ML19353A079
| ML19353A079 | |
| Person / Time | |
|---|---|
| Site: | Marble Hill |
| Issue date: | 12/16/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Shields S PSI ENERGY, INC. A/K/A PUBLIC SERVICE CO. OF INDIANA |
| References | |
| NUDOCS 8101070085 | |
| Download: ML19353A079 (1) | |
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UNITED STATES l'
' 7, NUCLEAR REGULATORY COMMISSION e
REGION 111 6,,
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CLLN E LLYN, ILLINOIS 60137 o
December 16, 1980 i,
i Those on Attached List:
The enclosed IE Information Notice No. 80-44 provides early notification of i
an event that may have safety significance.
Accordingly, you should review the Information Notice for possible applicability to your facility.
I No specific action or response is requested at this time; however, contingent upon the results of further staff evaluation, a Bulletin or Circular recom-mending or requesting specific licensee actions may be issued.
If you have any questions regarding this matter, please contact this office.
Sincerely, i
M.
ames G. Keppler' Director
Enclosure:
IE Information Notice No. 80-44 l
8101070 otT
s Docket No. 50-506 Docket No. 50-547 Public Service of Indiana ATTN:
?!r. S. W. Shields Senior Vice President Nuclear Division Post Office Box 190 New Washington, IN 47162 cc w/ encl:
Steve J. Brewer, Nuclea r Sa fety and Licensing Supervisor Central Files AD/ Licensing AD/ Operating Reactors PDR Local PDR LeBoeuf, Lamb, Leiby & flacRae Dave !!artin, Of fice of the Attorney General John R. Callo.ay, Staff Director, Environment, Energy and Ltural Resources Subccanittee I
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Accession No.
8012160001 IN 80-44 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 December 15, 1980 IE INFORMATION NOTICE N0. 80-44:
ACTUATION OF ECCS IN THE RECIRCULATION MODE WHILE IN HOT SHUTDOWN PURPOSE:
1 The intent of this Information Notice is to alert PWR licensees and holders of construction permits of a potentially generic problem involving inadvertent actuation of the emergency core cooling systen (ECCS) in the " Recirculation Mode" Such an event occurred at the Davis-Besse Nuclear Power Station (Docket No. 50-346) on December 5, 1980.
The plant was in a hot shutdown mode of opera-tion at the time of the event and was undergoing certain maintenance activities as described below.
DISCUSSION:
Just prior to the inadvertent actuation of the ECCS, the licensee was attempt-ing to isolate electrical shorts and/or grounds in the Safety Features Actua-tion System (SFAS).
Towards this end, A-C power had been removed from Channel 3 of the SFAS.
Upon reenergizing Channel 3 it was noted that an indicating lamp was out; therefore, an atterrpt was made to replace the f ailed lamp with a spare unit.
While removing a lamp from a spare output slot in a Channel 3 chassis, an arc was drawn between the lamp and the module chassis.
This arcing was apparent-ly due to a combination of shorts or grounds in the SFAS, which coupled with the " common" connection between Channel 1 and 3 resulted in the loss of a power supply in Channel 1.
Since all the bistable trips in Channel 3 had not been l
completely reset, and since a power supply to Channel I was lost, SFAS Levels 1, i
2, 3 and 5 were actuated by the two-out-of four actuation logic.
Since SFAS Level 5 indicates that the Borated Water Storage Tank (BWST) is at a low level, the ECCS was placed in a recirculation modc (i.e., the ECCS suction was aligned to the emergency containment sump.)
In order to place the ECCS system in the recirculation mode, the supply valves leading to the Decay Heat Removal (OHR) pumps from the BWST start closing after those in the ECCS line and from the containment emergency sump fully open.
Thus, during this valve transition period, a flow path existed to the reactor coolant system (RCS) via the BWST and the ECCS pumping system (i.e., the DHR pumps); however, since the RCS pressure was higher than that of the pumping system (2100 vs. 1600 psig) no BWST water was pumped into the RCS.
- Rather, during the valve transition time of about 1-1/2 minutes, approximately 15,000 gallons of borated water was drained from the BWST to the containment emergency sump.