ML20023C542
| ML20023C542 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 05/13/1983 |
| From: | Harrington W BOSTON EDISON CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| 83-124, GL-83-08, GL-83-8, NUDOCS 8305170418 | |
| Download: ML20023C542 (2) | |
Text
_ _ _ _
=
e EOSTON EDISON COMPANY j
800 BOYLSTOM STREET BOSTON, MASSACHUSETTS D2199 WILLIAM D. HARRINGTON May 13, 1983 BECo Letter No.83-124 Mr. Darrell G. Eisenhut, Director Division of Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 License No. DPR-35 Docket No. 50-293
Subject:
Generic Letter 83-08: Modification of Vacuum Breakers on Mark I Con-tainments
Reference:
Generic Letter 83-08, dated February 2,1983
Dear Sir:
In the. reference, you requested that Boston Edison provide plant-unique calcula-tions which either formed the bases for modifications, or justified their as-built acceptability.
The following responds to that request:
'l Vacuum Breaker Analysis Results Based on Continuum Dynamics, Inc. (CDI) Technical Note No. 82-19, " Improved Dynamic Vacuum Breaker Response for Pilgrim," Revision 1, dated September 1982, the expected vacuum breaker pallet velocity is 6.99 rad /sec and the design is (6.99 x 1.18) 8.25 rad /sec.
Stress levels were determined by Nutech Engir.eers, Inc. for a range of pallet velocities, and the maximum stress of 59.4 k91 was found to occur in the pallet at the design velocity of 8.25 rad /sec.
The pallet, hinge arms, hinge shaft and hinge shaft stud materials will all be upgraded because existing materials were shown to be beyond ASME Code allowables for the design pallet veMcity.
The pallet gasket will also be replaced with an improved design to eliminate gasket foldover.
Modification Schedule 4
. Boston Edison purchased upgraded vacuum breaker materials based on G.E.
recom-mendations in 1981, but the subsequent CDI and Nutech work indicated that the new materials would not be adequate for recently calculated stress levels.
Current plans are to procure suitable materials from the original valve manu-facturer, GPE, and to modify the vacuum breakers during the 1985 Modification Outage. This completion date is based on the Pilgrim Nuclear Power Station Long Term Program date for modifying torus internals, which was presented to the NRC in April,1983.
fooI 8305170418 830513 PDR ADOCK 05000293 p
PM i
..__,,,,r.
,,_____.,.._-._,,,,,__,._-ym__
m
,.,.,.,_y
e COOTON EDCON COMPANY Mr. Darrell G. Eisenhut, Direcf.or May 13,1983 Page 2 We believe the above information satisfactorily addresses the request transmitted in the reference.
Should you require further information on this issue, please contact us.
Very truly yours, 1
4 l
1 r
t