ML19290F053
| ML19290F053 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 03/07/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Gary R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| References | |
| NUDOCS 8003180012 | |
| Download: ML19290F053 (1) | |
Text
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UNITED STATES
[ 7 ) y.cg[',j NUCLEAR REGULATORY COMMISSION
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611 RYAN PLAZA oRIVE, SUITE 1000 E
REGION IV c,
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ARLINGTON, TEX AS 76012 March 7, 1980 In Reply Refer To:
RIV Docket Nos.
50-445/IE Information Notice No. 50-10 50-446/IE Information Notice No. 80-1v Texas Utilities Generating Company ATTN:
Mr. R. J. Gary, Executive Vice President and General Manager 2001 Bryan Tower Dallas, Texas 75201 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will distribute this Notice to their operating personnel and will review the information for poss4.ble applicability to their facilities.
No specific response is requested at this time. However, we anticipate *.aat further NRC evaluations will result in issuance of an Addendum to IE Bulletin 79-27 in the near future which will recommend or request specific applicant or licensee actions.
If you have questions re;arding the matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely,
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f dU Karl V. fiey,fri't /
Director
Enclosures:
1.
IE Information Notice No. 80-10 2.
List of IE Information Notices Recently Issued 800318001%
SSINS No.
6870 UNITED STATES Accession No.
NUCLEAR REGULATORY COMMISSION 8002280640 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 March 7, 1980 IE Information Notice No. 80-10 PARTIAL LOSS OF NON-NUCLEAR INSTRUMENT SYSTEM POWER SUPPLY DURING OPERATION Description of Circumstances:
This notice contains information regarding Crystal River Unit-3 response to a loss of non-nuclear instrumentation (NNI) as a consequence of loss of the
+24 volt power supply to the NNI.
At 2:23 p.m. on February 26 with Crystal River Unit-3 at 100% power, the
+24 volt power supply to the NNI was lost, due to a short to ground.
This initiated a sequence of events (detailed in the enclosure) wherein the PORV opened and stayed open as a direct result of the NNI power supply loss.
HPI initiated as a result of depressurization through the open PORV, and with approximately 70% of NNI inoperable or inaccurate, the operator correctly decided that there was insufficient information available to justify terminating HPI.
Therefore, the pressurizer was pumped solid, one safety valve lifted, and flow through the safety valve was sufficient to rupture the RC Drain Tank rupture disk, spilling approximately forty-three thousand gallons of primary water into containment.
The Crystal River-3 event is closely related to the November 10, 1979 event at Oconee Unit-3 wherein the inverter supplying power to the Integrated Control System (ICS) and to parts of the NNI failed.
That event was the subject of IE Information Notice 79-29 (November 16, 1979) which was followed by IE Bulletin 79-27 (November 30, 1979).
The CR-3 event involved loss of only part of the power available from an inverter, rather than the inverter itself, since the +24v supply is only one of several power supplies drawing power from one inverter.
The effects are very similar, however, in that the ICS lost part of its input signals in both events.
The +24 volt power supply short to ground has tentatively been identified by the licensee to have occurred between knife edge connectors of a Bailey Control Company Voltage Buffer Card. The voltage buffer card was misaligned in its receptacle, and adjacent connectors carrying +24v and " common" were bent such that they contacted one another. This subsequent re-energizing of the power printed circuit card.
Subsequent revi-DUPLICATE DOCUMENT voltage buffer card which was also mis The specific circuit cards whic. were '
Entire dociunent previously The connectors on these cards are slig entered into system under:
different angle than those found on si
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carry part numbers 6624608A1 or 662460 AN0i O
more subject to misalignment.
p No. of pages:
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