Text

Summary of 981202-03 Meeting with NEI & BWROG to Discuss App R Safe Shutdown Circuit Analysis Issues.Meeting Agenda, List of Attendees & Copies of Meeting Handouts Encl
	ML20203C268
Person / Time
Issue date:	02/01/1999
From:	Marlone Davis; NRC (Affiliation Not Assigned)
To:	Frank Akstulewicz; NRC (Affiliation Not Assigned)
References
	PROJECT-689, PROJECT-691 NUDOCS 9902110319
	Download: ML20203C268 (100)
	v • d • e

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s g &. UNITED STATES NUCLEAR REGULATORY COMMISSION t WASHINGTON, D.C. 20586-0001 k.*****j February 1, 1999 l'

T MEMORANDUM TO: Frank Akstulewicz, Acting Chief Generic lasues and Environmental Projects Branch Division of Reactor Program Management, NRR FROM: Michael J. Davis, Project Manager Generic lasues and Environmental Projects Branch

/// j , s #W Division of Reactor Program Management, NRR

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SUBJECT:

SUMMARY

OF DECEMBER 2 - 3,1998, MEETING BETWEEN THE NRC l STAFF, THE NUCLEAR ENERGY INSTITUTJ (NEI), AND THE BOILING l

l. WATER REACTOR OWNERS GROUP (BWROG) ON APPENDIX R l FIRE PROTECTION ISSUES !

. 4 i

On December 2 and 3,1998, members of the staff met with NEl and the BWROG Apperidix R l Committee to discuss Appendix R Safe Shutdown Circuit Analysis issues. Portions of the l meeting were closed to the public at the request of the BWROG when GE proprietary . !

information was to be discussed. The meeting agenda is provided as Attachment 1, a list of j meeting attendees is given in Attachment 2 and copies of meeting handouts are inclu,ded as Attachment 3.

The first part of the meeting was an Industry /NRC Interface session presented by the.NEl l

i representative. The two main topics of discussion were: (1) Coordination of response to fire protection issues and (2) NEl Circuit Failure issues Task Force activities. NEl commented that with all the fire protection issues being considered it might be wise to coordinate an integrated -

approach. NEl proposed to develop a roadmap letter integrating the topia and submit the document to the NRC by December 31,1998 (letter has been received). The staff expressed the need to be careful of obscuring the boundary between the regulatory role and the industry role. The NRC and industry can work together when it doesn't encroach on each others' needs L and responsibilities. Working together on circuit analysis and a comprehensive Regulatory l: Guide should be acceptable, but we need to be aware of where the line is.

L I; NEl stated that the Circuit Failure issues Task Force would submit a proposal for' safety significance determination to the NRC in early 1999. Also NFPA Standard 805-2000, Rev. 6.3 is l available for review and may be the subject of a meeting this spring to incorporate comments.

l; NEl next presented a slide showing NEl Task Force coordination with industry on the various I fire protection issues.

p NEl next presented slides on circuit analysis elements for resolution. NEl stated the current focus should be on control cable failure modes from within a cable and felt that external hot shorts were of low probability. NEl would like to show on a generic basis the low impact of a second cable failure for both a broad range of cables and specific cables and also on a generic basis the low probability of any failure. With plant specific analyses NEl plans to demonstrate (

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EL F. Akstulewicz -

2- February 1, 1999 the low impact of 2"d cable failures, the low probability of any failure, and the use of a deterministic analysis method.

NEl next covered elements of a probabilistic method which considers both the probability and consequences of cable failures in attempting to predict how cables will fail and the likelihood of operator recovery of function. The Circuit Failure issues Task Force is currently looking at cable failure modes and probabilities. A staff member from the NRC Office of Research (RES) stated that a project is underway to identify, through a literature search, failure mode probabilities for a spectrum of failures. After the information is gathered, the next step would be to identify what additional experiments might be needed. NEl commented that feedback was needed from the NRC on the proposed industry schedule, on the staff's views on proposed industry coordination with RES on cable failure research, and on what is needed to make other probabilistic elements acceptable. Further discussion on development of a probabilistic method will occur at the next :

scheduled meeting with NEl.

1 The aftemoon session on December 2,1998, was listed as proprietary. One member of the public raised an objection to being excluded. The staff and the BWROG gave non-proprietary summaries of the topics discussed at the afternoon session on the morning of December 3, 1998, when the meeting was again open to the public. Subsequent to the meeting the BWROG was requested to submit an affidavit for proprietary withholding of the slides from the closed portion of the meeting. GE management subsequently decided to no longer protect this information from public disclosure. The slides from this portion of the meeting are included in Attachment 3. ,

During the closed portion of the meeting the BWROG presented two positions on Hot Short Duration and Loss of Offsite Power. The BWROG also presented 4 definitions.they had developed fer the following terms: redundant, attemative, dedicated, and free of fire damage.

Also included in the discussion were two new positions, achieving cold shutdown vs. maintaining hot shutdown and using safety relief valves and low pressure systems as redundant safe shutdown paths. There were lengthy discussions on the above mentioned topics. The BWROG is considering preparing a white paper on some of the above topics and submitting it as a separate activity outside the circuit analysis topical repod. The staff agreed to consider the positions put forward in that possible future white paper This will be discussed further in future meetings. .

The meeting continued on the morning of December 3,1998, with a discussion of which. circuit failure modes to consider in determining positions. The BWROG suggested that some cable fault types might be eliminated by applying engineering principles, such as fuses protecting a ;

low voltage cable from a fault from a high voltage line. After some discussion it was agreed that !

. the BWROG would develop a list of situations in which the probability of cable to cable faults is

]

deemed to be low.

Other topics discussed included the number of hot shods to consider per cable, component, or fire area; how to interpret GL 86-10 section 5.3.1; spurious operation of associated circuits; control room fire considerations; functional versus mechanistic failure states; associated, circuits with a common power source; and multiple high impedance faults. ,

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l T. Akstulewicz - -3 ' February 1, 1999 .

i A timeframe of late February or March was suggested for the next meeting. The staff commented that a meeting after the BWROG develops their white paper would be beneficial.

Having the issues on paper will accebrate the process.

Project Nos. 689 & 691 .

' Attachments': As stated :

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. T. Essig February 1, 1999 j

. A timeframe of late February or March was suggested for the next meeting. The staff -

commented that a meeting after the BWROG develops their white paper would be beneficial.

.Having the issues on paper will accelerate the process.

Project Nos. 689 & 691 !

. Attachments: As stated cc w/atts: See next page j

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DISTRIBUTION: See attached page

Document Name: G:\mjdii1202mtsum.wpd OFFICE. PM:PGJk/SC:PGEBggjBC:SPLE(

NAME. MDaviA:sd RArchitzef LMarsh h DATE 1/24/99- 1/J8/99' gy I /99

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Nuclear Energy institute Project No. 689 cc: Mr. Ralph Beedle Ms. Lynnette Hendricks, Director Senior Vice President Plant Support and Chief Nuclear Officer Nuclear Energy Institute l Nuclear Energy Institute Suite 400 l Suite 400 1776 i Street, NW 1776 l Street, NW Washington, DC 20006-3708- )

Washington, DC 20006-3708 -

Mr. Alex Marion, Director Mr. Charles B. Brinkman, Director Programs Washington Operations Nuclear Energy Institute ABB-Combustion Engineering, Inc.

Suite 400 12300 Twinbrook Parkway, Suite 330 ;

1776 l Street, NW Rockville, Maryland 208R l Washington, DC 20006-3708 '

Mr. David Modeen, Director Engineering Nuclear Energy Institute Suite 400 1776 i Street, NW Washington, DC 20006-3708' l

l

- Mr. Anthony Pietrangelo, Director -

Licensing Nuclear Energy Institute Suite 400 1776 i Street, NW Washington, DC 20006-3708 Mr. Nicholas J.' Liparulo, Manager Nuclear Safety and Regulatory Activities Nuclear and Advanced Technology Division Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, Pennsylvania 15230 Mr. Jim Davis, Director Operations Nuclear Energy Institute Suite 400 1776 i Street, NW Washington, DC 20006-3708

Project No. 691 .

Boiling Water Reactor Owners Group I cci " Thomas J. Rausch, Chairman Warren W. Glenn $

, Boiling Water Reactor Owners' Group Southern Nuclear / Georgia Power

? Commonwealth Edison Company l

E.I. Hatch Nuclear Plant .i

. Nuclear Fuel Services PO Box 1295 M/C B052 ;

i 1400 Opus Place,4th Floor ETWill Birmingham, AL 35201 j Downers Grove, IL 60515 '

Carl D. Terry. .

Dennis B. Townsend - -

Vice President, Nuclear Engineering GE Nuclear Energy.

Niagara Mohawk Power Corporation M/C 182 -;

l Nine Mile Point-2 175 Curtner Avenue -

^

PO Box 63 -- San Jose, CA 95125 j

Lycoming, NY 13093 i

' Drew B. Fetters Thomas A. Green -

PECO Energy GE Nuclear Energy j Nuclear Group Headquarters Mail Code 182 :

MC 62C-3 175 Curtner Avenue I 965 Chesterbrook Blvd. San Jose, CA 95125 l

- Wayne, PA 19087 *

" John Hosner. K.' K. Sedney i L Commonwealth Edison GE Nuclear Energy

.)

Executive Towers,4th Floor _ ' 175 Curtner Ave, M/C 182 :

1400 Opus Place . _ .

San Jose, CA 95125 ,

1

- Downers Grove, IL - 60515 ' . < -

j George T. Jones .

' Pennsylvania Power & Light; .)

MC A6-1. ' . , .

"Two North Ninth Street .

Allentown, PA 18101~ w i Lewis H. E,.:mner . ,

t e Southern Nuclear / Georgia Power - -

E.- 1. Hatch Nuclear Power Plant

U.S. Route 1 North, Box 439

' Baxley, GA 31513 L. A. England ,

Entergy Operations Inc.-

- PO Box 31995 Jackson, MS -39286 -

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AGENDA t

December 2nd \

NEl / NRC Meetina l 10:00 am - 10:10 am introductions NRC/NEl

! '10:10 am - 10:45 am NEl Circuit Failure issue Task Force NEl (CF ITF)/ NRC Status Update Meeting BWROG / NRC Meetina 11:00 am - 11:05 am introductions NRC/BWROG 11:00 am - 12:00 pm Review of Guidance Document Philosophy BWROG

& Layout & NRC comments incorporated in 2 " Draft" positions"

.12 :00 pm - 1:00 pm Lunch 1:00 pm - 1:45 pm R

' eview of four" Draft" Definitions" BWROG 1:45 pm - 2:30 pm Review of" Draft" Hot and Cold BWROG l Shutdown Position" j

2:30 pm .- 2:45 pm Break i

2:45 pm - 3:30 pm Review of " Draft" Shutdown Paths" BWROG

\

i December 3rd \

- BWROG / NRC Meetina !

9:00 cm - 10:15 pm Discuss issues and Approaches to BWROG/NRC four Positions i

10:15 am - 10:30 am Break

~10:30 am - 11:45 pm Discuss issues and Approaches to BWROG/NRC four Positions 11i45 am - 12:00 pm Summary & schedule for next meeting BWROG/NRC

- GE proprietary informa: ion willbe discussed during this portion of the meeting. This portion of the meeting willbe

. closed to the public. -

Attachment 1

LIST OF ATTENDEES AT MEETING WITH NEI/BWROG IN ROCKVILLE, MARYLAND ON DECEMBER 2 - 3,1998 NAME AFFILIATION L. Whitney NRC/SPLB P. Madden -

. NRC/SPLB -

M. Davis NRC/PGEB '

G. Stramback GE/BWROG T. Gorman . PP&UBWROG J. Ribeiro DE&S/BWROG

' V. Bacanskas : EOl/BWROG' D. Parker. ~ Southem ColBWROG F. Emerson NEl G. Warren SNC/BWROG S. Hardy CP&UBWROG C. Pragman ' PECO/BWROG G. Eckert GENE / Tech Services V Warren PECO/NEl A. Ettlinger NYPA/BWROG T.Rausch Comed /BWROG J. Hyslop NRC/SPSB D. Stellfox - McGraw-Hill T. Eaton NRC/SPLB P. Qualls NRC/SPLB/FPES E. Conner NRCISPLB/FPES N.Siu NRC/RES/ DST /PRAB S. Wong NRC/SPSB K. Sullivan BNL K.' S. West NRC/SPLB L. B. Marsh NRC/SPLB R. Woods NRC/RES/ DST /PRAB G. Thomas NRC/SRXB

, R. Jenkins NRC/EELB ATTACHMENT 2

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I Industry / NRC Interface Meeting December 2,1998 Bethesda, MD QEI i

Overview -

= Coordination of response to fire protection issues

= NEI Circuit Failures Issue Task Force v'

Attachment 3 1

1

-~ - - - -

, Fire issue Coordination a Opportunities to make significant progress on important fire protection issues

. Fire-induced circuit failures

. Fire protection assessments

. Comprehensive regulatory guide

. Use of risk information and performance bases

. Need for additional research a Need integrated approach by NRC and industry

. NEI proposal before December 31 EI l

Circuit Analysis Guidance i Products a NEI ITF - propose safety significance l determination method for discussion with NRC early 1999

= BWROG - LTR submittal for SER ,

a NFPA Standard 805 - 2000

= All products to reflect consistent guidance j

'1$ '

l 2

9 i

E NEI Task Force / Industry Coordination [

i 4

I NEI Circuit Failures issue Task Force i i ! i i ,

BWROG ffFPA 805 EPRI BWROG PWR Appcndix R Committee FP & Circuit Anaipis,PSA RBR(PSA) Cable Fail Modes,Cire Analpis 2 Reps 2 Reps 1 Rep 1 Rep 2 Reps b

b w .

i

l Industry Circuit Analysis Elements for Resolution a PSA tools

. Equipment & circuits in a given area (BWROG App R)

. Internal events PSA system dependencies for a given area (ITF/NFPA)

. Likelihood of fire initiation and growth to a damaging l level (ITF/NFPA)

. Likelihood of cable failure modes given a damaging fire l (ITF/NFPA) l

= Non-PSA tools (BWROG App R) g i

Industry Circuit Analysis .

Elements for Resolution l

= Defense in depth (NFPA rep. input) l

= Safety margins (BWROG IRBR)

= Performance monitoring (NFPA rep.

input)

= Enforcement (NEI)

'1e '

1

l

' 1 1 .

1 Current Focus a Control cables

. Unacceptable component changes of state come primarily from control cable failures a Failure modes within a cable, not from external cables

. Should be able to show external hot shorts low probability

= Likelihood of 2nd simultaneous hot short

. Plants have already analyzed for one EI Would Like To Show...

1. Generic: Low impact of 2nd failure, broad range of cables and combustion conditions

2. Generic: Low impact of 2nd failure, specific cables and combustion conditions

3. Generic: Low frequency of any failure

4. Plant-specific:

-low impact of 2nd failure

- low frequency of any failure

- deterministic analysis method QEI 2

-6 Elements of Probabilistic Method a Fire initiation frequency a Fire exposure

. Location

. Growth (E-119 cun'e)

. Size and combustibles

. Barriers a Detection and manual suppression ,

i Elements of Probabilistic Method (continued)

= Automatic suppression a Cable Bilure probability and modes

. Contributors to be defined

= Consequences of cable failure Recovery of function a Availability ofredundant shutdown QEI 3

i Elements of Probabilistic Method

= Fire initiation frequency l

= Fire exposure i

. Location

. Growth (E-119 curve)

. Size and combustibles <

. Barriers a Detection and manual suppression ,

Elements of Probabilistic .

Method (continued)

= Automatic suppression a Cable failure probability and modes

. Contributors to be defined a Consequences of cable failure

. . Recovery of function

= Availability of redundant shutdown QEI 3

I a I

Committee Actions

= Cable failure modes / probability

. Coordination with / input to RES research

=Other probabilistic elements Next ITF meeting December 7-8 TEI Feedback Needed From NRC

= Views on proposed industry coordination with RES on cable failure research

= Views on what is needed to make other probabilistic elements acceptable

! = Industry schedule EI 4

l

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.j i

4

/k Discussion Points i

-Document Adjustments

- Position Selection Process

- Revised Position Format 0]/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis ] ;

Assessment

- .I

! I A

/t Document Adjustments

- More Emphasis on Methodology

- Methodology Section Drives Positions i

- Technical Basis Included in Section 4.0 0J/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 2 !

Assessment f

c. - ..

th Position Selection Process

- Topics Identified for NRC Interaction

- Topic Reviewed by BWROG for inclusion as

-BWROG Position or,

-BWROG Definition 01/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 3 Assessment

i

/

+

f Revised Position Format

- Reason for Position Included Upfront i

- Concise Position Statement Provided

- Basis for Position Included at the End 01/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 4 Assessment

< ; hDefinitions

/h Redundant

- Any combination of equipment and systems with the capability to perform the shutdown functions of reactivity control, inventory control, decay heat removal, process monitoring and associated support functions when used within the capabilities ofits design.

4 -

i Draft BWROG Generic Guidancefor Post-Fire Safe Situtdown Circuit Analysis 1 i 01/29/99 Assessment i

i i

b: Definitions i c)pf( Alternative

- Where the redundant safe shutdown capability has not been demonstrated to be " free of fire damage" and dedicated equipment is not provided, the shutdown systems used are classified as alternative.

W O1/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 2 Assessment

N N=

vegniaans K_ Dedicated

- A system or set of equipment specifically installed to provide one or more of the post-fire safe shutdown functions of inventory control, reactivity control, decay heat removal, process monitoring, and support as a separate train or path.

0]/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Situtdown Circuit Analysis 3 Assessment

_-_ _ - _ _----_ _ -_--_-- _-- __----_---__ __ _ _ _ _ _ _ - - _ _ _ _ _ _ _ _ _ ~ . _ _ _ _ . _ _ __

\w( Definitions

=hc - !

fh Free of Fire Damage i

i

-The structure, system or component under consideration is capable of performing its intended function during and after the postulated fire, as needed.

l It may perform this function automatically, by remote control, or by manual operations.

0J/29/99 Draft B WROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 4 Assessment i

Introduction to Position on Use ofSafety Relief Valves and 4, O Low Pressure Systems as Redundant Safe Shutdown Pr*hs

[,% Why is the BWROG Developing this Position?

- The meaning of" Safe Shutdown" has become obscured over time.

i

- The introduction of the term " Preferred system" in GL 86-10, Question 3.8.3 has resulted in more confusion, not less.

t t

- 1982 Mattson - Rubenstein memo "Use of ADS and LPCI to meet Appx R, Alternate Shutdown Goals" is now being interpreted to preclude the use of these systems for Safe / Redundant Shutdown.

t

]2/0J/98 Draft BWROG Generic Guidancefor Post-Fire Safe Strutdown Circuit Analysis Assessment l

Introduction to Position on Use ofSafety Relief Valves and i

+ Low Pressure Systems as Redundant Safe Shutdown Paths c :, -

i g Generic Safe Shutdown Performance Goals

- ANS/ ANSI-52.1-1983 provides the following generic definition of safe ;

shutdown. A safe shutdown is a shutdown with:

1

- the reactivity of the reactor kept to a margin below criticality consistent with technical specifications; i i

- the core decay heat being removed at a controlled rate sufficient to !

prevent core or reactor coolant system thermal design limits from i being exceeded; i

- components and systems necessary to maintain these conditions operating within their design limits; and

- components and systems, necessary to keep doses within prescribed limits operating properly. ;

i 12/01/98 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis Assessment 2

Introduction to Position on Use ofSafety Relief Valves and c

l-Low Pressure Systems as Redundant Safe Shutdown Paths gg What the Performance Goals Hean?

- SCRAM is achieved I i

- Decay heat is removed ,

- Radiological boundaries are intact

- Systems are capable of performing the necessary functions.

4 Necessary supporting functions are also provided -

i

]2/0]/98 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis Assessment . 3 i

. _ _ _ _ _ _ _ - _ _ _ _ . _ _ _- ____-___ __ _ _ _ _-_ _ _- - -___ _______-__1

i l Introduction to Position on Use ofSafety Relief Valves and h Low Pressure Systems as Redundant Safe Shutdown Paths ;

au c 'T BWR. Considerations for Satisfying Performance Goals-

[

i

- Reactivity

- Achieve SCRAM -

- Prevent subsequent re-criticality

- Decay Heat removal

- Reactor to Cold shutdown within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months l - Satisfy Containment Thermal / Pressure Design Limits

- Radiological Boundaries

- Fuel Cladding Integrity

- Reactor Vessel Integrity

- Containment Integrity

> The BWR has several trains of equipment that are capable ofsatisfying the performancegoals l

y ]2/0])98 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis Assessment 4

" i i

Introduction to Position on Use ofSafety Relief Valves and h Low Pressure Systems as Redundant Safe Shutdown Paths

-= fj x What if the Performance Goals Can't be Met?

t i

- When these trains cannot be provided with the separation required by Appendix R III.G.2:

- Provide Alternative or Dedicated Shutdown capability per III.G.3

- Satisfy " modified" performance goals ofIII.L i

12/01/98 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis Assessment 5

?

Introduction to Position on Use ofSafety Relief Valves and N 5 LLow Pressure Systems as Redundant Safe Shutdown Paths ,

< K ~ Examples of BWR Approach to Meet Performance Goals

- Reactivity - Inherently Fail-Safe for BWRs

- Decay-Heat removal

> Reactor to Coldshutdown within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months ,

- Containment Limits - Pressure suppression capability is maintained t

- Radiological Boundaries

> Fuel Cladding Integrity - Assure adeauate core cooling (ex., PCT <

1500 deg F)

> Reactor Vessel Integrity - Overpressure protection & Hi/ Low pressure i interfaces l

> ContainmentIntegrity - Containmentpressure within design limits 12/0J/98 Draft BWRoG Generic Guidancefor Post-Fire Safe shutdown Circuit Analysis Assessment 6 i

i Introduction to Position on Use ofSafety Relief Valves and l,.

Low Pressure Systems as Redundant Safe Shutdown Paths

\ Guidance the BWR Fleet Has Implemented to Satisfy Appendix R

- The following guidance was available-at the time Appendix R was ;

promulgated:

- NUREG-0626 - Generic Evaluation of Feedwater Transients and Small Break Loss-of-Coolant Accidents in GE-Designed Operating Plants and Near-Term Operating License Applications, January 1980 t

- NEDO-24708A - Additional Information Required for NRC Staff Generic Report on Boiling Water Reactors, Revision 1, December 1980

- NEDO-24934 - Emergency Procedure Guidelines, BWR 1 through 6, Revision 3, December 1982 i

- NRC Staff Guidance that clearly stated that ADS with LPCI or LPCS were acceptable for Safe / Redundant Shutdown 12/0Jj98 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis Assessment 7 ,

Introduction to Position on Use ofSafety Relief Valves and ;

C D Low Pressure Systems as Redundant Safe Shutdown Paths

</\ What the Guidance Tells Us

~

-ADS LPCI and ADS LPCS provide adequate core cooling i

12/01/98 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis Assessment 8

y

, Achieving ColdShutdown vs.

MaintainingHotShutdown g@/

/ Reason for Position

- This position is provided to clarify the provisions of Appendix R Section III.G.I.Section III.G.1 should be applied in its entirety. Instead, III.G.1.a is being i interpreted exclusive of III.G.1.b. This has led to an interpretation that credited systems must be capable of maintaining the reactor in hot shutdown even when cold shutdown capability is available. Section III.G.1 is provided in the Regulation section that follows.:

i 01/29/99 Draft BWROG Ge=teric Guidancefor Post-Fire Safe Shutdown Circuit Analysis ]

Assessment

Achieving ColdShutdown vs.

NV, QiaintainingHotShutdown

$ BWROG Position

- A prompt transition to cold shutdown is acceptable as described in the Statement of Considerations for Appendix R (Ref. Federal Register #45FR76602 AT 50-SC-55, dated 9/1/82). The capability to maintain hot shutdown for a duration of 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months is not the goal of the requirements. !

However, if repairs are required for cold shutdown equipment, the capability of maintaining hot shutdown must be demonstrated until repairs are completed, with an upper limit of 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

t Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 2 0Q9/99 Assessment l

- - - -- - - - - -- -- - - -- - - - - - n

a

Achieving ColdShutdown vs. ,

W Q aintainingHotShutdown j% B asis for Position !

- Demonstrating the ability to achieve and maintain cold shutdown following a fire is the ultimate goal of Appendix R. The provisions of Section III.G.1 of Appendix R have been interpreted to require that hot shutdown must be maintained for 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , even when the capability to achieve cold shutdown is t available. Appendix R Section III.G.la and b prescribe reactor conditions relative to Technical Specification modes, however the goal is to provide positive control of the essential hot shutdown functions so that the reactor can be directed to cold shutdown promptly.

- Section III.G.1 does not require maintaining hot shutdown for 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months but i does allow maintaining hot shutdown for up to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months while making necessary repairs. Appendix R makes provisions for maintaining the unit in a stable hot shutdown condition while equipment required for cold shutdown is repaired. ;

0J/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 3 ;

y Assessment I

p y Achieving ColdShutdown vs.

==c W > Maintaining Hot Shutdown

% Reference Documents (Regulations)

> 10 CFR 50. Appendix R Section IILG.la and b

> G. Fire protection ofsafe shutdown capability.

I Fire protectionfeatures shall be providedfor structures. systems, and components important to safe shutdown. These features shall be capable oflimitingfire damage so that:

a. One train of systems necessary to achieve and maintain hot shutdown conditions from either the control room or emergency control station (s) isfree offire damage; and

b. Systems necessary to achieve and maintain cold shutdownfrom either the control room or emergency control station (s) can be repaired within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

Part 50 Statements ofConsideration (Technical Basis for IIL L)

Fire damage to cold shutdown capability is limited to damage that can be repaired within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to provide a margin achieving cold shutdown conditions.

Part 50 Statements efConsideration (Comment Resolution for IILL )

1t is generally understood that coldshutdown is the ultimate safe shutdown condition and that,for eachfire area, diferent means may be used and may be necessary to achieve coldshutdown.

Part 50 Statements ofConsideration (Comment Resolution for IIL G)

Many commenters suggested that thefirst paragraph be changed slightly and the rest of this section deleted. The basisfor their contention is that the rule shouldstate simply the requirement to protect cables or equipment ofsystems necessaryfor safe shutdown ofthe plant and leave specific implementation details in some other type of document. We have modified this section by removing the listing of considerations, deleting Table 1, and revising the wording to provide clarification.

01/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Situtdown Circuit Analysis 4 Assessment

i

. Achieving ColdShutdown vs.

L Tiaintaining Hot Shutdown f l Reference Documents (Guidance)

~ Generic Letter 86-10. Enclosure 2. Appendix R Questions and Answers. Section 5.2.1.

Shutdown and Repair Basis i

> 5.2.1 Shutdown and Repair Basis QUESTION

> With regard to the term " post-fire procedures" the Commission states that it is impossible to predict the course and extent of a fire. Given this, how does one write post-fire shutdown and repair procedures that are both symptomatic and usable to an operator?

> i

> RESPONSE

> Safe shutdown capabilities including alternative shutdown capabilities are all designedfor some '

maximum level offire damage (system unavailabilities, spurious actuations). Since the extent of the fire cannot be predicted, it seems prudent to have the post-fire shutdown procedures guide the operatorfromfidl system availability to the minimum shutdown capability. Asfor repairprocedure, similar conditions exist. A repair procedure can be written based on the maximum level ofdamage ;

that is expected. This procedure would then provide shutdown capability without accurately predicting likelyfIre damage.

0](29/99 Draft BWRoG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 5 Assessment

,r n, Achieving ColdShutdown vS.

.f MaintaininrHotShutdown ;

-c ,f Reference Documents (Other Documentation)

//

~ SECY 83-269. Attachment C. NRC Staff Positions on Post Fire Shutdown Capability.

Allowable Time to Achieve Safe Shutdown

> Some difficulty was being experienced on the part of the stafand licensees concerning the time allowed to achieve cold shutdown and whether credit for ofsite power could be used in designing the cold shutdown capability. To establish consistency in all plant designs, the staffissued the following position (reference: memorandum from R.

Mattson to R. Vollmer, datedJudy 2,1982).

- Section llL G to Appendix R states thatfire damage to coldshutdown capability must be limited to damage that can be repaired within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . Section IllL1 ofAppendix R states that the alternative shutdown capability shall be able to achieve cold shutdown within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . Further, Section HLL.5 ofAppendix R states thatfire damage shall be limited so that the systems can be made operable and cold shutdown achieved within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . Sections HLL I and IH L5 states that a plant must be capable ofachieving coldshutdown using only onsite powerprior to the elapse of 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

Section HLL5 also clearly states that offsite power is assumed restored after 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months in that equipment and sy. stems not needed until 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months may be powered by ofsite power only.

- We have been using andpropose to continue to use Sections HILI and HLL5 in our evaluations. Thus, a licensee should have the capability of repairing equipment and achieving cold shutdown within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months using only onsite I power. The 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months is considered an upper limit; a licensee may limit the repairs and achieve cold shutdown in a shorter timeframe.

0J/29/99 Draft BWRoG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 6 Assessment

Use ofSafety Relief Valves and Low Pressure i

[ Systems as Redundant Safe Shutdown Paths i w i Reason for Position

- The NRC Staff has identified in recent correspondence that the use of Safety Relief Valves (SRVs) and low pressure l systems (LPCI/CS) are not capable of satisfying certain shutdown system performance criteria specified in Section III.G and III.L of Appendix R to 10CFR50 and therefore must be considered Alternative Shutdown Systems. This new Staff position is not in full accord with previous Staff positions, and several plants' licensing bases.

01/29/99 Draft BWRoG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis ]

Assessment

.l Use ofSafety Relief Valves and Low Pressure Systems as Redundant Safe Shutdown Paths ,

<Q..\

/ BWROG Position i

w

- It is acceptable to use a combination of SRVs and low pressure systems (LPCI/CS) as a redundant shutdown path. SRVs and low pressure systems (LPCI/CS) are one of a number of redundant safe shutdown paths that are part of the original design of the GE BWR.

The effects of using this shutdown path have been evaluated extensively and are known to be acceptable.

- In plant fire areas where the systems and components required for this shutdown path satisfy the separation requirements of Appendix R Section III.G.2, this path is considered a redundant shutdown path.

t 0]/29/99 Draft BWRoG Generic Guidancefor Post-Fire Safe shutdown Circuit Analysis 2 Assessment

Use ofSafety Relief Valves and Low Pressure i

=c y f Systems as Redundant Safe Shutdown Paths

/Q Basis for Position W r

- This position is based on BWROG Position 3-1 (Achievmg ,

Cold Shutdown vs. Maintaining Hot Shutdown) and GE report No. GE-NE-T43-00002-01 " Original Safe Shutdown Paths for the BWR". Generic Letter 86-10, Section 3.8.3 identifies that "If the system is being used to provide its design function, it generally is considered redundant.", therefore based on GE Report No. GE-TE- ,

I T43-00002-01 the use of SRVs and low pressure systems would be considered a redundant path to high pressure systems.

Q9/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 3 Assessment ,

L Use ofSafety Relief Valves and Low Pressure

' 'y Systems as Redundant Safe Shutdown Paths ('

<d:nReference Documents (Regulations)

- Part 50 Statements of Consideration (Comment Resolutionfor HI.G)

- "Many commenters suggested that the first paragraph be changed slightly and the rest of this section deleted. The basis for their contention is that the rule should state simply the requirement to protect cables or equipment of systems necessary for safe shutdown of the plant and leave specific implementation details in some other type ofdocument.

- We have modified this section by removing the listing of considerations, deleting Table I, and revising the wording to provide clarification."

(Q/29j99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 4 Assessment

Use ofSafety Relief Valves and Low Pressure 4

f. wSystems as Redundant Safe Shutdown Paths Reference Documents (Guidance 1/3)

Generic Letter 86-10. Enclosure 2. Appendit R Questions and Answers. Section 3.8.3.

Redundant Trains / Alternate Shutdown QUESTION Confusion exists as to what will be classified as an alternate shutdown system and thus what systems might be required to be protected by suppression and detection under Section III.G.3.b. For example, while we are relying upon the turbine building condensate system for a reactor building fire and the RIIR system for a turbine building fire, would one system be considered the alternative to the other. If so, would suppression and detection be required )

for either or both systems under III.G.3.b? An explanation of alternative shutdown needs to be advanced for all licensees.

- RESPONSE 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 does not meet the separation criteria of Section III.G.2, the system is considered an alternative shutdown capability. Thus, for the example above, it appears that the condensate system is providing altemative shutdown capability in lieu of separating redundant components of the RHR System. Fire detection and a fixed fire suppression system would be required in the area where separation of redundant components of the RHR system is not provided. However, in the event of a turbine building fire, the RHR system would be used for safe shutdown and is not considered an altemative capability. However, one train of the RHR system must be separated from the turbine building.

f/29/99 Draft BWRoG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 5 Assessment

Use ofSafety Relief Valves and Low Pressure f Systems as Redundant Safe Shutdown Paths Reference Documents (Guidance - 2/3)

- Generic Letter 86-10. Enclosure 2. Appendit R Questions and Answers. Section 5.1.2.

Pre-Existine Alternative Shutdown Capability

> QUESTIONS

- Some licensees defined safe shutdown capability for purposes of analysis to Section III.G criteria as being composed of both the normal safe shutdown capability and the pre-existing redundant or remote safe shutdown capability which was previously installed as part of the ;

Appendix A process.This definition often took the form of two " safe shutdown trains" comprising (1) one of the two normal safe shutdown trains, and (2) a second safe shutdown train ability which was being provided by the pre-existing remote shutdown capability. This i

definitional process, which was undertaken by a number of licensees, makes a significant difference in the implementation of Appendix R.

Under such a definition, doesSection III.L criteria apply when the Commission did not call out Section III.L as a backfit?

- RESPONSE

- The definitional process mentioned considers an alternative shutdown capability provided under the Appendix A review as a redundant shutdown capability under the Appendix R review. This definitional process is incorrect. For the purpose of analysis to Section III.G.2 criteria, the safe shutdown capability is defined as one of the two normal safe shutdown trains. If the criteria of Section III.G.2 are not met, an alternative shutdown capability is required. The alternative shutdown

- capability may utilize existing remote shutdown capabilities and must meet the criteria of Sections III.G.3 and III.L of Appendix R. See also the response to 5.1.3.

0]/29/99 Draft BWROG Generic Guidancefor Post-Fire safe shutdown Circuit Analysis 6 i Assessment

Use ofSafety Relief Valves and Low Pressure WwSystems s as Redundant Safe Shutdown Paths Reference Documents (Guidance - 3/3?

- Generic Letter 86-10. Enclosure 2. Appendit R Questions and Answers. Section 5.2.3.

Alternate Shutdown Capability

- QUESTION

- Is it acceptable to develop post-fire operating procedures only for those areas where alternative shutdown is required? (For other areas standard, emergency operating procedures would be utilized in the presence of potential fire damage to c. single train.)

- RESPONSE

- Yes. The only requirement for post-fire operating procedures is for those areas where alternative shutdown is required. For other areas of the plant, shutdown would be achieved utilizing one of the two normal trains of shutdown system. Shutdown in degraded modes (one train unavailable) should be covered by present operator training and abnormal and emergency operating procedures. If the degraded modes of operation are not presently covered, we would suggest that the operation staff of the plant determine whether additional training or procedures are needed.

0]/29j99 Draft BWROG Generic Guidancefor Post-Fire safe shutdown Circuit Analysis 7 Assessment

P Use ofSafety Relief Valves and Low Pressure 2 / Systems as Redundant Safe Shutdown Paths rw Reference Documents (Other Documentation)

> Request for Additional Information Regardine Reauest for Fremption from 10 CFR Part 50. I Appendit R. Fire Protection Programfor Nuclear Power Facilities - Brunswick Steam Electric ;

Plant. Units I and 2 (TAC Nos. M93545 and M93546) pages 3 and 4. dated Mar 23. I997 t

- "Unlike RCIC, low pressure injection shutdown methodologies, such as the licensee's proposed use of LPCI in conjunction with safety /rei ;f valves, are not capable of ;

satisfying certain shutdown system performance criteria specified in Sections III.G and III.L of Appendix R to 10CFR50. Specifically, this approach:

- (a) is not capable of achieving and maintaining hot-shutdown conditions, as specified in Sections III.G.1.a and III.L.l.c of Appendix R to 10CFR50. ;

- (b) is not capable of maintaining the reactor coolant level above the top of the core, as required by Sections III.L.l.b and III.L.2(b) of Appendix R to 10CFR50.

- The normal, preferred, method of shutdown in the event of fire in a BWR is through the use of High Pressure Injection Systems (e.g., HPCI or RCIC)."

t 01/29/99 Draft BWRoG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 8 Assessment ;

Comment Resolution h'b y 3 Hot Short Duration Comment Resolution

- Need ' Reason for Position' Statement

- Additional Design Considerations Related to BWROG Position

- Previous statement read:

"The consequences of the spurious operation of safe shutdown equipment as the result of a hot short must be evaluated."

- Discussed rewording statement to read:

"The consequences of the spurious operation on safe shutdown as the result of a hot short must be evaluated."

This section was deleted during reformatting; comment worked into ' Reason for Position' section.

W 0]/29/99 Draft B WRoG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis ]

Assessment

.j Comment Resolution W,

i Loss of Offsite Power Comment Resolutionf1/2) 4

- Need ' Reason for Position' Statement

- Additional Design Considerations Related to BWROG Position i

- Previous statement read:

- "It is acceptable to assume offsite power is either available or has been restored after 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . Any manual actions necessary to restore offsite power are not considered Appendix R manual actions (reference BWROG Position 3.1.20); therefore, these manual operator actions are not governed by the requirements of Appendix R.."

0]/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 2

- Assessment

y Comment Resolution

~

p Loss of Offsite Power Comment Resolution (2/2?

Comment was that all actions necessary to restore offsite power should meet all Appendix R requirements (Written- procedures with materials available onsite, emergency lighting, etc.) This would require offsite power to be analyzed for every fire area and procedures written for any location where fire could produce a loss of offsite power.

This section was deleted during reformatting; the above statement was worked into

'BWROG Position'section and reworded per further discussions with the NRC to read:

" Actions necessary to restore offsite power systems are considered to be performed under the purview of the emergency response organization."

m-0]/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 3 Assessment

__j

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. Loss ofOffsite Power p!-

f[ Reason for Position

- The loss of offsite power has the potential to adversely affect safe shutdown equipment due to a loss of power to active safe shutdown equipment. In addition, the requirements for offsite power differ between the redundant and alternative / dedicated shutdown capability.

Therefore, consideration must be given for the loss of offsite power when evaluating its effect on safe shutdown.

0]/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis ]

Assessment i

x Loss of Offsite Power '

jl BWROG Position t I

- For redundant shutdown, offsite power may be credited if demonstrated to be free of fire damage.

- Alternative / dedicated systems must demonstrate shutdown capability where offsite power is available and where offsite power is not available for 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . If such equipment and systems used prior to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months after the fire will not be capable of being powered by both onsite and offsite electric power systems because of fire damage, an independent onsite power system shall be provided. Equipment and systems used after 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months may be powered by

, offsite power only. Hence, offsite power is assumed to be restored after 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

- Actions necessary to restore offsite power systems are considered to be performed under the purview of the emergency response organization.

M/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 2 Assessment

Loss ofOffsite Power i JC

$ Basis for Position w.

- The BWROG's position on offsite power requirements for alternative / dedicated shutdown capability meets the requirements outlined in 10 CFR 50, Appendix R, Section III.L, paragraph III.L.3. For shutdown approaches that are not classified as alternative / dedicated shutdown, there is no requirement to consider a loss of offsite power unless the actual fire damage causes such a loss.

01/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 3 Assessment

a Loss ofOffsite Power 5

c[/- Reference Documents (Regulations)

~ 10 CFR 50. Appendix R. Section HLL. Alternate and DedicatedSitutdown Capability

- "...the alternative shutdown capability shall be independent of the specific fire area (s) and shall accommodate postfire conditions where offsite power is available and where offsite power is not available for 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

- "4. If the capability to achieve and maintain cold shutdown will not be available because of fire damage, the equipment and systems comprising the means to achieve and maintain the hot standby or hot shutdown condition shall be capable of maintaining such conditions until cold shutdown can be achieved. If such equipment and systems will not be capable of being powered by both onsite and offsite electric power systems because of fire damage, an independent onsite power system shall be provided. The number of operating shift personnel, exclusive of fire brigade members, required to operate such equipment and systems shall be on site at all times."

- "5. Equipment and systems comprising the means to achieve and maintain cold shutdown conditions shall not be damaged by fire; or the fire damage to such equipment and systems shall be limited so that the systems can be made operable and cold shutdown can be achieved within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . Materials for such repairs shall be readily available on site and procedures shall be in effect to implement such repairs. If such equipment and systems used prior to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months after the fire will not be capable of being powered by both onsite and offsite electric power systems because of fire damage, an independent onsite power system shall be provided. Equipment and systems used after 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months may be powered by offsite power only."

W/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 4 Assessment

i

. Loss ofOffsite Power 1

f(wReference Documents (Guidance - 1 i

> Generic Letter 81-12. Enclosure 1. StaffPosition. Safe Shutdown Capability.

Section 1

i

- The design basis event for considering the need for alternative.

shutdown is a postulated. fire in a specific fire area containing redundant safe shutdown cables / equipment in close proximity where it i has been determined that fire protection means cannot assure that safe ;

shutdown capability will be preserved. Two cases should be considered: (1) offsite power is available; and (2) offsite power is not ;

available. !

i 0]/29,99 Draft BWRoG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 5 Assessment ,

f

4 Loss ofOffsite Power

\c

=i> Reference Documents (Guidance 2/2) -

> Generic Letter 86-10. Enclosure 2. Appendit R Questions and Answers. Section 5.3.6.

On-Site Power QUESTION

- Appendix R, Section llI.L.4 states in part, 'If such equipment and systems will not be capable of being powered by both on-site and off-site electrical power systems because of fire damage, an independent on-site power system shall be provided.' Again, in Appendix R,Section III.L.5, the statement is made 'If such equipment and systems used prior to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months after the fire will not be capable of being powered by both onsite and offsite electrical power systems because of fire damage, an independent onsite power system shall be provided.' An interpretation is needed of the meaning and the applicability of these two quotes relative to alternative shutdown capabilities. ;

- RESPONSE

- "These statements are meant to indicate that the alternative shutdown capability should be powered from an onsite power system independent (both electrically and physically) from the area under consideration. Further, if the normal emergency onsite power supplies (diesel generators) are not available because of fire damage, then a separate and independent onsite power system shall be provided. As an example, some plants are utilizing a dedicated onsite diesel l generator or gas turbine to power instrumentation and control panels which are a part of the attemative shutdown capability."

()J/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 6 Assessment

i Loss ofOffsite Power MV_ :

Reference Documents (Other Documentation - 1/2)

I

~

Information Notice 84-09. Attachment 1.Section X.

Proceduresfor Alternative Shutdown CapabiliN ;

. - ...Section III.L.3 of Appendix R requires that alternative shutdown procedures be in effect which accommodate post-fire conditions, where offsite power is available and where offsite power is not available for 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months ."

t 0]/29/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 7 Assessment

Loss ofOffsite Power c

y y-k Reference Documents (Other Documentation - 2/2)

~ SECY 83-269. Attachntent C. NRC Staff Positions on Post Fire Shutdown Capability.

Allowable Tinte to Achieve Safe Shutdown

- Some difficulty was being experienced on the part of the staff and licensees concerning the time allowed to achieve cold shutdown and whether credit for offsite power could be used in designing the cold shutdown capability. To establish consistency in all plant designs, the staff issued the following position (reference: memorandum from R.

Mattson to R. Vollmer, dated July 2,1982).

- Section III.G to Appendix R states that fire damage to cold shutdown capability must be limited to damage that can be repaired within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .Section III.L.! of Appendix R states that the alternative shutdown capability shall be able to achieve cold shutdown within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . Further,Section III.L.5 of Appendix R states that fire damage shall be limited so that the systems can be made operable and cold shutdown achieved within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . Sections Ill.L.1 and ill L.5 states that a plant must be capable of achieving cold shutdown using only onsite power prior to the elapse of 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .Section III.L.5 also clearly states that offsite power is assumed restored after 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months in that equipment and nstems not needed until 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months may be powered by offsite power only.

- We have been using and propose to continue to use Sections III.L.1 and III.L.5 in our evaluations. Thus, a licensee should have the capability of repairing equipment and achieving cold shutdown within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months using only onsite power. The 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months is considered an upper limit; a licensee may limit the repairs and achieve cold shutdown in a shorter time frame. ,

ON9/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 8 Assessment

,W ,o H t Short Duration k Reason for Position

~

- A hot short has the potential to cause spurious actuation of equipment. The affect of the spurious actuation may be dependent on the length of time the hot short condition exists. Therefore, this position serves to clarify the consideration given to the hot short duration when evaluating its effect on safe shutdown.

02/0ft99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 1 Assessment

i HotShortDuration ,

f,( ;

p"( BWROG Position l

w -

- A hot short is postulated to exist until either action to isolate the given circuit from the fire area is taken, or other appropriate actions to negate the effects of the resulting

! spurious actuation are taken.

For analysis purposes, it is not assumed the fire will eventually clear the hot short.

W i i

02/01/99 Draft B WROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 2 Assessment i i

i

t Hot ShortDuration '

s c.

f% Basi.s for Position

-The basis for the BWROG position on hot short duration is provided in Generic Letter 86-10, Section 5.3.2.

1 02/o1/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 3 Assessment i

I F

i

Hot Short Duration i g3 Reference Documents (Regulations) i

- Not specifically addressed in any regulation.

.h 02/01/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 4 '

Assessment

2 s Hot Short Duration g$ Reference Documents (Guidance)

> Generic Letter 86-1(1. Enclosure 2. Appendit R Questions and Answers. Section S.3.2. '

' Hot Sitort' Duration QUESTION

- "If one mode of fire damage involves a ' hot short' how long does that condition exist as a result of fire damage prior to terminating in a ground or open circuit and stopping the t spurious actuation?" -

t

- RESPONSE

- "We would postulate that a ' hot short' condition exists until action has been taken to .

isolate the given circuit from the fire area, or other actions as appropriate have been taken to negate the effects of the spurious actuation. We do not postulate that the fire .

would eventually clear the ' hot short.'"

i 02/0]/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 5 Assessment ,

t I

.. .1 Hot Short Duration

<uzy h

Reference Documents (Other Documentation) i

- None t

i 02/01/99 Draft BWROG Generic Guidancefor Post-Fire Safe Shutdown Circuit Analysis 6 Assessment l

4

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