ML20106E870
| ML20106E870 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 09/21/1984 |
| From: | Harrington W BOSTON EDISON CO. |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 84-152, IEB-84-03, IEB-84-3, NUDOCS 8410300154 | |
| Download: ML20106E870 (2) | |
Text
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Y BOSTON EDISON COMPANY 800 BOYLaTON STRErr BDaTON, M AssACHUSETTs 0 2199 WILLIAM D. HARRINGTON esuson vess enseessm?
Ortf aksAR September 21, 1984 BEco 84-152 Dr. Thomas E. Murley Regional Administrator Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 License No. DPR-35 Docket No. 50-293
Reference:
IE Bulletin 84-03:
" Refueling Cavity Water Seal" dated August 24, 1984
Dear Sir:
Boston Edison Company (BECo) has evaluated the concern identified in IE Bulletin 84-03, and concludes that there is no potential of refueling cavity water drainage due to seal failure at Pilgrim Nuclear Power Station (PNPS).
This conclusion is based upon the following:
a)
PNPS has metal refueling bellows that form a seal between the reactor vessel and the surrounding primary containment drywell to permit flooding of the space above the vessel during refueling operations, specifically, fuel movement. The bellow assembly consists of stainless steel bellows, a backing plate, spring seal which acts as a secondary seal, and a removable guard ring. The assembly is welded to a support skirt and the reactor well seal bulkhead plate. The bellows' support skirt is welded to the vessel shell flange and the well seal bulkhead plate bridges the distance to the primary containment drywell wall. The backing plate surrounds the outer circumference of the bellows to protect it, and is equipped with a tap for testing and leakage monitoring. A self-actuated spring seal is located between the bellows and the backing plate to limit water inss during a bellows rupture by yielding to make a tight fit to the i
becking plate when subjected to full hydrostatic pressure. The guard ring attaches to the assembly and protects the inner circumference of th,i bellows.
This ring can also be removed to allow inspection of the bellows.
b)
As demonstrated in the above description, the refueling cavity water seal at PNPS is of an entirely different design than that used at Haddam Neck.
The Haddam Neck design consists of air actuated seals, 8410300154 840921 PDR ADOCK 05000293 G
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, BOITON EDCON COMPANY Dr. Thomas E. Murley September 21, 1984 Page 2 whereas, PNPS uses permanent metallic bellows with no active i
components, and has a spring seal to act as a secondary seal should the primary seal fail.
c)
Prior to_ filling the reactor cavity, reactor vessel disassembly sequence require that covers be bolted in place over reactor cavity ventilation air supply and return ducts to prevent water leakage into the ventilation system during cavity flood up.
This activity is accomplished via maintenance procedure and is returned to normal venting conditions upon completion of refueling. During refueling outage,.the O' rings will be replaced and checked during cavity flood up to ensure no leakage. There are a total of six watertight hinged covers, closed and bolted in place for normal refueling operation.
For the aforementioned reasons, we do not have immediate concern of gross seal failure at PNPS.
However, a safety evaluation will be performed and will be submitted to the NRC on or before December 31, 1984.
We believe this response falls within the Bulletin's " Action 2" schedule because PNPS, while shutdown for refueling, has its mode switch in the shutdown position and has not yet begun to reload fuel. Should you have any questions concerning this response, please contact us.
Very truly yours.
WGL/ns cc:
U. S. Nuclear Regulatory Commission Document Control Desk Washington, D. C.
20555 Commonwealth of Massachusetts)
County of Suffolk
)
i Then personally appeared before me W. D. Harrington, who, being duly sworn, did state that he is Senior Vice President - Nuclear of the Boston Edison Company, the applicant herein, and that he is duly authorized to execute and file the submittal contained herein in the name and on behalf of the Boston Edison Company and that the statements in said submittal are true to the best i
of his knowledge and belief.
bN 7 1
My Commission expires: OS2/;1988
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