ML13324A721
| ML13324A721 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/05/1985 |
| From: | Bay H SOUTHERN CALIFORNIA EDISON CO. |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 8509270017 | |
| Download: ML13324A721 (2) | |
Text
Southem California Edison Company I95 SEp 9 P. O.
BOX 128 SAN CLEMENTE, CALIFORNIA 92672 HAROLD B. RAY September 5, 1985 VICE PRESIDENT & SITE MANAGER TELEPHONE SAN ONOFRE 714-361-8470 U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement R:2gion V
1450 Maria Lane, Suite 210 Walnut Creek, California 94596-5368 Attention:
Mr.
John B. Martin, Regional Administrator
Dear Sir:
Subject:
Docket No. 50-206 PORV Block Valve Operability San Onofre Nuclear Generating Station Unit 1 The purpose of this letter is to inform you of our interpretation of certain requirements of the San Onofre Unit 1 Technical Specifications applicable to the Power-Operated Relief Valve (PORV) block valves.
We consider it appropriate to do this because we believe the requirements are subject to more than one interpretation.
Technical Specification 3.1.5, Pressurizer Relief Valves, addresses OPERABILITY of two PORVs and their associated block valves in Modes 1, 2, and 3.
Specifically, in the event that one or more PORV become INOPERABLE, the Action Statements require that within one hour either:
- 1.
The PORV be restored to OPERABLE status; or,
- 2.
The associated block valve(s) be closed and maintained closed; or
- 3.
Unit shutdown begins in accordance with the Action Statement.
In the event that one or more of the PORV block valve(s) become INOPERABLE, the Action Statements require that within one hour either:
- 1.
The block valve(s) be restored to OPERABLE status; or,
- 2.
Unit shutdown begins in accordance with the Action Statement.
8509270017 850905 PDR ADOCK 05000206 PDR
Mr. J. B. Martin
-2 The PORVs are provided to relieve Reactor Coolant System pressure below the setpoints of the pressurizer safety valves in order to minimize challenges to the safety valves.
The PORV block valves are remote-manually operated to provide positive means of securing blowdown flow through a PORV in the event of PORV actuation and failure to reseat.
No credit is taken in the licensing basis of the Unit for operation of the PORYs.
On September 3, 1985, during in-service valve testing required by Technical Specification 4.7, a PORV block valve associated with an OPERABLE PORV failed to close within 15 seconds as specified in SCE's In-Service Test program.
The block valve was cycled several times without mreeting the 15 second closure time, and then it was left in the closed position.
Although the block valve had not met its closure timing requirement, and therefore would be INOPERABLE if opened, SCE considers it to be OPERABLE when closed, as it is then serving its required safety function.
As discussed above, there is no requirement that the valve be capable of opening.
It has no automatic opening or closing feature.
In addition, the associated PORV is closed and has been taken out of automatic control.
Both valves are administratively controlled to remain in their closed position until the Unit is next taken to cold shutdown when the block valve will be examined and repaired, as necessary.
The block valve is maintained closed by air pressure.
A containment entry has been made and the integrity and satisfactory operation of the air supply and position indication was verified.
The cause of the slow closing time for the block valve appears to be internal to the valve.
In summary, the Technical Specifications permit continued operation with one or both PORVs out of service.
The safety function of the PORV block valves is to close and isolate a PORV, in the event it should open and fail to close properly.
This safety function is served by maintaining the block valve in its closed position.
The Technical Specification requirements concerning an INOPERABLE block valve apply to circumstances when the block valve is open, and it does not meet its surveillance requirement for OPERABILITY, which is to close within 15 seconds and remain closed.
It is Edison's position, therefore, that with the PORV and its associated block valve administratively controlled in the closed position, the required safety function is met and continued operation is permitted.
Should you have any questions concerning this position, please contact the undersigned.
Sincerely, cc: F. R. Huey (USNRC Senior Site Representative)