ML18085A438
| ML18085A438 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 12/16/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Schneider F Public Service Enterprise Group |
| References | |
| NUDOCS 8101060816 | |
| Download: ML18085A438 (4) | |
Text
Docket Nos.
50~272 50-311 a
UNITEDSTATEs
_
- I
~UCLEAR REGULATORY COMMISSI r~
REGION I 631 PARK AVENUE KING OF PRUSSIA, PENNSYLVANIA 19406 Public Service Electric and Gas Company ATTN:
Mr. F. W. Schneider Vice President - Production 80 Park Plaza - 15A Newark, New Jersey 07101 Gentlemen:
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DEC 15 1980-The enclosed IE Information Notice No. 80-44, 11Actuation of ECCS in the Recircu-lation Mode While in Hot Shutdown, 11 is forwarded to you for information.
No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, Grier
Enclosures:
- 1.
IE Information Notice No. 80-44
- 2.
List of Recently Issued IE Information Notices CONTACT:
F. G. Greenman (215-337-5267) cc w/encls:
F. P. Librizzi, General Manager - Electric Production E. N. Schwalje, Manager - Quality Assurance R. L. Mittl, General Manager - Licensing and Environment H. J. Midura, Manager - Salem Generating Station R. A. Uderitz, General Manager - Fuel Supply Department
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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 December 15, 1980 SSINS No.:
£835 Accession No.:
8012160001 IN 80-44 IE INFORMATION NOTICE NO. 80-44:
ACTUATION OF ECCS IN THE RECIRCULATION MODE WHILE IN HOT SHUTDOWN PURPOSE:
The intent of this Information Notice is to alert PWR licensees and holders
~f construction permits of a potentially generic problem involving inadve~tent actuation of the emergency core cooling system (ECCS) in the 11Recirculation Mode 11
- 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.
DI?CUSSION:
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 attempt was made to replace the failed 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 11 common 11 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
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completely reset, and since a power supply to Channel 1 was lost, SFAS Levels 1,
- 1 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 recirtulation mode (i.e., the ECCS suction was aligned to the emergency containment sump.)
In order to place the ECCS system in ~he 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 OHR 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.
IN 80-44 December 16, 1980 Page 2 of 2 The Davis-Besse Nuclear Power Station has experienced several events during the past three and one-half years which have either degraded the OHR system or caused a temporary interruption of OHR operation.
Of these, the one most closely paralleling the event described above occurred on April 19, 1980.
(See IE Infor-mation Notice 80-20, 11 Loss of Decay Heat Removal Operabil.ity at Davis Besse Unit 1 While in A Refueling Mode 11 dated May 8, 1980 and IE Bulletin No. 80-12, 11Decay Heat Removal System Operability 11 dated May 9, 1980.) Du.ring the Decem-ber 5, 1980 event, the plant was in a hot shutdown mode with RCS pressure at approximately 2100 psig; therefore, the operator was able to promptly trip the OHR pumps, thereby precluding air entrapment in the system or pump damage.
In contrast, the Apr11 19, 1980 event occurred while the plant was in a quasi refueling mode (i.e., the reactor head was in place but detensioned, RCS water level was below the steam generator's bottom plate, the RCS was vented to the atmosphere by an open man ho le at the top of the steam generator,.and decay heat was being removed by one OHR system).
Since the OHR pump was being used to remove decay heat during the April 19.event, it was left running for approxi-mately two minutes after the pump had been aligned to the recirculation mode of operation, and tripped when water was discharged from a temporary tygon line.
Since the OHR system was the only system available for decay heat removal, the OHR pump was restarted approximately forty minutes later; however, it was tripped shortly thereafter when it was determined that there was air in the suction line of the system.
In all, the April 19, 1980 event required approx-imately two and one-half hours to vent the OHR system and reestablish OHR flow.*. As a consequence of the reJatively long recovery time, the temperature limit specified in the Technical Specification for *the refueling mode of opera-,
tion was exceeded duririg the April 19, 1980 event.*
The above events illustrate means whereby the integrity of a major ECCS system can be jeopardized by inadvertently or prematurely aligning the ECCS to the recirculation mode of operation.
T~e major concern in such cases is that the 1
OHR pumps could become air bound if their suction lines are aligned to a dry
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sump.
At best, with the pumps air bound, the pump mo:tor would trip automatically'.!
or could be tripped manually before any damage occurred, in which case flow could be established after the system is vented; at worst, the pumps could be damaged and become inoperable, in which case the active portion of the ECCS would not be available, if needed at that time.
This Information Notice is provided as an early notifi~ation of a possibly signi-ficant matter that is still under review by the NRC staff.
Recipients should re-view the information for possible applicability to their facilities.* No specific action or response 1s requested at this time; however, if NRC evaluations so indicate, further licensee actions may be requested or required.
If you have any question regarding this matter, please contact the director of the appropriate NRC Regional Office.
- IE Information* Notice No. 80-44 Detember 16, 1980 Information Notice No. 80-43 80-29 Supplement No. 1 80-42 80-41 80-40 80-39 80-38.
80-37 80-36 RECENTLY ISSUED IE INFORMATION NOTICES Subj e_ct
- Date Issued Failures of the 12/5/80 Continuous Water Level Monitor for the Scram Discharge Volume at Dresden Unit No. 2 Broken.Studs on Terry 11/26/80 Turbi~~ Steam Inlet Flange Effects of Radiation on 11/24/80 Hydraulic Snubber Fluid Failure of Swing Check 11/10/80 Valve in the Decay Heat Removal System at Davis-Besse Unit No. 1 Excessive Nitrogen 11/6/80 Supply Pressure Activates Safety-Relief Valve Operation to Cause Reactor Depressurization Malfunctions *of 10/31/80 Solenoid Valves Manufactured by Valcor Engineering Corporation Cracking in Charging Pump Casing Cladding Containment Cooler Leaks and Reactor Cavity Flooding at Indian Point Unit 2 Failure of Steam Generator Support Bolting 10/30/8Q 10/24/80 10/10/80
.Issued to*
All holders of a BWR power reactor.
OL or CP All holders ~f a power reactor OL or CP All holders of a*
power reactor OL or CP All holders of a power reactor OL or CP All holders of a power reactor OL or CP All holders of a power reactor OL or CP All holders of a PWR power reactor OL or CP All holders of a power reactor OL or CP All holders of a power reactor OL or,-CP
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