for resolving issues 
raised in PRM-50-96.
    The NRC has decided to consider and resolve the issues raised in 
this PRM in a phased manner, given the NRC activities already underway 
that may have a bearing on those issues. The phased approach would 
consist of the following activities: to begin with, the

[[Page 74790]]

NRC will access the ongoing Fukushima-related activities to assess the 
degree of additional protection that will be provided by those efforts 
and if these measures will resolve the petitioner's issues. 
Specifically, the NRC staff will assess the implementation of Order EA-
12-049 (ADAMS Accession No. ML12054A736)--which requires that licensees 
develop, implement, and maintain guidance and strategies to maintain or 
restore core cooling, containment, and SFP cooling capabilities 
following a beyond-design-basis external event--and the ongoing 
enhancements to the station blackout rule being developed under 
Fukushima NTTF Recommendation 4.1. The NRC staff will also assess 
possible rulemakings in response to Fukushima NTTF Recommendation 7.2, 
which could potentially require all licensees to provide Class 1E 
(safety-grade) electric power to spent fuel makeup systems, and the 
emergency preparedness activities being developed for prolonged station 
blackout scenarios under Fukushima NTTF Recommendations 8 and 9.
    However, if additional capabilities are judged to be necessary, the 
NRC will then consider appropriate mechanisms for requiring NPP 
licensees to consider long-term grid collapse scenarios in their site 

Comment NEI-2

    The scenario postulated by the Petitioner, where no offsite 
response to a nuclear emergency would be available for two years, 
posits a cataclysmic loss of the nation's infrastructure. In that 
situation, significant preparedness demands would be placed on all 
public and private institutions. Prior to assessing any regulatory 
needs, the credibility of this scenario should first be established in 
the broader context before more narrow regulatory needs are 
contemplated. A national assessment of this scenario and the need to 
prepare for it must first be made before any single regulatory agency 
begins requiring specific preparedness measures. Indeed the efforts of 
many different government agencies would need to be carefully 
coordinated and response priorities set. Otherwise, no action taken by 
any NRC licensee in response to this petition could be assessed for its 
adequacy because the availability of any response resources could not 
be assured absent such coordination. This coordination task would be an 
extremely significant task to which resources would only be committed 
once the credibility of the scenario was established. However, there is 
no such coordination underway because none of the agencies that would 
be involved have determined that the scenario is credible. In absence 
of the establishment of the basis for the credibility of this scenario, 
the petition lacks the basis to determine that there is a valid safety 

NRC Response

    The NRC agrees with the comment that the long-term grid collapse 
scenario postulated by the petitioner would necessitate a coordinated 
response by various government agencies. However, the NRC disagrees 
with the commenter's assertion that no such coordination is underway or 
that such coordination does not exist, because the regulatory agencies 
referred to by the commenter have not determined that the scenario is 
credible. The NRC is currently coordinating with the National 
Aeronautics and Space Administration to ensure a common understanding 
of the technical phenomena associated with solar storms. In addition, 
the NRC is coordinating with the U.S. Department of Energy (DOE), the 
FERC, and the Federal Emergency Management Agency (FEMA) to develop 
both preventative and mitigating strategies to address the potential 
for a widespread and long-term grid collapse caused by a geomagnetic 
storm. Consideration of the issues raised by the petitioner 
necessitates further in-depth analyses. The NRC rulemaking process is a 
mechanism to look at these events, establish roles and 
responsibilities, and participate in defining the process for enhanced 
coordination between government agencies, should the NRC decide to 
develop and publish a proposed rule for public comment.

Comment NEI-3

    The central argument of the petition is the claim that a spent fuel 
pool accident, namely zirconium ignition, poses a significant safety 
concern. This claim is based upon the credibility of a Long-Term loss 
of off-site power event based upon a new initiating event (severe space 
weather), and the assumption that mitigative actions (specifically 
diesel fuel resupply from offsite and human intervention) would not be 
successful in preventing spent fuel pool drain-down and subsequent 
zirconium ignition resulting from a long term loss of off-site power 
event. Despite the new information referenced by the Petitioner, the 
Petitioner offers no data to support the conclusion that a long term 
loss of off-site power event due to severe space weather is credible. 
Petitioner has also not established any basis to support the conclusion 
that actions to mitigate a long term loss of off-site power event could 
or would not be taken in time to prevent zirconium ignition. In both 
cases, the Petition is entirely speculative. Thus, the Petitioner has 
not demonstrated that a new and significant basis exists to challenge 
the NRC's prior determinations of the safety of spent fuel pools.

NRC Response

    The NRC agrees with the comment that the credibility of the event 
postulated by the petitioner (i.e., a widespread, prolonged grid 
failure of sufficient magnitude that normal commercial infrastructure 
would not be available to resupply diesel fuel) must be established 
before regulatory action is taken. However, the NRC disagrees with the 
comment's unsupported assertion that the petition is entirely 
speculative. The NRC's initial evaluation of available information 
indicates that the likelihood of an extreme solar storm (similar to the 
1859 Carrington event \1\) is plausible with a frequency in the range 
of once in 153 to once in 500 years (2E-3 to 6.5E-3 per year). The 
probability of the petitioner's postulated catastrophic grid failure, 
given a Carrington-like event, is not known with certainty. However, 
based on the NRC's review of the existing data, the NRC believes that 
there is insufficient information for the NRC to conclude that the 
overall frequency of a series of events potentially leading to core 
damage at multiple nuclear sites is acceptably low such that no 
regulatory action is needed. Thus, the NRC concludes that the 
petitioner's scenario is sufficiently credible to require consideration 
of emergency planning and response capabilities under such 
circumstances. Accordingly, the NRC intends to further evaluate the 
petitioner's concerns in the NRC rulemaking process.

    \1\ The Carrington event in 1859 is the largest solar storm ever 

Comment NEI-4

    The Petition does not recognize that the issue of grid reliability 
and its effects on nuclear safety is already fully and adequately 
addressed through existing regulation. The NRC has previously made 
decisions regarding how the issue of grid reliability is addressed 
within the context of NRC regulatory authority in 10 CFR Part 50, and 
within the context of protecting public health and safety. The NRC 
regulatory structure to address grid reliability is best described in 
Regulatory Information Summary (RIS) 2004-5 ``Grid Operability and the 
Impact on Plant Risk and the

[[Page 74791]]

Operability of Offsite Power.'' In summary, issues involving grid 
reliability are addressed through 10 CFR 50.65, ``Requirements for 
monitoring the effectiveness of maintenance at nuclear power plants;'' 
10 CFR 50.63, ``Loss of all alternating current power;'' 10 CFR Part 50 
Appendix A, General Design Criteria (GDC) 17, ``Electric power 
systems;'' and through nuclear power plant Technical Specifications 
(TS) on operability of offsite power.''

NRC Response

    The NRC agrees that the NRC regulations and the NRC regulatory 
documents cited in the comment address the NRC's current approach to 
consideration of grid stability with respect to the safety of NPPs. 
However, the comment does not address the PRM's apparent underlying 
premise that the regulations and guidance are not adequate, or that the 
licensing bases for NPPs may be inadequate because they do not address 
a reasonably foreseeable condition attributable to natural hazards. The 
comment does not explain how the NRC's regulations, or the regulatory 
documents referenced, address the matters raised in the PRM in 
sufficient manner as to prevent the need for further NRC regulatory 

Comment NEI-5

    The Petition presents a Probabilistic Risk Assessment to conclude a 
long term loss of off-site power at a nuclear power facility resulting 
from severe space weather is a credible event. The Petitioner's 
assessment is based upon key inputs from the ORNL report regarding the 
frequency and severity of severe space weather and assumed effects on 
the commercial power grid. Specifically, the Petition assumes that a 
once in 100 year severe space weather event results in a probability of 
1% per year that a 1-2 year loss of off-site power event would occur. 
Unfortunately, the Petition has misinterpreted the data presented in 
the ORNL report. In fact, the ORNL report qualifies its discussion of 
any potential permanent damage to the power grid, stating that such 
discussion is only to ``provide perspectives * * * of potential level 
of damage that may be possible to the infrastructure.'', and indicating 
that there is a low level of certainty in the ability to assess what 
the potential damage could be. Specifically, the report acknowledges 
the difficulty in determining what would be damaged, the extent of 
damage, and the complexity and duration for repairing the damage. The 
myriad of probabilities regarding damage to the grid and length of time 
a nuclear power plant might be without off-site power quite frankly are 
not known and likely are extremely small. Therefore, absent further 
scientific and technical investigation, Petitioners claims amount to 
nothing more than speculation and the discussion in the ORNL report 
should not be used to conclude that a once in 100 year severe space 
weather event would result in a 1-2 year loss of off-site power event. 
Further, it is important to note that there has never been a long term 
loss of electric power due to severe space weather. For the worst event 
of this type in modern history, the commercial power grid was restored 
to 83% within 11 hours, and permanent damage to transformers and other 
grid components was extremely small. Effects were extrapolated from 
this event to the postulated once in 100 year storm, however, it is not 
possible to determine whether a 1-2 year loss of off-site power event 
is a realistic consequence. Thus, the ORNL report does not demonstrate 
that a long term loss of off-site power due to severe space weather is 
a credible event.

NRC Response

    The NRC agrees with the commenter's assertion that the petitioner 
has not conclusively demonstrated that a long-term catastrophic grid 
collapse is certain to result from a once-in-100-year storm, but the 
NRC disagrees with the comment's inference that a long-term loss-of-
offsite power due to severe space weather is not a credible event. 
Although there is a great deal of uncertainty associated with the 
frequency and magnitude of solar storms, as discussed in Section IV.C, 
``Frequency of Geomagnetic Storms with Potential Adverse Effects on the 
Electrical Grid,'' of this document, the NRC has concluded that the 
expected frequency of such storms is not remote compared to other 
hazards that the NRC requires NPPs licensees to consider. The comment 
addresses the credibility of once-in-100-year storms, whereas the NRC 
considers initiating events with frequencies of 1E-3 years or less in 
the licensing of NPPs. The comment also implies that grid restoration 
time after a severe solar storm would typically be hours or days 
instead of 1 to 2 years, but the comment provides no supporting 
analyses of the age and vulnerability of existing transformers 
installed in the electrical grid to support this implied inference. 
Accordingly, the NRC believes that it is possible that a geomagnetic 
storm-induced outage could be long-lasting and could last long enough 
that the onsite supply of fuel for the emergency generators would be 
exhausted. It is also possible that a widespread, prolonged grid outage 
could cause some disruption to society and to the Nation's 
infrastructure such that normal commercial deliveries of diesel fuel 
could be disrupted. In such a situation, it would be prudent for 
licensees to have procedures in place to address long-term grid 
collapse scenarios. In extreme situations, it is possible that 
government assets could be called on to facilitate emergency deliveries 
of fuel to NPP sites before the fuel stored onsite is exhausted. All 
these issues need further research, review, and analysis before 
formulating mitigating actions. The NRC rulemaking process is an 
appropriate mechanism for consideration of the petitioner's issues.

IV. NRC Evaluation

    The NRC conducted a preliminary review and analysis of the issues 
raised in the petition and public comments to reach a conclusion 
regarding the resolution of this petition. The analysis is described in 
the following five sections.

A. NRC Requirements for Governing Spent Fuel Pool Cooling and Provision 
of Electric Power for Accidents

    Commercial NPPs are required to have multiple sources of offsite 
power and safety-related onsite sources of power, typically provided by 
emergency diesel generators arranged in redundant electrical trains. As 
specified by GDC 17, ``Electric Power Systems,'' of appendix A, 
``General Design Criteria for Nuclear Power Plants,'' to 10 CFR part 
50, ``Domestic Licensing of Production and Utilization Facilities,'' 
each operating reactor shall have an onsite electric power system and 
an offsite electric power system that supports the functioning of 
structures, systems, and components important to safety. The safety 
function for each system is to provide sufficient capacity and 
capability to assure that (1) specified acceptable fuel design limits 
and design conditions of the reactor coolant pressure boundary are not 
exceeded as a result of anticipated operational occurrences, and (2) 
the core is cooled and containment integrity and other vital functions 
are maintained in the event of postulated accidents.
    Commercial NPPs rely on the electric power transmission networks to 
export power, and NPPs normally use electric power from the 
transmission network for normal operation of plant equipment, to safely 
shut down the plant when required, and for accident mitigation. The 
existing NRC regulations consider the historically

[[Page 74792]]

high reliability of an electric power transmission system in 
maintaining the safety of the reactor and fuel stored in SFPs. However, 
if offsite power from the transmission network is unavailable, safety-
related onsite back up power systems (typically powered by EDGs) are 
relied on for essential power to safely shutdown the reactor, mitigate 
any accidents, and provide long-term cooling for the reactor core and 
fuel in the SFP. These safety-related onsite power sources are 
typically maintained with at least a 3- to 7-day supply of fuel and 
lubricating oil. In addition, the NRC regulations require capabilities 
to withstand a station blackout and the development and implementation 
of strategies to maintain or restore core cooling, containment, and SFP 
cooling capabilities under the circumstances associated with loss of 
large areas of the plant due to explosions or fire. These requirements 
are satisfied by equipment independent of the electric power 
transmission network.
    The spent fuel pool structure typically consists of a stainless-
steel liner covering a steel-reinforced concrete structure several feet 
thick. The SFP structure is designed to withstand the effects of 
natural phenomena, including earthquakes, floods, and tornados, without 
loss of its leak-tight integrity. Consistent with the requirements of 
GDC 61, ``Fuel Storage and Handling and Radioactivity Control,'' of 
appendix A to 10 CFR part 50 or similar plant-specific design criteria, 
SFPs are designed to prevent a significant loss of water inventory 
under normal and accident conditions. An inadvertent loss of coolant 
inventory is prevented by design, typically through the absence of 
drains in the SFP, the location of piping penetrations though the SFP 
structure well above the top of stored fuel, and the use of design 
features to prevent siphoning of water. A reliable forced cooling 
system minimizes coolant evaporation during normal operation and 
postulated accident conditions. When necessary, operators can provide 
makeup water to maintain SFP coolant inventory using any one of many 
makeup water systems, including safety-related systems at most 
operating reactors. The maintenance of an adequate coolant inventory 
alone is sufficient to protect the integrity of the fuel, provide 
shielding, and contain any minor releases of radioactivity that may 
result from cladding damage.
    As the March 2011 events at the Fukushima Dai-ichi site 
demonstrated, the robust structure of the SFP and the provisions to 
prevent loss of coolant inventory provide substantial time to implement 
appropriate methods to makeup coolant inventory lost to evaporation. In 
most common operating configurations, the existing pool inventory is 
typically adequate to maintain the fuel covered with water for 1 week 
or more following a loss of forced cooling. Each facility safety 
analysis report describes the capability to provide forced cooling and 
makeup water using installed systems, and these systems may be operated 
using onsite sources of power. Diesel-driven fire pumps are available 
at all operating reactors and are among the design capabilities to 
provide makeup water to the SFP. Beyond these design capabilities, 10 
CFR 50.54(hh)(2) requires licensees to develop and implement guidance 
and strategies intended to maintain or restore SFP cooling capabilities 
under the circumstances associated with loss of large areas of the 
plant as a result of explosions or fire. These capabilities required by 
10 CFR 50.54(hh)(2) may further extend the time spent fuel can be 
adequately cooled using on site resources. Thus, assuming an adequate 
supply of fuel for permanently installed and portable emergency 
equipment, currently required onsite capabilities would support 
adequate cooling of spent fuel for weeks following loss of the offsite 
electric power transmission network.
    As directed by the Commission in Staff Requirements Memorandum 
SECY-12-0025, dated March 9, 2012, (ADAMS Accession No. ML120690347), 
the NRC staff has undertaken regulatory actions to further enhance 
reactor and SFP safety as a result of recommendations developed through 
evaluation of early information from the March 2011 events at the 
Fukushima Dai-ichi site. On March 12, 2012, the NRC staff issued Order 
EA-12-051 (ADAMS Accession No. ML12054A679), which requires that 
licensees install reliable means of remotely monitoring wide-range SFP 
levels to support effective prioritization of event mitigation and 
recovery actions in the event of a challenging external event. In 
addition, the NRC staff issued Order EA-12-049 (ADAMS Accession No. 
ML12054A736), which requires that licensees develop, implement, and 
maintain guidance and strategies to maintain or restore core cooling, 
containment, and SFP cooling capabilities following a beyond-design-
basis external event. Upon full implementation of these Orders at NPPs, 
the NRC staff believes that overall protection of public health and 
safety will be further increased.

B. Geomagnetic Storms and Effects on the Earth

    Periodically, the earth's magnetic field is bombarded by charged 
particles emitted from the sun due to violent eruptions of plasma and 
magnetic fields from the sun`s corona, known as coronal mass ejections 
    Solar storms generally follow the sunspot cycle and vary in 
intensity over the 11-year cycle. The most severe geomagnetic 
disturbances (GMD) during a cycle have been observed to follow the peak 
in sunspot activity by 2 to 3 years. Thus, electrical power system 
disturbances resulting from current cycle 24 are expected to peak in 
    Geomagnetic storms are created when the earth's magnetic field 
captures these ionized particles causing very slow magnetic field 
variations, with rise times as fast as a few seconds and pulse widths 
of up to an hour. The rate of change of the magnetic field creates 
electric fields in the earth that induce current flow in long man-made 
conducting paths such as power transmission networks, railway lines, 
and pipelines. These geomagnetically-induced currents (GIC) exit bulk-
power systems through neutrals of grounded power transformers and can 
disrupt the normal operation of the system and even damage the 
transformers if the transformer core becomes saturated.
    Operating experience indicates that there are two risks that result 
from the introduction of GICs in the bulk-power system:
    (1) Damage to bulk-power system assets, typically associated with 
transformers; and
    (2) Loss of reactive power support, which could lead to voltage 
instability and power system collapse.
    The GICs (quasi-direct currents) that flow through the grounded 
neutral of a transformer during a geomagnetic disturbance cause the 
core of the transformer to magnetically saturate on alternate half-
cycles. Saturated transformers result in harmonic distortions and 
additional reactive power or volt-ampere reactive (VAR) demands on 
electric power systems. The increased VAR demands can cause both a 
reduction in system voltage and overloading of long transmission tie-
lines. In addition, harmonics can cause protective relays to operate 
improperly and shunt capacitor banks to overload. These conditions can 
lead to major power failures, moving the system closer to voltage 
    The immediate and direct impact of geomagnetic storms may be an 
electrical power outage. The amount of time required to restore the 
electrical grid

[[Page 74793]]

will depend upon the extent of damage to bulk-power system assets. 
There is a concern about the effects of a long-term power outage over 
extended portions of the U.S. transmission systems, during which 
critical services that rely on electrical power may be disrupted. For 
instance, the petitioner noted that the onsite fuel for backup electric 
power sources at NPPs would run out in several days to weeks. 
Furthermore, the petitioner asserted that, since the capability to 
resupply fuel through gasoline and diesel fuel pumps also generally 
relies on electrical power systems, a power blackout lasting longer 
than 2 to 3 days could create long-term implications for interdependent 
public and private infrastructures. Such a long-term power outage could 
interrupt communication systems, stop freight transportation, and 
affect the operations of major industries including fuel (oil and gas) 
    In addition, potential disruptions due to societal stress could 
significantly hamper the ability to provide fuel resupply deliveries to 
nuclear power plants.

C. Frequency of Geomagnetic Storms With Potential Adverse Effects on 
the Electrical Grid

    The petitioner references a report prepared for the Oak Ridge 
National Laboratory (``Metatech report'') \2\ that uses a frequency 
estimate of 1 in 100 years (1E-2/yr) for extreme space weather/
geomagnetic disturbance to perform calculations that predict the likely 
collapse of two large portions of the North American power grid. The 
intensity of the storm postulated in the Metatech report, in terms of 
magnetic flux density per time, was 4,800 nano-Teslas/minute (nT/min). 
The Metatech report predicted that over 300 Extra High Voltage (EHV) 
transformers would be at-risk for failure or permanent damage from the 
event. The Metatech report concludes that, with a loss of this many 
transformers, the power system would not remain intact, leading to 
probable power system collapse in the Northeast, Mid-Atlantic, and 
Pacific Northwest, affecting a population in excess of 130 million.

    \2\ Metatech Report Meta-R-319, ``Geomagnetic Storms and Their 
Impacts on the U.S. Power Grid,'' John Kappenman (January 2010).

    The NRC staff investigated the assertion of 1E-2/yr frequency of 
occurrence of a serious geomagnetic disturbance by conducting a 
literature review (via Internet) to find relevant information. However, 
it is difficult to obtain an objective estimate for the frequency of 
occurrence of a ``serious'' disturbance, which the Metatech report says 
can produce magnetic flux density changes on the order of 4,800 nT/min. 
As noted in a report prepared for the United States Department of 
Homeland Security (DHS),\3\ there is currently no framework for 
developing a hazard curve (e.g., annual probability of exceeding a 
given magnetic flux density rate-of-change) for geomagnetic storms.

    \3\ ``Geomagnetic Storms,'' prepared by CENTRA Technology, Inc., 
on behalf of the Office of Risk Management and Analysis, United 
States Department of Homeland Security (January 14, 2011).

    There are several factors making it difficult to objectively 
predict the frequency of occurrence of a given level of a geomagnetic 
event in terms of magnetic flux density change over time (i.e., to 
produce an appropriate hazard curve), including:
     Paucity of recorded data;
     Relative recentness of monitoring the appropriate 
parameter (nT/min);
     Lack of correlation between the magnetic flux disturbance 
intensity (in nT) and its time rate of change (nT/min); and
     Geographical variations that affect how much a given 
geomagnetic storm impacts a selected location.
    The Metatech report provides estimates of the frequency of severe 
geomagnetic storms. Speculating from observed data, and taking into 
account that about one-third of the storms would be positioned to 
adversely impact the United States, Metatech concluded that a storm 
producing ~2400 nT/min could impact the U.S. grid about every 30 years 
and that a ~5,000 nT/min storm could be experienced every 100 years.
    An article in Spectrum magazine \4\ provided annual probabilities 
of magnetic storms producing more than 300 nT/min in North America. 
This intensity (rate-of-change of magnetic flux density) is closer to 
the ~480 nT/min experienced by Quebec Hydro in 1989. The annual 
probabilities set forth in Spectrum ranged from 2E-3 at the most 
vulnerable geographic locations to 2E-5 in the least vulnerable. Most 
of the northern United States would fall into the 1E-3 annual 
probability range.

    \4\ Molinski, Tom S., et al., ``Shielding Grids from Solar 
Storms,'' IEEE Spectrum, November 2000.

    The largest recorded geomagnetic storm, the Carrington event of 
1859, may have exceeded 5,000 nT/min. However, this event marked the 
beginning of scientific observation and data recording of these 
magnetic storms. In the 153 years since that event, many magnetic 
storms have been experienced, but none at that level. In order to 
calculate a meaningful estimate of the return period for such an event, 
an appropriate time period would have to be assumed. However, there may 
be a way to estimate the intensity of geomagnetic storms that occurred 
before the Carrington event. As stated in a Scientific American 
article,\5\ ice-core data from Greenland and Antarctica demonstrate 
sudden jumps in the concentration of trapped nitrate gases, which in 
recent decades appear to correlate with known blasts of solar 
particles. The researchers stated that the nitrate anomaly found for 
1859 stands out as the biggest of the past 500 years, with the severity 
roughly equivalent to the sum of all the major events of the past 40 
years. Using 153 years as a lower-bound return period and 500 years as 
an alternative view yields a frequency for experiencing a Carrington-
sized event ranging from 2E-3 to 6.5E-3 per year.

    \5\ Odenwald, Sten F. and James L. Green, ``Bracing the 
Satellite Infrastructure for a Solar Superstorm,'' Scientific 
American (July 28, 2008).

    Additionally, the NRC establishes its expectation, in GDC 2, 
``Design bases for protection against natural phenomena,'' that 
structures, systems, and components important to safety at nuclear 
power plants are designed to withstand the most severe of the natural 
phenomena that have been historically reported for the site and 
surrounding area, with sufficient margin for the limited accuracy, 
quantity, and period of time in which the historical data have been 
accumulated. Solar storms are not specifically identified as natural 
hazards in GDC 2, but the information currently available to the NRC 
indicates that the frequency of these storms may be consistent with 
other natural hazards within the intended scope of the GDC.
    Based on this limited analysis, the NRC concludes that the 
frequency of occurrence of an extreme magnetic storm that could result 
in unprecedented adverse impacts on the U.S. electrical grid is not 
remote compared to other hazards that the NRC requires NPP licensees to 
consider. Accordingly, it is appropriate for the NRC to consider 
regulatory actions that could be needed to ensure adequate protection 
of public health and safety during and after a severe geomagnetic 

D. Experience With the Effects of Geomagnetic Storms on the Electrical 

    The Oak Ridge National Laboratory (ORNL) Report ORNL-6665, 
``Electric Utility Experience with Geomagnetic Disturbances,'' 
published in September

[[Page 74794]]

1991,\6\ discusses electric utility experience with geomagnetic storms 
to determine the probable impact of severe geomagnetic storms. The 
report states, as follows:

    \6\ Available at http://www.ornl.gov/~webworks/cpr/v823/rpt/

    The first reports of geomagnetic storm effects on electric power 
systems in the United States resulted from the solar storm on March 
24, 1940 during solar cycle 17. Disturbances were reported in the 
northern United States and Canada. The Philadelphia Electric Company 
system experienced reactive power swings of 20% and voltage surges. 
In the same period, two transformers in this system and several 
power transformers on the Central Maine Power Co. and Ontario Hydro 
system tripped out. The Consolidated Edison Company in New York City 
also experienced voltage disturbances and dips up to 10% due to the 
large increase in reactive power on that system. Since that time, 
power system disturbances have been recorded for geomagnetic storms 
that occurred during solar cycles that followed. Some of the more 
severe disturbances occurred on August 17, 1959 (solar cycle 19); 
August 4, 1972 (solar cycle 20); and March 13, 1989 (solar cycle 

    Grid Issues: The ORNL Report details circuit breaker failures or 
inadvertent circuit breaker operations resulting in degradation of 
transmission systems. Specifically, the report states:

    Past mishaps attributed to GIC include the tripping of circuit 
breakers from protection system malfunctions. On September 22, 1957, 
a 230-kV circuit breaker at Jamestown, North Dakota, tripped because 
of excessive third harmonic currents in the ground relays produced 
by saturated transformer cores. On November 13, 1960, a severe 
geomagnetic disturbance caused 30 circuit breakers to trip 
simultaneously on the 400-220-130-kV Swedish power system. In 
October 1980 and again in April 1986, a new 749-km 500-kV 
transmission line linking Winnipeg, Manitoba, with Minneapolis-St. 
Paul, Minnesota was tripped by protection system malfunctions due to 

    The report further discusses malfunctions in capacitor banks and 
static VAR (reactive power) compensators, which provide rapid voltage 
regulation and reactive power compensation via thyristor-controlled 
capacitor banks. Cascading failures of voltage control devices can 
result in grid instability and eventual blackout. The extent of 
blackout depends on the magnitude of the GICs and the compensatory 
actions taken by grid operators. The grid becomes unstable due to false 
relay operations resulting in unnecessary breaker trips, which cause 
isolation of transmission lines or voltage support equipment. 
Transformers may also be damaged when GIC passes through some 
transformers damaging the insulation and resulting in isolation of 
associated transmission lines. Isolation of transmission lines can 
result in grid collapse.
    Transformers: The ORNL Report further looks at the impact on large 
transformers and states, as follows:

    A few transformer failures and problems over the decades have 
been attributed to geomagnetic storms. In December 1980, a 735-kV 
transformer failed eight days after a geomagnetic storm at James 
Bay, Canada. A replacement 735-kV transformer at the same location 
failed on April 13, 1981, again during a geomagnetic storm. However, 
analysis and tests by Hydro-Quebec determined that GIC could not 
explain the failures but abnormal operating conditions may have 
caused the damage. The failures of the generator step-up 
transformers at the Salem Unit 1 nuclear generating station of 
Public Service Electric & Gas Co. during the March 13, 1989, storm 
probably have attracted the most attention. The 288.8/24-kV single-
phase shell-form transformers, which are rated at 406 MVA, are 
connected grounded-wye. The damage to the transformers included 
damage to the low-voltage windings, thermal degradation of the 
insulation of all three phases, and conductor melting. The Salem 
plant occupies a vulnerable position in the power system network 
with respect to GICs since it is located at the eastern end of a 
long EHV transmission system traversing a region of igneous rock (on 
the Delaware river near the Atlantic Ocean) and is therefore very 
well grounded. (This position thus acts as a collection point for 
ground currents since the eastern end of the power network is close 
to the Atlantic Ocean and that station has a very low grounding 
resistance.) During the March 13th disturbance, Salem Unit 1 
experienced VAR excursions of 150 to 200 MVAR. Additional VARs were 
consumed by the saturated step-up transformers.

    Transformer failures in South Africa are documented in several 
reports associated with geomagnetic storms. A technical paper \7\ 
entitled ``Transformer failures in regions incorrectly considered to 
have low GIC-risk,'' by C. T Gaunt and G. Coetzee, cites failures or 
degradation of large transformers. Specifically, the paper notes:

    \7\ Available at http://www.labplan.ufsc.br/congressos/powertech07/papers/445.pdf.

    After the severe geomagnetic storm at the beginning of November 
2003, often referred to as the `Halloween storm,' the levels of some 
dissolved gasses in the transformers increased rapidly. A 
transformer at Lethabo power station tripped on protection on 17 
November. There was a further severe storm on 20 November. On 23 
November the Matimba 3 transformer tripped on protection 
and on 19 January 2004 one of the transformers at Tutuka was taken 
out of service. Two more transformers at Matimba power station 
(5 and 6) had to be removed from service.

    Recent analysis by Metatech estimates that in a once-in-100-year 
geomagnetic storm, more than 300 large EHV transformers would be 
exposed to levels of GIC sufficiently high to place these units at risk 
of failure or permanent damage requiring replacement.\8\ The GICs 
contribute to the heat-related degradation that may affect transformer 
insulation. An older transformer design, known as ``Shell'' type (as 
discussed in the Salem failure), was susceptible to overheating due to 
circulating currents. Recent studies indicate that a few isolated cases 
of premature transformer failures that were attributed to accelerated 
GIC-related degradation have been limited to this special design. 
Transformer manufacturers consider modern ``core'' type transformer 
designs to not be prone to GIC-related premature or catastrophic 

    \8\ It should be noted that the NERC`s Interim 2012 Reliability 
Assessment report, based on discussions with transformer 
manufacturers and some technical papers published by industry 
experts, implicitly concludes that the worst case scenario of long-
term grid collapse would not be a likely result of a severe 
geomagnetic event.
    \9\ IEEE paper ``Effects of GIC on Power Transformers and Power 
Systems'' R.Girgis, Fellow IEEE, K. Vedante, Senior Member IEEE ABB 
Power Transformers St. Louis, MO, USA; available at http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=06281595.

    Large transformers are very expensive to replace and few spares are 
available. Manufacturing lead times for new equipment range from 12 
months to more than 2 years. Such large-scale damage to these EHV 
transformers would likely lead to prolonged restoration and long-term 
shortages of supply to the affected regions. Prototype rapid 
replacement transformer concepts are being evaluated but have only had 
minimal field testing. While promising, there are currently no plans in 
place to develop the stockpile of such spare transformers that would 
have to be available, and transformer replacement would still take 6 
weeks or longer. Utilities are working to build up quantities of 
internally managed spares (e.g., by keeping the highest quality 
replaced units during regularly scheduled replacements), but this will 
not provide sufficient quantities to alleviate the concern.
    Current Industry and Agency Efforts: The electric utilities and 
Federal agencies (FERC, DOE, NERC, NASA) have expended considerable 
resources in an attempt to quantify the impacts of the severe 
geomagnetic storm threats to the U.S. power grid. The efforts are 
focused on developing models that translate the geomagnetic field 
environment into specific impacts on the operation of the electric 
power grid.

[[Page 74795]]

The NERC released an Interim 2012 Special Reliability Assessment report 
entitled ``Effects of Geomagnetic Disturbances on the Bulk Power 
System'' NERC Report.'' \10\ Based on an assumed frequency of a once-
in-100-year geomagnetic event, the NERC report indicates that potential 
damage to EHV transformers of recent design is of a low probability, 
and thus challenges the assertions of the Metatech report that 300 
large EHV transformers would be at risk of failure. The report also 
indicates that GIC-related insulation damage is most likely to result 
in failure of transformers near the end of their life, or in 
transformers of earlier designs such as shell[hyphen]type pre-1972 with 
brazed windings that may have high circulating currents. The loss of 
one or two EHV transformers (greater than 345-kV on the high side) 
would rarely challenge bulk system reliability. Also, the failure or 
loss of a number of large High Voltage transformers, electrically 
remote from the EHV system, would not have a significant impact on the 
bulk-power system capability for an extended duration. The report 
states: ``The most likely consequence of a strong GMD and the 
accompanying GIC is the increase of reactive power consumption and the 
loss of voltage stability. The stability of the bulk-power system can 
be affected by changes in reactive power profiles.''

    \10\ Available at http://www.nerc.com/page.php?cid=4%7C61.

    The NERC report implicitly concludes that the worst case scenario 
of long-term grid collapse would not be a likely result of a severe 
geomagnetic event. However, the NRC notes that the NERC's concept of a 
``rare'' event for purposes of electrical grid reliability is different 
from the NRC's when considering the safe design of nuclear power 
reactors. For example, the NERC report refers to a ``severe storm'' as 
once-in-100 years and a ``serious storm'' as once in 10 years. By 
contrast, the NRC's requirements regarding consideration of natural 
hazards for the design of NPPs, as set forth in GDC 2, establish a much 
more stringent consideration of natural hazards:

    Criterion 2--Design bases for protection against natural 
phenomena. Structures, systems, and components important to safety 
shall be designed to withstand the effects of natural phenomena such 
as earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches 
without loss of capability to perform their safety functions. The 
design bases for these structures, systems, and components shall 
reflect: (1) Appropriate consideration of the most severe of the 
natural phenomena that have been historically reported for the site 
and surrounding area, with sufficient margin for the limited 
accuracy, quantity, and period of time in which the historical data 
have been accumulated, (2) appropriate combinations of the effects 
of normal and accident conditions with the effects of the natural 
phenomena and (3) the importance of the safety functions to be 

    The NERC's implicit conclusion--that grid collapse caused by 
simultaneous catastrophic failure of multiple EHV transformers is not 
likely during a large GIC event--must be interpreted with these 
frequencies in mind. Therefore, the NRC staff does not find that 
conclusion compelling, absent data or more information on how this 
assumption has been validated.
    The literature on mitigating risk of geomagnetic storm effects on 
electric power systems is very consistent, focusing on two basic 
methods of reducing either the vulnerability or the consequences. The 
first risk mitigation method is to harden equipment to reduce its 
vulnerability to GIC; the second is to establish operational procedures 
to reduce the impact of GIC. Electric power utilities can harden their 
systems against GICs through passive devices or circuit modifications 
that can reduce or prevent the flow of GICs. Hardening is most 
effective for critical transformers that play a major role in power 
transmission, which are very expensive and time-consuming to replace. 
In response to the March 13, 1989, blackout event when a geomagnetic 
storm affected Canadian and U.S. power systems, Hydro Quebec, a 
Canadian utility, implemented hardening measures such as transmission 
line series capacitors and transformer protection that cost more than 
$1.2 billion in Canadian dollars. The cost benefits of these measures 
are indeterminate, because there has not been a storm of similar 
magnitude to challenge the system, and the uncertainties or variable 
factors associated with analyzing GICs raise questions about the 
effectiveness of the measures.
    In the U.S., a number of utilities have GMD response operating 
procedures that are triggered by forecast information and/or field GIC 
sensors. Existing response procedures generally focus on adding more 
reactive power capability and unloading key equipment at the onset of a 
GMD event. The NERC report concludes that more tools are needed for 
planners and operators to determine the best operating procedures to 
address specific system configurations. Currently, the FERC has 
directed the NERC to develop reliability standards that addresses the 
impact of geomagnetic disturbances on the reliable operation of the 
bulk power system (77 FR 64935).
    Nuclear Power Plant Operation and Shutdown: In the United States, 
the minimum requirements for electrical power for plant operation and 
safe shutdown are delineated in 10 CFR part 50, appendix A, GDC 17. The 
grid provides the offsite or the preferred power source and redundant 
divisions of onsite power distribution system support plant operation 
and safe shutdown capability. In the event that offsite power is lost, 
redundant onsite electrical power sources (e.g., EDGs) are available to 
support plant shutdown. Geomagnetic storms have the potential to 
degrade both offsite and onsite power systems. The offsite power system 
may be lost due to loss of reactive power support or bulk-power system 
asset damage (e.g., transformer damage). The onsite power system is 
vulnerable to shortage of fuel oil for EDGs after onsite stored 
capacity has been depleted.
    Nuclear Plant Assets Susceptible to GIC Damage: A typical NPP 
single unit configuration consists of one fully rated or two 50 percent 
rated main step up transformers (MT), two unit auxiliary transformers 
(UAT), and two start up or standby transformers (SAT). During normal 
plant operation, the MTs are fully loaded and connected to the high 
voltage transmission network. These MTs are vulnerable to GIC and 
subharmonics generated in the transmission network. The MTs are fully 
loaded when the NPP is at-power and they have a grounded neutral that 
provides a path for GIC, and are therefore susceptible to core 
saturation and thermal damage. The Salem Nuclear Generating Station 
transformers, identified in the ORNL report as examples of damage due 
to GICs, were main step up transformers. From a nuclear safety 
perspective, the MTs can be used to supply offsite power to plant 
auxiliaries (via a backfeed scheme) but are generally not the preferred 
source of power for plant shutdown. The nuclear plant operators (NPO) 
in areas most vulnerable to GIC-related transformer damage have 
procedures to reduce plant power output (hence the load on MTs) when 
solar storm warnings are issued by the National Oceanographic and 
Atmospheric Administration Space Weather Prediction Center.
    During normal plant operation, the UATs supply power to the plant 
auxiliary system and are connected to the output of the main generator. 
These transformers, though fully loaded, are not directly connected to 
the grid, operate at lower voltages, and are ``shielded'' from GICs by 
the MTs, which are the interface point between the NPP and the grid. 
Therefore, these transformers are not expected to be

[[Page 74796]]

vulnerable to GICs and will be available for plant shutdown as long as 
the transmission network in the vicinity of the plant is stable.
    The source of offsite power required by GDC 17 for plant shutdown 
is normally through the SATs. During normal operation, these 
transformers are energized and lightly loaded. The minimum rating of 
SATs exceeds the total power requirements of safety significant loads. 
There are a few plants that use the SATs for supplying all station 
auxiliary loads during normal operation. In these cases, there should 
be a margin between the normal loading and maximum rating of the 
transformers to accommodate additional safety-related loads that would 
be sequenced by an accident signal. Therefore, the transformers should 
be able to handle some overloading or heating effects related to GICs 
during normal operation. Though these transformers have grounded 
neutrals and are connected to the EHV transmission network, they are 
not expected to be vulnerable to GIC damage, as the heating effects 
would be minimal due to the light load on the transformers during 
normal operation. To date, no SAT failures have been attributed to GIC-
related damage. Since the SATs are the normal source of offsite power 
to the NPPs for safe shutdown during postulated accidents and design 
basis events and since they would not experience significant GIC-
related overheating or damage, the offsite power capabilities of NPPs 
are not expected to be degraded by solar storms.
    This generalized evaluation of transformers and offsite power 
system designs is provided to illustrate the potential system 
vulnerability to geomagnetic storms. For long-term impact on 
transformers, the NRC staff is following industry developments for 
transformers in the bulk-power transmission systems. If the NERC and 
the FERC mandate that certain types of transformers or certain critical 
transformers are susceptible to GIC-related failures and that load 
reduction will reduce the potential for catastrophic failures, then the 
NRC will take appropriate actions for nuclear plants that operate with 
startup transformers fully loaded. The NRC staff will review plant-
specific designs to establish if any start-up transformers are 
operating close to their nominal rating during normal plant operation 
and are susceptible to GIC damage.
    The onsite power system EDGs are normally in a standby state and 
are not expected to be affected by solar storms. In the unlikely event 
that EDGs are operating in test mode during a solar event, the grounded 
neutrals of station transformers (UATs or SATs) are expected to drain 
GICs into the ground, thus shielding the EDGs. The NPOs test EDGs at 
nominal rating for a few hours during normal plant operation. The EDGs 
have a nominal rating and a short-term overload capacity. Thus, any 
GICs that enter the plant's electrical system during EDG operation 
should not result in excessive overheating of the generator windings. 
The EDGs are designed for extended operation and have the capability of 
mitigating the consequences of an accident and supporting spent fuel 
pool loads. In the event of loss of offsite power, the EDGs 
automatically start and energize safe shutdown buses of the plant. The 
design basis of most U.S. plants requires onsite storage of EDG fuel 
oil capability for 7 days of operation without replenishment. Many 
plants also have additional fuel oil stored for non-safety significant 
equipment such as auxiliary boilers that might be available for EDG 
operation. The NPOs typically have agreements with fuel oil suppliers 
(in some cases refineries) to support fuel oil deliveries on short 
notice. If an offsite power blackout lasts longer than 7 days and 
creates long-term implications for freight transportation and emergency 
resources of the NPOs, then Federal emergency resources would have to 
coordinate relief supplies to critical facilities. The relief supplies 
would include fuel oil for nuclear plants.
    Offsite Power Source Vulnerability: The NPP offsite power systems 
are vulnerable to grid perturbations resulting from GMDs. The scope of 
protecting transmission networks is beyond the jurisdiction of the NRC. 
The NRC can recommend protective/precautionary measures that NPPs and 
grid operators can implement when the magnitude of predicted solar 
storms is estimated to be potentially damaging to systems in the 
vicinity of NPPs.
    The correlation between the magnitude and duration of geomagnetic 
storms and the potential degradation of the transmission system is the 
subject of several ongoing studies between the NERC, FERC, Electric 
Power Research Institute, and national research institutes such as 
ORNL. The Metatech report, entitled ``Geomagnetic Storms and Their 
Impacts on the U.S. Power Grid,'' discusses methods that can be used to 
comprehensively assess the vulnerability of the U.S. power grid to the 
geomagnetic storm environment produced by solar activity. These 
modeling techniques have been used to replicate geomagnetic storm 
events and perform detailed forensic analysis of geomagnetic storm 
impacts to electric power systems. It should be noted that these 
modeling techniques are in a developmental stage. There is no industry 
standard or model that has been endorsed by a nationally recognized 
body. The capability may also be applied towards providing predictive 
geomagnetic storm forecasting services to the electric power industry 
and specifically to NPOs. The NPOs can then take appropriate actions, 
based on solar storm warnings, to minimize the risk of damage to 
nuclear plant assets.
    The NERC report considers the most likely outcome of a major solar 
storm to be grid instability caused by excessive reactive power demand. 
This scenario results in protective relays separating critical sections 
of the power grid and potential large scale blackout but limited 
equipment (transformer) damage within localized areas with highest GIC. 
Recovery from such an event is expected to be relatively quick (within 
a day or two) and as such should not be a major concern for nuclear 
plant safe shutdown capability. In the event that the reactive power 
demands do not result in separation of the grid system, the cascading 
effects of the GIC through critical transformers may result in large 
scale equipment damage and subsequent long-term shutdown of the extra 
high voltage transmission network due to the long replacement time 
necessitated by the long lead time for manufacture and installation of 
large transformers. Nuclear power plants in the blacked out area would 
require external resources to support shutdown capability and fuel pool 
cooling for an extended duration.

E. Federal Government Coordination and Emergency Response

    A number of different Federal government agencies are involved in 
assessing the risk to the U.S. power grid from geomagnetic storms. 
While it is recognized that CME events can pose a serious threat, a 
sufficient technical basis for the frequency and impact of significant 
CME events has not been developed to the level typically expected by 
the NRC for other natural hazards (floods, earthquakes, hurricanes, 
tornadoes, etc.). The FEMA has promulgated a basis for the development 
of contingency plans for a significant CME.
    The FEMA's planning efforts are captured in the National Response 
Framework (NRF),\11\ which is a guide to how the Nation conducts all-
hazards response. It is built upon scalable,

[[Page 74797]]

flexible, and adaptable coordinating structures to align key roles and 
responsibilities across the Nation. It describes specific authorities 
and best practices for managing incidents that range from the serious 
(but purely local) to large-scale terrorist attacks or catastrophic 
natural disasters. Within the NRF are annexes that plan the emergency 
response for various infrastructure sectors. ``Emergency Support 
Function 12-Energy Annex'' is the annex relevant to a CME and 
its effects upon the electrical power grid, and the DOE is the lead 
agency for coordinating the required Federal response with the NRC as a 
support agency.

    \11\ Available at http://www.fema.gov/national-response-framework.

    The NRC has an extensive and well-practiced emergency response 
capability. The NRC response is practiced several times a year in 
conjunction with inspected licensee exercises. The NRC response 
organization focuses on protection of the public and the support of NPP 
needs to mitigate accidents. In the event of a damaged electrical grid, 
the NRC Operations Center could be engaged in responding to one or more 
NPPs (and perhaps other licensees) located in the area. Initially, the 
NPP would only be in the lowest level of emergency because onsite 
emergency generators are expected to operate and supply power to safety 
systems. However, as the loss of offsite power continues to the point 
when fuel supply is challenged, the NRC would consider the need to 
activate its response capabilities in order to ensure public health and 
safety with respect to the impacted nuclear plant(s).
    The normal progression of emergency response is that the plant 
operator (NRC licensee) would solve its own logistical needs through 
commercial arrangements. Should this not be possible due to legalities 
or degradation of commercial supply capabilities, the licensee would 
then call upon local offsite response organization support, such as 
local law enforcement agencies and fire departments. Local authorities 
might be able to assist with the logistics and/or prioritization of 
fuel supply, but generally they would not have any transport equipment. 
When an emergency exceeds local response capabilities, the state is 
then called upon for assistance. If a geomagnetic storm resulted in a 
long-term loss of the electrical grid, local authorities would likely 
require state assistance; this could involve the National Guard and/or 
assistance from neighboring states or regions to acquire transport 
equipment and fuel supplies for emergency generators. Local priorities 
would likely be provided to the state response organization for 
disposition. Finally, if the emergency situation exceeds state 
capabilities, then Federal response could be requested through DHS and 
    Throughout any accident at a licensed facility, the NRC would 
remain in direct contact with the licensee and would be aware of the 
status of each nuclear plant, including availability of electrical 
power and fuel oil. Should a licensee need logistical support, the NRC 
could facilitate that support. Further, nuclear plant licensees can 
obtain emergency support through corporate, sister plant, and industry 
assets. As a response to the Fukushima accident, licensees are 
cooperatively developing regional emergency equipment depots. However, 
this capability is not in place and may not adequately address fuel 
supply and transport issues associated with a long-term grid collapse.
    The FEMA recognizes the significant impact a CME-induced grid 
collapse would have on a wide range of infrastructure with public 
safety concerns and recognizes that nuclear power plants would be one 
of the many important concerns. To address this concern, the FEMA is 
considering the potential impact of CMEs as part of an overall concept 
of addressing all types of impacts on the critical infrastructure.

V. Conclusion

    Recent experience and associated analyses regarding space weather 
events suggest a potentially adverse outcome for today's infrastructure 
if a historically large geomagnetic storm should recur. The industry 
and the FERC are considering whether EHV transformers that are critical 
for stable grid operation should be hardened to protect them from 
potential GIC damage and whether existing procedures for coping with a 
GIC event require significant improvements. The transformers required 
for offsite power for nuclear plants are normally in a standby state or 
have built-in design margins and are unlikely to be degraded by GICs. 
The safe shutdown capability of NPPs is not an immediate concern 
because the onsite EDGs can provide adequate power. In addition, the 
near-term actions (including a revised station blackout rulemaking (RIN 
3150-AJ08, NRC-2011-0299) currently underway in response to the event 
at the Fukushima Dai-ichi nuclear power plant on March 11, 2011, are 
expected to include deployment of resources from remote locations to 
cope with loss of offsite and onsite power for an extended duration. 
However, in the event of a widespread electrical transmission system 
blackout for an extended duration (beyond 7 days and up to several 
months), it may not be possible to transport these and other necessary 
offsite resources to the affected NPPs in a timely manner. Thus, 
government assistance (local, state, or Federal) may be necessary to 
maintain the capability to safely shutdown nuclear plants and cool 
spent fuel pools in the affected areas. Prior planning is needed to 
efficiently and effectively use government resources to ensure 
protection of public health and safety. Current NRC regulations do not 
require power reactor licensees to undertake mitigating efforts for 
prolonged grid failure scenarios that could be caused by GICs resulting 
from an extreme solar storm. Thus, the NRC concludes that the issues 
and concerns raised by the petitioner need to be further evaluated.
    To that end, the NRC will consider the issues raised in the 
petition in the NRC rulemaking process. The NRC will initiate the 
rulemaking process for development of a regulatory basis in a phased 
approach. Initially, the NRC will monitor the progress of several 
ongoing and potential regulatory activities. The NRC staff will monitor 
the implementation of Order EA-12-049, which requires that licensees 
develop, implement, and maintain guidance and strategies to maintain or 
restore core cooling, containment, and SFP cooling capabilities 
following a beyond-design-basis external event, and the ongoing 
enhancements to the station blackout rule being developed under 
Fukushima NTTF Recommendation 4.1. The NRC staff will also monitor 
possible rulemakings in response to Fukushima NTTF Recommendation 7.2, 
which could potentially require all licensees to provide Class 1E 
(safety-grade) electric power to SFP makeup systems, and the activities 
being developed for prolonged station blackout scenarios under 
Fukushima NTTF Recommendations 8 and 9. If an assessment of the 
progress in these areas concludes that the efforts are not likely to 
address the diesel generator fuel depletion and resupply issue raised 
by the petition, then the NRC will begin work to develop a regulatory 
basis to address the extensive grid outage scenario that could 
potentially be caused by an extreme solar storm.
    Preparation of a proposed rule for public comment and publication 
in the FR would begin only if a viable regulatory basis is developed. 
If the NRC proceeds with a proposed rule, the NRC will address the 
comments received in favor of the PRM. In addition, the petitioner's 
issue of 2 years unattended water makeup of SFPs would be

[[Page 74798]]

addressed as part of that rulemaking action.
    If the effort to establish the regulatory basis for this rulemaking 
does not support the issuance of a proposed rule, then the NRC will 
issue a supplemental FRN that addresses why the petitioner's requested 
rulemaking changes were not adopted by the NRC and addresses the 
comments received in favor of the PRM. Finally, with the publication of 
this FRN detailing the NRC's decision to consider, in a phased 
approach, the PRM issues in the NRC rulemaking process, the NRC closes 
the docket for PRM-50-96.
    Although outside the scope of this PRM, it should be noted that the 
NRC, as a part of its core mission to protect public health and safety, 
is updating its previous evaluation of the effects of geomagnetic 
storms on systems and components needed to ensure safe shutdown and 
core cooling at nuclear power reactors.

VI. Resolution of the Petition

    The NRC will review and analyze the underlying technical and policy 
issues relevant to the PRM and the comments submitted in support of the 
PRM in the NRC rulemaking process, to address the petitioner's 
requested rulemaking changes and reliable emergency systems capable to 
operate for a period of 2 years without human intervention and without 
offsite fuel resupply. If this phased utilization of the NRC rulemaking 
process results in the development of a regulatory basis sufficient for 
a proposed rule, then a proposed rule will be prepared for publication 
and public comment. If a regulatory basis sufficient for a proposed 
rule is not feasible, then a supplemental FRN explaining this result 
will be published. Thus the docket for PRM-50-96 is closed.

    Dated at Rockville, Maryland, this 3rd day of December 2012.

    For the Nuclear Regulatory Commission.
Michael R. Johnson,
Acting Executive Director for Operations.
[FR Doc. 2012-30452 Filed 12-17-12; 8:45 am]