ML20012C498

Final & Interim Deficiency Rept CP-90-02 Re Diesel Generator Starting Air Receiver Tank Relief Valves.Initially Reported on 900205.Support Structure on Fourth Relief Valve Modified

ML20012C498
Person / Time
Site:	Comanche Peak
Issue date:	03/07/1990
From:	William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CP-90-02, CP-90-2, TXX-90064, NUDOCS 9003220076
Download: ML20012C498 (2)

Text

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,, s. - J Log # TXX-90064 i F7 File # 10110 l

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909.5  !

Z Ref. # 10CFR50.55(e) l M/ ELECTRIC 10CFR21 March 7, 1990 ES$"/80s, U. S. Nuclear Regulatory Commission l Attn: Document Control Desk Washington, D. C. 20555 l

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET NOS 50-445 AND 50 446 DIESEL GENERATOR STARTING AIR RECEIVER TANK RELIEF VALVES l SDAR: CP 90-02 (FINAL REPORT FOR UNIT 1)

(INTERIM REPORT FOR UNIT 2) ,

Gentlemen:

On February 5,1990, TV Electric verbally notified the NRC of a deficiency regarding Crosby style JMBU/JRU relief valves used on the diesel generator (DG) starting air receiver tank. This deficiency was identified as a result of a 10 CFR Part 21 report issued by the Enterprise Energy Services, Energy

• Services Group (ESG) of Cooper Industries. ESG identified that Enterprise Energy Services (formerly Transamerica Delaval, Inc.) did not s)ecify a relief valve blowdown pressure above the DG emergency start signal loc (out pressure.

Additionally, tae 10 CFR Part 21 report noted that both Perry Nuclear Power r Plant (PNPP) and CPSES relief valves had lifted when bumped by personnel.

These incidents called into question the ability of the relief valves to retain air receiver tank pressure during a seismic event, because they introduce a mechanism for the simultaneous lifting of these relief valves.

In response to the relief valve sensitivity to agitation, PNPP performed seismic testing of the valves with operating pressure applied to the valve ,

seats. This testing demonstrated that the valves would not actuate during a seismic event. TU Electric has reviewed the PNPP seismic test data and -

determined that three of the four CPSES relief valves were enveloped by the PNPP test and would not have lifted under CPSES design basis SSE accelerations. Thus, a seismic event does not have the potential to cause a common mode failure. For individual valve actuation, the starting air system design (two 100% capacity receiver tanks per DG) assures that at least one DG will be available to start upon receipt of an emergency start signal.

Therefore, TU Electric concludes that this issue is not reportable per 10 CFR I 50.55(e) as a deficiency does not exist which could have adversely affected I the safe operation of Unit 1 if it had gone uncorrected. This deficiency is l not reportable per 10 CFR Part 21 because it does not represent a defect or noncompliance which creates a substantial safety hazard at CPSES.

ObOON b f

f 400 North Olive Street L B. 81 Dallas Texas 75201

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TXX-90064' I March 7, 1990 l Page 2 of 2 1 Although this condition is not reportable, the support structure on the fourth relief valve (ID0-229) has been modified and the relief valve is now enveloped by the PNPP test data. In addition, DG availability is being monitored through three separate control room alarms. The safety significance of this  ;

deficiency for Unit 2 will be evaluated prior to Unit 2 fuel load. i l

Records supporting this determination are available at the site for your  ;

inspectors review.

Sincerely, l 5 .

/

William J. Cahill, Jr.

MCP/vid ,

c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3) -

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