ML20239A136

SER Re License Request for NRC Review & Concurrence W/Changes to NRC-approved Fire Protection Program

ML20239A136
Person / Time
Site:	Vermont Yankee
Issue date:	09/02/1998
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20239A134	List: ML20239A132 ML20239A136
References
NUDOCS 9809080254
Download: ML20239A136 (3)

Text

.

U p ,

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30006-4001

~%,***,* FETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RFLATED TO LICENSEE REQUEST FOR NRC REVIEW AND CONCURRENCE l

1 VERMONT YANKFF NUCLEAR POWER CORPORATION VERMONT YANKFF NUCLEAR POWER STATION DOCKET NO. f h.2Z.1

1.0 INTRODUCTION

By letter dated January 31,1977, as supplemented by letters dated March 18, July 14, August 18, September 13, and November 30,1977, Vermont Yankee Nuclear Power Corporation (WNPC, the licensee) submitted the Vermont Yankee Power Station (WPS) fire protection program for U.S. Nuclear Regulatory Commission (NRC) staff review. By ]

letter dated January 13,1978, the staff issued Amendment No. 43 to Facility Operating License No. DPR-28 for WPS and its supporting safety evaluation (SE). In i Section 5.14.6 of this SE, which documented the staff's evaluaticn of the WPS fire protection program, the staff accepted the licensee's commitment to upgrade all cable penetrations between the cable spreading room (CSR)' and the main control room (MCR) to provide 3-hour fire rated protection. By letter dated July 13,1995, as supplemented by letters dated January 20 and August 8,1997, the licensee requested NRC staff review and concurrence with the following changes to the NRC approved fire protection program: (1) predesignation of the MCR, CSR, and battery room as a single fire area, and (2) delete the requirement to maintain the electrical penetration seal between the MCR and the CSR as a rated fire barrier.

2.0 DISCUSSION The MCR is on the 272' elevation, directly above the CSR, which is on the 260' elevation.

The MCR contains automatic smoke detectors. The battery room is considered par 1 of the CSR for purposes of the safe shutdown analysis (SSA). The CSR/ battery room contains an automatic smoke detection system and an automatic CO2 fire suppression system. Both East and West switchgear (SWGR) rooms are located on the 248' elevation, directly below the CSR. The switchgear rooms are separated by a 1-hour fire rated barrier, and contain automatic smoke detection systems, and an automatic CO2 fire suppression systems.

Post-fire safe shutdown can be achieved and maintained for a single fire that simultaneously disables the MCR, CSR, and the battery room. For these fire zones, which are designated the Altemative Shutdown Fire Area (FA-ASD) in the Vermont Yankee Safe Shutdown Capability Analysis, a fire requires implementation of Appendix R, altemative shutdown strategies. This involves Reactor Core Isolation Cooling (RCIC) operation from the RCIC room, and Residual Heat Removal operation from the RHR altemate shutdown panelin the reactor building. Power sources include two attemate shutdown batteries and a diesel generator operated in the altemate shutdown mode.

9909090254 990902 #

PDR ADOCK 05000271 4 F PDR 3 i

' Note: The NRC and WNPC use the terms ' cable spreading room" and " cable I vault" interchangeably. Based on the language in WNPC Amendment No. 43, j this safety evaluation willidentify the room as the cable spreading room.

ENCLOSURE j

U 2

The East and West switchgear rooms are two separate fire areas. The rooms are

. provided with automatic detection and automatic suppression systems and are separated by a 1-hour rated fire barrier. Equipment separation meets the criteria of Appendix R, Section Ill.G.2.b. For a fire that disables equiproent in one switchgear room, post fire l safe shutdown can be achieved and maintained using equipment in the unaffected switchgear room.

During a recent once-per-cycle surveillance of vital fire barrier penetration seals, as required by Technical Specification Section 4.13.E.1, the licensee discovered that some electrical penetrations in the fire barrier between the MCR (floor) and the CSR (ceiling) '

did not conform with a fire tested configuration. The licensee determined that the ceiling is estimated to pass a fire test with a duration of at least 30 minutes and would provide an adequate seal to ensure that the required concentration of CO 21s maintained in the CSR/battry room. Therefore, the licensee reclassified this barrier from a fire rated barrier to a smoke / gas seal banier. The electrical penetration seals in this barrier are constructed of silicone foam.

VYNPC stated that the most significant change associated with reclassifying the MCR floor /CSR ceiling, is that this barrier will no longer be maintained as a rated fire barrier.

In its submittal of August 8,1997, the licensee committed to maintain the barrier between the MCR and the CSR as a smoke / gas seal to ensure no negative effects on the CSR automatic CO2 suppression system or on MCR habitability. VYNPC will control the current configuration of the barrierwith the following proce'dures: (1) Procedure OP 0042;

" Plant Fire Prevention and Fire Protection," (2) Procedure OP 0046; " Installation and Repair of Fire Barrier Penetration Seals, Fire Breaks, and Flood Seals," and (3)

Procedure OP 4019;" Surveillance of Plant Fire Barriers and Fire Rated Assemblies." On the basis of its review of the licensee's evaluation provided in a letter dated August 8,1997, it is the staffs judgement that these procedures will provide reasonable  !

. assurance that the penetration seals are inspected and maintained in operable condition. I i

On the basis of its evaluation, the licensee concluded that since the same altemate safe shutdown equipment is affected by a fire in the CSR or the MCR, no additional safety benefit would be achieved by maintaining the MCR, CSR, and battery room as separate fire areas. j 4.0 EVALUATION The staff was concemed that in the event of a fire in the CSR, the lack of a fire rated barrier between the MCR and the CSR could adversely effect the ability to achieve and maintain post-fire safe shutdown.

In the staffs view, the automatic smoke detection systems provide reasonable assurance i that a fire in the CSR would be detected in its incipient stage. The fire brigade would then l extinguish the fire using available equipment. In the event the fire grows beyond the incipient stage before the fire brigade responds, there is reasonable assurance that the automatic CO2 fire suppression system will actuate and extinguish the fire. Although the penetration seal installed between the CSR and MCR is not a qualified fire rated design, there is reasonable assurance that it will have sufficient fire resistance to prevent the spread of fire from the CSR to the MCR unti! either the fire brigade or the automatic CO2

- fire suppression system extinguishes the fire.

. .u j 3

As discussed above, in the event of a CSR fire, the licensee will use the allemative safe shutdown capability to achieve and maintain post fire safe shutdown. In the event that the fire spreads from the CSR to the MCR, the same attemative safe shutdown strategy will be used. Therefore, the lack of a fire-rated penetration seal between the CSR and ,

MCR does not adversely impact the post-fire safe shutdown capability. k

5.0 CONCLUSION

On the basis of its evaluation, as documented above, and contingent on the licensee's {

commitment to maintain the barrier between the MCR and the CSR in its current configuration, the staff concurs with the following changes to the VYPS fire protection program: (1) redesignated the MCR, CSR, and battery room as a single fire area, and l (2) reclassify the barrier between the MCR and the CSR, including the electrical  !

penetration seals, as a smoke / gas barrier, rather than a rated fire barrier.

' Principal Contributor: T. Eaton l

Date: September 2, 1998 I l

i l

i i

f i

I f

L 1

I

)