ML15264A274
| ML15264A274 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 02/11/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML15264A273 | List: |
| References | |
| GL-83-28, NUDOCS 8502250940 | |
| Download: ML15264A274 (5) | |
Text
SAFETY EVALUATION REPORT DOCKET NOS. 50-269, 270 AND 287 OCONEE - UNITS 1, 2 AND 3 GENERIC LETTER 83-28, ITEM 4.3 REACTOR TRIP SYSTEM RELIABILITY - AUTOMATIC ACTUATION OF THE SHUNT TRIP ATTACHMENT FOR B&W PLANTS INTRODUCTION AND
SUMMARY
Generic Letter 83-28 entitled, "Required Actions Based on Generic Implications of Salem ATWS Events" was issued by NRC on July 8, 1983.
By letter dated December 30, 1983,.the licensee, Duke Power Company, indicated that it would incorporate the generic design modifications endorsed by the B&W Owners Group for the incorporation of the automatic actuation of the shunt trip attachment for the reactor trip breakers and provided responses to the plant specific questions identified by the staff in its September, 1983 safety evaluation report of the generic design. By letter dated October 23, 1984, the licensee provided a set of updated schematics that have been modified to be consistent with the generic design.
The staff has reviewed the licensee's proposed design for the automatic actuation of the reactor trip breaker shunt trip attachments and finds that it is acceptable.
EVALUATION The following required plant specific questions were identified based on the staff's review of the B&W Owners Group proposed generic design for this modification:
P5O2250940 8a PDR ADOCK 05000269 PDR
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- 1. A statement confirming that the UV sensor (high speed undervoltage relay)
Model ITE-27H-211R, is environmentally and seismically qualified for its service conditions.
The licensee has substituted a relay to sense the removal of power from the undervoltage trip attachment and thereby provide a contact to energize the shunt trip attachment. The relay is used in lieu of the undervoltage sensor which required an external source of power and has an adjustable trip setting.. We find this change to the generic design acceptable.
The licensee has confirmed that the relay, utilized in many safety related applications throughout the plant, will be located in a mild environment and is seismically qualified for the installed location. We find this acceptable and, therefore, this matter is closed.
- 2. A statement confirming that all other additional components involved in the shunt trip circuits are environmentally and seismically quali fied for their service conditions.
The licensee.has confirmed that all other additional components involved in the shunt trip circuits will be located in a mild environment and are seismically qualified for the installed locations. We find this accept able and, therefore, this matter is closed.
- 3. A statement confirming that the shunt trip attachment is or will be en vironmentally and seismically qualified for its service conditions.
The licensee has indicated that the shunt trip attachments for the reactor trip breakers are located in a mild environment and are suitably qualified but have not yet been confirmed to be seismically qualified. The licensee will provide an update on the status of its ongoing review of this matter.
The staff concludes that the resolution of the seismic qualification of
-3 the shunt trip attachment should not delay implementation of the proposed modifications.
- 4. Identify the classification (safety related or not) and separation (train or channel identification) for the reactor trip shunt and UV trip cir cuits, power supplies, and any interface isolation devices.
The licenisee has identified the power supplies and has confirmed that they are installed as safety related and that channel separation will be main tained in the cable routing of the shunt and undervoltage trip circuits.
The original plant design included a feature to automatically trip the AC reactor trip breakers via the shunt trip attachment by source interruption device circuits. The source interruption device circuits are not classi fied as safety related circuits but they will be isolated from the safety related shunt trip circuits by the use of isolation relays. Separation of safety channels will be maintained in accordance with the criteria in Section 8 of the Oconee FSAR. We find this acceptable and, therefore, this matter is closed.
- 5. If the wiring to the UV sensor involves different separation groups (train or channel) identify the minimum separation (distance) between wiring of the different groups. Provide an analysis of the consequences of short circuits between wiring in different separation groups to confirm that the consequences do not adversely impact redundant safety related systems.
The licensee has provided the schematics for the reactor trip breakers.
The review of the UV and shunt trip circuits for each breaker indicates that they are in the same safety channel and therefore do not introduce
-4 a separation problem. We find this acceptable and, therefore, this matter is closed.
- 6. Provide an outline of the test procedures to independently verify the operability of the shunt and UV trip circuits and components.
Identify the sequence of actions to be performed. Address your intent regarding periodic'surveillance to confirm the operability of the power failure alarms.
The licensee provided an outline of the steps and sequence to independent ly verify the operability of the shunt and undervoltage trip attachments for an automatic reactor trip as well as the operability of the reactor trip breakers for a manually initiated trip. The shunt and undervoltage trip test will be performed on a monthly basis. Periodic surveillance of the power failure alarms will be conducted on a refueling outage in terval along with the normal preventative maintenance checks. We find this acceptable and, therefore, this matter is closed.
- 7. Provide a draft of any proposed technical specification changes as a result of this modification.
The licensee notes that the existing Oconee Technical Specifications governing operability and surveillance of the reactor protection system and control rod drive trip breakers envelop operability and surveillance requirements for the shunt trip. As such, no changes to the existing Technical Specifications are deemed necessary.
We find that the technical specification should be revised to explicitly note that the testing independently confirms the operability of the shunt
-5 and undervoltage trip attachments consistent with the test procedure out line provided by the licensee. The staff will require that revised tech nical specifications be proposed following the implementation of these changes.
The licensee submitted the electrical schematics for the shunt and UV trip circuits. Based on our review, we find that the Oconee design is consistent with the generic design and is, therefore, acceptable.
CONCLUSION Based on the review of the licensee's response to the plant specific question identified in the staff's evaluation of the Owners Group generic design modi fications, we conclude that the design is acceptable. The licensee should con firm that the shunt trip attachment has been seismically qualified when the ongoing investigation of this matter has been concluded. Finally, the licensee should submit proposed Technical Specification changes, as noted in item 7 above, following the implementation of these changes.
Dated:
February 11, 1985 Principal Contributor: T. Dunning