ML19290E701
| ML19290E701 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/07/1980 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Mary Johnson SOUTH CAROLINA ELECTRIC & GAS CO. |
| References | |
| NUDOCS 8003140404 | |
| Download: ML19290E701 (2) | |
Text
.
- pa uracq'o, UNITED STATES 8
NUCLEAR REGULATORY COMMISSION n
E REGION 11 0,
.[
101 MARIETTA ST., N.W., SUITE 3100 b
ATLANTA, G EORGIA 30303 o
MAR 0 71980 In Reply Refer To:
R11:JPO.
[50-395j South Carolina Electric and Gas Company Attn:
M. C. Johnson, Vice President Special Services and Purchasing P. O. Box 764 Columbia, SC 29218 Centlemen:
This Information Notice is provided at an early notification of a possible significant matter.
It is expected that recipients will distribute this Notice to their operating personnel and will review the information for possible applic-ability to their facilities. No specific response is requested 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 actions.
If you have questions regarding the matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely CY
' m mes P. O'Reilly D ector r
Enclosures:
x 1.
IE Information Notice N
No. 80-10 w/its Enclosure 2.
List of IE Information Notices Recently Issued S 0031409 b
" 49 0 7 1980 South Carolina Electric and Gas Company.
cc w/ encl:
T. B. Conners, Jr.
Conners, Moore and Corber 1747 Pennsylvania Avenue, N.W.
Washington, D.C.
20006 A. A. Smith Quality Assurance Post Office Box 8 Jenkinsville, South Carolina 29065 O. S. Bradham, Manager Nuclear Operations Post Office Box 8 Jenkinsville, South Carolina 29065
.ma e
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 INSTRL.fENT 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 B2ffer Card. The voltage buffer card was misaligned in its receptacle, and adjacent connectors carrying +24v and " common" that they contacted one another. Thi subsequent re-energizing of the power printed circuit card.
Subsequent re DUPLICATE DOCUMENT voltage buffer card which was also mi The specific circuit cards which were Entire dcctunent Previously The connectors on these cards are sli entered into system under:
different angle than those found on s 330 h M b
carry part numbers 6624608A1 or 66246 more subject to misalignment.
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