ML19351D898
| ML19351D898 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/20/1980 |
| From: | Polk J Office of Nuclear Reactor Regulation |
| To: | Novak T Office of Nuclear Reactor Regulation |
| References | |
| REF-GTECI-B-45, REF-GTECI-NE, TASK-B-45, TASK-OR NUDOCS 8011200347 | |
| Download: ML19351D898 (3) | |
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October 20, 1980 Docket No. 50-346 MEMORANDUM FOR:
T. M. Novak, Assistant Director for Operating Reactors, DL FROM:
P. J. Polk, Lead Engineer Generic Implementation Activity B-45 THRU:
T. A. Ippolito, Chief, ORB #2, DL
SUBJECT:
PRIMARY COOLANT SYSTEM PRESSURE ISOLATION VALVE FAILURE AT DAVIS-BESSE (UNIT 1) - WASH-140s EVENT V Time and Date:
1:00 P.M., October 20, 1980 Location:
Room P-110, Phillips Building Bethesda, Maryland
Purpose:
Atford B&W Owner's Group the opportunity to discuss corrective action regarding undetectable Vellan check valve failures'; i.e, measures to be taken to preclude a WASH-1400 Event V intersystem LOCA.
Participants:
Nuclear Regulatory Commission T. Novak, T. Ippolito, K. Wichman, A. Cappucci, P. Pol k, V. Nerses, M. Taylor, D. Garner, R. Reid, R. Bosnak, E. Jordan, G. Lainas, J. Knight, P. Check, C. Michaelson B & W Regulatory Response Group J. J. Mattimoe I
Q Philip J Polk, Project Manager Operating Reactors Branch #2 Division of Licensing
Enclosure:
Davis-Besse Daily Highlight of October 9,1980.
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DAILY HIGHLIGHT October 9,1980 Davis-Besse, Unit No. 1 On October 8,1980, the plant staff was conducting leak testing on check valves isolating the reactor coolant system (RCS) from the discharge lines 6 of the low pressure injection system (LPIS). The system is isolated by
- two check valves in series with a normally open motor operated valve.
One of the check valves failed the leak testing with approximately a 200 gallon
~
per minute leak rate at 2150 psig reactor coolant system pressure.
The test was being conducted after plant heatup following the facility's first refueling outage.
This valve failure is significant due to the potential for an intersystem loss of coolant accident in which the failure during plant operation could lead to a rupture of the LPIS outside of containment with no means of recirculating the lost water to the RCS.
This accident was identified as a significant contributor to risk frcm core melt accidents in the Reactor Safety Study (WASH-1400) and was referred to as Event V.
In a letter to all ligr.t water reactor licensees dated February 23, 1980, the NRC identified the concern for the Event V accident and requested all licensees with the valving arrangement in question to commit to periodic tests or surveillance on the check valves as soon as possible.
Sone licensees have not adequately responded to NRC concerns.
Toledo Edison, operator of the Davis-Besse plant, is considering depressurizing and draining down of the RCS in order to work on the defective valve.
The NRC Resident Inspector is following the actions by the plant staff and is keeping Region III and Nuclear Reactor Regulation informed.
Ap? roved by:
Rccert Purple, Deputy Director cc:
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