ML19305C282
| ML19305C282 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 03/10/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Davidson D CLEVELAND ELECTRIC ILLUMINATING CO. |
| References | |
| NUDOCS 8003260472 | |
| Download: ML19305C282 (1) | |
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$ 1U 1000 Docket No. 50-440 Docket No. 50-441 The Cleveland Electric Illuminating Company ATTN:
Mr. Dalwyn R. Davidson Vice President System Engineering and Construction P. O. Box 5000 Cleveland, OH 44101 Gent'.emen:
This Information Notice is provided as an early notification of a possibly significant matter. 7t 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 re-quested at this time. However, we anticipate that 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 ac-tions.
If you have questions regarding the matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, James G. Keppler Director a
Enclosure:
IE Information Notice No. 80-10 cc w nel:
tral Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Harold W. Kohn, Power Siting Commission Mr. Daniel D. Wilt, Attorney Helen W. Evans, State of Ohio RIII RIII piore/c WL lli/km Keppler 3/7/80 8003260 4
m 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 O 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 This
+24 volt power supply to the NNI was lost, due to a short to ground.
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 Therefore, the pressurizer was pumped solid, one safety valve lifted, HPI.
and flow through the safety valve was sufficient to rupture the RC Orain Tank rupture disk, spilling approximately forty-three tnousand 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
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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 The effects are of several power supplies drawing power from one inverter.
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 The voltage buffer card was misaligned in its Company Voltage Buffer Card.
receptacle, and adjacent connectors carrying +24v and " common" were bent such This short circuit cleared itself during that they contacted one another.
subsequent re-energizing of the power supply by burning through the foil on a Subsequent review by the licensee identified a second printed circuit card.
voltage buffer card which was also misaligned but had not caused a short circuit.
6624609L1.
The specific circuit cards which were misaligned carried part number The connectors on these cards are slightly thinner and appear to have a somewhat different angle than those found on similar cards elsewhere in the NNI which carry part numbers 6624608A1 or 6624609A1.
The 6624609LI cards appear to be more subject to misalignment.
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