ML20206G043

Safety Evaluation Concluding That All Issues Raised Under Item Resolved & Item 4.3 Closed

ML20206G043
Person / Time
Site:	Beaver Valley
Issue date:	11/17/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20206G032	List: ML20206G030 ML20206G043
References
GL-83-28, NUDOCS 8811220013
Download: ML20206G043 (6)

Text

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SAFETY EVALUATION BY THE OrFICE OF NUCLEAR REACTOR REGULATION

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1.0 INTRODUCTION

Generic Letter 83 28, issued by the NPC on July 8, 1983, indicated actions to be taken by licensees based on generic inplications of the Salem ATWS events.

Item 4.3 of that letter required that modifications be made to irprove the reliability of the reactor trip system by inplementation of a schere to automatically initiate the reactor trip breaker shunt trip attachnent. The licensee responded to this item in letters dated March 30, 1984, September 7, 19E4 August 7, 1985 April 24, 1987, and May 7, 1987. The initial respense, which stated that autoratic actuation of the shunt trip of the reactor trip '

breakers would not substantially improve the plant protection, was found unacceptable. In its September 7,1984 response, the licensee corrnitted to install the Westinghcuse Owners Group (WOG) Generic Design Fodification and in its April 74, 1987 response stated that this rodification had been ccepleted for Unit 2. In the safety evaluation accepting the WOG Generic Design Vodification the staff identified thirteen plant-specific corcerns that needed to be addressed to cocplete the review of this iten. By letter dated August 7,1965, the licensee tocriitted to provide this inforTation by June 30, 1986. We received this infern.ation in a letter dated Fay 7,190,7. We have corpleted our review of this infernation and find it acceptable as follcws:

7.0 EVALUATION We have reviewed the licersee's com.ittent to install the VCG-recorrended desigi modification and found it acceptable, conditioned on confirration of installation and review of S4tisfactory response to the thirteen identified plant-specific concerns. The licensee's April 74, 1987 response stated that this rodification was installed by field change notice D%H-10610. We found this confirfnation acceptable, as we stated in 3upplement No. 6 of the Beaver Valley Unit 2 Safety Evaluation Report (NUREG-1057, Supp. 5).

The licensee responded to the thirteen plant specific concerns in its May 7, 1987 submittal and our evaluation of these responses is presented below.

1. . Concern Provide the electrical scheratic/elerentary diagrars for the reactor trip and bypass breakers shcwing the undervoltage and shunt coil achaticn circuits as well as the breaker control (e.g., closing) circuits, and circuits providing breaker status infortnation/ alarms to the control room.

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Evaluation The licensee provided the electrical scheratic diagrarts for the reactor trip and byLass breakers showing the undervoltage and the shunt trip circuits. The design of the electrical circuits for the automatic actuation of the shunt trip attachment has been reviewed and found to be consistent with the WCG generic proposed design, which was previously reviewed and ap proved. The revised design shown in the schematics provides for rmote brea(er position indication on the r.ain control board for both the reactor trip and bypass breakers. We find this a:ceptable.

.. Concern Identify the power sourcts for the shunt trip coils. Verify that they are Class 1E and that all conponents providing power to the shunt trip circuitry

. are Class 1E and that any faults within non-Class IE circuitry wili not

! degrade the shunt trip function. Describe th) annunciati n/ indication j provided ir the control roca upon loss of power to the shunt trip circuits.

Also describe the evervoltage protection and/or alares provided to prevent or alert the cperator(s) to an overvoltage condition that could effect both the undervoltage (UY) coil and the parallel shunt trip actuation relay.

Evaluatien l

Redundant Class 1E power sources are used fer the shunt trip actuation of i

the reat. tor trip breakers ar.d for the shunt trip of the bypass breakers.

The licensee states that the Class 1E circuitry is separated frco non-class 1E circuitry in accordance with criteria in effect at the tire of licersing, and that a fault occurring within non-Class IE circuitry will not degrade the shunt trip function. These criteria are in accord with the reccarendations of R.G. 1.76 and this respense is acceptable.

Loss of pc'wer to the 125 VCC vital busses which supply the power to actuate the shunt trip is arnunciated in the rain control roce. The reactor trip breaker position status lights are used to supervise the availability of power to the shunt trip circuit of the reactor trip and bypass breakers. The red light, which is connected in series with the shunt coil and the "a" auxiliary contact of each breaker, indicates that the breaker is closed and also indicates that pcwer is available to the shunt trip device and, therefore, provides detectability of pcwer fat are to the shunt trip coil. Norra11y, the shunt trip coils in the reace.r breakers are in a de energized condition. When the trip breakers are c'.osed, the red larp current, which is rct large enough to actuate the trip coil arrature, flows through the trip coil to ronttor the circuit conticuity. Since the current through the shunt trip coils is interrupted when the breaker trips, erergiration of the sbunt trip coil is only rorentary. The .raxirum available voltage occurs during a battery l equaliting charge at a s.axinum voltage of 115% of the non.inal voltage.

Due to the short duty cycle of the shunt trip coil, it can cperate at this overvoltage condition without hamful effects.

The added shunt trip circuitry tnd undervoltage trip attachnent (VVTA) are powered from the reactor protection logic voltace supplies. Two 48-Vdc power supplies (1a one train) are auctioneered to fonn one 48-Vdc bus.

If an overvoltage condition exists (115% of nominal 48-Vde), the power supply will turn off and the redundant supply will carry the load. This condition will be annunciated in the control room and will light a warning lamp on the SSPS logic cabinet. If the overvolt.;e condition renains, the redundant power will be turned off, thus removing the load and ae-energizing the undervoltage coil and shunt trip actuation relay. Since the power is removed frtm the UV coil and shunt trip actuation relay, it will not have any hannful effects on these components. This is in accordance with requirements, and is, therefore, acceptable.

3. Concern Verify that the relays added for the autcratic thunt trip function are within the capacity of their associated power supplies and that the relay contacts are adequately sized to accoeplish the shunt trip function. If the added relays are other than the Potter & Brumfield MDR series relays (P/N 2383A38 or P/N 955655) recomended by 'Jestinghouse, provide a description of the relays and their design specifications.

Evaluatio_n _

TFe design at Beaver Valley Unit 2 includes the Potter & Brumfield MCR series P/N 955655 relays as specified in the WOG generic design for the autcrratic shunt trip function. The relay contacts are adequately sized to acccn.plish the shunt trip function. We find this aspect of the design to be acceptable.

4 Concern State whether the test procedure / sequence used to independently verify operability of the undervoltage and shunt trip devices in response te an autmatic reactor trip signal is identical to the test procedure proposed by the WOG. Identify any differences between the WOG test procedure and the test procedure to be used and provide the rationale / justification for these differences.

Evalu s ti,on The licensee states that Maintenance Surveillance Procedures will independently verify the operability of the undervoltage and shunt trip i devices in a tranner identical to that proposed by the WOG, as submitted l in their letter, OG-101, dated June 14, 1983. We find this response acceptable.

5. Concern I

Verify that the circuitry used tc implement the autcratic shunt trip function is Class 1E (safety related), and the procurenent,

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-4 installation, operation, testing and maintenance of this circuitry will be in accordance with the Quality Assurance criteria set forth in Appendix B to 10 CFR Part 50.

Evaluation The licensee confirmed that the circuitry used to implement the autertatic shunt trip function is Class 1E (safety-related), and the procurement, insta11atier, operation, testing and maintenance of this circuitry will be in accordance with the Duquesne Light Company Quality Assurance Program, which satisfies the quality assurance requirements of Appendix B to 10 CFR Part 50. We find this to be acceptable.

6. Concern Verify that the shunt trip attachnents and associated circuitry are/will be seismically qualified (i.e., be demonstrated to be operable during and after a seismic event) in accordance with the provisions of Regulatory Guide 1.100, Revision 1 which endorses IEEE Standard 344, and that all non-safety related circuitry / components, in physical proximity to or associated with the automatic shunt trip function, will not degrade this function during or after a seismic event.

Eyaluation The licensee states that the shunt trip attachnents and the associated .

circuitry contained in the automatic shunt trip panels were supplied by Westinghouse, and are seismically and environnentally qualified in accordance with IEEE Standard 3a4-1975 and IEEE Standard 323-1974, l respectively. The licensee stated that the separation criteria will

' prevent non-safety-related components in proximity to safety-related components from degrading the automatic actuation of the shunt trip.

We find this response acceptable.

7. Cone y Verify that the components used to accomplish the automatic shunt trip function are designed for the environment where they are located.

Evaluation The licensee has verified that the plant-specific environmental ccnditions defined in the WOG generic design package. Table 1, envelope the Beaver Valley 2 motor-generator room conditions. We find this acceptable.

8. Concern Describe the physical separation provided between the circuits used to tranually initiate the shunt trip attachnents of the redundant reactor

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trip breakers. If physical separation is not maintained between these circuits, demonstrate that faults occurring within these circuits cannot degrade both redundant trains.

Evaluation Physical separation between the cir:uits used to manua'ly initiate the shunt trip attachments of the redundant trip breakers is maintained by routing the field cabling from the main control board and reactor protection logic to redundant train A and train B reactor trip switchgear as train A and train B circuits. Main control board manual reactor trip switches are provided with fire barriers between the redundant train switch decks. The interposing relays used to actuate the shunt trip attachments and their associated terminal blocks are mounted in separate ir,Et&l enclosurGs. The ie6ctor prutection sysi.em logic output energizing the interposing relays are enclosed in existing separate metal enclosures.

We find this meets the guidance of R.G.1.75 and is, therefore, acceptable.

9. Concern Verify that the operability of the control room manual reactor trip switch contacts and wirits will be adequately tested prior to startup after each refueling cutage. Verify that the test procedure used will not involve installing jumpers, lifting leads, or pulling fuses and identify any deviation from the V0G procedure. Permanently installed test connections (i.c., to allcw connection of a voltreter) are acceptable.

Evaluation.

The licensee states that operating surveillance testing will adequately test Control Room nanual reactor trip switch contacts and wiring. The licensee further states that this testing is performed at each refueling ,

outage and prior to startup, if not perforned within the previous seven days. The licensee confims that this testing will not involve installing junpers, lifting leads, or pulling fuses. We find the stated test provisions to be in accordance with guidance and is, therefore, acceptable.

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10. Concern Verify that each bypass breaker will be tested to demonstrate its l operability prior to placing it into service for reactor trip breaker l testing, j

, Evaluation, I

The licensee states that Maintenance Surveillance Procedures 2MSP-1.04-I, 2MSP-1.04A-I 2MSP-1.05A and the Beaver Valley 2 Technical Specifications. -

Tt ble 4.3-1, contain requirements and provisions for verifying the operability of by> ass breakers prior to placing them into service for  :

reactor trip breacer testing. We find this response acceptable.

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11. Concern Verify that the test procedure used to determine reactor trip breaker operability will also demenstrate proper operation of the associated control room indication / annunciation.

Evaluation The licensee states that Operating Surveillance Test 2.1.7 contains provisions for denonstrating proper operation of the associated control room indication /annuciation. We find this response acceptable.

12. Concern Verify that the response time of the automatic shunt trip feature will be tested periodically and shown to be less than or equal to that assumed in the FSAR analyses or that specified in the technical specifications.

Evaluation The licensee states that Maintenance Surveillance Procedures 2MSP-1.14A-1, 2MSP-1.14B-1, and BVT 2.1-11.1.2 provide for measurement of the response time of the automatic shunt trip feature,and that the Reactor Trip Breaker Monitoring Program will compare response time test data to acceptance 1

criteria. We find this program to be acceptable.

- 13. Concern .

Propose technical specification changes to require periodic testing of the undervoltage and shunt trip functions and the manual reactor trip switch contacts and wiring.

Evaluation

This concern became the subject of Generic Letter 85-09. The licensee's responses were reviewed and have been incorporated into the Beaver Valley Unit?TechnicalSpecifications(NUREG-1279).

3.0 CONCLUSION

On the basis of our review of the licensee's submittals, we concluded that all issues raised under this item have been resolved and Item 4.3 is closed.

Principal Contributor: Don Lasher Dated: November 1988

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