ML20037B277
| ML20037B277 | |
| Person / Time | |
|---|---|
| Site: | Monticello, Dresden, Palisades, Fermi, Point Beach, Quad Cities, Big Rock Point, 05000115  |
| Issue date: | 04/28/1972 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8009100879 | |
| Download: ML20037B277 (3) | |
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April 28, 1972 C rr.cnwaalth Edisen Ccnpany Lacket.:,. 50-10 AT~ :: Lyrca Lee, Jr.
Decke: ':c. 50-237 Assic: ant to the Presiden:
Docke: :o. 50-249 P. O.
.cn 767 Docket : o. 50-254 Chicago, Illinois 60690 Docker :To. 50-265 Centlenen:
Further info =ntien is now available to supplcnent the TO' sent to you by this office en raccaber 9, 1971, which informed you of the failure of the relief valves on the secondary side of a stean generator of a pressurized water reactor. The cause of this failure has now been deternined to be the failure to consider the reaction forces of discharging relief valves in the design of the nozzles attach ng the valves to the header.
- 1..e a result of this occurrence, severr_1 licensees have condu::ed dynanic s:qss analyses of : heir safety and relief valve installations.
In several ads'es, the analyses have indicated that the stresses under certain condi-tions would be above those allowed by code.
In view cf the significance and extent of this situation, you nay wish to re-evaluate the stress analyses for all safety and relief valve installa-cions inportant to nuclear safety at your facilities. Any re-evaluation should focus special attention on t:echanical restraints and the assunptions used in the analyses fcr safety and relief valve installations within the prinary and secondary systens.
Our assigned inspector will discuss your re-evaluations with you during.
the nent inspection of your facilities.
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