ML17305A637
| ML17305A637 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/26/1990 |
| From: | Zimmerman R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| NUDOCS 9004090064 | |
| Download: ML17305A637 (4) | |
Text
MAR 2 6 1990 Docket No. 50-530 Arizona Public Service Company P. 0.
Box 52034 Phoenix, Arizona 85072-2034 Attn:
Mr. William F.
Conway Executive Vice President, Nuclear Gentlemen:
Subject:
Temporary Waiver of Compliance Regarding Palo Verde Unit 3 Technical Specification Requirement 3.6.3 In your letter dated March 22,
- 1990, supplemented by your letter dated March 23,
- 1990, and in discussions with the NRC staff on March 23, 1990, you requested temporary relief from Technical Specifications (TS) Action Statement 3.6.3.1.a, regarding the length of time to restore the feedwater containment isolation valves to operable status after removal from service for maintenance.
In order to replace four-way actuators on feedwater containment isolation valves, which may contain "0" rings of an incorrect material, you estimate that the work may take approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
TS 3.6.3.1.a allows only four hours to restore the associated valves to an operable status.
You concluded that extending the allowed out-of-service time from four hours to twelve hours when operating at 100% power was of negligible increased risk for the following reasons:
The redundant valves in each feedwater line have been verified to contain the correct material and each will be tested for operability prior to commencing work on the suspect feedwater isolation valves.
There are two check valves installed on each feedwater line inside containment in series with the isolation valves to prevent leakage outside conta.inment in the event of a feedwater line break.
The isolation valve work will only be done on one valve at a time.
Prior to the commencement of this work, personnel will be thoroughly briefed on the activity, the possible problems which may occur while the work is in progress, and the appropriate response to the problems.
The control room operators will be prepared should an isolation signal occur while work on the isolation valve is ongoing. If there are any indications that the redundant feedwater isolation valve fails to fully
- close, the handswitch in the control room will be used to attempt closure and if the valve fails to close, the feedwater pumps will be tripped and the feedwater pump discharge valves closed from the control room.
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0 Your preliminary probabilistic risk assessment of the increase in core damage frequency due to this activity is negligible (less than I x lOE-09) and the increase in the probability of the loss of containment integrity is also negligible (less than I x 10E-09).
Work on similar replacements on the main steam isolation valves have been successfully done while at power.
Based on the above and based on discussions with NRR, a temporary waiver of compliance for the subject TS action statement only is granted from 8:00 a.m.
(MST), March 27, 1990 to expire at ll:00 p.m.
(MST), March 29, 1990.
This temporary waiver extends the allowable time for the feedwater isolation valves to be inoperable from four to twelve hours.
All other TS requirements remain in affect.
If our understanding concerning your actions is not correct, you should promptly notify this office.
Sincerely, r'~/
Roy P.
Zimmerman, Director Divisi on of Reactor Sa fety and Projects cc:
J. Martin, RV T. Murley, NRR J. Taylor, EDO J. Lieberman, OE bcc:
G. Holahan, NRR T. Chan, NRR J. Craig, NRR D. Coe, Palo Verde M. Slossom, Technical Assistant, Div. of Reactor Projects - I/II, NRR ptgjJ RV HWong:jb 03/g.gj'90 P~ gc.e~~
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