ML16341D306
| ML16341D306 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/08/1985 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML16341D305 | List: |
| References | |
| GL-83-28, NUDOCS 8507190224 | |
| Download: ML16341D306 (6) | |
Text
Enclosure 1
SAFETY EVALUATION DIABLO CANYON UNITS 1 AND 2 ITEM 4.1 - REACTOR TRIP SYSTEM RELIABILITY VENDOR RELATED MODIFICATIONS)
GENERIC LETTER 83-28 1.
INTRODUCTION On February 25, 1983, during startup of the Salem Unit I plant, both 1
circuit breakers in the Reactor System failed to open automatically upon receipt of a valid trip signal.
As a result of that event, the NRC Office of Inspection and Enforcement issued IE Bulletin 83-01 which described the event and requested specified prompt corrective and preventive actions by licensees.
As the cause and ramifications of the event were more clearly developed, the NRC Office of Nuclear Reactor Regulation issued on July 8, 1983, Generic Letter 83-28, "Required Actions Based on Generic Implications of Salem ATWS Events."
This letter addressed issues related to reactor trip system reliability and general management capability.
The letter was sent to all licensees of operating
- reactors, applicants for operating licenses and holders of construction permits.
One of the areas of reactor trip system reliability considered in Generic Letter 83-28 (GL 83-28), is that of vendor-recommended modifications.
This is identified 8 as Item 4. 1 - Reactor Trip System Reliability (Vendor Related Modifications) in GL 83-28.
This 8507i90224 850708 PDR ADOCK 05000275 P
evaluation addresses the acceptability of the response to this item provided by the Pacific Gas and Electric Company (PGSE) for Diablo Canyon Units 1 and 2.
2.
EVALUATION Item 4. 1 of GL 83-28 states that "All vendor-recommended reactor trip modifications shall be reviewed to verify that either:
(1) each modification has, in fact, been implemented; or (2) a written evaluation of the technical reasons for not implementing a modification exists."
This item of GL 83-28 also states that licensees should submit a
statement confirming that this action has been implemented.
By letter dated November 7, 1983, PGSE responded to a number of GL 83-28 items, including Item 4.1.
In response to Item 4.1, PGSE stated that it had verified that all initial vendor recommended reactor trip breaker modifications had been incorporated for Units 1 and 2.
In a discussion in early June 1984 by NRC Region V staff with PGSE regarding the meaning of the term "initial vendor recommended modifications,"
PGSE stated that all modifications that had been recommended at the time of responding to GL 83-28 had been implemented, but it does not cover new recommendations that might be developed as a result of the Salem event.
The NRC staff finds this is consistent with the staff's interpretation that Item 4. 1 applies to vendor-recommended modifications existing at the time GL 83-28 was issued.
~ ~
3.
CONCLUSION Based on PG8E's confirmation that the facility has implemented all vendor-recommended modifications existing at the time of issuance of the generic letter, the staff concludes that PG&E has satisfactorily completed for Diablo Canyon Units 1 and 2 the actions prescribed by Item 4. 1 of Generic Letter 83-28.
Accordingly, this item is closed.