Proposed Generic Communication; Post-Fire Safe-Shutdown Circuit Analysis Spurious Actuations, 60859-60864 [E5-5752]

Agencies

• NUCLEAR REGULATORY COMMISSION

[Federal Register Volume 70, Number 201 (Wednesday, October 19, 2005)]
[Notices]
[Pages 60859-60864]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E5-5752]


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NUCLEAR REGULATORY COMMISSION


Proposed Generic Communication; Post-Fire Safe-Shutdown Circuit 
Analysis Spurious Actuations

AGENCY: Nuclear Regulatory Commission.

ACTION: Notice of opportunity for public comment.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is proposing to 
issue a generic letter (GL) to:
    (1) Request addressees to review their fire protection program to 
confirm compliance with existing applicable regulatory requirements 
regarding their assumptions of the phrase ``one-at-a-time'' in light of 
the information provided in this GL and, if appropriate, take 
additional actions to return to compliance. Specifically, although some 
licensees have performed their post-fire, safe-shutdown circuit 
analyses based on an assumption of only a single spurious actuation per 
fire event or that spurious actuations will occur ``one-at-a-time,'' 
recent industry cable fire test results demonstrated that these 
assumptions are not valid.
    (2) Require addressees to submit a written response to the NRC in 
accordance with NRC regulations in Title 10 of the Code of Federal 
Regulations, Section 50.54(f) (10 CFR 50.54(f)).
    This Federal Register notice is available through the NRC's 
Agencywide Documents Access and Management System (ADAMS) under 
accession number ML051650017.

DATES: Comment period expires [60 days after FRN is published]. 
Comments submitted after this date will be considered if it is 
practical to do so, but assurance of consideration cannot be given 
except for comments received on or before this date.

ADDRESSES: Submit written comments to the Chief, Rules and Directives 
Branch, Division of Administrative Services, Office of Administration, 
U.S. Nuclear Regulatory Commission, Mail Stop T6-D59, Washington, DC 
20555-0001, and cite the publication date and page number of this 
Federal Register notice. Written comments may also be delivered to NRC 
Headquarters, 11545 Rockville Pike (Room T-6D59), Rockville, Maryland, 
between 7:30 am and 4:15 pm on Federal workdays.

FOR FURTHER INFORMATION, CONTACT: Robert Wolfgang at 301-415-1624 or by 
e-mail rjw1@nrc.gov or Chandu Patel at 301-415-3025 or by e-mail at 
cpp@nrc.gov.

SUPPLEMENTARY INFORMATION: NRC Generic Letter 2005-Xx; Post-Fire Safe-
Shutdown Circuit Analysis Spurious Actuations.

Addresses

    All holders of operating licenses for nuclear power reactors, 
except those who have permanently ceased operations and have certified 
that fuel has been permanently removed from the reactor vessel.

Purpose

    The U.S. Nuclear Regulatory Commission (NRC) is issuing this 
generic letter (GL) to:
    (1) Request addressees to review their fire protection program to 
confirm compliance with existing applicable regulatory requirements 
regarding their assumptions of the phrase ``one-at-a-time'' in light of 
the information provided in this GL and, if appropriate, take 
additional actions to return to compliance. Specifically, although some 
licensees have performed their post-fire, safe-shutdown circuit 
analyses based on an assumption of only a single spurious actuation per 
fire event or that spurious actuations will occur ``one-at-a-time,'' 
recent industry cable fire test results demonstrated that these 
assumptions are not valid.
    (2) Require addressees to submit a written response to the NRC in 
accordance with NRC regulations in Title 10 of the Code of Federal 
Regulations, Section 50.54(f) (10 CFR 50.54(f)).
    The reason for this request is that the results from the Electric 
Power Research Institute (EPRI)/Nuclear Energy Institute (NEI) cable 
fire tests showed a relatively high probability of multiple spurious 
actuations occurring simultaneously or in rapid succession during or 
after a fire (ref. EPRI Report No. 1006961, ``Spurious Actuation of 
Electrical Circuits Due to Cable Fires: Results of an Expert 
Elicitation,'' dated May 2002 and NUREG/CR-6776, ``Cable Insulation 
Resistance Measurements Made During Cable Fire Tests,'' dated June 
2002). Some licensees have assumed only a single spurious actuation, 
and others have assumed that multiple spurious actuations can only 
occur ``one-at-a-time,'' with sufficient delay between actuations to 
allow for mitigation. The EPRI/NEI test data clearly show that the use 
of ``one-at-a-time'' spurious actuations assumption is not credible. If 
multiple spurious actuations occurring simultaneously or in rapid 
succession during or after a fire have not been considered by licensees 
in their post-fire safe-shutdown circuit analysis, it is possible that 
they are not in compliance with 10 CFR 50.48 and 10 CFR Part 50, 
General Design Criterion (GDC) 3. The licensees who conclude that they 
are no longer in compliance with 10 CFR 50.48 and 10 CFR Part 50, GDC 
3, based on the information provided in this GL, are expected to come 
into compliance with 10 CFR 50.48 and 10 CFR Part 50, GDC 3, using 
risk-informed or deterministic methods as appropriate to their 
licensing basis.

Background

    The regulatory requirements for post-fire safe shutdown are given 
in 10 CFR 50.48 and 10 CFR Part 50, Appendix A, GDC 3. Additionally, 
all nuclear power plants (NPPs) licensed to operate before January 1, 
1979, are required to comply with 10 CFR Part 50, Appendix R, Section 
III.G, ``Fire Protection of Safe Shutdown Capability.'' All NPPs 
licensed to operate after January 1, 1979, were evaluated against 
Section 9.5.1 of NUREG-0800, Standard Review Plan (SRP). The fire 
protection plan (FPP) and the associated safety evaluation report (SER) 
are specifically incorporated into those plants' licensing bases. All 
NPP licensees are responsible for meeting fire protection commitments 
and license conditions made during the establishment of their fire 
protection program.
    The objective of the fire protection requirements and guidance is 
to provide reasonable assurance that one train of systems necessary to 
achieve and maintain hot shutdown is free of fire damage. This includes 
protecting circuits whose fire-induced failure could prevent the 
operation, or cause maloperation, of equipment necessary to achieve and 
maintain post-fire safe shutdown. As part of its fire protection 
program, each licensee performs a

[[Page 60860]]

circuit analysis to identify these circuits and to provide adequate 
protection against fire-induced failures.
    Beginning in 1997, the NRC staff noticed that a series of licensee 
event reports (LERs) identified plant-specific problems related to 
potential fire-induced electrical circuit failures that could prevent 
operation, or cause maloperation, of equipment necessary to achieve and 
maintain hot shutdown. The staff documented these problems in 
Information Notice 99-17, ``Problems Associated With Post-Fire Safe-
Shutdown Circuit Analysis.'' Based on the number of similar LERs, the 
NRC treated the issue generically. In 1998 the NRC staff started to 
interact with interested stakeholders in an attempt to understand the 
problem and develop an effective risk-informed solution to the circuit 
analysis issue. NRC also issued Enforcement Guidance Memorandum (EGM) 
98-002, Rev. 2 (ADAMS Accession No. ML003710123), to provide a process 
for treating inspection findings while the issues were being clarified. 
Due to the number of different stakeholder interpretations of the 
regulations, the NRC decided to temporarily suspend the associated 
circuit part of fire protection inspections. This decision is 
documented in an NRC memorandum from John Hannon (Chief, Plant Systems 
Branch, Office of Nuclear Reactor Regulation (NRR)) to Gary Holahan 
(Director, DSSA, NRR) dated November 29, 2000 (ADAMS Accession No. 
ML003773142). In 2001 EPRI and NEI did a series of cable functionality 
fire tests to further the nuclear industry's understanding of fire-
induced circuit failures, particularly spurious equipment actuations 
initiated by hot shorts. EPRI coordinated this effort and issued the 
final report (EPRI Report No. 1006961). Additional analysis of the 
EPRI/NEI test results can be found in NUREG/CR-6776. Based on the test 
results, the NRC staff and NEI concluded that the probability of fire-
induced circuit failures can be relatively high and that there can be a 
relatively high probability of multiple spurious actuations occurring 
simultaneously or in rapid succession.

Discussion

    Although both the NRC and the industry have used the phrase ``one-
at-a-time'' in connection with post-fire spurious actuations caused by 
hot shorts, it is not defined in 10 CFR 50 regulations or guidance 
documents for fire protection. The phrase has been interpreted in at 
least two different ways. Some licensees have interpreted ``one-at-a-
time'' to mean that only one spurious actuation need be postulated for 
any single fire event. Other licensees have interpreted the term to 
mean that multiple spurious actuations do not occur simultaneously, and 
that there would be sufficient time between spurious actuations to 
allow operators to take corrective actions. NRC has issued SERs that 
accepted both interpretations for specific situations in specific 
plants (e.g., NUREG-0876, Supplement No. 6, ``Safety Evaluation Report 
related to the operation of Byron Station, Units 1 and 2,'' ADAMS 
Accession No. 8411200507). However, current NRC regulations only allow 
these interpretations with respect to the design of alternate shutdown 
capability. The EPRI/NEI cable fire testing conducted in 2001 
demonstrated that neither interpretation conforms with the likely 
effects of a fire in an area containing safe-shutdown cables. 
Therefore, these interpretations do not ensure safe shutdown.
    In a S.J. Collins (NRC) letter to R.E. Beedle (NEI) dated March 11, 
1997 (ADAMS Accession No. ML003716454), the NRC reiterated its position 
that multiple spurious actuations must be considered and evaluated. 
Subsequent to the Collins letter, the 2001 EPRI/NEI fire testing 
demonstrated that multiple spurious actuations can occur with a 
relatively high likelihood and that they can occur simultaneously or in 
rapid succession without sufficient time for mitigation between 
actuations.
    One of the key observations of the test report was that, ``given 
that a hot short occurs in a multi-conductor cable, it is highly 
probable (over 80 percent) that multiple target conductors will be 
affected (i.e., multiple simultaneous dependent hot shorts).'' The 
testing covered most of the types of cable insulation and jacketing 
materials and types of raceways commonly used in nuclear power plants. 
During the testing, numerous variables were introduced to investigate 
the impact of various factors on cable performance and failure 
characteristics.
    While the staff has maintained that post-fire multiple spurious 
actuations should be considered, the number of actuations that must be 
considered has not been defined. Since the deterministic approach to 
post-fire safe-shutdown analyses assumes that all cables in a fire area 
are damaged by the fire (except where protection is provided in 
accordance with Section III.G.2 of 10 CFR part 50, Appendix R), it 
follows that all possible spurious actuations, as well as the 
cumulative effect of the actuations, should be considered.
    The SERs incorporated into the licensing bases of some plants (for 
example, Byron and Braidwood) specifically allow a design assumption of 
a single spurious actuation per fire event when performing the post-
fire safe-shutdown circuit analysis. However, most plants postulated in 
their licensing basis that multiple spurious actuations occur one-at-a-
time. All plants must review their circuits analysis, assuming possible 
multiple spurious actuations occurring simultaneously from a fire. 
Depending on the results of this review, licensees may conclude that 
they are no longer in compliance with the fire protection regulations. 
Those licensees who determine that they are no longer in compliance 
will either have to make plant modifications to protect against 
possible multiple spurious actuations or request an exemption (or 
license amendment, as applicable) as described in the ``METHODS OF 
COMPLIANCE'' section of this GL.
    An NEI letter dated May 30, 1997, presents the industry's position 
on the phrase ``one-at-a-time.'' The industry's position is that 
``possible functional failure states from a single hot short in the 
component's control circuitry should be analyzed one-at-a-time (not 
sequentially nor with cumulative consequences) for a fire in a certain 
fire area.'' As one basis for this position, the letter references the 
Response to Question 5.3.10 in GL 86-10, ``Implementation of Fire 
Protection Requirements.'' Although this response states that ``the 
safe shutdown capability should not be adversely affected by any one 
spurious actuation or signal resulting from a fire in any plant area,'' 
per Question 5.3.10, the response applies only to Appendix R, Section 
III.L, ``Alternative and Dedicated Shutdown Capability.'' The NRC 
emphasized this position in a letter from Dennis M. Crutchfield (Chief, 
Operating Reactors Branch 5, Division of Licensing) to P.B. 
Fiedler (Vice President & Director--Oyster Creek) dated April 30, 1982 
(ADAMS Accession No. ML011150521) by stating that ``it is essential to 
remember that these alternative requirements (i.e., III.G.3 and III.L) 
are not deemed to be equivalent'' to III.G.2 protection.
    As noted in the attachment to a February 6, 1997, memorandum from 
L.B. Marsh (Chief, Plant Systems Branch, NRR) to J.F. Stolz (Director, 
Project Directorate I-2) regarding the NRC policy on the interpretation 
of NRC GL 86-10 guidance on spurious valve actuation, the reference to 
``any one spurious actuation'' in the response to Question 5.3.10 is 
intended to provide

[[Page 60861]]

a design basis for determining the capacity and capability of the 
alternative or dedicated shutdown train (e.g., size of the pump and the 
support systems needed to maintain reactor coolant inventory, the scope 
of onsite electrical power distribution and power needs, and an 
operational baseline and set of plant conditions to define the scope of 
initial manual actions to restore systems necessary to accomplish the 
required reactor performance goals). Again, these alternative 
requirements do not provide the same level of protection as III.G.2. 
NEI also stated in the May 30, 1997, letter that ``any other 
interpretation leads to complex and costly analysis which is not 
justified for the very small safety benefit.'' The NEI letter offered 
no assessment of the safety significance of multiple sequential and 
cumulative failures. It is important to note that the NEI letter of May 
30, 1997, preceded the 2001 EPRI/NEI fire testing, and that before the 
testing, the industry had long claimed that spurious actuations were 
not credible. As noted above, the cable functionality fire testing 
demonstrated that multiple spurious actuations can occur and that they 
can occur in rapid succession without sufficient time for mitigation. 
Therefore, if a licensee does not account for multiple spurious 
actuations in their circuits analysis, they are not in compliance with 
10 CFR 50.48 and 10 CFR part 50, GDC 3, which require that a licensee 
is to provide reasonable assurance that one train of systems necessary 
to achieve and maintain hot shutdown is free of fire damage.

Methods of Compliance

    Based on the information provided in this GL, if a licensee 
concludes that they are no longer in compliance with the fire 
protection regulations, there are several acceptable methods for them 
to re-establish full regulatory compliance. One way is to re-perform 
the post-fire safe-shutdown circuit analysis based on guidance provided 
in this GL and make modifications necessary to come into compliance. 
Another method to address this issue is to perform either a risk-
informed evaluation that considers defense-in-depth and safety margins 
or a deterministic evaluation:
     If a licensee proposes to use a risk-informed approach to 
justify an exemption in accordance with 10 CFR 50.12, then this 
approach should follow the guidance of RG 1.174, ``An Approach for 
Using Probabilistic Risk Assessment in Risk-Informed Decisions on 
Plant-Specific Changes to the Licensing Basis.''
     For those licensees who have adopted the standard fire 
protection license condition as promulgated in GL 86-10, changes to the 
approved fire protection program can be made without prior staff 
approval if those changes would not adversely affect the ability to 
achieve and maintain safe shutdown in the event of a fire. GL 86-10, 
``Implementation of Fire Protection Requirements,'' provides guidance 
on performing and documenting these changes. Plants licensed after 
January 1, 1979, that use a risk-informed approach must submit a 
license amendment in accordance with 10 CFR 50.90. The exception to 10 
CFR 50.90, provided in the standard license condition and in 10 CFR 
50.48(f)(3), does not apply because the risk assessment approaches used 
by plants deviate from the approved deterministic approaches used in 
their licensing basis. Furthermore, the licensees' risk assessment 
tools have not been reviewed or inspected against quality standards 
found acceptable to the NRC staff. Consequently, the staff believes 
that the use of risk informed approaches without prior NRC approval may 
result in changes that could adversely affect safe shutdown.
    Fire modeling and risk techniques acceptable to the staff should be 
used when performing risk-informed evaluations.
    An additional method to achieve compliance is the adoption of a 
performance-based fire protection program in accordance with 10 CFR 
50.48(c), ``National Fire Protection Association Standard NFPA 805.'' 
The Draft Regulatory Guide DG-1139, ``Risk-Informed, Performance-Based 
Fire Protection for Existing Light-Water Nuclear Power Plants,'' dated 
September 2004 (ADAMS Accession No. ML042740308) and NEI 04-02, 
``Guidance for Implementing a Risk-Informed, Performance-Based Fire 
Protection Program Under 10 CFR 50.48(c),'' Rev. 0, dated May 2005 
(ADAMS Accession No. ML051440805), provide additional guidance to 
licensees who plan to use this option.

Applicable Regulatory Requirements

    NRC regulations in 10 CFR 50.48 and 10 CFR Part 50, Appendix A, GDC 
3, require each operating NPP (licensed before or after issuance of GDC 
3) to have a FPP providing post-fire safe shutdown capability. That is, 
a means must be provided of ensuring that one of the redundant trains 
of safe shutdown structures, systems, and components must be protected 
so that it remains free of fire damage, allowing safe shutdown of the 
plant. The regulation in 10 CFR 50.90 requires a licensee who desires 
to amend their license, to submit an amendment request to the NRC. A 
NPP licensed to operate before January 1, 1979, may submit an exemption 
request in accordance with 10 CFR 50.12.
    All NPPs licensed to operate before January 1, 1979 (pre-1979 
plants), are required to comply with 10 CFR Part 50, Appendix R, 
paragraph III.G, ``Fire Protection of Safe Shutdown Capability.'' 
Paragraph III.G states, in part, that ``one train of systems necessary 
to achieve and maintain hot shutdown conditions from either the control 
room or emergency control station(s) is free of fire damage.'' 
Paragraph III.G.2 states, in part, ``where cables or equipment, 
including associated non-safety circuits that could prevent operation 
or cause maloperation due to hot shorts, open circuits, or shorts to 
ground, of redundant trains of systems necessary to achieve and 
maintain hot shutdown conditions are located within the same fire area 
outside of primary containment, one of the following means of ensuring 
that one of the redundant trains is free of fire damage shall be 
provided:'' All NPPs licensed to operate after January 1, 1979, are 
required to comply with 10 CFR 50.48(a), which requires that each 
operating NPP have a FPP that satisfies GDC 3. The FPP is incorporated 
into the operating license for post-1979 plants as a license condition. 
This license condition specifically cites the staff SER in the 
licensee's FPP, to demonstrate that the license condition has been met 
(although licensees may modify their FPP as long as there is no adverse 
effect on safe shutdown).
    Based on the new information provided by the EPRI/NEI cable fire 
tests, approved fire protection programs that do not include protection 
against possible multiple spurious actuations occurring simultaneously 
(including programs for plants with SERs that specifically approve an 
assumption of one-only spurious actuation per fire event) may not 
comply with these regulatory requirements.

Applicable Regulatory Guidance

    Fire-induced hot shorts that cause spurious actuations can prevent 
a train from performing its post-fire safe-shutdown function. NRC 
regulations, while noting that spurious actuations must be considered, 
do not set a limit on the number of spurious actuations that can occur. 
In addition, NRC regulations do not state whether multiple spurious 
actuations should be assumed to occur simultaneously or sequentially.
    Any limits or assumptions used by the licensee in performing the 
post-fire safe-shutdown circuit analysis should be adequately 
justified.

[[Page 60862]]

    In order to demonstrate compliance with the regulatory requirement 
that one safe shutdown train remain free of fire damage, licensees must 
address the potential for multiple, concurrent spurious actuations by 
analyzing for these failures and providing adequate protection where 
required. Fire modeling techniques and risk analysis techniques which 
the staff has found acceptable are provided in Section 4.0 of Draft 
Regulatory Guide DG-1139, ``Risk-Informed, Performance-Based Fire 
Protection for Existing Light-Water Nuclear Power Plants,'' dated 
September 2004 (ADAMS Accession No. ML042740308) and may be used in the 
evaluations.
    The deterministic methodology in NEI 00-01, Rev. 1 (January 2005), 
``Guidance for Post-Fire Safe Shutdown Circuit Analysis,'' Chapter 3, 
for analysis of post-fire safe-shutdown circuits, in conjunction with 
the guidance provided in this GL, is one acceptable approach to 
achieving regulatory compliance with post-fire safe-shutdown circuit 
protection requirements for multiple spurious actuations. Licensees 
should assume that the fire may affect all unprotected cables and 
equipment within the fire area and address all cable and equipment 
impacts affecting the required safe shutdown path in the fire area. All 
potential impacts within the fire area must be addressed.
    The risk significance analysis methodology provided in Chapter 4 of 
NEI 00-01 should not be applied as a basis for regulatory compliance, 
except where a National Fire Protection Association (NFPA) 805 
licensing basis has been adopted in accordance with 10 CFR 50.48(c). 
Risk-informed or performance-based methodologies that use the methods 
and information provided in NEI 00-01 (e.g., Chapter 4 and Appendix B-
1) may be used to support exemption requests for plants that have not 
adopted an NFPA licensing basis. Furthermore, regardless of the plant 
licensing basis, the NRC agrees with the NEI 00-01 guidance that ``all 
failures deemed to be risk significant, whether they are clearly 
compliance issues or not, should be placed in the Corrective Action 
Program with an appropriate priority for action.'' The remaining 
sections of NEI 00-01 provide acceptable circuit analysis guidance on 
both the deterministic approach and the risk-informed, performance-
based approach.

Requested Actions

    Within 90 days of the date of this letter, all addressees are 
requested to take the following actions:
    (1) Assess plant post-fire safe-shutdown circuit analyses for 
regulatory compliance in accordance with the information contained in 
this GL. The NRC informed licensees of these compliance expectations in 
a public meeting in October 2004 (ADAMS Accession No. ML043290020).
    (2) Take appropriate compensatory measures in accordance with plant 
fire protection programs if the addressees' interpretation and use of 
multiple spurious actuations in their circuits analysis leads to the 
conclusion that the addressee is no longer in compliance with the fire 
protection regulations.
    (3) Submit licensee's plans for plant modifications, license 
amendments or exemption requests that the above evaluation identifies 
as necessary to re-establish compliance with regulatory requirements 
and the plant's licensing basis in accordance with the information 
contained in this GL.

Requested Information

    All addressees are requested to provide the following information:
    (1) Within 90 days of the date of this GL, provide a statement on 
whether or not you conclude you are in compliance with the regulatory 
requirements as described in the Applicable Regulatory Requirements 
section of this GL. Addressees who conclude that they continue to be in 
compliance with the regulatory requirements in light of the information 
provided in this GL should state the basis for their conclusion.
    (2) Addressees who conclude that they are not in compliance with 
the regulatory requirements as described in the Applicable Regulatory 
Requirements section of this GL, provide the following information:
    a. An assessment of the functionality of affected structures, 
systems, and components that addresses the ability to achieve and 
maintain safe shutdown in light of multiple spurious hot shorts as a 
result of a fire. An acceptable assessment would be consistent with an 
evaluation performed for GL 91-18, Rev. 1.
    b. A detailed description of the compensatory measures in place to 
maintain the safe shutdown function of affected areas of the plant, and 
an explanation of how the compensatory measures provide adequate 
protection.
    c. A general description and planned schedule for any plant 
modifications made to ensure compliance with the regulatory 
requirements listed in the Applicable Regulatory Requirements section 
of this GL.
    d. A general description and planned schedule for any changes to 
the plant licensing bases resulting from any evaluation performed to 
ensure compliance with the regulatory requirements listed in the 
Applicable Regulatory Requirements section of this GL. Include a 
discussion and schedule for any license amendment or exemption requests 
needed to support changes to the plant licensing basis.
    e. Where the licensee plans no action under (a) or (b) or (c) or 
(d), provide a justification for not assessing safety significance or 
taking compensatory and corrective actions.

Required Response

    In accordance with 10 CFR 50.54(f), in order to determine whether a 
facility license should be modified, suspended, or revoked, or whether 
other action should be taken, an addressee is required to respond as 
described below.
    Within 30 days of the date of this GL, an addressee is required to 
submit a written response if it is unable to provide the information or 
it cannot meet the requested completion date. The addressee must 
address in its response any alternative course of action that it 
proposes to take, including the basis for the acceptability of the 
proposed alternative course of action.
    The required written responses should be addressed to the U.S. 
Nuclear Regulatory Commission, ATTN: Document Control Desk, 11555 
Rockville Pike, Rockville, Maryland 20852, under oath or affirmation 
under the provisions of Section 182a of the Atomic Energy Act of 1954, 
as amended, and 10 CFR 50.54(f). In addition, submit a copy of the 
response to the appropriate regional administrator.

Reason for Information Request

    As discussed above, EPRI/NEI-performed cable fire testing in 2001 
demonstrated that multiple spurious actuations can occur with 
relatively high likelihood and that they can occur simultaneously or in 
rapid succession without sufficient time for mitigation between 
actuations.
    However, many licensees' circuits analysis and/or safe-shutdown 
analysis did not consider this relatively high probability.
    The NRC staff will review the responses to this GL and will notify 
affected addressees if concerns are identified regarding compliance 
with NRC regulations. The staff may also conduct inspections to 
determine addressees' effectiveness in addressing the GL.

Related Generic Communications

    GL 86-10, ``Implementation of Fire Protection Requirements,'' April 
24, 1986.

[[Page 60863]]

    GL 91-18 Rev. 1, ``Information to Licensees Regarding NRC 
Inspection Manual Section on Resolution of Degraded and Nonconforming 
Conditions,'' October 8, 1997.
    Information Notice (IN) 92-18, ``Potential for Loss of Remote 
Shutdown Capability During a Control Room Fire,'' February 28, 1992.
    RIS 2004-03, ``Risk-Informed Approach for Post-Fire Safe-Shutdown 
Associated Circuit Inspections,'' March 2, 2004.
    RIS 2004-03 Rev. 1, ``Risk-Informed Approach for Post-Fire Safe 
Shutdown Circuit Inspections,'' December 29, 2004.
    RIS 2005-XXX, ``Clarification of Post-Fire Safe-Shutdown Circuit 
Regulatory Requirements'' (Draft issued for public comment on May 13, 
2005).

Backfit Discussion

    Under the provisions of Section 182a of the Atomic Energy Act of 
1954, as amended, 10 CFR 50.109(a)(4)(I), and 10 CFR 50.54(f), this GL 
requests addressees to evaluate their facilities to confirm compliance 
with the existing applicable regulatory requirements as discussed in 
this GL. The fundamental regulatory requirement is that at least one 
safe-shutdown path be maintained free of fire damage in the event of 
fire. The NRC's position concerning this regulatory requirement has not 
changed. All NPPs licensed to operate before January 1, 1979, (pre-1979 
plants) are required to comply with 10 CFR Part 50, Appendix R, 
paragraph III.G, ``Fire Protection of Safe Shutdown Capability,'' 
including Paragraph III.G.2. Paragraph III.G states, in part, that 
``one train of systems necessary to achieve and maintain hot shutdown 
conditions from either the control room or emergency control station(s) 
is free of fire damage.'' Paragraph III.G.2 states, in part, ``where 
cables or equipment, including associated non-safety circuits that 
could prevent operation or cause maloperation due to hot shorts, open 
circuits, or shorts to ground, of redundant trains of systems necessary 
to achieve and maintain hot shutdown conditions are located within the 
same fire area outside of primary containment, one of the following 
means of ensuring that one of the redundant trains is free of fire 
damage shall be provided:''
    All NPPs licensed to operate after January 1, 1979, are required to 
comply with 10 CFR 50.48(a), which requires that each operating nuclear 
power plant have a FPP that satisfies GDC 3. The fire protection plan 
is incorporated into the operating license for post-1979 plant as a 
license condition. This license condition specifically cites the staff 
SER on the licensee's FPP, to demonstrate that the license condition 
has been met (although licensees may modify their FPP as long as there 
is no adverse effect on safe shutdown). All NPP licensees are required 
to implement their approved fire protection program, considering 
multiple spurious actuations, in accordance with the applicable 
regulatory requirements.
    Fire-induced hot shorts that cause spurious actuations can prevent 
a train from performing its post-fire safe shutdown function. The 
regulations note that spurious actuations must be considered. Prior to 
the EPRI/NEI cable fire tests in 2001, very little data was available 
to provide a basis for predicting the extent or behavior of spurious 
actuations during a fire. Based on the available data and expert 
opinion, the industry assumed and, in some specific cases, the NRC 
accepted that spurious actuations that could prevent safe shutdown were 
highly improbable. Consequently, some licensees assumed only a single 
spurious actuation per fire event. Others assumed multiple spurious 
actuations, but assumed that they would only occur ``one-at-a-time'' 
with time between actuations to take corrective actions. These 
assumptions were never included in the regulations or generally adopted 
by the NRC.
    The 2001 EPRI/NEI fire test program demonstrated that the previous 
assumptions regarding spurious actuations do not adequately address the 
potential risk to safe shutdown. The EPRI/NEI cable fire tests clearly 
showed, during and after a fire, a relatively high probability that 
multiple spurious actuations will occur simultaneously or in rapid 
succession. Consequently, to demonstrate compliance with the regulatory 
requirement that one safe shutdown train remain free of fire damage 
(which has always been the NRC's position), and with licensees' 
licensing bases, licensees must address the potential for multiple 
concurrent spurious actuations by analyzing these failures and 
providing adequate protection where required.
    The information requested by this GL is therefore considered a 
compliance exception to the rule in accordance with 10 CFR 
50.109(a)(4)(I), as the staff's position set out in this GL regarding 
the term ``one-at-a-time'' is necessary for compliance with 10 CFR 50, 
Appendix R, Paragraph III.G (with respect to pre-1979 plants) and, with 
respect to post-1979 plants, is necessary for compliance with the 
plants' license conditions regarding fire protection.
    With regard to plants for which the NRC had in the past 
specifically accepted the assumption that only a single spurious 
actuation would occur per fire event, or that multiple spurious 
actuations would occur ``one-at-a-time'' with time between actuations 
to take corrective actions, this GL is considered a compliance 
exception to the backfit rule, in accordance with 10 CFR 
50.109(a)(4)(I). New information from the 2001 EPRI/NEI cable fire 
tests has shown that multiple, simultaneous spurious actuations must be 
considered for these licensees to be in compliance with NRC's unchanged 
interpretation of its fire protection requirements, which require that 
one safe shutdown train remain free of fire damage.

Federal Register Notification

    A notice of opportunity for public comment on this GL was published 
in the Federal Register (XX FR XXXXX) on October XX, 2005.

Small Business Regulatory Enforcement Fairness Act

    The NRC has determined that this action is not subject to the Small 
Business Regulatory Enforcement Fairness Act of 1996.

Paperwork Reduction Act Statement

    This GL contains information collections that are subject to the 
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.). These 
information collections were approved by the Office of Management and 
Budget (OMB), clearance number 3150-0011, which expires on February 28, 
2007.
    The burden to the public for these mandatory information 
collections is estimated to average 300 hours per response, including 
the time for reviewing instructions, searching existing data sources, 
gathering and maintaining the data needed, and completing and reviewing 
the information collection. The U.S. Nuclear Regulatory Commission is 
seeking public comment on the potential impact of the information 
collections contained in the GL and on the following issues:
    1. Is the proposed information collection necessary for the proper 
performance of the functions of the NRC, including whether the 
information will have practical utility?
    2. Is the estimate of burden accurate?
    3. Is there a way to enhance the quality, utility, and clarity of 
the information collected?
    4. How can the burden of the information collection be minimized, 
including the use of automated collection techniques?

[[Page 60864]]

    Send comments on any aspect of these information collections, 
including suggestions for reducing the burden, to the Records and FOIA/
Privacy Services Branch (T5-F52), U.S. Nuclear Regulatory Commission, 
Washington, DC 20555-0001, or by Internet electronic mail to 
BJS1@NRC.GOV; INFOCOLLECTS@NRC.GOV; and to the Desk Officer, Office of 
Information and Regulatory Affairs, NEOB-10202 (3150-0011), Office of 
Management and Budget, Washington, DC 20503.

Public Protection Notice

    The NRC may not conduct nor sponsor, and a person is not required 
to respond to, an information collection unless the requesting document 
displays a currently valid OMB control number.

Contact

    Please direct any questions about this matter to the technical 
contact or the Lead Project Manager listed below, or to the appropriate 
Office of Nuclear Reactor Regulation (NRR) project manager.
    Bruce A. Boger, Director, Division of Inspection Program 
Management, Office of Nuclear Reactor Regulation.
    Technical Contact: Robert Wolfgang, NRR, 301-415-1624, E-mail: 
rjw1@nrc.gov.
    Lead Project Manager: Chandu Patel, NRR, 301-415-3025, E-mail: 
cpp@nrc.gov.

    Note: NRC generic communications may be found on the NRC public 
Web site, https://www.nrc.gov under Electronic Reading Room/Document 
Collections.

End of Draft Generic Letter

    Documents may be examined, and/or copied for a fee, at the NRC's 
Public Document Room at One White Flint North, 11555 Rockville Pike 
(first floor), Rockville, Maryland. Publicly available records will be 
accessible electronically from the Agencywide Documents Access and 
Management System (ADAMS) Public Electronic Reading Room on the 
Internet at the NRC Web site, https://www.nrc.gov/NRC/ADAMS/. 
If you do not have access to ADAMS or if you have problems in accessing 
the documents in ADAMS, contact the NRC Public Document Room (PDR) 
reference staff at 1-800-397-4209 or 301-415-4737 or by e-mail to 
pdr@nrc.gov.

    Dated at Rockville, Maryland, this 13th day of October 2005.

    For the Nuclear Regulatory Commission.
Michael J. Case,
Deputy Director, Division of Inspection Program Management, Office of 
Nuclear Reactor Regulation.
 [FR Doc. E5-5752 Filed 10-18-05; 8:45 am]
BILLING CODE 7590-01-P