ML20005B184
| ML20005B184 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 06/26/1981 |
| From: | Morisi A BOSTON EDISON CO. |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| 81-137, NUDOCS 8107060438 | |
| Download: ML20005B184 (2) | |
Text
e BOSTON EDISDN COMPANY GEN ERAL O FFICES G OD BOYLSTON STRE ET BO STO N MAS SACHUSETTS O219 9 A. V. M O RISI MANAGER NUCLEAR QPERATIONS SUPPORT DEPARTMENT June 26, 1981 BECo. Ltr. #81-137 Mr. Thomas A. Ippolito, Chief Operating Reactors Branch #2 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 Response to Request for Additional Information Pilgrim Nuclear Power Station Unit 1 Containment Purge Valve Mechanical Operability
Dear Sir:
This document supplies the additional information requested by telephone on April 4,1981, pursuant to " Containment Vent and Purge Mechanical Operability" (BECo. Ltr. #81-46, March 4,1981).
1.
Provide the basis for the determination that the 5 Diameter (SD) separation, as indicated in your report, results in insignificant effects on the dynamic torque developed.
Response
Assuming the valve to be in its most unfavorable orientation in relation to the elbow, calculations indicate approximately a 12% increase in dynamic torque when the valve is 5 diameters downstream from it. The valve in question is i
450 to the plane of the elbow. Therefore, our estimate indicates an insigni-ficant torque increase of approximately 6%.
2.
Provide justification for the determination that the coefficients developed by other manufacturers for their disc designs apply to the Rockwell valve discs used in the Pilgrim Unit 1 Nuclear Plant.
Response
The Rockwell disc is synmetrical about the shaft, as is the Fisher 7600 valve.
The McNally disc is offset, but the highest coefficient (i.e. seal downstream) was used.
/)o3Y The Dover-Norris disc is symmetrical about the shaft, but the plane of the 5
0 to the shaft. This angle should reduce torque a disc is approximately 16 small amount, approximately 4%.
/
8107060438 810626' PDR ADOCK 05000293 P
pg
SO; TON E21 ON COMPANY Mr. Thomas A. Ippolito, Chief June 26, 1981 Page 2 In the. comparison of valves, dynamic torque coefficients were conservatively selected.
3.
Do the torques developed by the valve during closure exceed the design rating of the operator at any position in the stroke cycle?
Response
Calculations indicate a maximum dynamic torque on the disc to be less than 5000 inch-pounds. The torque capacity of the operator mechanism is approx-imately 20,000 inch-pounds. Therefore, torques developed during closure do not exceed the design rating of the operator.
If, after reviewing the above responses, you should require any additional information, please contact us.
Very truly yours, 4
1