ML19319E301
| ML19319E301 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 09/26/1975 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| References | |
| NUDOCS 8004040605 | |
| Download: ML19319E301 (3) | |
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SACRAMENTO MUNICIPAL UTILITY DISTRICT C 1708 59th Street, Box 15830. Sacramento, Caiifornia 95813;(916) 452 3211 September 26, 1975
'Q Mr. R. H. Engelken
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Director of Regulatory Operations, Region V 0g 7 $15 %
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Re:,0perating License DPR-54 Docket No. 50-312 l
Abnormal Occurrence 75-12
Dear Mr. Engelken:
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As defined by Proposed Amendment No. 30 to Technical Specifications for the Rancho Seco Nuclear Generating Station, Section.6.9.1, and Regulatory Guide 1.16, Revision 3, Section C.2.B.2, we are reporting the following Abnor-mal occurrence as A0-75-12.
Excessive air leakage cf the Reactor Building Purge Outlet Penetra-tion was detected August 27, 1975, while the Surveillance Procedure for local leak rate testing was being performed. The plant was in a cold shutdown con-dition for msintenance during this period.
Initial attempts to pressurize the penetration for measuring the leak rate failed, and leakage was detected through the 66 inch. inner butterfly valve.
j The valve seats on the inner valve were adjusted, and subsequent testing revealed leakage from the penetration of greater than 300,000 standard cc per minute, with a penetration pressure of 10 psig. Total leakage allowable from all penetrations inspected during a local leak' rate test, as stated in Technical Specifications. Section 4.4.1.2.3, is.06. percent of the Reactor Building atmosphere every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This limit converted to a leakage rate is 106,000 standard cc per minute at the minimum allowable test pressure (52 psig).
Further adjustments were made to the inner valve seats which reduced leakage through.that valve essentially to zero, as verified by local bubble testing.: The penetration leakage was measured at 33,550 standard cc per minute, which ~was through the outer penetration valve. Attempts to reduce
. leakage by adjustment of.the valve' seats were not successful, so the seats will; be replaced and ~ adjusted to give a proper seal. To assure that the leakage through the penetration remains within acceptable limits, the surveil-
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-lance procedure will-be repeated prior to reactor startup which is scheduled
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for November 7,.1975'.
A thin-film of silicon greas'e will periodically be applied
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to the seats to improve the seal.
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Mr. R. H.'Engelken -
September 26, 1975
.The' purge valves are 66 inch butterfly: valves, Model 60 WR manu-factured by Allis Chalmers Company.
'There was no-plant transient associated with this ever.t.
Respectfully,
.m c J. J. Mattimoe Assistant General Manager and Chief Engineer Enclosure ces: Director, MIPC(3)
. Director, IE(30)-
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LCENSI NUM8ER Cl AlR l$ l S'l'l }- l Ol 0l-l0 l0 l o l 0 l 0 l-30 31 32 AM 25 26 14 15-REPCRT CATE Ol 5l Ol-l 013 l1 l 2 } l 0l 812l 7l 7l5 j l 0 l 9 l 2 l 51 7l 5J EVENT DATE C'OCKET NUMBER 30 CATEGORY ? ' " TYPE 74 75 S
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68 69 57 58 59 60 Valve _]
leak rate test on the Reactor Building Purge Outlet 80 EVENT ' DESCRIPTION
.l tihile performing the local The outer valve
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he inner valve.
80 excessive 1erikane was found throuah t j
9 the inner valve seats were adiusted to l Penetration.
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-l was found to have'an acceptable leak rate, J
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I correct problem (AO-75-12).
80 9-I VOLATON MANuF R
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l A l1 l8g o'E Co"oE CcMPONENT CCOE 47 48 17 43 44 l9 10 11.
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Seats were adiusted to give 80 CAUSE DESCRIPTION 3lValveseatson66inchvalveimproper1vadiusted. Surve alintegrity.]
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80 89
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89 0SCQvERY OTHER STATUS l-W l
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44 45 46 12 13 B
9 10 LOCAfCN OF RELEASE -
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PERSONNEL EXPOSURES--
NUMBER TvPE DESCRIPTON 80
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OFFSITE CONSEGUENCES 60 h l ' N.' A.
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d Sacramento Bee notified 9/4/75.
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(916) 452-3211:
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