ML20244A614
| ML20244A614 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/23/1979 |
| From: | Bryan S, Klingler G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| FOIA-79-98 PNO-79-089, PNO-79-89, NUDOCS 7905110009 | |
| Download: ML20244A614 (2) | |
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y PRELIMINARY NOTIFICATION f
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l April 23, 1979 Qj; PRELIMINARY NOTIFICATION OF-EVENT OR UNUSUAL OCCURRENCE--PNO-79-89 b
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This preliminary notification t.onstitutes EARLY notico of an event of M5'51BLE safety or public interest significance.
The information
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presented is as' initially received without verification or evaluation /
-_and is basically all that is known by IE staff on this date.
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j Facility: ' Rancho Seco Nuclear Generating l
t Station, Unit No. 1 I
Clay Station, California (DN50-312)
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Subject:
LOSS OF INVERTER POWER SUPPLY - AUTOMATIC REACTOR TRIP
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l PLANT STATUS The resident inspector _ notified the Regional Office that at 1308 Hrs.
(PST)onApril 22, 1979 the-P.ancho Seco reactor sustained an automatic reactor shutdown from high reactor coolant system pressure. High reactor
,jp pressure was caused by failure of the "A" inverter power supply.
Loss O...
of the inverter affected.the Integrated Control System (ICS)' which caused i
a decrease in steam generator main feedwater flow rate.
The decrease-in Wl main feedwater flow caused reactor coolant pressure to increase from-normal operating pressure of approximately 2155 psig-to the automatic trip setpoint of 2300 psig.
Maximum reactor coolant pressure from the pressure recorder indicated approximately 2330 psig.
The minimum i
pressure reached during the occurence was approximately 1855 psig.-
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l Just prior to the trip the licensee had reset the setpoint for the
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pressurizer power operated relief valve from 2255 to 2450 psig, and I
was in the process of resetting the last of four reactor coolant system high pressure protection channels from 2355 to 2200 psig in accordance with IE Bulletin 79-05B, Item 3.
-There were no anomalies in. the reactor protection system or plant operator performance during the event.
The licensee completed repairs
-to the failed inverter and returned the unit to operation at about 5:30 a.m. (PST) April 23, 1979.
Local media inquiries were made of the, Region V duty officer and the Region V inspector present at the Rancho Sece olant.
The licensee publiorrffairs office responded to nedia ingeiries during the after-noon and evening of April 22, 1979.
CONTINUED 7
7905Noco?
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J Continutd h 4il 23,'1979 Lg Page 2-
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The Region V office was notifie'd o'f this occurence by(the ' Region V[
inspector at the facility of approximately 1320 Hrs.
PST)onApril'22 f
1979.
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Contact:
S. E. Bryan, IE x26019; G. R. Klingler, IE x28019 Distribution:
Transmitted H St 11.' 29
- Chairman Hendrie Commissioner Bradford S. J.. Chil k, SEC.Y Commissioner Kennedy Comroissioner Ahearne' C. C. Kammerer CA Commissioner Gilinsky (For Distribution)
' Transt'itted:
MNBB lH W P. Bldg //.' @
J. G. Davis, IE l " * ~ '
L. V. Gossick, EDO H. R. Denton, NRR Region T /b / fT' l
H. L. Ornstein EDO R. C. DeYoung,~ilRR J. J. Fouchard, PA R. J. Mattson, NRR N. M. Haller, MPA V. Stello, NRR (MAIL)
F R. G. F yan, OSP R. S. Boyd, NRR J J~ Cummings, 01A i
H. K. Shapar, ELD SS Bldg / 2 m q -
R. Minogue, SD W. J. Dircks, HMSS L
S. Levine, RES i
PRELIMINARY NOTIFICATION e
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