ML13309A192
| ML13309A192 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 02/27/1992 |
| From: | Rosenblum R SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-GTECI-070, REF-GTECI-094, REF-GTECI-NI, TASK-070, TASK-094, TASK-70, TASK-94, TASK-OR GL-90-06, GL-90-6, NUDOCS 9203020006 | |
| Download: ML13309A192 (4) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 R. M. ROSENBLUM TELEPHONE MANAGER OF (714) 454-4505 NUCLEAR REGULATORY AFFAIRS February 27, 1992 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Additional Response to Generic Letter 90-06, "Resolution of Generic Issue 70, 'Power-Operated Relief Valve and Block Valve Reliability', and Generic Issue 94, 'Additional Low-Temperature Overpressure Protection for Light-Water Reactors,' Pursuant to 10 CFR 50.54(f)," June 25, 1990.
San Onofre Nuclear Generating Station, Unit 1
References:
- 1. Letter, R. M. Rosenblum, SCE to NRC, "Response to Generic Letter 90-06, 'Resolution of Generic Issue 70, 'Power-Operated Relief Valve and Block Valve Reliability,'and Generic Issue 94,
'Additional Low-Temperature Overpressure Protection for Light Water Reactors,' Pursuant to 10 CFR 50.54(f),'"
December 27, 1990.
- 2. Letter, H. E. Morgan, SCE to NRC, "Amendment Application No.
194, Overpressure Mitigation System, SEP Topic V-11.B,
'Residual Heat Removal System Interlock Requirements,' Generic Letter 90-06," May 13, 1991.
This letter supplements SCE's response to Generic Letter (GL) No. 90-06 dated December 27, 1990 (Reference 1).
GL 90-06 requested commitments for:
- 1) improvements to the Technical Specifications for Power-Operated Relief Valves (PORVs), and 2) additional actions concerning maintenance, procurement of replacement parts, and testing of the PORVs and block valves.
In our letter dated December 27, 1990, we confirmed our commitment to comply with the requirements of GL 90-06 as applicable. Subsequently, we submitted an amendment application (Reference 2) which incorporated, among others, the changes to the Technical Specifications recommended in GL 90-06, Enclosures A and B, for power operations and low temperature overpressure protection.
Enclosure A required additional actions to be taken for the maintenance, procurement, and testing of the valves. This letter documents SCE's compliance to these additional requirements.
9203020006 920227 PDR ADOCK 05000206 PDR
Document Control Desk
- 2 SCE Compliance with Requirements of GL 90-06, Enclosure A On the basis of technical studies for GI-70 ("Power-Operated Relief Valve and Block Valve Reliability"), the NRC identified, in Section 3.1 of Enclosure A to GL 90-06, three major actions to be taken to improve the reliability of PORVs and block valves. The Action 3 requirements have been addressed in the referenced amendment application. The following information provides documentation of our compliance with the remaining two requested actions.
- 1. Include PORVs and block valves within the scope of an operational quality assurance program that is in compliance with 10 CFR Part 50, Appendix B.
This program should include the following elements:
- a. The addition of PORVs and block valves to the plant operational Quality Assurance List.
COMPLIANCE:
The PORVs and block valves, including the limit switch position indication, are classified as Safety-Related and, as such, are listed in the plant "Q List" and are therefore covered by our QA program.
- b. Implementation of a maintenance/refurbishment program for PORVs and block valves that is based on the manufacturer's recommendations or guidelines and is implemented by trained plant maintenance personnel.
COMPLIANCE:
Maintenance on the valves is performed in accordance with SCE maintenance procedures. The maintenance procedures applicable to these valves are based on previous experience with the components and the manufacturer's recommendations. The manufacturer's recommendations for these valves are limited to diaphragm replacement as required.
Maintenance personnel are trained on similar valves during the scheduled maintenance training program.
Maintenance activities on the PORV and the block valve parts are controlled and implemented via Repetitive Maintenance Orders (RMOs).
The current RMOs include: solenoid valve replacement every 9 years for the PORVs and the block valves; limit switch replacement every 5 years for the PORVs and every 8 years for the block valves; actuator overhaul every 5 years for the PORVs and every 6 refueling outages for the block valves; and diaphragm replacement every refueling outage for the PORVs and the block valves. We are conducting an investigation, in conjunction with the vendor, on the availability of improved diaphragm material.
If a new material is approved as a suitable replacement, the diaphragm replacement intervals will be modified accordingly.
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- 3
- c. When replacement parts and spares, as well as complete components, are required for existing non-safety grade PORVs and block valves (and associated control systems), it is the intent of this generic letter that these items may be procured in accordance with the original construction codes and standards.
COMPLIANCE:
The PORVs and the PORV block valves including the associated control systems, the back-up nitrogen system, and the instrument air system from the pressure control valve to the isolation boundary (first upstream check valve) are classified as Safety-Related.
Replacement parts are procured in accordance with the requirements for Safety-Related components under the Quality Assurance Program. Specific controls in the procurement process assure that the replacement components are verified to be suitable and meet or exceed the applicable standards.
- 2. Include PORVs, valves in PORV control air systems, and block valves within the scope of a program covered by Subsection IWV, "Inservice Testing of Valves in Nuclear Power Plants," of Section XI of the ASME Boiler and Pressure Vessel Code. Stroke testing of PORVs should only be performed during Mode 3 (HOT STANDBY) or Mode 4 (HOT SHUTDOWN) and in all cases prior to establishing conditions where the PORVs are used for low-temperature overpressure protection. Stroke testing of the PORVs should not be performed during power operation. Additionally, the PORV block valves should be included in the licensees' expanded MOV test program discussed in NRC Generic Letter 89-10, "Safety-Related Motor Operated Valve Testing and Surveillance," dated June 28, 1989.
COMPLIANCE:
The PORVs and the PORV block valves are included in the In-Service Testing (IST) Program. The check valves which supply service air and nitrogen to the PORVs and the PORV block valves are also included in the IST Program, and are tested in accordance with the intervals-specified in that program.
The pressure control valves which supply service air and nitrogen to the PORVs and the PORV block valves are exempted from testing per Section IWV-1200 of ASME Section XI, and therefore, are not included individually in the IST Program. However, these valves are required to operate satisfactorily for the PORV and the PORV block valves to be successfully stroked. Therefore, the pressure control valves are tested as part of the PORV and PORV block valve stroke tests.
Stroke testing of PORVs is not limited currently to Modes 3 or 4, or during power operation by the existing Technical Specifications. In practice, however, the PORVs are stroked only in Modes 5 and 6. Nonetheless, SCE has submitted an amendment request (Reference 2) proposing that the monthly channel test requirement in the existing Technical Specifications be
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- 4 replaced by an 18-month surveillance requirement performed in Modes 3 and
- 4. Upon approval by the NRC, this proposed change to the Technical Specifications will preclude stroke testing of the PORVs in Modes 1 and 2, in accordance with GL 90-06. The Technical Specification and the IST Program requirements will ensure that the PORVs are stroke tested prior to placing the Overpressure Mitigation System in operation.
The block valves are air-operated, and therefore, are not required to be included in the MOV testing program. As discussed above, testing of these valves is performed in accordance with the requirements of the IST Program.
If you have any questions or require additional information, please feel free to contact me.
Very truly yours, cc: J. B. Martin, Regional Administrator, NRC Region V George Kalman, NRC Senior Project Manager, San Onofre Units 1, 2&3 J. 0. Bradfute, NRC Project Manager, San Onofre Unit 1 C. W. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2&3