ML20212E626
| ML20212E626 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 12/22/1986 |
| From: | Williams J TOLEDO EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| REF-PT21-87-025-000 PT21-87-025-000, PT21-87-25, NUDOCS 8701050381 | |
| Download: ML20212E626 (1) | |
Text
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TOLEDO
%mm EDISON Docket No. 50-346 PRIORITY ROUTING License No. NPF-3 yW c
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Serial No. 1-699 ms, -y -,
December 22, 1986
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- uttIGS Mr. James G. Keppler, Regional Administrator United States Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137
Dear Mr. Keppler:
This letter confirms our conversation with Messrs. P. Byron and R. W.
DeFayette of your staff on December 18, 1986. Toledo Edison is investi-gating the possibility of reporting a 10CFR21 condition present in the 36-inch Rockwell International Globe Valves used as Main Steam Isolation Valves (MSIV) for the Davis-Besse Nuclear Power Station, Unit No. 1.
The concern is that the manufacturer may not have adequately accounted for changes in valve operating characteristics with the temperature and pressure in the design of this valve. Specifically, the measured stroke time for one of the two installed valves increases with increasing temper-atures and pressure.
This concern developed from Mode 4/ Mode 3 stroke time testing of the MSIVs as part of the Davis-Besse System Review and Test Program (SRTP) startup testing. The MSlVs are normally stroke time tested in Mode 4 (low temper-ature and pressure) to decermine the operability for higher Modes of Operation (Modes 3, 2 and 1).
The SRTP testing required at full tempera-ture and pressure was to demonstrate proper hydraulic control of the valves.
These Mode 3 tests showed that MSIV stroke time increased over those for Mode 4.
These changes apparently were not anticipated by the valve vendor. The root cause of stroke time increase with higher temperature and pressure is not presently obvious.
Toledo Edison is currently investigating the root cause of this increase in MSIV stroke time and will inform the NRC of any additional findings or conclusions as well as our final determination of 10CFR21 reportability.
Very truly yours, 8701050381 861222 PDR ADOCK 05000346 NIf (J)& (
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,s PDR W:BJC:plf cc: DB-1 NRC Resident Inspector THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO, OHlO 43652