Proposed Generic Communication; Clarification of Post-Fire Safe-Shutdown Circuit Regulatory Requirements, 25622-25628 [E5-2377]

Agencies

• NUCLEAR REGULATORY COMMISSION

[Federal Register Volume 70, Number 92 (Friday, May 13, 2005)]
[Notices]
[Pages 25622-25628]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E5-2377]


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NUCLEAR REGULATORY COMMISSION


Proposed Generic Communication; Clarification of Post-Fire Safe-
Shutdown Circuit Regulatory Requirements

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 regulatory information summary (RIS) to clarify regulatory 
requirement issues associated with post-fire safe-shutdown circuit 
analyses and protection, particularly the requirements of Title 10 of 
the Code of Federal Regulations, Part 50 (10 CFR 50), Appendix R, which 
have been interpreted by licensees in a manner that is not consistent 
with regulatory expectations. The industry and NRC regional inspectors 
have requested clarification of regulatory expectations with respect to 
post-fire safe-shutdown circuits. In addition, clarification of these 
requirements will assist licensees in evaluating the transition to a 
risk-informed, performance-based fire protection program.
    Three terms are to be addressed in this RIS: ``any-and-all'' (with 
respect to spurious actuations), ``associated circuits,'' and 
``emergency control station.'' Clarification of the term ``one-at-a-
time'' (with respect to spurious actuations) will be provided in a 
separate generic communication. For each term addressed, this RIS 
identifies the applicable NRC regulatory requirement, provides the 
regulatory expectation with respect to the requirement, and specifies 
one acceptable approach to achieving regulatory compliance.
    Attachment 1 to this RIS provides additional discussion that 
explains the basis for the regulatory expectations, including a 
discussion of the various ways in which each term or phrase has been 
interpreted by stakeholders.
    This RIS also gives the staff's views on the use of Nuclear Energy 
Institute (NEI) guidance document NEI 00-01, ``Guidance for Post-Fire 
Safe Shutdown Circuit Analysis,'' Revision 1 (ML050310295), in 
complying with Appendix R. The deterministic methodology presented in 
NEI 00-01, in conjunction with the guidance in this RIS, is one 
acceptable approach to achieving regulatory compliance with post-fire 
safe-shutdown circuit protection requirements. Note that RIS 2004-03, 
Revision 1, ``Risk-Informed Approach for Post-Fire Safe-Shutdown 
Circuit Inspections'' (ML042440791) provides guidance on conducting 
risk-informed circuit inspections, whereas this RIS clarifies the 
regulatory requirements for compliance with Appendix R.
    This Federal Register notice is available through the NRC's 
Agencywide Documents Access and Management System (ADAMS) under 
accession number ML051110160.

DATES: Comment period expires July 12, 2005. 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 F. Radlinski at 301-415-3174 
or by email rfr1@nrc.gov, Chandu Patel at 301-415-3025 or email 
cpp@nrc.gov, or Sunil Weerakkody at 301-415-2870 or by email at 
sdw1@nrc.gov.

SUPPLEMENTARY INFORMATION: 

NRC Regulatory Issue Summary 2005-XX; Clarification of Post-Fire Safe-
Shutdown Circuit Regulatory Requirements

Addressees

    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.

Intent

    The U.S. Nuclear Regulatory Commission (NRC) is issuing this

[[Page 25623]]

regulatory issue summary (RIS) to clarify regulatory requirement issues 
associated with post-fire safe-shutdown circuit analyses and 
protection, particularly the requirements of Title 10 of the Code of 
Federal Regulations, Part 50 (10 CFR 50), Appendix R, which have been 
interpreted by licensees in a manner that is not consistent with 
regulatory expectations.
    The industry and NRC regional inspectors have requested 
clarification of regulatory expectations with respect to post-fire 
safe-shutdown circuits. In addition, clarification of these 
requirements will assist licensees in evaluating the transition to a 
risk-informed performance-based fire protection program.
    Three terms are to be addressed in this RIS: ``any-and-all'' (with 
respect to spurious actuations), ``associated circuits,'' and 
``emergency control station.'' Clarification of the term ``one-at-a-
time'' (with respect to spurious actuations) will be provided in a 
separate generic communication. For each term addressed, this RIS 
identifies the applicable NRC regulatory requirement, provides the 
regulatory expectation with respect to the requirement, and specifies 
one acceptable approach to achieving regulatory compliance.
    Attachment 1 to this RIS provides additional discussion that 
explains the basis for the regulatory expectations, including a 
discussion of the various ways in which each term or phrase has been 
interpreted by stakeholders.
    This RIS also gives the staff's views on the use of Nuclear Energy 
Institute (NEI) guidance document NEI 00-01, ``Guidance for Post-Fire 
Safe Shutdown Circuit Analysis,'' Revision 1 (ML050310295), in 
complying with Appendix R. The deterministic methodology presented in 
NEI 00-01, in conjunction with the guidance in this RIS, is one 
acceptable approach to achieving regulatory compliance with post-fire 
safe-shutdown circuit protection requirements. Note that RIS 2004-03, 
Revision 1, ``Risk-Informed Approach for Post-Fire Safe-Shutdown 
Circuit Inspections'' (ML042440791) provides guidance on conducting 
risk-informed circuit inspections, whereas this RIS clarifies the 
regulatory requirements for compliance with Appendix R.
    This RIS requires no action or written response on the part of an 
addressee.

Background Information

    The regulatory requirements regarding post-fire safe shutdown are 
contained in 10 CFR 50.48 and 10 CFR Part 50, Appendix A, General 
Design Criterion (GDC) 3. Additionally, all nuclear power plants (NPPs) 
licensed to operate prior to 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). All NPP licensees are responsible for meeting fire 
protection and license condition commitments 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 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, Revision 2 (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 portion of 
fire protection inspections. This decision is documented in an NRC 
memorandum from John Hannon to Gary Holahan dated November 29, 2000 
(ML003773142). In 2001 the Electric Power Research Institute (EPRI) and 
NEI performed a series of cable functionality fire tests to further the 
nuclear industry's knowledge about the nature and characteristics of 
fire-induced circuit failures, particularly the potential for spurious 
equipment actuations initiated by hot shorts. The Electric Power 
Research Institute (EPRI) coordinated this effort and issued the final 
report, ``Spurious Actuation of Electrical Circuits Due to Cable Fires: 
Results of an Expert Elicitation'' (Report No. 1006961, May 2002).\1\ 
The results of the testing were considered in the preparation of NEI 
00-01.
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    \1\ Additional analysis of the EPRI/NEI test results can be 
found in NUREG/CR-6776, ``Cable Insulation Resistance Measurements 
Made During Cable Fire Tests,'' which can be accessed on the NRC's 
public Web site.
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    Over the past 5 years, the industry and the staff have worked 
together to gain a better understanding of possible and probable modes 
of circuit failures. This work has included numerous meetings and 
facilitated public workshops. Based on this work the staff has 
identified circuit configurations that are likely to fail in the event 
of a fire and circuit configurations that have little or no likelihood 
of failing. The results of this work are reflected in RIS 2004-03 and 
in the revised inspection procedures. Inspection of fire-induced safe-
shutdown circuits was resumed in January 2005.
    The issues clarified in this RIS were discussed in an NRC public 
meeting on October 14, 2004, in Atlanta, GA (Summary of October 2004 
Public Meeting on Fire Protection in Atlanta, ML043290020). The 
clarifications in this RIS have considered the comments provided by 
stakeholders during the October meeting and subsequent to the meeting.

Summary of Issue

    Although the NRC has issued a number of guidance documents to 
assist licensees in assuring compliance with fire protection 
requirements, certain terms related to post-fire safe-shutdown circuit 
analysis have been interpreted differently by stakeholders or in a 
manner inconsistent with our regulatory expectations/requirements. In 
accordance with SECY-99-143, ``Revisions to Generic Communication 
Program,'' dated May 26, 1999 (ML992850037), the staff believes that a 
RIS is the appropriate regulatory vehicle to address this need for 
additional clarification. This RIS clarifies terms related to post-fire 
safe-shutdown circuits to help a licensee understand the staff's 
expectations with respect to regulatory requirements.
    The variety of interpretations of the terms addressed in this RIS 
is due in part to the previous lack of knowledge regarding the 
potential for certain types of circuit failure mechanisms. The cable 
fire tests performed by EPRI/NEI

[[Page 25624]]

significantly increased the body of knowledge available to the industry 
and the NRC with respect to fire-induced circuit failures and their 
potential to cause spurious actuations that could impact post-fire safe 
shutdown. The staff positions presented in this RIS are justified based 
on the potential safety significance of these issues and on compliance 
with the current regulations applicable to these circuits. The staff 
positions are also consistent with the National Fire Protection 
Association (NFPA) industry consensus standard NFPA 805, ``Performance-
Based Standard for Fire Protection for Light Water Reactor Electric 
Generating Plants,'' 2001 Edition, as they relate to deterministic-
based fire protection program features.
    The positions presented in this RIS describe the bases for 
compliance with the current deterministic regulations applicable to 
post-fire safe-shutdown circuits. With the issuance of 10 CFR 50.48(c), 
licensees have the alternative of adopting a fire protection licensing 
basis which allows the use of risk-informed, performance-based methods 
to address program features that do not comply with the deterministic 
regulations. In accordance with 10 CFR 50.12 and 10 CFR 50.90, 
licensees may also submit exemption requests or license amendment 
requests for NRC's consideration where deviations from the regulatory 
requirements can be adequately justified for a plant-specific 
condition.
    The deterministic methodology in NEI 00-01, Chapter 3, for analysis 
of post-fire safe-shutdown circuits, in conjunction with the guidance 
provided in this RIS, is one acceptable approach to achieving 
regulatory compliance with post-fire safe-shutdown circuit protection 
requirements. 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 an NFPA 805 licensing basis has been adopted in 
accordance with 10 CFR 50.48(c). Risk-informed or performance-based 
methodologies which use the methods and information provided in NEI 00-
01 (e.g., Chapter 4 and Appendix B-1) may also be used to support 
exemption requests for plants that have not adopted an NFPA 805 
licensing basis. Furthermore, regardless of the plant licensing basis, 
the NRC endorses 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 plant 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.
    The phrase ``one-at-a-time,'' as used to characterize fire-induced 
hot shorts that cause spurious actuations that could impact safe 
shutdown has been interpreted in a number of different ways. However, 
since the staff position on the regulatory basis for this phrase may be 
considered a new staff position by some stakeholders, the staff 
position on this phrase will be handled in a separate generic 
communication.
    Three terms are to be addressed in this RIS: ``any-and-all'' (with 
respect to spurious actuations), ``associated circuits,'' and 
``emergency control station.'' The discussion for each term includes a 
summary description of the regulatory requirement, a statement of the 
NRC staff position and a method to achieve compliance. A more detailed 
discussion of the staff's positions is contained in the Attachment.

Any-and-All

    A. NRC Regulatory Requirement--Paragraph III.G.2 of Appendix R 
states that ``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'' 
must be protected.
    B. NRC Staff Position--The requirement to protect against ``any-
and-all'' spurious actuations is implicit in Paragraph III.G.2. Post-
fire safe-shutdown circuit analyses should address any-and-all possible 
failures and combinations of multiple failures caused by spurious 
actuations resulting from fire-induced circuit failures in redundant 
systems in areas in which the failures could impact safe shutdown 
(III.G.2 areas).
    The requirement to protect against ``any-and-all'' possible 
failures includes, for example, the requirement to protect against a 
possible failure of a motor operated valve as a result of a fire-
induced spurious signal that could override the valve motor's 
protective features, causing valve failure, where such fire-induced 
valve damage could impair the capability to shut down the plant and 
maintain it in a safe-shutdown condition.
    C. Method To Achieve Compliance--The staff position described above 
with respect to the term ``any-and-all'' is consistent with the circuit 
analysis approach described in NEI 00-01, Revision 1. The deterministic 
methodology presented in Chapter 3 and Appendix B of NEI 00-01, in 
conjunction with the guidance provided in this RIS, is one acceptable 
approach to achieving regulatory compliance with respect to the 
application of the term ``any-and-all.''
    Further discussion of the staff's position on this issue is 
contained in the Attachment.

Associated Circuits

    A. NRC Regulatory Requirement--Appendix R, Section III.G.2, states: 
``Except as provided for in paragraph G.3 of this section, 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 * * *''
    B. NRC Staff Position--Any-and-all cables that could cause 
maloperation of redundant trains in a III.G.2 area due to fire-induced 
hot shorts must be protected. Unless approved by the NRC, post-fire 
safe-shutdown circuit analyses may not credit operator manual actions 
(under current regulations for plants that have not adopted an NFPA 805 
licensing basis) for protection against spurious actuations caused by 
fire-induced failure of circuits associated with a redundant safe 
shutdown train located in a III.G.2 area.
    The requirement to protect ``associated'' circuits includes a 
requirement to protect against circuits that are themselves not 
directly required to perform safe-shutdown function but which could 
cause a spurious actuation that could impact safe shutdown. Therefore, 
operator manual actions may not be credited for such circuits.
    C. Method To Achieve Compliance--The deterministic methodology 
presented in Chapter 3 and Appendix B of NEI 00-01, in conjunction with 
the guidance provided in this RIS, is one acceptable approach to 
achieving regulatory compliance with respect to the application of the 
term ``associated circuit''. The NEI 00-01 approach to identifying 
circuits that must be protected and to protecting those circuits is 
consistent with the NRC position on this issue.
    Further discussion of the staff's position on this issue is 
contained in the Attachment.

[[Page 25625]]

Emergency Control Station

    A. NRC Regulatory Requirement--10 CFR Part 50, Appendix R, Section 
I, ``Introduction and Scope,'' states: ``One train of equipment 
necessary to achieve hot shutdown from either the control room or 
emergency control station(s) must be maintained free of fire damage by 
a single fire, including an exposure fire.'' Paragraph III.G.1.a of 
Appendix R also refers to emergency control stations.
    B. NRC Staff Position--III.G.1 protection for redundant safe-
shutdown systems may not be claimed for redundant systems in a III.G.2 
area by crediting an operator manual action at an emergency control 
station. Unless alternative or dedicated shutdown capability is 
provided, redundant circuits credited for post-fire safe shutdown and 
located in the same fire area must be protected in accordance with 
III.G.2 without the use of emergency control stations of any kind.
    C. Method To Achieve Compliance--The deterministic methodology 
presented in Chapter 3 and Appendix B of NEI 00-01, in conjunction with 
the guidance provided in this RIS, is one acceptable approach to 
achieving regulatory compliance with respect to the application of the 
term ``emergency control station.'' NEI 00-01 refers to the 
regulations, the plant licensing basis, and NRC approvals for guidance 
on this issue. The NEI guidance document also includes the NRC position 
on this issue without commenting on the position.
    Further discussion of the staff's position on this issue is 
contained in the Attachment.

Backfit Discussion

    Some inspectors have not challenged alternative licensee 
interpretations of the regulatory requirements mentioned in this RIS. 
However, as stated in NUREG-1409, ``Backfitting Guidelines,'' if a 
determination is made that action is needed to bring the licensee back 
into compliance with the regulations, no backfit analysis is required. 
Section 3.3(1) of NUREG-1409 states that ``simply not challenging a 
licensee's practice would not be considered tacit approval.'' Since 
this RIS does not change any staff position on the terms addressed 
herein and does not require an action or written response from 
licensees, this RIS is not a backfit under 10 CFR 50.109. Consequently, 
the staff did not perform a backfit analysis.

Federal Register Notification

    The subject matter of this RIS was discussed on October 14, 2004, 
at a public meeting in Atlanta, Georgia. Stakeholder feedback was 
considered in developing the final version of this RIS.
    In addition, a notice of opportunity for public comment on this RIS 
will be published in the Federal Register.

Small Business Regulatory Enforcement Fairness Act of 1996

    In accordance with the Small Business Regulatory Enforcement 
Fairness Act of 1996, the NRC has determined that this action is not a 
major rule and has verified this determination with the Office of 
Information and Regulatory Affairs of OMB.

Paperwork Reduction Act Statement

    This RIS does not contain information collections and, therefore, 
is not subject to the requirements of the Paperwork Reduction Act of 
1995 (44 U.S.C. 3501 et seq.).

Contact

    Please direct any questions about this matter to the technical 
contact(s) or the Lead Project Manager listed below, or to the 
appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
    Patrick L. Hilland, Chief, Reactor Operations Branch, Division of 
Inspection Program Management, Office of Nuclear Reactor Regulation.
    Technical Contact: Bob Radlinski, NRR/DSSA/SPLB, 301-415-3174. E-
mail: rfr1@nrc.gov.
    Lead Project Manager: Chandu Patel, NRR/DLPM, 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.

Attachment 1--Discussion of Regulatory Expectations Post-Fire Safe-
Shutdown Circuit Analysis

    The following discussion provides the background of each of the 
terms that have been clarified by the RIS. This background discussion 
identifies the various interpretations that have been applied to the 
terms and notes the regulatory position and the basis for that position 
for each interpretation.

Any-and-All

    Appendix R, paragraph III.G.2, does not identify any exceptions to 
the type of post-fire safe-shutdown circuit failures that must be 
protected against in accordance with III.G.2. However, Generic Letter 
86-10 (response to Question 5.3.1) describes two specific exceptions to 
the circuit evaluation requirement of ``all possible functional failure 
states.'' These two exceptions are (1) three-phase hot shorts in proper 
sequence and (2) more than two hot shorts of the proper polarity in 
ungrounded DC circuits (the response does not allow either of these 
exceptions to be applied to high/low pressure interfaces). Since these 
two exceptions were not characterized in GL 86-10 as examples of 
exceptions, they are the only exceptions allowed by GL 86-10 to the 
type of post-fire safe-shutdown circuit failures that must be protected 
against in accordance with III.G.2. Furthermore, it is generally agreed 
that for a deterministic approach to fire protection, such as that 
required by Appendix R, a fire is assumed to damage all circuits and 
equipment in the fire area under consideration. Therefore, any-and-all 
other post-fire safe-shutdown circuits must be protected in accordance 
with III.G.2 (unless an alternative or dedicated shutdown system is 
provided in accordance with III.G.3).
    One industry challenge to the ``any-and-all'' scope of circuit 
failures defined by Appendix R and GL 86-10 was presented to the NRC in 
a letter from R.E. Beedle of NEI dated January 14, 1997, to F.J. 
Miraglia, Jr. of the NRC and in a letter from D.J. Modeen of NEI dated 
May 30, 1997, to L. B. Marsh of the NRC. These letters were in response 
to Information Notice 92-18, ``Potential for Loss of Remote Shutdown 
Capability During a Control Room Fire'' (IN 92-18). The letters stated 
the industry's position on the possible failure of motor operated 
valves as a result of a fire-induced spurious signal that could 
override the valve motor's protective features, causing valve failure. 
Although the industry agreed that IN 92-18 describes a credible failure 
and that some licensees had addressed this failure mechanism in 
response to IN 92-18, the industry's position on this type of failure 
is that it is highly improbable and does not warrant consideration.
    The NRC position on this issue, as noted in IN 92-18, is that such 
fire-induced valve damage could impair the capability to shut down the 
plant and maintain it in a safe-shutdown condition. In addition, in 
Regulatory Guide 1.106, ``Thermal Overload Protection for Electric 
Motors on Motor-Operated Valves'' (RG 1.106), the staff had stated that 
if thermal overload protection devices are bypassed, it is important to 
ensure that the bypassing does not jeopardize the completion of the 
safety function or degrade other safety systems because of any 
sustained abnormal circuit currents that may be present.
    Following the January 14, 1997, letter from NEI, a public meeting 
was held on

[[Page 25626]]

February 7, 1997, in which the NRC staff discussed with NEI the 
questions and comments in NEI's letter. Following the meeting, an NRC 
letter was sent from S.J. Collins dated March 11, 1997, to R.E. Beedle 
of NEI to further document and clarify the NRC's position on this 
issue. During the meeting and in the followup letter the staff stated 
that the safety issue addressed in IN 92-18 does not represent a new 
staff position and is within the scope of the existing fire protection 
regulation. Consequently, fire-induced failure, whether direct (failure 
to perform a safe-shutdown function) or indirect (maloperation that 
impacts safe shutdown), of a motor-operated valve that is required for 
post-fire safe shutdown must be addressed. The May 30, 1997, letter 
response from NEI did not result in a change to the NRC's original 
position. The second NEI letter also questioned whether the potential 
risk is applicable to fires in areas other than the control room since 
IN 92-18 identified a potential failure resulting from a control room 
fire. Regulatory requirements do not identify any exceptions for fires 
in other areas of the plant. Consequently, if the mechanistic failure 
of a motor-operated valve, as described in IN 92-18, can be caused by 
the fire-induced failure of an electrical circuit and prevent safe 
shutdown, the circuit must be protected. Where a licensee can make a 
case that this type of failure is possible but not safety significant 
in a specific fire area, the licensee can apply for an exemption or 
adopt a licensing basis in accordance with 10 CFR 50.48(c) and address 
the issue in accordance with this rule.

Associated Circuits

    The Appendix R requirement to protect circuits from the effects of 
fire does not exempt any type of circuits and specifically mentions 
nonsafety circuits to emphasize that all circuits whose fire-induced 
failure could prevent safe shutdown must be protected from the effects 
of fire, even nonsafety circuits. The term ``associated circuit'' has 
been used to identify circuits that are not directly required to 
perform a safe-shutdown function (e.g., the control circuit cable to a 
pump suction valve that is normally in the correct position for post-
fire shutdown) but must also not cause a spurious actuation that could 
impact safe shutdown. However, no distinction is made in Appendix R 
between circuits whose failure could directly affect safe shutdown and 
those whose failure could indirectly affect safe shutdown (e.g., by 
causing spurious actuations).
    Note that the term ``associated circuits'' has a different 
connotation in Regulatory Guide 1.75, ``Criteria for Independence of 
Electrical Safety Systems,'' than it does for fire protection. 
Regulatory Guide 1.75 defines ``associated circuits'' as ``non-safety-
related circuits that are not physically separated or not electrically 
isolated from safety-related circuits by acceptable separation 
distance, safety class structures, barriers, or isolation devices.'' 
The ``associated circuits'' in Appendix R include both safety-related 
and non-safety-related circuits. Post-fire safe-shutdown capability is 
distinctly different from, and credits operability of different 
equipment than the safety-related equipment required for emergency 
shutdown of a nuclear power plant. In 1981, the NRC issued Generic 
Letter (GL) 81-12, ``Fire Protection Rule'' (45 FR 76602, November 19, 
1980), to clarify and provide guidance on alternative and dedicated 
shutdown systems. Enclosure 2 of GL 81-12 gives the following 
definition of associated circuits (called ``associated circuits of 
concern'') as they relate to alternative and dedicated shutdown 
systems: ``In evaluating alternative shutdown methods, associated 
circuits are circuits that could prevent operation or cause 
maloperation of the alternative train which is used to achieve and 
maintain hot shutdown condition due to fire induced hot shorts, open 
circuits or shorts to ground.'' The NRC provided additional guidance on 
alternative and dedicated shutdown systems in a followup memorandum of 
March 22, 1982, from R.J. Mattson to Darrell G. Eisenhut (ML050140137). 
This memorandum, which was made publically available, defined 
associated circuits of concern as follows:
    Associated Circuits of Concern are defined as those cables (safety 
related, non-safety related, Class 1E, and non-Class 1E) that:
    1. Have a physical separation less than that required by Section 
III.G.2 of Appendix R, and;
    2. Have one of the following:
    a. A common power source with the shutdown equipment (redundant or 
alternative) and the power source is not electrically protected from 
the circuit of concern by coordinated breakers, fuses, or similar 
devices, or
    b. A connection to circuits of equipment whose spurious operation 
would adversely affect the shutdown capability (e.g., RHR/RCS isolation 
valves, ADS valves, PORVs, steam generator atmospheric dump valves, 
instrumentation, steam bypass, etc.), or
    c. A common enclosure (e.g., raceway, panel, junction) with the 
shutdown cables (redundant and alternative) and,
    (1) Are not electrically protected by circuit breakers, fuses or 
similar devices, or
    (2) Will allow propagation of the fire into the common enclosure.
    As noted above, these definitions of associated circuits were 
presented in the context of alternative and dedicated shutdown systems 
and apply to the specific categories of circuits specified in the 
definitions. The industry has also used the term ``associated'' to 
refer to a larger category of circuits that includes all post-fire 
safe-shutdown circuits that have the potential to cause spurious 
operations that could prevent or adversely affect safe shutdown. This 
broader definition of associated circuits has caused confusion about 
the protection required for post-fire safe-shutdown circuits.
    The Mattson/Eisenhut memorandum of March 1982 and Regulatory Guide 
1.189, ``Fire Protection for Operating Nuclear Power Plants,'' noted 
acceptable methods for mitigating spurious actuations, including 
operator manual actions. However, these methods are only applicable to 
alternative and dedicated shutdown systems and they do not comply with 
regulations for protection of post-fire safe-shutdown circuits in 
III.G.2 areas. The NRC has specifically noted in correspondence with 
licensees 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. The examples of equipment identified in 
the above definition belong to a specific category of systems and 
components that does not include redundant shutdown components and 
systems.
    Redundant safe-shutdown systems are defined in the response to 
Question 3.8.3 in GL 86-10 as follows: ``If the system is being used to 
provide its design function, it generally is considered redundant. If 
the system is being used in lieu of the preferred system because the 
redundant components of the preferred system do not meet the separation 
criteria of paragraph III.G.2, the system is considered an alternative 
shutdown capability.'' The GL 81-12 definition of associated circuits 
specifically refers to both redundant and alternative shutdown trains 
with respect to circuits associated by common enclosures and common 
power supplies (2.a and 2.c above), but does not mention redundant 
systems with respect to circuits associated by spurious actuation (2.b 
above). The examples given in GL 81-

[[Page 25627]]

12 for components that could spuriously actuate and affect the safe-
shutdown capability are not components of normal redundant safe-
shutdown systems (the RHR/RCS isolation valves are in a normal 
redundant safe-shutdown system, but the post-fire function of these 
valves is to prevent a loss-of-coolant accident). These components were 
included in the definition as possible alternative shutdown components.
    The response to Question 5.3.8 of GL 86-10 allows operators to 
clear multiple high-impedance faults by manual breaker trips governed 
by written procedures. This question and response apply to a unique set 
of circuits associated with redundant safe-shutdown systems by virtue 
of having a common power supply where multiple high impedance faults 
could cause a loss of that power supply to the safe-shutdown equipment. 
The response references III.G.2 areas and allows operator manual action 
to mitigate the fault. Some licensees have interpreted this response to 
imply that the regulations allow them to credit operator manual actions 
in III.G.2 areas for any associated circuit, including circuits whose 
failure could cause spurious actuations. However, multiple high-
impedance faults are not the same as spurious actuation faults. 
Consequently, this response does not provide a basis for crediting 
operator manual actions for mitigation of spurious actuations.
    The reference to III.G.2 in the GL 86-10 Question 5.3.8 response is 
recognition that a high-impendence fault could affect a redundant 
shutdown train located in a III.G.2 area and does not imply that manual 
actions may be credited in these areas for other types of faults. It is 
also important to note that the questions and responses in GL 86-10 are 
under the heading Alternative and Dedicated Shutdown Capability. 
Therefore it is not appropriate to apply the guidance provided by this 
response to the protection of spurious actuation circuit faults for 
redundant safe-shutdown systems in III.G.2 areas of the plant.
    The staff position on associated circuits presented in this RIS is 
consistent with Section 9.5.1 of the SRP, which distinguishes between 
``associated circuits'' and ``associated circuits of concern'' by 
giving a separate definition for each. Associated circuits are defined 
as ``circuits within a fire area that may be subject to fire damage 
that can affect or prevent post-fire safe shutdown capability.'' 
Associated circuits of concern are defined as ``those cables (safety-
related, non-safety-related Class 1E and non-Class 1E) that do not meet 
fire separation requirements and have (1) a common power source with 
the safe shutdown equipment, (2) a connection to circuits for equipment 
whose spurious operation could adversely affect safe shutdown, or (3) a 
common enclosure with safe shutdown circuits.'' This section of the SRP 
also states: ``Manual actions may not be credited in lieu of providing 
the required separation of redundant systems or associated circuits 
located in the same fire area unless alternate, dedicated, or backup 
shutdown capability is provided.''
    To summarize, circuits that are associated with the operation of 
credited redundant post-fire safe-shutdown systems in accordance with 
III.G.2 such as ``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'' 
must be protected in accordance with III.G.2 and operator manual 
actions may not be credited for III.G.2 redundant train circuits under 
regulations for plants that have not adopted an NFPA 805 licensing 
basis (except through staff-approved exemptions for specific manual 
actions). This staff position was reiterated in a May 16, 2002, NRC 
letter from J. N. Hannon to A. Marion of NEI (ML021410026). Committee 
To Review Generic Requirements (CRGR) Meeting Minutes No. 367 
(ML021750218) noted that this letter does not contain any new staff 
positions.
    This staff position is also supported by the results of the EPRI/
NEI fire testing. The distinction between associated circuits and other 
safe-shutdown circuits has been used as a basis for addressing hot 
shorts and spurious actuations that could prevent safe shutdown by 
crediting operator manual actions to maintain redundant safe-shutdown 
trains free of fire damage. The tests demonstrated that operator manual 
actions may not be practical or possible for the required mitigation 
between multiple spurious actuations since there may not be sufficient 
time to take action.
    To clarify this issue for all stakeholders, future NRC 
documentation related to post-fire safe-shutdown circuits will not 
distinguish between associated circuits and other post-fire safe-
shutdown circuits, except for alternative and dedicated shutdown 
systems as defined by GL 81-12. RIS 2004-03, ``Risk-Informed Approach 
for Post-Fire Safe-Shutdown Associated Circuit Inspections'' 
(ML040620400), has been revised and reissued as RIS 2004-03, Revision 
1, ``Risk-Informed Approach for Post-Fire Safe-Shutdown Circuit 
Inspections'' (ML042440791), to eliminate this distinction in 
inspection guidance. NFPA 805 uses a similar approach, noting that any 
circuit whose function or absence of malfunction, including circuits 
whose failure can cause a spurious actuation, is required for safe 
shutdown and should be protected from fire.

Emergency Control Station

    The term ``emergency control station'' has not been clearly defined 
and it has not been used consistently by the industry. The term was 
most recently defined in Regulatory Guide 1.189 as a ``location outside 
the main control room where actions are taken by operations personnel 
to manipulate plant systems and controls to achieve safe shutdown of 
the reactor.'' However, this definition does not tell what type of 
hardware is considered an emergency control station, a control panel 
with multiple functions or a single device such as a valve or breaker. 
The definition also does not indicate the number of emergency control 
stations that are considered reasonable and acceptable to maintain a 
single train free of fire damage.
    Since Appendix R did not require post-fire protection of automatic 
functioning of systems, manual actions may be credited to maintain a 
train free of fire damage in accordance with III.G.1, as noted in an 
NRC memorandum of July 2, 1982, from R. J. Mattson to R. H. Vollmer 
(ML050140106). This memorandum, which was made public, notes that for 
III.G.1 areas, ``manual operation of valves, switches and circuit 
breakers is allowed to operate equipment and isolate systems and is not 
considered a repair.'' This allowance for manual operation of 
individual devices for III.G.1 areas has led to the interpretation that 
emergency control stations include individual valves, switches, and 
circuit breakers.
    The interpretation of emergency control station to include 
individual devices has been used by some licensees as a basis for 
substituting operator manual actions for the protection of redundant 
safe-shutdown trains located in the same fire area. This industry 
position is that if operator manual actions can restore a post-fire 
safe-shutdown train to a free-of-fire-damage condition, the criteria 
for a III.G.1 level of protection have been met and therefore even 
where redundant trains are located in the same fire area, the

[[Page 25628]]

protection requirements of III.G.2 are not applicable. During an NRC 
internal meeting on May 7, 1986, to discuss SECY-85-306, ``Appendix R, 
Post-Fire Safe Shutdown'' (ML050140123), one staff member voiced this 
industry position. In that meeting, the NRC Office of the Executive 
Legal Director (now Office of General Counsel) confirmed that the line 
of reasoning proposed is only applicable to licensees that have 
requested and received an exemption, as this position does not meet 
regulatory requirements. These meeting minutes later became publicly 
available.
    The requirements of paragraph III.G.1 are not independent of the 
requirements of paragraph III.G.2 and the requirements are not 
necessarily progressive. Paragraph III.G.2 states: ``Except as provided 
for in paragraph G.3 of this section, 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: * * * '' Consequently, unless alternative or dedicated 
shutdown capability is provided, redundant circuits credited for post-
fire safe shutdown and located in the same fire area must be protected 
in accordance with III.G.2 without the use of emergency control 
stations of any kind. The regulatory requirement to provide either 
III.G.2 or III.G.3 protection was noted in GL 86-10 (response to 
Question 5.1.2).
    This staff position was reiterated in the May 16, 2002, letter from 
J. N. Hannon of the NRC to A. Marion of NEI (ML021410026), and 
Committee To Review Generic Requirements (CRGR) Meeting Minutes No. 367 
(ML021750218) noted that this letter does not contain any new staff 
positions.
    This RIS does not give a precise definition of emergency control 
stations, but clarifies that, under the current regulations, manual 
actions may not be credited to claim that a III.G.2 area is a III.G.1 
area. Where redundant trains are located in the same fire area and 
where an alternative shutdown capability is not provided, the 
protection required by III.G.2, including detection and suppression 
(where noted), must be provided.
    The operator manual actions rulemaking currently in process is 
expected to provide guidance to licensees on using operator manual 
actions to comply with III.G.2. In addition, licensees may address 
these issues by adopting a risk-informed, performance-based fire 
protection program in accordance with NFPA 805 and 10 CFR 50.48(c).

 End of Draft Regulatory Issue Summary

    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 4th day of May 2005.

    For the Nuclear Regulatory Commission.
Patrick H. Hiland,
Chief, Reactor Operations Branch, Division of Inspection Program 
Management, Office of Nuclear Reactor Regulation.
[FR Doc. E5-2377 Filed 5-12-05; 8:45 am]
BILLING CODE 7590-01-P