ML20133K893

Deficiency & Part 21 Rept Re Error in Torrey Pines Bypass Limit Switch Setting Procedure Contributing to Limitorque Valve Operator Torquing Out.Bypass Limit Switch Setting Procedure Modified.Addl Info Will Be Provided in 30-day LER

ML20133K893
Person / Time
Site:	Davis Besse
Issue date:	07/29/1985
From:	Williams J TOLEDO EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
REF-PT21-85, REF-PT21-85-347-000 1-558, PT21-85-347, PT21-85-347-000, NUDOCS 8508120409
Download: ML20133K893 (2)

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El DESIGNATED ORIGINAL Certified B7 -

. TOLEDO

%mma EDISON Docket No. 50-346 License No. NPF-3 Serial No. 1-558 July 29, 1985 Mr. James G. Keppler, Regional Administrator United States Nuclear Regulatory Commission Region IIL 799 Roosevelt Ibad' Glen Ellyn, Illinois 60137

Subject:

10 CFR Part 21 Report Torrey Pines Technology Limitorque Setting Procedure This letter is to serve as a notification of a 10 CFR Part 21 defect which was identified by the Toledo Edison Company on July 24, 1985. This letter confirms a conversation between your Messrs. Nick Jackiw and Bruce Burgess and Toledo Edison's Messrs. Steve Wideman and Jan Stotz on July 25, 1985.

Toledo Edison used a bypass limit switch setting procedure prepared by Torrey Pines Technology for Davis-Besse Limitorque motor operated valves.

Investigation of the problems of the June 9, 1985, event determined that an error existed in the Torrey Pines bypass limit switch setting procedure and significantly contributed to the Limitorque valve operator torquing out.

The procedure for setting the bypass limit switch with the valve and limit switch closed said to rotate the handwheel in the open direction until the coast and backlash is taken up, and then continue opening until the valve was 0.5% of a full stroke open. For gate and globe valves, the number was 2.5%, and for gate and globe valves greater than four inches, the number is 5.0% of full stroke open. The defect in the procedure is that the 0.5%, 2.5%, or 5.0% was to be an additional amount beyond what it took to remove the coast and backlash.

As an example, a 6 inch gate valve requiring 170 turns for a full stroke would require almost 8 turns to get the coast and backlash out af ter the valve had been closed. Per procedure, the bypass limit switch should be set to cut the torque switch back in at the 8 turn position, only a half turn extra. But in fact, the intent was that the bypass limit switch should be set at 8h turns beyond the 8 turns for a total of 16 turns of full stroke open. Therefore, the procedure should have referenced gate or 8508120409 850729 6 h0 ADOCK 0500 ED! SON PLAZA 300 MADISON AVENUE TOLEDO. OHIO 43652 \

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Docket No. 50-346 1f License No. NPF-3 Serial No. 1-558 July 29, 1985 Page 2 disk motion instead of stem motion. As a result of testing the Auxiliary Feedwater Icolation Valves AF599 and AF608, it was found that 5% of full stroke travel was not adequate for unseating these valves, especially when they were experiencing a large differential pressure across their seat.

Based on Toledo Edison test results, the torque switch will be bypassed for 20% of valve stem travel. This includes coast and backlash.

Toledo Edison intends to modify its bypass limit switch setting procedure accordingly. In addition, the open torque switch setting will also be increasedcto the maximum allowable value to insure valves will not torque out during unseating.

Toledo Edison will review the setting of all its nuclear safety related Limitorque operated valves that were set using information from the Torrey

, Pines procedure. The review and resetting will be completed before starting from the present outage.

Based on discussions with Torrey Pines Technology, similar work has been completed for Fort St. Vrain in Colorado. The extent of implementation of information.concerning our report is unknown. It is our understanding that other similar work is under contract but not yet released to utility clients. Although Torrey Pines has not been a source of this information to others, Toledo Edison has reason to believe that a bypass setting in the 3 to 10% range is a standard used by many utilities.

This report satisfies the requirement for written notification within five days of determination of a defect. Additional information will be provided in a 30 day Licensee Event Report (LER), which will be provided per 10CFR50.73.

Very truly yours, W  % V W

r. Joe Williams, Jr.

Senior Vice President, Nuclear

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l cc: DB-1 NRC Resident Inspector USNRC Document Control Desk j Washington, D. C.

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