ML19260B994
| ML19260B994 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 11/20/1979 |
| From: | Reyes L, Tambling T, Warnick R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| References | |
| PNO-III-79-042, PNO-III-79-42, NUDOCS 7912180094 | |
| Download: ML19260B994 (2) | |
Text
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PFM MTW.RY NOTIFICATION Date:
November 20, 1979 PREI.IMINARY NOTIFICATION OF EVENT OR UFDSUAL OCCURRENCE--PNO-III-79-42 This prelim:inary notification constitutes EARI.Y notice of events of POSSIBI.E safety cr public interest significance.
The inforn.ation presented is as initially received without vertfication or evaluation and is basically all that is known by 1E st.af f on this date.
Facility:
Toledo Edison Company, Davis-Besse Unit 1 Oak harbor, OH Docket No. 50-346
Subject:
RETURN TO OPERATION Anr.R A 26 DAY OUTAGE The unit vent critical at 04:19a.m., EST on November 20, 1979 after a 26 day caintenance and modification outage that started with a reactor trip on October 25,19 79 (PN-III-79-21).
The trip was caused by loss of a reactor coolant pump (RCP) during switching of emergency lighting buses.
The unit was operating on three RCP's at the time of the trip due to degraded shaf t seals on RCP 1-1 (PN-III-79-19).
During this outage tae licensee replaced the shaft seals on all four RCP's.
~ne cause of the RCP trippin;; when the emergency lighting loads vere s -itched was traced to a ground caused by an anchor bolt that penetrated c buried electrical conduit.
The ground was climinated.
The reactor outage was extended by the following additonal work:
(1) Arc suppressor diodes were added to the component cooJing water interlock circuirs on the RCP's.
All other safety related interlock circuits were reviewed a:d tested for inductive loads and are suppression diodes were added to 27 of these circuits as a preventive codification.
(2)
Eleven pipe restraints on safety related systems were upgraded as a result of the analysis done under IE Bulletin 79-02, Rev. 1, Supp. 1.
(3) Based upon the review and analysis perforned for IE Bulletin 79-21, the setpoints on the stent generat:r startup range level were corrected for temperature, pressure, and difference in elevation.
(4)
The blowdown reset precsures of eight min steam line code safety valves were readjusted to minimize excessive couldown of the reactor coolant system following a reactor trip.
The new setpoints are based upon special tests conducted at Wylie L.aboratory.
This PN is issued for information and to close out earlier PN's.
The licensee is planning to cake a press release on November 21, 1979.
The resident Inspector Js at the site following the startup and power ascension.
The State of Chio is being notified.
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PPMMTMAPJ NOTIFICATION 7 91218 o O Y
PPrT.TMTNARY NOTIFICATION PN-III-79-42 Faciliry: ' Toledo Edison Company
Subject:
RETURS TO OPERATION AFTER A 26 DAY OUTAGE This information is current as of 1:00 p.m. cn November 20, 1979.
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Contact:
L. A. Reyes, Resident Insnector, 419/388-8200 T. N. Tambling, I?'FW RIII, 384-2542 R. F. Warnick, RIII. 384-2565 Distribution:
Transmitted H St Chairman Hendrie Commissioner Bradford S. J. Chilk, SECT Commissioner rennedy Co:m:issioner Ahearne C. C. Iammerer, CA ce=-issioner n414neky ACRS (For Distribution)
Transmitted: ENBB P.Bldgof'n/3/#
IE:XDOS (II: EQ Dist L. V. Gossick, IDO
,H. R. Dentra, NRR H. L. Ornstein, EDO R. C. DeYoung, NRR J. J. Touchard, PA R. J. Mattson, NRR Landow (6 min /page)
N. E. Haller, EPA D. Vassallo, NRR J. J. Cummings, DIA R. G. Ryan, OSP f.D.Eisenhut,NER B. I. Shapar, EID
. SS Bldg (MATL)
'jk. J. Dircks. NMSS R. 211nogue, SD S. Icvine, RES IE:IDOS P m TMTMARY ROTIFICATION
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