ML20091C420

Forwards Revs to Main Steam Safety Valve Testing/Insp Plan to Be Implemented During Upcoming Seventh Refueling Outage. Initial Plan Submitted to Address 850609 Loss of Feedwater Event

ML20091C420
Person / Time
Site:	Davis Besse
Issue date:	07/30/1991
From:	Shelton D CENTERIOR ENERGY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
1958, NUDOCS 9108060287
Download: ML20091C420 (4)

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i CENTERDOR W ENERGY i

Don 6d c. stenon 300 Mad 5m Amoe i y,ce Prem. Nuclear Toledo, OH 436 20001 I gavg ges.,e (419)249 2300 Docket Number 50-346 License Numbet NPF-3 Serial Number 1958 July 30, 1991 United States Nuclear Regulatory Commission Document Control Desk Vashington, D. C. 20555

Subject:

Revision to Inspection Plan of Hain Steam Safety Valves Gentlemen The purpose of this letter is to advise the Nuclear Regulator y Commission (NRC) of Toledo Edison's (TE) inspection plan for the Main Steam Safety Valves (MSSVs) commencing with the upcoming seventh refueling outage.

In June 1986, the NRC issued NUREG-ll?7, which was the NRC staff's Safety Evaluation Report on the restart of Davis-Besse Nuclear Power Station following the loss of feedvater event of June 9, 1985. In Section 3.2.1.9 of NUREG-1177, the NRC requested that TE submit a plan for future refueling outage inspections of the main steam safety valves. The NRC issued a letter (Log Number 2062, dated August 28, 1986) identifying TE's Action Commitments resulting from NUPEG-1177. Item 36 of Log 2062 documents the applicable commitment identified in Section 3.2.1.9 of NUREG-1177. Item 36 states:

" Licensee to submit (sic) plan for inspection of MSSVs at each refueling outage within 90 days following restart (p 3-34)."

Toledo Edison submitted its plan for inspection of the MSSVs in a letter dated March 31, 1987 (Serial Number 1364). This plan consisted of a five (5) criteria approach for inspecting the MSSVs at each refueling outage. During the fifth and cixth refueling outages all the HSEVs vere disassembled and inspected.

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Docket Number 50-346 License Number NPP-3 Serial Number 1958 Page 2 In addition to the inspection plan, root cause analyses, extensive corrective actions, and modifications were performed to incicase the reliability of the MSSVs at Davis-Besse. The modifications included material and design changes to certain valve components, setpoint changes, and installation of position monitoring instrumentation for selected HSSVs.

The success of the corrective actionr, has been demonstrated by the performance of the MSSVs during the sixth and seventh operating cycles.

The valves operated satisfactorily during each of the five plant trips that occurred during these cycles. After each trip, the petformance of the MSSVs was evaluated using linear variable differential transducer (LVDT) traces and/or by direct visual inspections. The recorded data and valve inspection results indicate that the MSSVs responded in the proper manner.

Based on the successful identification of the root causes for HSsv failures, corrective actions and modifications made, and demonstrated satisfactory performance of these valves, Toledo Edison is revising its inspection plan to be concistent with the requirements of the 1986 ASME Boiler and Pressure Vessel Code. This revised inspection plan ir in accordance with 10CFR50.55a and Davfs-Besse Technical Specification 4.0.5. The revised plan and frequencies vill commence statting with the upcoming seventh refueling outage.

A more detailed discussion of the five (5) specific criteria of the former inspection plan and how they ate impacted by the revised plan is contained in Attachment 1.

Should you have questions concerning this matter, please contact Mr. R. V. Schrauder, Manager - Nuclear Licensing, at (419) 249-2366.

Very truly yours,

/G f DCS/KAF/ach Attachment cc P. H. Byron, NRC Region III, DB-1 Senior Resident Inspector A. B. Davis, Regional Administrator, NRC Region III J. B. Hopkins, NRC/NRR DB-1 Senior Project Manager Utility Radiological Safety Board

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, , Docket Number 50-346 License Number NPF-3 Serial Number 1958 Attachment 1 Page 1 of 2 l

REVISED HSSV TESTING / INSPECTION PLAN Commitments

1. Vith the plant in Mode 3 and steam pressure greater than 800 psig all the MSSVs vill be inspected for visual and audible leakage.

Any valve found to be leaking vill be tested to verily setpoint. )

If the leakage persists the valve vill be disassembled, inspected 1 and repaired. l 1

Revision: -All HSSVs which are scheduled for maintenance or set '

pressure adjustment, or both, shall be tested per the requirements I of Section 7.3.2.1 of ANSI /ASME OH-1-1981.

Justification: Per ANSI /ASHE OH-1-1981 Section 1.3.3.1.2, all the l HSSVs are required to be set pressure tested within a specific time  !

interval (see paragraph 2 below). When a HSSV is scheduled to be pressure tested, or when maintenhnee on a HSSV is required, the tests specified in Section 7.3.2.1 shall be performed.

Furthermore, Section 7.4.2.1 of this Standard requires those valves >

vith identified leakage to be refurbirhed or replaced.

2. Setpoint vill be verified on each of the 1050 psig setpoint valves and each of 1070 psig setpoint valves each refueling (eight valves total). The remaining MSSVs vill be tested on an 10xN/60 (N-number of months since last refueling) frequency each refueling to assure the testing / inspection plan meets the minimum requirements of the Technical Specifications. Failures of the 1090 psig setpoint and 1100 psig setpoint valves vill require additional valves to be tested. Failures of the 1050 psig and 1070 psig setroint valves vill not require the testing of additional valves.

Revision: All MSSVs shall be tested within a 5 year period with a minimum of 20% of the valves tested within any 24 months. This 20%

shall be previously untested valves, if they exist.

Justification: The Commission issued Amendment No. 117 to Facility Operating License No. NPF-3 for the Davis-Besse Nuclear Power Station, Unit No. 1 on August 24, 1988 to change the MSSV setpoints. Each of the two main steam headers include nine HSSVs.

Seven HSSVs on each header have setpoints of 1100 psig. The remaining two MSSVs on each header have setpoints of 1050 psig.

Vith the improvements in the MSSVs at Davis-Besse and with the revised setpoints, a revision to this commitment is justified. The commitment should be revised as stated above to comply with Section 1.3.3.1.2 of ANSI /ASME OH-1-1981.

3. Valves with serpoints that are within 3% of desired setpoint and adjustable vill be adjusted to 1% of d> sired setpoint.

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, , , Docket Number 50-346 License Number NPF-3 Serial Number 1958 ,

Attachment 1 Page 2 of 2 Revision: Delete this commitment.

Justification: Davis-Besse Technical Specification 3.7.1.1 Turbine, Cycle, requires the HSSVs to be within 1% of desired setpoint. This commitment is redundant to the Technical Specification and should therefore be deleted.

4. Valves with setpoints that are outside 3% of desired setpoint vill ,

be inspected to find potential causes for the setpoint change.

(Note inspection may include disassembly and internals inspection.)

Revision: Any valve exceeding its stamped set pressure by 3% or greater shall be repaired or replaced, the_cause of failure determined and corrected, and shall successfully pass a retest before that valve is returned to service.

! Justification: This commitment should be revised as stated above to be consistent with ANSI /ASHE OH-1-1981 Section 1.3.3.1.5.b.

5. Valves with leakage-that persist through the testing vill be inspected to determine the cause of the leakage.  !

Revision: Valves with leakage that persist through the testing Ull be~~ subject to the requirements of Sections 7.3.2.1 and 7.4.2.1.1 of ANSI /ASME OH-1-1981.

i; Justification: The requirements for testing, inspecting, and refurbishing the HSSVs that are specified in Sections 7.3.2.1 and 7.4.2.1.1 of ANSI /ASME OH-1-1981 are more stringent than the current commitment.

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