ML20002C762
| ML20002C762 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 06/12/1973 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20002C760 | List: |
| References | |
| NUDOCS 8101100830 | |
| Download: ML20002C762 (2) | |
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Mr. Boyce H. Grier Directorate of Regulatory Operations Region III US Atomic Energy Commission 799 Roosevelt Road Glen Ellyn, IL 60137
Dear Mr. Grier:
This letter contains information resulting from a review of our proposed valve vall thickness verification progra::: at the Big Rock Point Plant as requested in your letter of April 20, 1973 It is proposed that twenty-five (25) percent of the applicable valves, as listed in Attachment II of ~our January 31, 1973 submittal to you, be tested to verify the presence of adequate wall thickness. The minimum number of valves to be tested is sixteen (16). The valves to be tested will be selected by choosing at least one valve from each of the twelve valve manufacturers represented in Attachment II.
The balance of the sa=ple will be completed by selecting valves from manufacturers supplying relatively large numbers of valves at Big Rock ' Point (as repre-sented in Attachment II). For example, valves supplied by Chapman, Powell, BS'cB and Crosley m.ight be selected since these manufacturers supplied forty-three of the sixty-four applicable valves.
It is contemplated that these inspections will be performed using ultrasonic techniques. Best efforts will be extended to produce results with a measurement error of 2% relative to calibration blocks selected for their similarity to the material undergoing test.
If the examinations reveal a wall thickness deficiency, all valves of that manufacturer represented in Attachment II will be tested.
The proposed examinations can only be conducted during a pro-longed reactor shutdown. Consequently, these inspections will commence at the next scheduled refueling (currently early in 1974) and.will be completed in 1975 M ' "
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June 12, 1973 It is intended that the data generated be analyzed to develop a statistical confidence statement for the valves in Attachment II.
We believe this testing program will provide additional assur-ance of the existence of appropriate pressure boundary conditions when coupled with existing inherent " safety factors" and successful operating experience. These safety factors are shown in Attachment II and are the result of operation of the plant at 1350 psi when it was designed to operate at 1500 psi plus numerous instances where the design rating of valves exceeds the service requirements by a substantial margin. Big Rock Point has had a long (approximately ten-year) successful experience with valve pressure t,oundary integrity.
Yours very truly,
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.i.&f RBS/ map Ralph B. Sewell Nuclear Licensing Administrator G
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