ML20138J023

Forwards List of Staff Technical Positions Re Key Issue 12, Involving Acceptability of W Approach for Fire Protection

ML20138J023
Person / Time
Site:	05200003
Issue date:	05/05/1997
From:	Slosson M NRC (Affiliation Not Assigned)
To:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
References
NUDOCS 9705070368
Download: ML20138J023 (7)

Text

May 5, 1997 p..

Mr. Nicholas J. Liparulo, Manager Nuclear Safety and Regulatory Analysis Nuclear and Advanced Technology Division Westinghouse Electric Corporation P.O. Box 355

~Pittsburgh, PA 15230

SUBJECT:

FIRE PROTECTION POSITIONS RELATED TO THE AP600 REACTOR DESIGN

Dear Mr. Liparulo:

In a letter dated December 6, 1996, the Nuclear Regulatory Commission (NRC) sent you a list of potential critical path issues in the design certification process for the AP600. One of the issues, Key Issue #12, involves the acceptability of the Westinghouse approach for fire protection. On the basis of-its review of the AP600 Standard Safety Analysis Report, the Plant Systems Branch staff has developed technical positions for the outstanding fire protection issues that it has identified thus far. The staff discussed these positions.with Westinghouse during meetings on April 7, 1997, and i

April 21,'1997.

Enclosed is the staff's technical. positions for this issue.

l If the staff develops additional fire protection issues during its review, it will discuss.them with Westinghouse and will prepare additional technical positions, as needed.

If you have any questions regarding this matter, you may contact Diane Jackson at (301) 415-8548.

1 Sincerely, I

l OMnalSignedBy:

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l Marylee Slosson, Acting Director Division of Reactor Program Management Office of Nuclear Reactor Regulation l

Docket No.52-003 l

Enclosure:

As stated cc w/ enclosure:

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9, Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600 cc: Mr. B. A. McIntyre Mr. Ronald Simard, Director Advanced Plant Safety & Licensing Advanced Reactor Programs Westinghouse Electric Corporation Nuclear Energy Institute Energy Systems Business Unit 1776 Eye Street, N.W.

P.O. Box 355 Suite 300 Pittsburgh, PA 15230 Washington, DC 20006-3706 Ms. Cindy L. Haag Ms. Lynn Connor Advanced Plant Safety & Licensing Doc-Search Associates i

Westinghouse Electric Corporation Post Office Box 34 Energy Systems Business Unit Cabin John, MD 20818 Box 355 Pittsburgh, PA 15230 Mr. James E. Quinn, Projects Manager LMR and SBWR Programs Mr. M. D. Beaumont GE Nuclear Energy Nuclear and Advanced Technology Division 175 Curtner Avenue, M/C 165 Westinghouse Electric Corporation San Jose, CA 95125 One Montrose Metro 11921 Rockville Pike Mr. Robert H. Buchholz l

Suite 350 GE Nuclear Energy l

Rockville, MD 20852 175 Curtner Avenue, MC-781 1

San Jose, CA 95125 Mr. Sterling Franks j

l U.S. Department of Energy Barton Z. Cowan, Esq.

NE-50 Eckert Seamans Cherin & Mellott l

19901 Germantown Road 600 Grant Street 42nd Floor Germantown, MD 20874 Pittsburgh, PA 15219 Mr. S. M. Modro Mr. Ed Rodwell, Manager Nuclear Systems Analysis Technologies PWR Design Certification Lockheed Idaho Technologies Company Electric Power Research Institute Post Office Box 1625 3412 Hillview Avenue Idaho Falls, ID 83415 Palo Alto, CA 94303 Mr. Frank A. Ross Mr. Charles Thompson, Nuclear Engineer U.S. Department of Energy, NE-42 AP600 Certification Office of LWR Safety and Technology NE-50 19901 Germantown Road 19901 Germantown Road l

Germantown, MD 20874 Germantown, MD 20874 l

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TECHNICAL POSITIONS BY THE OFFICE OF NUCLEAR REACTOR REGULATION PLANT SYSTEMS BRANCH l

DIVISION OF SYSTEMS SAFETY AND ANALYSIS 3

FIRE PROTECTION ISSUES RELATED TO THE DESIGN OF THE WESTINGHOUSE AP600 ADVANCED LIGHT WATER REACTOR i

I.

Introduction l

The fire protection review criteria for the advanced light water reactors (ALWRs) is specified in SECY 90-016 dated January 12, 1990, SECY 93-087 dated April 2, 1993, SECY 94-084 dated March 28, 1994, and the corresponding staff requirements memorandums (SRMs) dated June 26, 1990, July 21, 1993, and j

June 30, 1994. Title 10 CFR 52.83 states that all provisions of 10 CFR Part 50 and its appendices applicable to holders of operating licenses also apply to holders of combined licenses.

The fire protection criteria specifies that the ALWRs will comply with the requirements specified in 10 CFR 50.48 Fire Protection, Criterion 3-Fire protection of Appendix A to 10 CFR Part 50, l

and Appendix R to 10 CFR Part 50.

Basic fire protection guidance for nuclear power plants is provided in Branch i

Technical Position (BTP) CMEB 9.5-1,-" Guidelines for Fire Protection for Nuclear Power Plants." In addition to the above listed requirements, the Nuclear Regulatory Commission (NRC) has specified that ALWRs shall provide an enhanced level of fire protection to ensure that safe shutdown can be achieved assuming that all equipment in any one fire area is rendered inoperative due to fire damage, and that re-entry into the fire area by plant personnel for repairs or operator actions is not possible. Because of its physical configu-ration, the control room is excluded from this approach, provided an indepen-dent alternative shutdown capability that is physically and electrically independent of the control room is included in the design. ALWRs must provide fire protection for redundant shutdown systems in the reactor containment building that will ensure, to the extent practicable, that one shutdown division will be free of fire damage. The design must also ensure that smoke, hot gases, and fire suppressants do not migrate into other fire areas to the extent that they could adversely affect safe-shutdown capabilities, including operator actions.

The NRC staff interpretations and positions related to fire protection published in generic communications will be used as applicable in the review of the AP600.

In SECY 93-087 and the corresponding SRM, the NRC specified that passive plant design applications will be reviewed using the newest industry codes and standards that have been endorsed by the NRC. The standard applicable to ALWR fire protection is NFPA 804, " Standard for Fire Protection for Advanced Light Water Reactor Electric Generating Plants," published by the National Fire Protection Association (NFPA). This standard has not been i

formally endorsed by the NRC. However, consistent with SECY 93-087, it will be used as appropriate during the review of the AP600 to supplement existing NRC fire protection guidance.

j Enclosure l

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I II. Technical Positions ij' l.

Safe Shutdown Canability l

In the submittal dated March 20, 1997, Westinghouse Electric Corporation (the applicant), states that safe shutdown capability following a design basis fire event, would be provided using safety-related systems only.

The safety-related systems credited in the analysis are the reactor coolant system, the i

steam generator system, containment isolation, the Class IE DC batteries, the 2

passive core cooling system, and the passive containment cooling system.

In Appendix 9A of the AP600 Standard Safety Analysis Report (SSAR), the applicant states that a single active component failure (independent of the fire) is not i

assumed. This assumption is not consistent with the assumptions used in the assessment of other design basis events. This unique approach is not ad-i dressed in the fire protection discussion provided to the Commission in the i

aforementioned SECY papers.

The plants currently licensed to operate do not consider fire as a design basis event, rather fire is considered as an operational transient (such as a loss of normal ac power), and a single active j-component failure is not assumed independent of the fire.

I Safe shutdown capability for most fire areas, with the general exception of 4

the main control room and cable spreading room, in the currently licensed j

plants is provided by ensuring that one train of the normal method for i

achieving hot shutdown is maintained free of fire damage for any single fire, i

and that at least one train of the normal method for achieving cold shutdown can be repaired within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. These requirements are specified in Section

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III.G of Appendix R to 10 CFR Part 50. Where one train of the normal hot i

shutdown method cannot be protected from fire damage, an alternative or j

dedicated method of shutdown is provided.

For areas where alternative or dedicated shutdown capability is provided,Section III.G.3 of Appendix R 4

j specifies that the area, room, or zone under consideration shall be provided j

with automatic detection and a fixed fire suppression system.

l The staff has determined that the normal shutdown method for the AP600 is the j

nonsafety-related systems, such as the feedwater systems, main condenser, circulating water system, chemical volume and control system, and reactor coolant pumps. The normal shutdown method is not considered available for any fire area in the AP600. Reliance is placed, therefore, on the alternative i

method using the safety-related systems described above.

Although fire detection and manual hose stations are provided in most plant areas, fixed fire suppression is not.

In its submittal of March 20, 1997, the applicant incorrectly classifies the standpipe and hose stations as a " fixed fire suppression system" for meeting the criteria specified in Section III.G.3 of Appendix R for areas, rooms, or zones where alternative or dedicated shutdown capability is required.

In Generic Letter 83-33, the staff position states that a fixed fire suppression system shall have discharge heads and the distribution piping for such heads installed. The position also states that hose-stations do not satisfy this requirement.

The addition of a fixed fire suppression system in these areas is a defense-in-depth measure to provide for the control of a fire during its incipient

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stages, to reduce the potential for damage to the normal shutdown systems, and to minimize reliance on the alternative dedicated shutdown method. The j

current AP600 design is not in accordance with the criteria specified in Section III.G.3 of Appendix R.

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Seoaration of Redundant Divisions The containment / shield building consists of a single fire area, which is not i

inerted during normal operation to eliminate the potential for a fire. The redundant divisions of the safety-related safe shutdown systems located in the containment building are located in the same fire area. The redundant trains are located in separate fire zones that are separated by non-fire rated structural barriers or labyrinths. The applicant states that fire will not 4-propagate between zones such that redundant divisions will be damaged by a i

single fire. However, the applicant has not provided technical justification j

to support its determination.

4 The applicant utilizes the equivalent fire severity methodology based on the i

expected average combustible load in the fire area or zone for evaluating the j

fire hazard in the area or zone and for determining the adequacy of the fire barriers separating the area or zone from adjacent areas or zones. This methodology is based on the assumptions that:

(1) an equal area under the time-temperature fire exposure curve equates to equivalent fire performance and (2) that the combustible load is the only important factor that determines 4

fire intensity. Both of these assumptions are incorrect.

In addition, the i

National Fire Protection Association specifies that the application of the equivalent fire severity methodology should be limited to light hazard j

occupancies, where the combustible materials are evenly distributed over the floor area, the fuel is normal cellulosic materials such as paper and wood, and the combustibles are located solely at the floor level. This is not j

representative of the configuration of the AP600. On these bases, the staff informed the applicant that this methodology is not adequate for evaluating i

the fire hazards or the performance of barriers separating adjacent fire areas or zones.

Important factors that effect fire severity such as ventilation, l

fuel geometry, fuel type, and compartment geometry should be considered in the j

fire hazard analysis.

j 3.

Standnines and Hose Stations

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l Section III.D of Appendix R to 10 CFR Part 50 states that standpipe and hose L

systems shall be installed so that at least one effective hose stream will be 4

able to reach any location that contains or presents an exposure fire hazard to structures systems, or components important to safety.

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The standard applicable to the design and installation of standpipe and hose systems is NFPA 14, " Standpipe and Hose Systems." NFPA 14 provides for three i

classes of standpipe systems: Class I, Class II and Class III.

Sec-tion 9.5.1.2.1.5 of the SSAR states that standpipe systems are provided for each building in accordance with NFPA 14 requirements for Class II service.

Class 11 service is intended for the control of incipient fires by the 1

building occupants. The limited flow and pressure provided by a Class II j

standpipe is not adequate for the suppression of developed fires or exposures 4

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-4 by the plant fire brigade. Class I systems provide for effective hose streams r

during the more advanced stages of a fire and for exposure protection.

Class III systems provides both Class I and Class II capability.

Position 6.c.(4) of BTP 9.5-1 states that provisions should be made to supply water at least to standpipes and hose connections for manual fire fighting in areas containing equipment required for safe shutdown in the event of a safe shutdown earthquake.

The water supply for this condition may be obtained by operator actuation of valves in a connection to the hose standpipe from a seismic Category I water system.

This connection should be capable of providing flow to at least two hose stations of approximately 75 gallons per minute per hose station.

i Section 9.5.1.2.1.5 of the SSAR states that a seismic standpipe system is provided in all areas required for safe shutdown following a safe shutdown earthquake. The volume of water from this system is sufficient to supply two hose streams with 75 gallons per minute each. The seismic standpipe system is operated in the same manner during normal plant operation as it is following a safe shutdown earthquake.

The seismic standpipe system is not in compliance with NFPA 14 or the criteria specified in Section III.D of Appendix R, 'for fires during normal plant operation.

This system is not capable of providing an effective hose stream able to reach any location that contains or presents an exposure fire hazard to structures systems, or components important to safety.

4.

Fire Protection Water Suooly System Section III.A of Appendix R to 10 CFR Part 50 states that two separate water supplies shall be provided to furnish necessary water volume and pressure to the fire main loop.

Each supply shall consist of a storage tank, pump, i

j piping, and appropriate isolation and control valves.

The supplies shall be separated so that a failure of one supply will not result in a failure of the other supply.

i Figure 9.5.1-1 of the SSAR, which depicts the fire protection system piping and instrumentation diagram, indicates that a failure of the fire protection water loop in the turbine building cannot be isolated from the remainder of the fire protection water supply system without entering the turbine building.

The turbine building is a single fire area with the exception of the auxiliary boiler room, stairwells, fire pump room, lube oil storage and reservoir rooms, sampling laboratory, and electrical and switchgear rooms. A turbine failure or fire could damage the fire protection piping located in the turbine building such that the water supply would not be available.

Personnel entry into the turbine building to isolate the fire protection loop is not expected to be achievable immediately following a turbine failure or fire. This configuration is not compliance with the criteria specified in Section III.A of Appendix R.

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Stairwells Position C.5.a.(6) of BTP 9.5-1 states that stairwells outside primary containment serving as escape routes, access routes for fire fighting, or access routes to areas containing equipment necessary for safe shutdown should be enclosed in masonry or concrete towers with a minimum fire rating of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and self-closing Class B fire doors.

In Table 9.5.1-1 of the SSAR, the applicant states that stairwells are enclosed in towers constructed of gypsum boards having a fire rating of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The applicant has not provided technical justification for this deviation from the guidance provided in BTP 9.5-1.

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