ML20054L183

Responds to NUREG-0737,Item II.D.1 Re Pressurizer Code Safety & Pilot Operated Relief Valve Testing.Util Participated in EPRI Administered Safety & Relief Valve Testing Program.Evaluation to Be Submitted by 821231

ML20054L183
Person / Time
Site:	Davis Besse
Issue date:	07/01/1982
From:	Crouse R TOLEDO EDISON CO.
To:	Stolz J Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.D.1, TASK-TM 44572, 834, TAC-44572, NUDOCS 8207070238
Download: ML20054L183 (2)

Text

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Docket No. 50-346 yotgoo License No. NPF-3 Serial No. 834 Rwa n.

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'em ess sa2i July 1, 1982 Director of Nuclear Reactor Regulation Attention: Mr. John F. Stolz Operating Reactors Branch No. 4 Division of Operating Reactors United States Nuclear Regulatory Commission Washington, D. C. 20555

Dear Mr. Stolz:

This letter is submitted in reference to NUREC 0737, " Clarification of TM1 Action Plan Requirements", Item II.D.I. This item deals with testing of pressurizer code safety and pilot operated relief valves (PORVs).

Toledo Edison participated in the Safety and Relief Valve Testing Program administered by the Electric Power Research Institute (EPRI) and notified you of our intent to analyze the results as they pertained to Davis-Besse Nuclear Power Station Unit No. 1 in our letter dated March 31, 1982 (Serial No. 800).

Although the testing showed generally acceptable results.potentially undesirable aspects of valve performance appeared to be related to solid water operations and piping configurations. The specific configuration items included:

A. Inlet Pipe Length - As the length of the pipe inlet to the safety valves increases the probability of valve chatter appears to increase. Davis-Besse has in excess of 30 feet of inlet pipe to its safety valve.

B. Inlet Loop Seal - EPRI tests tended to show a higher incidence of safety valve chatter during the blowdown period of inlet piping.

Additionally, the blowdown effects of the inlet loop seal indicated larger stress loadings on the valve discharge piping than previously predicted.

Both of the configuration related aspects affecting valve performance were present on the Davis-Besse design. Our preliminary review focused on the desirability of retaining the current arrangement while analytically attempting to reconcile acceptable valve performance with such a con-figuration. This review resulted in the relocation of the Davis-Besse pressurizer safety valves. This program is two phase in schedule and will encompass activities in the current extended refueling outage as ,

well as Refueling Outage 3, the next planned outage.

02hh THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO, OHIO 43S52

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82070702 2 820701 PDR ADOCK 05000346 P PDR .

Docket No. 50-346 License No. NPF-3 Serial No. 834 July 1, 1982 The current outage program will result in: 1) The relocation of the two existing Crosby 4M6 safety valves to the top of the pressurizer without an inlet piping loop seal. 2) Replacement of pressurizer safety valve disc with material more resistant to hydrogen attack. 3) Possible connection of safety valve discharge pip.'ng to the reactor coolant system quench tank to collect valve leakage only. 4) Relocation of the pressurizer safety valve acoustic flow indication system to the new location. 5) The retention of the pressurizer PORV in its current off pressurizer loop seal configuration. 6) Modified heat tracing for the pressurizer PORV piping inlet. This phase of the effort will occur prior to startup from our current refueling outage.

Due to the required evaluation and decisions relating to the pressurizer safety valve relocation and the PORV piping analysis, the final Davis-Besse specific report pertaining to the EPRI test results is not yet complete. We now expect to forward the NUREG 0737, item II.D.1 evaluation results for the revised configuration by December 31, 1982.

Each step of the reconfiguration program is developed to improve expected valve performance based on the experience gained through the EPRI valve testing program. Davis-Besse retains its low head high pressure injection characteristics that preclude safety valve solid water operations.

These combine to give reasonable assurance of acceptable safety and pilot operated relief valve performance for the Davis-Besse Nuclear Power Station, Unit 1.

Very truly yours,

,. l e RPC:MGP: lab cc: DB-1 Resident Inspector