[Federal Register Volume 75, Number 128 (Tuesday, July 6, 2010)]
[Notices]
[Pages 38845-38850]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-16352]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-289; NRC-2010-0221]
Exelon Generation Company, LLC; Three Mile Island Nuclear
Station, Unit No. 1; Exemption
1.0 Background
Exelon Generation Company, LLC (Exelon, the licensee) is the holder
of Facility Operating License No. DPR-50 which authorizes operation of
the Three Mile Island Nuclear Station, Unit 1 (TMI-1). The license
provides, among other things, that the facility is subject to all
rules, regulations, and orders of the U.S. Nuclear Regulatory
Commission (NRC, the Commission) now or hereafter in effect.
The facility consists of a pressurized-water reactor (PWR) located
in Dauphin County, Pennsylvania.
2.0 Request/Action
Title 10 of the Code of Federal Regulations (10 CFR) part 50,
Section 50.48, requires that nuclear power plants that were licensed
before January 1, 1979, must satisfy the requirements of 10 CFR part
50, appendix R, section III.G, ``Fire protection of safe shutdown
capability.'' TMI-1 was licensed to operate prior to January 1, 1979.
As
[[Page 38846]]
such, the licensee's Fire Protection Program (FPP) must satisfy the
established fire protection features of 10 CFR part 50, appendix R,
section III.G.
TMI-1 proposes to utilize an operator manual action (OMA) in lieu
of meeting the circuit separation and/or protection requirements
contained in 10 CFR part 50, appendix R, section III.G.2 (III.G.2),
which requires ensuring that one of the redundant trains of systems
necessary to achieve and maintain hot shutdown is maintained free of
fire damage. In this case, the OMA is proposed for a fire occurring in
Fire Zone 6 of the plant's Auxiliary Building (AB-FZ-6). The prescribed
action involves opening a breaker and manually opening valve MU-V-36
within 40 minutes to support maintaining a makeup pump minimum
recirculation path. By letter dated December 30, 1986 (ADAMS Legacy
Library Accession No. 8701090216), this OMA was previously approved by
the NRC; however, the time requirement has been shortened,
necessitating this exemption.
In summary, by letter dated March 3, 2009 (Agencywide Documents
Access and Management System (ADAMS) Accession No. ML090630134), as
supplemented by letter dated March 15, 2010 (ADAMS Accession No.
ML100750093), Exelon requested an exemption for TMI-1 from certain
technical requirements of III.G.2 for the use of an OMA in lieu of
meeting the circuit separation and/or protection requirements contained
in III.G.2 for AB-FZ-6.
3.0 Discussion
Pursuant to 10 CFR 50.12, the Commission may, upon application by
any interested person or upon its own initiative, grant exemptions from
the requirements of 10 CFR part 50 when: (1) The exemptions are
authorized by law, will not present an undue risk to public health or
safety, and are consistent with the common defense and security; and
(2) when special circumstances are present. These circumstances include
the special circumstances that the application of the regulation is not
necessary to achieve the underlying purpose of the rule.
In its March 15, 2010, letter, the licensee discussed financial
implications associated with plant modifications that may be necessary
to comply with the regulation. If such costs have been shown to be
significantly in excess of those contemplated at the time the
regulation was adopted, or are significantly in excess of those
incurred by others similarly situated, this may be considered a basis
for considering an exemption request. However, financial implications
were not considered in the regulatory review of their request since no
substantiation was provided regarding such financial implications. Even
though no financial substantiation was provided, the licensee did
submit sufficient regulatory basis to support a technical review of
their exemption request in that the application of the regulation in
this particular circumstance is not necessary to achieve the underlying
purpose of the rule.
In accordance with 10 CFR 50.48(b), nuclear power plants licensed
before January 1, 1979, are required to meet section III.G, of 10 CFR
part 50, appendix R. The underlying purpose of 10 CFR part 50, appendix
R, section III.G is to ensure that the ability to achieve and maintain
safe shutdown is preserved following a fire event. The regulation
intends for licensees to accomplish this by extending the concept of
defense-in-depth to:
(1) Prevent fires from starting;
(2) Rapidly detect, control, and extinguish promptly those fires
that do occur;
(3) Provide protection for structures, systems, and components
important to safety so that a fire that is not promptly extinguished by
the fire suppression activities will not prevent the safe shutdown of
the plant.
The stated purpose of III.G.2 is to ensure that one of the
redundant trains necessary to achieve and maintain hot shutdown
conditions remains free of fire damage in the event of a fire. Section
III.G.2 requires one of the following means to ensure that a redundant
train of safe shutdown cables and equipment is free of fire damage,
where redundant trains are located in the same fire area outside of
primary containment:
(1) Separation of cables and equipment by a fire barrier having a
3-hour rating;
(2) Separation of cables and equipment by a horizontal distance of
more than 20 feet with no intervening combustibles or fire hazards and
with fire detectors and an automatic fire suppression system installed
in the fire area; or
(3) Enclosure of cables and equipment of one redundant train in a
fire barrier having a 1-hour rating and with fire detectors and an
automatic fire suppression system installed in the fire area.
Exelon has requested an exemption from the requirements of III.G.2
for TMI-1 to the extent that one of the redundant trains of systems
necessary to achieve and maintain hot shutdown is not maintained free
of fire damage in accordance with one of the required means, for a fire
occurring in Fire Zone AB-FZ-6 in the Auxiliary Building. In its March
15, 2010, response to the NRC's request for additional information, the
licensee stated that the purpose of its request was to credit the use
of an OMA, in conjunction with other forms of defense-in-depth, in lieu
of the separation and protective measures required by III.G.2 for a
fire in Fire Zone AB-FZ-6. Specifically, Fire Zone AB-FZ-6 is not
protected throughout by an automatic fire suppression system and rated
fire barriers or 20 feet of spatial separation are not provided between
the redundant equipment. The OMA entails locally opening a feeder
breaker (1P 480V Switchgear Unit 4C) located in Fire Zone CB-FA-2a and
a valve (MU-V-36), which is located in Fire Zone AB-FZ-3, to establish
a makeup pump recirculation flow path.
In summary, TMI-1 does not meet the requirements of III.G.2 for a
fire in Fire Zone AB-FZ-6 and an OMA may be necessary to achieve and
maintain hot shutdown capability. The licensee also indicated that the
only credible scenario for a fire in Fire Zone AB-FZ-6 that may require
the need to manually open valve MU-V-36 is as follows: the fire must
initiate within the MU-V-36 breaker compartment of the 1A Engineered
Safeguards Valve (ESV) motor control center (MCC), cause a fault on an
energized circuit to make MU-V-36 close, cause power failure of the 1A
ESV MCC, spread to and damage the instrument air tubing causing valves
MU-V-18 and MU-V-20 to close, and cause failure of the 1B ESV MCC power
circuit, which is contained within a 4-inch galvanized steel conduit.
See Section 3.3 below for additional details addressing the spatial
separation between cables and instrument air tubing. In addition, the
TMI-1 analysis assumes that fire damage may occur immediately upon
first detection of the fire to all components in the fire area. The
licensee stated that after confirmation of a fire, the fire abnormal
operating procedure (AOP) for Fire Zone AB-FZ-6 would be entered.
The licensee has described in its initial request, and subsequent
documents, elements of the fire protection program that provide
justification that the concept of defense-in-depth that is in place in
Fire Zone AB-FZ-6 is consistent with that intended by the regulation.
To accomplish this, the licensee provides various forms of protection
in order to maintain the concept of defense-in-
[[Page 38847]]
depth. The licensee's approach is discussed below.
3.1 Fire Prevention
The licensee has stated that it has an administrative controls
program in place to control ignition sources, hot work activities
(activities such as welding or grinding), in situ and transient
combustibles, and fire system impairments. The administrative controls
program is described in the TMI-1 Updated Final Safety Analysis Report
(UFSAR) and in the Fire Hazards Analysis Report (FHAR), which is
incorporated by reference into the UFSAR. Transient combustibles are
restricted in Fire Zone AB-FZ-6 and particularly in the 1A ESV MCC
area.
In addition to these measures, the licensee has stated that the
power and control cables with voltages up to 480V AC and 480/120V in
the fire zone are thermoset (Kerite with ethylene propylene rubber
(EPR) insulation). Thermoset cables are resistant to self-ignited cable
fires and are not considered to represent an ignition source. Other
ignition sources in the area consist of control power transformers
inside the 1A ESV MCC. The licensee also stated that the transformers
are contained within the metal-clad MCC housing and contain no
combustible or flammable liquids and that the control cables are
located in open trays while the 480V power cables are in conduit or use
armor jacketed cable. Therefore, due to limited ignition sources and
the cables installed in conduit and armored jacketed cables, flame
propagation is not expected to present a hazard.
3.2 Detection, Control and Extinguishment
Fire Zone AB-FZ-6 is provided with a ceiling-mounted photoelectric
smoke detection system, which is connected to the Auxiliary Building
fire detection panel, located near the 1A ESV MCC. The licensee has
indicated that if smoke is detected, a local horn and strobe light are
actuated at the fire alarm panel as well as in the control room. There
are two smoke detectors located within a few feet horizontally and
approximately 13 feet vertically above the 1A ESV MCC. The smoke
detection system is designed and installed in accordance with National
Fire Protection Association (NFPA) 72D (1975), ``Proprietary Protective
Signaling Systems for Guard, Fire Alarm and Supervisory Service,'' and
NFPA 72E (1978), ``Automatic Fire Detectors.''
A hose reel, with at least 100 feet of hose, is provided in
adjacent Fire Zone AB-FZ-9. The hose reel is less than 100 feet from
the 1A ESV MCC area or any other area in Fire Zone AB-FZ-6. The hose
reels were designed and installed in accordance with NFPA 14 (1978),
``Standpipe and Hose Systems,'' and have electrically-safe fog nozzles
installed, which make them safe to use in the vicinity of electrical
equipment. Portable dry chemical and carbon dioxide fire extinguishers
are also permanently mounted in Fire Zone AB-FZ-6 and adjacent fire
zones. These extinguishers have been installed in accordance with NFPA
10, ``Standard for Portable Fire Extinguishers.'' The licensee stated
that all fire protection equipment is maintained in accordance with the
site FPP to ensure operability.
A water curtain is provided for fire protection of the zone
boundary between Fire Zones AB-FZ-6 and AB-FZ-7. The pre-action water
curtain system between Fire Zones AB-FZ-6 and AB-FZ-7 is actuated by
the cross-zone smoke detection system but is not credited for fire
suppression within Fire Zone AB-FZ-6. The water curtain is only
provided for fire protection of the zone boundary between Fire Zones
AB-FZ-6 and AB-FZ-7 and all other openings are sealed with material
having at least a 1-hour fire rating.
The remaining zone boundaries consist of reinforced concrete walls,
floors and ceilings. The south boundary and portion of the ceiling are
not adjacent to any other plant areas. The remainder of the ceiling
adjacent to the chemical addition area and Emergency Safeguards
Features (ESF) Ventilation Room is a 3-hour fire barrier. Most of the
north boundary is adjacent to Fire Zone AB-FZ-7 with an open passage,
discussed above, between the zones. The remainder of the north boundary
is adjacent to the Reactor Building, which is a 3-hour rated fire
barrier. The east boundary is adjacent to Fire Zones FH-FZ-1 and FH-FZ-
2 and is made of reinforced concrete. A 3-hour rated fire barrier is
provided on the floor where this zone is adjacent to Fire Zones AB-FZ-
2a, AB-FZ-2b and AB-FZ-2c. An automatic pre-action system is located in
Fire Zone AB-FZ-4 where the floor of Fire Zone AB-FZ-6 is adjacent to
Fire Zone AB-FZ-4.
3.3 Preservation of Safe Shutdown Capability
The licensee has stated that the postulated fire event that may
require the OMA to open MU-V-36 would include at least four independent
failures to occur; two of which are sequence dependent (i.e., MU-V-36
hot short occurs prior to loss of MCC) as described below:
While 1A ESV MCC is energized, the fire causes a hot short
(within 1A ESV MCC), which establishes proper voltage in the closing
circuit and causes MU-V-36 to travel closed (MU-V-36 control cable
CQ232A).
After MU-V-36 is closed, the fire causes loss of 1A ESV
MCC (cable LP8 within MCC), which is located in the fire zone. This
eliminates remote control of MU-V-16A and MU-V-16B and would isolate
the `A' train emergency makeup (High Pressure Injection [HPI]) flow
path (valves normally closed).
The fire causes a loss of integrity of the \1/4\-inch
outside diameter copper tubing which causes a sufficient reduction in
the Auxiliary Building instrument air supply pressure for MU-V-18 to
close and eventually for MU-V-20 to close. Loss of control of MU-V-18
eliminates the use of the normal Reactor Coolant System (RCS) makeup
flow path and depressurization of the MU-V-20 actuator would cause seal
injection flow to the RCP to be isolated.
Fire causes loss of power to 1B ESV MCC (cable LS7A). This
eliminates remote control of MU-V-16C and MU-V-16D and would eliminate
the `B' train emergency makeup (HPI) flow path as an alternate means of
RCS makeup (valves normally closed).
In order for a fire to cause MU-V-36 to close, the licensee has
indicated that `` * * * the fire must cause an intra-cable hot short
between a normally energized conductor in multi-conductor cable CQ232A
and the conductor that picks up the closing coil. This would short out
the remote control switch and energize the closing coil for MU-V-36.
The fire must maintain this hot short without grounding the circuit and
blowing the control power fuses or otherwise causing a loss of control
power, such as loss of the main 1A ESV MCC power cable LP8. The MU-V-36
circuits of concern are located within the MCC breaker compartment
along with the control power fuses. It is unlikely that a fire could
sufficiently damage cable CQ232A insulation and short the proper
conductors to energize the closing coil for MU-V-36 prior to blowing
the control power fuses. Because the fire must cause a hot short to
close MU-V-36 prior to loss of control power, the most likely fire
ignition location within Fire Zone AB-FZ-6 is in the MU-V-36 breaker
compartment. Fires in other areas of 1A ESV MCC would be likely to trip
the main bus breaker or otherwise damage the 1A ESV MCC power cable LP8
prior to affecting MU-V-36 circuits.''
Next, the licensee has indicated that ``[t]he primary combustible
in Fire Zone AB-FZ-6 is 1A ESV MCC and
[[Page 38848]]
associated cables * * * [t]he tubing closest to 1A ESV MCC is \1/4\-
inch outside diameter tubing used for testing reactor building pressure
switches. This tubing is at least 6 feet from the MCC with no
intervening combustibles. The loss of integrity of these \1/4\-inch
outside diameter tubing lines may not be sufficient to exceed the
capacity of the instrument air supply and reduce the instrument air
supply pressure to MU-V-18 (normal RCS makeup isolation valve) below 60
psig [pounds per square inch gauge]. Both instrument air compressors
are unaffected by a fire in Fire Zone AB-FZ-6 and would attempt to
maintain the instrument air supply to MU-V-18. The loss of instrument
air system integrity occurs in a section supplied through \3/8\-inch
regulators and \1/4\-inch outside diameter tubing. The main instrument
air system distribution headers are 2-inch lines. This specific failure
may not be sufficient to reduce the air supply pressure to MU-V-18
enough to prevent adequate RCS makeup flow. The next closest copper
tubing in Fire Zone AB-FZ-6 is against the containment wall. This
tubing is further separated from 1A ESV MCC by at least 10 feet of
distance with no intervening combustibles. Based on the existing
separation with no intervening combustibles and outside diameter of the
instrument air lines within Fire Zone AB-FZ-6, it is unlikely that a
fire in 1A ESV MCC would cause a loss of Auxiliary Building instrument
air pressure.''
The licensee further indicated that ``[t]he power cable for 1B ESV
MCC (LS7A) is routed through Fire Zone AB-FZ-6. The cable comes through
the 1-hour-rated wall (similar to UL-tested configuration U-410)
separating Fire Zones AB-FZ-6a and AB-FZ-6 in 4-inch galvanized steel
conduit as it passes through the area near 1A ESV MCC. As it turns away
from 1A ESV MCC (at least 6 feet of separation with no intervening
combustibles), it exits the conduit and enters a tray (via a splice
box). There is at least 12 feet of vertical separation with no
intervening combustibles between the top of 1A ESV MCC and the 4-inch
conduit that holds LS7A. Based on the existing separation and conduit
protection, it is unlikely that the 1B ESV MCC power cable would be
damaged, even if 1A ESV MCC were fully consumed in a fire.''
Additionally, the Auxiliary Building ventilation system is not
credited for smoke removal. If the primary safe shutdown (SSD) operator
becomes aware of smoke in the Auxiliary Building, the operator will don
a self-contained breathing apparatus (SCBA) to perform actions when
directed by the control room. Two SCBAs are staged near the primary
operator station on Auxiliary Building 305' elevation. All operators
assigned to fire brigade or SSD duties are qualified to use a SCBA.
Validation exercises have been performed to demonstrate that operators
can reliably don a SCBA in less than 3 minutes.
Given the lack of combustibles, separation of cables described
above, and the sequence of events required, it is unlikely that the OMA
to open MU-V-36 would be required. It is also likely that a fire would
be detected and suppressed before the sequence of events and failures
described above fully evolved. In the unlikely occurrence that the
sequence does fully evolve, the OMA is available to provide assurance
that safe shutdown can be achieved.
3.4 Feasibility and Reliability of the OMAs
This analysis postulates that the features described in Sections
3.1, 3.2 and 3.3, are not sufficient to assure safe shutdown
capability. The licensee has proposed an OMA to be performed in
addition to the above discussed fire protection features.
NUREG-1852, ``Demonstrating the Feasibility and Reliability of
Operator Manual Actions in Response to Fire,'' provides criteria and
associated technical bases for evaluating the feasibility and
reliability of post-fire OMAs in nuclear power plants. The following
provides the TMI-1 analysis of these criteria for justifying the OMA
specified in this request for Fire Zone AB-FZ-6.
3.4.1 Bases for Establishing Feasibility and Reliability
The licensee's analysis addresses factors such as environmental
concerns, equipment functionality and accessibility, available
indications, communications, portable equipment, personnel protection
equipment, procedures and training, staffing and demonstrations.
In their March 3, 2009, letter, and further supported by their
March 15, 2010, letter, the licensee stated that environmental
considerations such as radiological concerns, emergency lighting,
temperature and humidity conditions and smoke and toxic gases were
evaluated and found to not represent a negative impact on the
operators' abilities to complete the OMA. The licensee stated that
radiation levels expected during travel to or at the OMA location in
the Auxiliary Building are minimal with dose rates that would be less
than 10 millirem per hour. The licensee also confirmed that sufficient
emergency lighting exists at the areas where actions are performed and
along the travel routes to the areas. The licensee has stated that
operators also have access to 8-hour battery-powered portable lights,
as well. The licensee also has confirmed that temperature and humidity
conditions will not challenge the operators performing the OMA. The
licensee stated that radio and page communications are available for
this OMA. Additionally, the licensee indicated that heat and smoke or
gas generation from the fire will not impact the operator performing
the OMA. This is further supported by the fact that the location of the
postulated fire event is in a different fire zone than the locations
for where actions are performed.
The licensee stated that the functionality of equipment and cables
needed to perform the required OMA is documented in the OMA procedures,
which reflect equipment availability and provide specific direction
where functionality of equipment and cables may be compromised by fire.
In addition, in-plant OMA walk downs were performed and demonstrated
that the OMA equipment was accessible. The physical location of the
components where the OMA is to be performed is identified in the fire
AOPs and where components cannot be operated from the floor, installed
ladders or portable ladders are provided. Other than keys, portable
lighting, and portable ladders, the operators use no other additional
support equipment. The fire AOPs identify when a key is required to
perform the OMA. Keys required by operators are in the possession of
the operator and the specific key number required for the OMA is
identified in the fire AOP.
With regard to available indications, the licensee has stated that
available diagnostic instrumentation is listed in the fire AOP for each
fire area; however, instrumentation or indications are generally not
relied upon to perform the OMA. Explicit steps in the fire AOPs direct
the operators on how to perform the OMA such that one train of
available indications is always available for a fire in a given fire
area or zone. The licensee stated that the OMA does not require any
indication to support completion of the OMA; however, lack of
indication may be used to initiate an action and that successful
accomplishment of the OMA is directly observable by the operator
performing the OMA. The successful completion of the action is then
reported to the Control Room operators. Additionally, emergency
[[Page 38849]]
makeup flow indication is available for a fire in Fire Zone AB-FZ-6.
With regard to communications, the licensee stated that TMI-1 has
portable radio and installed phones available as part of the normal
plant communications available between the Control Room and the
operators and the radio and phone systems are robustly designed such
that they should be available following most fire scenarios. If the
various communication systems are not available, the method of
communication will be face-to-face or using radios via line-of-sight
(i.e., no repeaters). The licensee simulated face-to-face communication
was simulated by having operators start the manual action from directly
outside the Control Room. Task completion is normally reported by
portable hand held radio or installed phones but may also be reported
by face-to-face communication if plant communication systems are not
available. The General Announcing System, Operations Radio System,
Plant Telephone System, Sound Powered Phone System, and Face-to-Face
Communications are all available to Control Room operators and
operators performing OMAs.
The licensee stated that operators performing the OMA are provided
with standard personal protective equipment (PPE), including hardhat,
gloves, and protective glasses. In the unlikely event that smoke
conditions would require SCBAs to be worn, the plant equipment
operators are qualified to wear SCBAs and the SCBAs are staged at
strategic locations in the plant with additional SCBAs in the fire
brigade locker.
The licensee stated that fire AOPs have been developed for each
fire area or zone and that the fire AOPs are staged in certain
strategic locations that are easily accessible to the operators. The
individual procedures are presented in a standardized procedure format
that the operators are familiar with. The fire AOPs contain both
preventive actions to prevent potential adverse fire effects, as well
as reactive actions to direct timely action if a fire causes a
particular adverse condition (i.e., valve spuriously opens or closes).
The procedures for individual fire areas are used in conjunction with
the symptom-based (reactive) Emergency Operating Procedures (EOPs) and
other symptom-based AOPs to provide a combined preventive (fire AOPs)
and reactive (EOPs and all AOPs, including fire) approach to achieve
safe shutdown following a fire. The individual fire area shutdown
procedures provide the operators with information as to the available
equipment (including instrumentation) that can be relied upon following
a fire. The fire AOP procedures provide specific guidance to the
operators as to what equipment could be affected by the fire and are
written in order of time criticality (i.e., the most time critical
actions are in the front of the procedure) to ensure that the actions
are taken within the analyzed time required in the safe shutdown
analysis.
With regard to staffing and demonstrations, the licensee stated
that three qualified operators are available to perform the manual
action at all times and that demonstrations were performed in the TMI-1
plant simulator and in the plant by operator walk downs to show that
the OMAs can be performed within the times as described in the safe
shutdown analysis.
3.4.2 Feasibility
The licensee's analysis demonstrates that, for the expected
scenario, the OMAs can be diagnosed and executed in 19 minutes while
the time available to complete them is 40 minutes. The licensee stated
that the 40-minute time limit itself is a conservative measure since
recent testing on the MU-V-20 backup air supply demonstrated that MU-V-
20 would only stay open for approximately 75 minutes. The licensee's
analysis also demonstrates that various factors, as discussed above,
have been considered to address uncertainties in estimating the time
available. Therefore, the OMA included in this review is feasible
because there is adequate time available for the operator to perform
the required manual actions to achieve and maintain hot shutdown
following a fire in Fire Zone AB-FZ-6.
3.4.3 Reliability
The stated completion time of 19 minutes provides reasonable
assurance that the OMA can reliably be performed under a wide range of
conceivable conditions by different plant crews because it, in
conjunction with the 21-minute margin and other installed fire
protection features, accounts for sources of uncertainty such as
variations in fire and plant conditions, factors unable to be recreated
in demonstrations and human-centered factors. Therefore, the OMA
included in this review is reliable because there is adequate time
available to account for uncertainties not only in estimates of the
time available, but also in estimates of how long it takes to diagnose
a fire and execute the OMAs (e.g., as based, at least in part, on a
plant demonstration of the actions under nonfire conditions).
3.5 Defense-In-Depth Summary
In summary, the defense-in-depth concept for a fire in Fire Zone
AB-FZ-6 provides a level of safety that results in the unlikely
occurrence of fires; rapid detection, control, and extinguishment of
fires that do occur; and the protection of structures, systems, and
components important to safety. As discussed above, in the unlikely
event of a fire that challenges safe shutdown capability, the licensee
has provided preventative and protective measures in addition to a
feasible and reliable OMA that together demonstrate the licensee's
ability to preserve or maintain safe shutdown capability at TMI-1 in
the event of a fire in Fire Zone AB-FZ-6.
3.6 Authorized by Law
This exemption would allow TMI-1 to utilize an OMA, in conjunction
with the other installed fire protection features, to ensure that at
least one means of achieving and maintaining hot shutdown remains
available during and following a postulated fire event, as part of its
fire protection program, in lieu of meeting the circuit separation and/
or protection requirements specified in III.G.2 for a fire in Fire Zone
AB-FZ-6. As stated above, 10 CFR 50.12 allows the NRC to grant
exemptions from the requirements of 10 CFR part 50. The NRC staff has
determined that granting of the licensee's proposed Exemption will not
result in a violation of the Atomic Energy Act of 1954, as amended, or
the Commission's regulations. Therefore, the exemption is authorized by
law.
3.7 No Undue Risk to Public Health and Safety
The underlying purpose of 10 CFR part 50, appendix R, section III.G
is to ensure that at least one means of achieving and maintaining hot
shutdown remains available during and following a postulated fire
event. Because the use of the specific OMA, in conjunction with the
other installed fire protection features, only impacts the response to
the specific Fire Zone AB-FZ-6 scenario described above, the
probability of postulated accidents is not increased. Also, based on
the above, the consequences of postulated accidents are not increased.
Therefore, there is no undue risk to public health and safety.
3.8 Consistent With Common Defense and Security
The proposed exemption would allow TMI-1 to utilize a specific OMA,
in conjunction with the other installed fire protection features, in
response to a fire in Fire Zone AB-FZ-6 in lieu of
[[Page 38850]]
meeting the requirements specified in III.G.2. This change, to the
operation of the plant, has no relation to security issues. Therefore,
the common defense and security is not diminished by this exemption.
3.9 Special Circumstances
Special circumstances in accordance with 10 CFR 50.12(a)(2)(ii) are
present whenever application of the regulation in the particular
circumstances is not necessary to achieve the underlying purpose of the
rule. The underlying purpose of 10 CFR Part 50, Appendix R, Section
III.G is to ensure that at least one means of achieving and maintaining
hot shutdown remains available during and following a postulated fire
event. Therefore, since the underlying purpose of Appendix R, Section
III.G is achieved, the special circumstances for granting an exemption
from 10 CFR Part 50, Appendix R, Section III.G exist, as required by 10
CFR 50.12(a)(2)(ii).
4.0 Conclusion
Accordingly, the Commission has determined that, pursuant to 10 CFR
50.12(a), the exemption is authorized by law, will not present an undue
risk to the public health and safety, and is consistent with the common
defense and security. Also, special circumstances are present.
Therefore, the Commission hereby grants Exelon an exemption from the
requirements of section III.G.2 of appendix R of 10 CFR part 50, to
TMI-1 for the OMA discussed above.
Pursuant to 10 CFR 51.32, the Commission has determined that the
granting of this exemption will not have a significant effect on the
quality of the human environment (75 FR 36700).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 28th day of June 2010.
For The Nuclear Regulatory Commission.
Joseph G. Giitter,
Director, Division of Operating Reactor Licensing, Office of Nuclear
Reactor Regulation.
[FR Doc. 2010-16352 Filed 7-2-10; 8:45 am]
BILLING CODE 7590-01-P