ML19290F051
| ML19290F051 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 03/07/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | William Jones OMAHA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 8003180009 | |
| Download: ML19290F051 (1) | |
Text
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o UNITED STATES NUCLEAR REGULATORY COMMISSION (PDR J '-
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March 7, 1980 States Docket No.
50-285 Omaha Public Power District ATTN:
W. C. Jones, Division Manager -
Production Operations 1623 Harney Street Omaha, Nebraska 68102 Gentlemen:
This Infor=ation Notice is provided as an early notification of a possibly significant satter.
It is expected that recipients will distribute this Notice to their operating personnel and will review the information for possible applicability to their facilities.
No specific response is requested at this time. However, we anticipate that further NRC evaluations will result in issuance of an Addeadum to IE Bulletin 79-27 in the near future which will reco= mend or request specific applicant or licensee actions.
If you have questions regarding the matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, 4
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/atL.Wjlit/p t
L' d
Karl V. Seyrr Director
Enclosures:
1.
IE Information Notice No. 80-10 2.
List of IE Information Notices Recently Issued cc:
S. C. Stevens, Manager Fort Calhoun Station Post Office Box 98 Fort Calhoun, Nebraska 68102 8003innooi
SSINS No.-
6870 UNITED STATES Accession No.:
NUCLEAR REGULATORY COMMISSION 8002280640 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 Mac '
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
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subsequent re-energizing of the power printed circuit card.
Subsequent revi.
DUPLICATE DOCUMENT voltage buffer card which was also mis The specific circuit cards which were '
Entire document previously The connectors on these cards are slig entered into system unde :
different angle than those found on si-
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carry part numbers 6624608A1 or 662460 AN0i more subject to misalignment.
O e
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