ML20236U373

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PN-75-051:on 750714,Sacramento Municipal Utility District Notified Region V by Telephone That 47 of 69 CRD Stator Coils Damaged Due to Overheating.Crd Stator Cooling Sys Shutdown
ML20236U373
Person / Time
Site: Rancho Seco
Issue date: 07/16/1975
From: Bryan S, Jennifer Davis, Thornburg H
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:
References
PN-75-051, PN-75-51, NUDOCS 9807300085
Download: ML20236U373 (1)


Text

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PRELIMINARY NOTIFICATION - NOT FOR PUBLIC DISCLOSURE July 16, 1975 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE --PN-75-51

( This preliminary notification constitutes EARLY notice of events of POSSIBLE safaty or public interest significance. The information l

presented is as initially received without verification or evaluation s and is basically all that is known by OIE staff as of 8:30 a.m. on the date of this notification. IT SHOULD BE SPECIFICALLY NOTED THAT THIS NOTIFICATION MAY CONTAIN INFORMATION THAT LATER MAY BE DETERMINED TO BE INACCURATE OR INCONSISTENT. AN OFFICE OF INSPECTION AND ENFORCEFEFT NOTIFICATION OF AN INCIDENT OR OCCURRENCE (BLUE SHEET) SUBSEQUENTLY WILL BE ISSUED IF WARRAh" FED.

- -Facility: Rancho Seco

. Sacramento Municipal Utility District

Subject:

CRD Motor Stator Overheating The Sacramento Municipal Utility District notified the NRC Region V office by telephone that 47 of 69 Control Rod Drive (CRD) stator coils have been damaged due to overheating. Rod control system tests were being performed which required momentary energizatica and de-energization of the CRD stators. The CRD stator cooling system had been shutdown which is the normal condition with the reactor in the cold shutdown condition (currently shutdown for turbine repairs) .

Following completion of the tests, the operator failed to de-energize gg

- the stator power supply and take corrective action upon initial receipt of high temperature alarms. Heat input to the stators as a result of the CRD trip tests under these conditions is minimal during the few 5

l minutes power is applied for test purposes. However, with the cooling system shut down and power continuously applied to the stators, over-I heating resulted.

Representatives from Diamond Power, the CRD stator manufacturer, are on site to evalua'te the extent of repairs required. The licensee q anticipates that a three week extension of the present two month /'

outage for turbine repairs will be required to permit replacement or #

repair of the CRD stators.

The licensee is planning to issue a press release on July 15, 1975. N

t. a Region V issued a press release on July 8, 1975, concerning the D extended outage cau.wd by the turbine failure. No release is planned 2 for this specific event.

$ gn.OIE received 7

" J"1 ,14, initial notification of this occurrence by telephone 1975 fro;n, Rancho Seco management.

s . .

O

Contact:

SEBrycn, IE x1353 HDThornburg, IE x7353 JGDavis, IE x7541 N

Q , Distribution:

Wn Chairman Anders Commissioner Mason S. J. Chilk, SECY

$? Commissioner Gilinsky Commissioner Rowden G. F. Murphy, JCAE 3 f Commissioner Kennedy C. C. Kammerer, CA OQ: I r.-

k J $k L. V. Gossick, EDO g

. U - d. F. Knuth, IE J. A. Harris, PA fjb B. C. Rusche, NRR H. H. Brown, ISP T. J. McTiernan, AIA K. R. Chapman, NMSS H. K. Shapar, ELD Transmitted: P Bldg e h ; H Stec ;oe g MNBB aeaf.w; Luge >,w../

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