ML17342A516
| ML17342A516 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 05/01/1986 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML17342A515 | List: |
| References | |
| GL-83-28, NUDOCS 8605080430 | |
| Download: ML17342A516 (4) | |
Text
SAFETY EVALUATION FOR GENERIC LETTER 83-28 ITEMS 4.1 AND 4.5.1 TURKEY POINT UNITS 3 AND 4 DOCKET NOS.
50-250 AND 50-251 I.
INTRODUCTION In February 1983, the Salem Nuclear Power Station experienced two failures of the reactor trip system upon the receipt of trip signals.
These failures were attributed to Westinghouse
- Type DB-50 reactor trip system (RTS) circuit breakers.
The failures at Salem on February 22 and 25, 1983, were believed to have been caused by a binding action within the undervoltage trip attachment (UVTA) located inside the breaker cubicle.
Due to problems with the circuit breakers at Salem and at other plants, NRC issued Generic Letter 83-28, Required Actions Based on Generic Implications of Salem Anticipated Transient Without Scram (ATWS) Events, dated July 8, 1983.
This letter described intermediate-term actions to be taken by licensees and applicants as a result of the Salem anticipated transient without scram events.
These actions were developed by the staff based on information contained in NUREG-1000, Generic Implications of ATWS Events at the Salem Nuclear Power Plant.
Actions to be performed included development of programs to provide for post-trip review, classification of equipment, vendor inter'face, post-maintenance
- testing, and RTS reliability improve-ments.
The Generic Letter stated that for Action Items 4.1 and 4.5.1 NRC Regional Offices would perform a post-implementation review and issue Safety Evaluations..
An NRC inspection was also conducted at the Turkey Point facility during October 22-26, 1984, to review the licensee's current program, planned program improvements, and implementation of present procedures associated with post-trip review, equipment classifi-cation, vendor interface, post-maintenance
- testing, and reactor trip system reliability.
The details of the inspection findings are discussed in Inspection Report Nos. 50-250/84-33, 50-251/84-34.
II.
REVIEW GUIDELINES The licensee's responses, provided by letter dated November 8, 1983, were evaluated for compliance with the staff's positions delineated in GL 83-28 for Action Items 4.1 and 4.5. 1.
The requirements of the above action items, as described in the Generic Letter, are paraphrased below:
4.1 Reactor Trip System Reliability (Vendor-Related Modifications)
Position All vendor-recommended reactor trip breaker modifications shall be reviewed to verify that either:
(I) each modification has, in fact, been implemented; or (2) a written evaluation of the technical reasons for not implementing a modification exists.
SS050804S0 SS0S0X PDR ADOCK 05000250 I
I P
4 i
?
A For example, the modifications recommended by Westinghouse in NCD-Elec-18 for the DB-50 breakers and a March 31, 1983, letter for the DS-4l6 breakers shall be implemented or a justification for not imple-menting shall be made available.
Modifications not previously made shall be incorporated or a written evaluation shall be provided.
4.5 Reactor Trip System Reliability (System Functional Testing)
Position On-line functional testing of the reactor trip system, including independent testing of the diverse trip features, shall be performed on all plants.
l.
The diverse trip features to be tested include the breaker under-voltage and shunt trip features on Westinghouse, BSW (see Action Item 4.3 of GL 83-28) and CE plants; the circuitry used for powe~
interruption with the silicon controlled rectifiers on BRW plants; and the scram pilot valve and backup scram valves (including all initiating circuitry) on GE plants.
III. EVALUATION We have evaluated the licensee's response against the NRC positions described in Section II above for completeness and adequacy.
The results of our evaluation and a brief summary of the licensee's responses are:
A.
Item 4.1, Reactor Trip System Reliability (Vendor-Related Modifications)
The licensee's response to this item is acceptable and meets the intent of GL 83-28.
The licensee stated that W records indicate that the modifications recommended in NCD Elec-18 for DB-50 switchgear have been implemented for Turkey Point Units 3 and 4 reactor trip breakers.
The licensee reconfirmed that these modifications had been completed by performing a visual inspection of the breakers.
The licensee's
- response, dated July 16, 1984, stated that the modi-fication for the shunt trip attachment, based on the Westinghouse Owners Group (WOG) design
- change, would be implemented on the first refueling after issuance of the Safety Evaluation.
The licensee stated that two other UVTA modifications identified by W in their March 31, 1983 letter and NSD-TB-75-2 of February 20, 1975 were not applicable to the Turkey Point units; however, the WOG generic design package for the automatic shunt trip modification is being considered.
B.
Item 4.5.1, Reactor Trip System Reliability (System Functjonal Testing)
The licensee's response to this item is acceptable and meets the intent of GL 83-28.
The licensee stated in its response that Turkey Point has a complete on-line system test procedure which is performed monthly.
This test checks the reactor trip breakers (via the undervoltage trip device),
the reactor trip relays and their associated logic relays, and checks calibration of the protective system inputs.
The licensee states that current shunt trip device and the undervoltage device are functionally bench tested every 6 months.
Jt was noted that no current provisions are available for on-line testing of the shunt trip device as it is only operated by using the manual trip push buttons.
The licensee stated that they will consider on-line testing of the shunt trip device when the automatic trip system design package submitted by WOG is completed.
IV.
Conclusion Based on our review and inspection, we have concluded that the licensee's response to Items 4. I and 4.5. 1 are acceptable and meet the intent of GL 83-28.