ML20154A115

Safety Evaluation Supporting Amend 141 to License NPF-1

ML20154A115
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	05/03/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20154A110	List: ML20154A106 ML20154A111 ML20154A115
References
NUDOCS 8805130146
Download: ML20154A115 (3)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENCMENT NO.-141TO FACILITY OPERATING LICENSE NO. NPF-1 PORTLAND GENERAL ELECTRIC COMPANY THE CITY OF EUGENE, GREGON ,

PACIFIC POWER AND LIGHT COMPANY TROJAN NUCLEAR PLANT C0CKET NO. 50-344

1.0 INTRODUCTION

During an Aucust 1986 NRC Safety System Functional Inspection, it was identified that under certain design basis conditions, automatic isolation of the nonseismic Category 1 portion of the Component Cooling Water (CCW) systen necessitated by an earthquake induced rupture of certain nonseismic Category 1 CCW piping, may not occur rapidly enough to prevent the blowdown of both CCW trains, thus rendering the safety-related portion of the systen inoperable.

As a result, Portland General Electric Company (PGE) ccmitted to upgrade the CCW System by either seismically supporting the nonseismic portions of the system, or installing a flow orifice which will restrict flow and indicate high flow conditions which will activate closure of the train isolation valves. PGE conuitted to complete this upgrade by no later than the end of the 1989 refueling cutage. Until that tire, PGE proposed that the CCW System be operated in a "split-train" configuration with the interface isolation valves for one train nonnally closed and with all three CCW pumps maintained in an operable status.

By letter dated December 15, 1987, the staff found this proposal to be acceptable provided that the Technical Specificatiens (TS) be revised to provide the same level of protection and safety in the proposed configuration as that of the current Technical Specifications. In a letter dated February 4,1988, PGE proposed changes to the Limii'ng Conditions for Operation (LCO), Action Statements, and Surveillance requirements (SR) to TS Section 3/4.7.3, "Component Cooling Water System."  !

2.0 DISCUS $!CN AND EVALUATION The CCW System provides heat removal from safety . elated and nonsafety-related components during nonnal operation, shutdown and k> bob P

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-2 cooldern of the reactor, and frem safety-related components after any accident leading to an emergency shutdown. In addition, the CCW System provides a monitored, intermediate barrier between the Reactor Coclent System (RCS) and the heat sink provided by the Service Water System (SWS). The portion of the CCW S EngineeredSafetyFeature(ESF)ystemthatsuppliescoolingwaterto equipment is safety-related and seismic Category I.

The CCW System consists of two seismic Cate0ery I flow paths, each of which serves a single train of identical ESF equipment. In addition, each of the seismic Category I flow paths serves a conson nonseismic Category I, nonsafety-related flow path. Each CCW train has air-eperated interface isolation valves to provide automatic isolation of the seismic Category I portion of the system from the nonseismic Category I portion of the system upon receipt of a safety injection signal (SIS) or a low CCW surge tank level signal. One purpose of this automatic isolation capability is to ensure that the failure cf nonscismic Category I equipment and components (including piping) does not adycrsely affect the operation ESF equipment essential to safe shutdown of the plant.

Given a full area rupture of the nonseismic Category I piping due to a seisnic event, it has been determined that the automatic interface isolation valves me) not close fast enough to prevent blowdown of the sefety-related porticr of the two CCW trains, resulting ir a complete loss of CCW. To preclude this scenario from occurring, the CCW system has been aligned in a split-train configuration with one train isolated from the nonseismic Category I flow path during Modes 1 throuch 4. This configuration ensures a continuous flow of CCW to at least one train of ESF equipment following a seismic event. In addition, the spare CCW pump will be meintained operable during Modes 1 through 4. This will := .re the availability of a CCW Icop even with a single failure concurrent with a seismic event.

Furthermore, since a Design Basis Accident (DBA) is not assumed to occur

, simultaneously with a seismic event that ruptures the nonseismic Category I CCK piping, at least one train of ESF equipment would be available to respend to accident demands assuming a single failure in the other CCW train.

I Luring Modes 5 and 6, the proposed change will require that et least two i CCW trains, or at least one CCW train and the spare CCW pump, be operable. '

This provision is an enhancement over the current provisions in the TS and therefore will provide greater assurance of CCW restoration following  ;

a seismic event. Also, because the plant is in at least a cold shutdown

condition during these modes and timely recovery actinns can be expected, the consequences of a seismically induced failure are bounded by current updated Final Safety Analysis Report accident analyses.

i Based on the above, we conclude that the prcposed changes to TS Section 3/4.7.3 "Component Cooling Water System" and associated Bases are acceptable.

3.0 _ CONTACT WITH STATE OFFICIAL The NRC staff has notified the Oregon Department of Energy of the propesed issuance of this amendment along with the prnposed detemination of no significant hazards consideration. No coments were received.

4.0 FHVIRONMENTAl. CONSIDFRATION This amendment involves a change in the installation or use of a facility comperent located within the restricted area as defined in 10 CFR Part 20. The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cunulative occupational radiation exposure. The Comission has previously published a proposed finding that the amendment involves no significant hazards consideratico and there has been no public coment on such finding. Accordingly, the '

amend meets the eligibility criteria for categorical exclusion set forth in10CFR651.2?(c)(9). Pursuant to 10 CFR 551.22(b), no environmental- ,

impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

5.0 CONCLUSION

We have concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will nct be endangered by operation in the proposed manner, and (2) such activities will be conoucted in compliance with the Comission's i regulations, and (3) the issuance cf the amendnent will nct be inimical to the comen defense and security or to the health and safety of the public, l

6.0 PRINCIPAL CONTRIBUTOR:

l T. Chan Dated: May 3, 1988 l

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