ML20053B373
| ML20053B373 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 05/24/1982 |
| From: | Randazza J Maine Yankee |
| To: | Novak T Office of Nuclear Reactor Regulation |
| References | |
| REF-GTECI-A-49, REF-GTECI-RV, TASK-A-49, TASK-OR IEB-79-06C, IEB-79-6C, NUDOCS 8205280345 | |
| Download: ML20053B373 (2) | |
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-O May 24, 1982
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Mr. Thomas Novak Assistant Director for Operating Reactors l
Office of Nuclear Reactor Regulations United States tbclear Regulatory Commission Washington, D.C.
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Dear Mr. Novak:
On Friday, May 7, we discussed the issue of tripping reactor coolant pumps in the context of the pmssurized thermal shock issue.
I was surprised when you indicated that the impetus for tripping pumps came from the NSSS vendors. My impression was that the NRC staff had impressed this operating strategy on the industry.
Maine Yankee adopted this strategy following the accident at TMI in order l
to comply with short term action item #1 of I&E Bulletin 79-06C, which said I
institute the following actions at your facility.
Upon mactor trip and initiation of high pressure injection caused by low reactor coolant system pmssure, immediately trip all reactor coolant pumps."
The Combustion Engineering Owners' Group authorized preparation of a E report on this matter.
This report, EN-ll5-P " Response to tRC IE Bulletin 79-06C Items 2 and 3 for E NSSS", indicated that from a licensing perspective, tripping all RCP's within 6 minutes upon SIAS is acceptable for any LOCA event.
The report also indicated that best estimate calculations l
showed than on balance, consideringng both LOCA and non LOCA events, it is l
better to maintain some forced flow.
Maine Yankee docketed EN-ll5-Pby reference through a letter dated August 31, 1979.
In that letter we stated " Existing procedures regarding RCP operation, as delineated by I&E Bulletin 79-06C, will remain in force until staff approval of the guidelines detailed in EN-ll5-P is received."
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M AINE Y ANKEE ATOMIC POWER COMPANY a
Mr. Thomas Novak May 24, 1982 United States Nuclear Regulatory Commission Page 2 The owners of Combustion Engineering reactors have been discussing relaxation of this reouirement ever since that time.
As recently as April 22, 1982 a CE owners group delegation met with Mr. Roger Mattson to reiterate CE's recommendation - that some forced flow of reactor coolant continue even in the situation covered in the I&E bulletin. Our position has been a constant refrain since the bulletin was first addressed, and reinforced, in light of the pressurized thermal shock concern.
There are three things Maine Yankee believes should be done promptly to reduce the risk of presurized thermal shock at our plant: low leakage core design, heated safety injection water, and maintaining mixing flow by not tripping all reactor coolant pumps.
We have moved ahead with the first two but cannot proceed with the third until the NRC staff permits us to do so by relaxing 79-06C pump trip reouirement.
Frankly, it appears that engineering and operating judgement on occasion takes a back seat to esoteric analysis of highly improbable events.
If you have any suggestions as to how we can pursue safety issues where our intuition tells us that we are being asked to take less conservative action, like pump tripping, we would be most interested.
Very truly yours MAINE YANKEE ATOMIC POWER COMPANY e
J. B. Randazza Vice President J3R:pjp I
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