ML20084D854
| ML20084D854 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/22/1995 |
| From: | Jeffery Wood CENTERIOR ENERGY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| AB-95-0023, AB-95-23, NP-33-95-002, NP-33-95-2, NUDOCS 9506010240 | |
| Download: ML20084D854 (2) | |
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TOLEDO
%sm EDISON A Centerlot Energy Cornpany Sb1 E
O Docket Number 50-346 License Number NPF-3 May 22, 1995 United States Nuclear Regulatory Commission NP 33-95-002 Document Control Desk AB-95-0023 Vashingtoa, D. C.
20555
Subject:
Voluntary Report on Pressurizer Code Safety Valve Setpoint Drift Gentlemen During the Ninth Refueling Outage (9RFO) in the Fall of 1994, the two installed Pressurizer Code Safety Valves were removed from service and delivered to an offsite laboratory for testing in accordance with the requirements of Section XI of the American Society of Hechanical Engineers (ASME) Code. The valvos were tested in April 1995.
One of the two valves' as-found initial lift setpoint exceeded the maximum setpoint of 2525.psig as specified in Technical Specification (TS) 3.4.3.
This occurrence was evaluated and was determined to not be subject to the reporting requirements of 10CFR50.72 or 10CFR50.73.
Since this event is of potential interest to the industry in view of ongoing efforts to address relief valve setpoint drift, this information is being submitted as a Voluntary Report.
During the 9RF0, conducted at Davis-Besse Nuclear Power Station (DBNPS) between October 1, 1994 and November 15, 1994 the two installed Pressurizer Code Safety Valves were removed and replaced with pretested spares. The removed valves were delivered to an offsite laboratory for testing.
At the laboratory, as-found testing was conducted on April 24, 1995 in accor-]ance with ANSI /ASME OH-1-1981.
During the testing, both valves exhibited acceptable lift setpoints within the + 3% of nameplate setpoint established for the as-found condition by ANSI /ASME OH-1-1981; however, the initial lift setpoint of one valve exceeded the maximum allowable lift setpoint of 2525 psig specified in TS 3.4.3.
The results of the as-found testing are summarized below.
Valve Serial Nameplate Initial Lift Percent Deviation From Number Setpoint Pressure Nameplate Setpoint N54891-00-0001 2500 psig 2496 psig
- 0.16%
)
N56264-00-0005 2500 psig 2561 psig
+ 2.44%
1 9506010240 950522 ADOCK 05000346 hDR PDR 0
L
- ,c, The two safety valves were refurbished and their setpoints adjusted to within the i 1% as-left tolerance specified by the ASME Code.
The valves were satisfactorily tested at the laboratory and vill be returned to DBNPS for installation during the Tenth Refueling Outage (10RF0).
j The Pressurizer Code Safety Valves at DBNPS are manufactured by Crosby Valve an.d Gage Company, Type HB-86-BPE. The function of the Pressurizer Code Safety Valves is to prevent the Reactor Coolant System (RCS) from being pressurized above its Safety Limit of 2750 psig.
An analysis performed as a result of previous occurrences of Pressurizer Code Ssfety Valve setpoints found out of tolerance concluded that a single safety valve with a lift setpoint less than or equal to 2525 psig is sufficient to mitigate all overpressure events and therefore, the as-found lift setpoints do not represent a safety concern for DBNPS.
The apparent cause of the valve test failure was determined to be setpoint drift, a recognized industry concern. As was stated above, the Pressurizer Code Safety Valves were refurbished as necessary and their lift setpoints were returned to within the + 1% as-left tolerance band. The valves will be returned to DBNPS for reinstallation during 10RF0.
In addition, Toledo Edison has initiated a change to the DBNPS TSs to expand the present 1
allovable lift setpoint tolerances. This change is expected to be submitted to the Nuclear Regulatory Com.nission (NRC) for approval by October 1, 1995.
i If you have any questions or require additional information, please contact Mr. Villiam f. O'Connor, Manager - Regulatory Affairs, at (419) 249-2366.
Very truly yours, 6
J. K. Vood
)
Plant Manager NKP/ eld cc:
L. L. Gundrum, NRC Project Manager J. B. Hartin, Regional Administrator, NRC Region III S. Stasek, DB-1 NRC Senior Resident Inspector Utility Radiological Safety Board
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