NRC Generic Letter 1991-09

NRC Generic Letter 1991-009: Modification of Surveillance Interval for the Electrical Protective Assemblies in Power Supplies for the Reactor Protection System

ML031140136
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Washington Public Power Supply System, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Clinch River
Issue date:	06/27/1991
From:	Partlow J Office of Nuclear Reactor Regulation
To:
References
GL-91-009, NUDOCS 9106260172
Download: ML031140136 (6)

• ,, REG&

UNITED STATES

NUCLEAR REGULATORY COMMISSION

m y WASHINGTON. D. C.20555

• June 27, 1991 TO: All HOLDERS OF OPERATING LICENSES FOR BOILING-WATER REACTORS

SUBJECT: MODIFICATION OF SURVEILLANCE INTERVAL FOR THE ELECTRICAL PROTECTIVE

ASSEMBLIES IN POWER SUPPLIES FOR.THE REACTOR PROTECTION SYSTEM

(Generic Letter 91-Q2)

.This generic letter provides guidance for requesting a license amendment to modify the surveillance interval for electrical protective assemblies (EPAs)

used in power supplies for the reactor protection system (RPS). The current standard technical specifications (STS) for boiling-water reactors (BWRs)

• require the licensee to perform channel functional tests of EPAs at a 6-month interval. The modification of EPA test interval provided by this generic letter is to change the TS to state that the test shall be performed each time the plant is in cold shutdown for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, unless the test was performed in the previous 6 months.

In a proposal on December 15, 1988, for Nine Mile Point Nuclear Station (NMP),

Unit 2, the Niagara Mohawk Power Corporation provided a Justification that this TS change benefits plant safety. During the recent review of this TS change for Dresden Nuclear Power Station, Units 2 and 3, the U.S. Nuclear Regulatory Commission (NRC) staff noted that this change from the guidance of the BWR STS

had been implemented in the TS issued with 9 of the last 14 BWR operating licenses. The staff concludes that the TS-change applies generical-ly for...BWRs....

its a line-item TS improvement. The enclosure provides guidance for preparing a license amendment request to implement this line-item TS improvement.

Licensees are encouraged to propose TS changes for BWR facilities that are consistent with the guidance provided in the enclosure. The NRC project manager for the facility will review amendment requests conforming to this guidance. Please contact the NRC project manager or the contact identified below if you have questions on this matter.

This letter does not require any licensee to propose changes to its plant TS.

Therefore, any action taken in response to the guidance'provided in this generic letter is voluntary and is not a backfit under 10 CFR 50.109.

Sincerely, ames . Partlow ssociate Director for Projects Office of Nuclear Reactor Regulation Enclosure: As stated 77i/A _S

Contact: Tom Dunning, NRR/OTSB

(301) 492-1189

9106260172 am DK aIorZo ScP0c0 3 t

Generic Letter 91-09

-- Enclosure MODIFICATION OF THE SURVEILLANCE INTERVAL REQUIREMENTS FOR

ELECTRICAL PROTECTION ASSEMBLIES IN REACTOR'PROTECTION POWER-SUPPLIES

Introduction This enclosure provides guidance for preparing a request for a license amendment to modify the technical specifications (TS) surveillance interval requirements for the electrical protection assemblies (EPAs) used in power supplies for the reactor protection system (RPS) for boiling-water reactors (BWRs). This change reduces the possibility for inadvertent reactor trips caused by testing of EPAs during power operation.

Discussion To protect RPS equipment from abnormal operating voltage or frequency produced by RPS motor generator (MG) sets or an alternate power supply, EPAs-will trip a breaker between the MG sets and the RPS. TS 4.8.4.4 in the standard technical specifications (STS) for BWRs addresses 'the surveillance requirements for EPAs.

This TS specifies that licensees perform a channel functional test every

6 months.

To functionally test an EPA channel, the licensee transfers the power for the RPS from the associated MG set to the alternate power supply. Because the transfer of RPS power involves a dead-bus transfer, power ismomentarily interrupted which causes a half scram or group isolation. Alternatively, the licensee could perform tests without a bus transfer, but this procedure also results in a momentary interruption of power to the RPS when each EPA channel is tripped during the channel functional test. At many BWR plants, licensees have encountered problems with the reset of the half-trip conditions, following testing of EPAs during power operation, resulting in inadvertent scrams and group isolations that challenge safety systems.

An alternative to testing the EPAs every 6 months during power operation has been to test them each time the plant is in cold shutdown for more than

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> if this test has not been performed within the previous 6 months.

This alternative eliminates the need to test the EPAs during power operation and, thereby, reduces the possibility of inadvertent challenges to the protec- tion systems. However, this alternative retains testing within the existing

6-month interval when the unit isshut down for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> during an operating cycle.

If the licensee does not encounter a cold shutdown of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or more during a fuel cycle, the effect of not testing EPAs during this interval is a small risk to safety. This alternative benefits safety by reducing the possibility for inadvertent trips and challenges to safety systems. The staff concludes that the benefit to safety of reducing the frequency of testing during power operation more than offsets the risk to safety from relaxing the surveillance requirement to test EPAs during power operation.

The following guidance provides an acceptable alternative inthe format of the current BWR STS for these surveillance requirements:

k Generic Letter 91-09

- 2 - Enclosure

4.8.4.4 The above specified RPS electrical shall be determined OPERABLE: power monitoring assemblies a. By performance of a CHANNEL FUNCTIONAL

plant is in COLD SHUTDOWN for a period of TEST each time the unless performed in the previous 6 months. more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, Summary The modification of the surveillance interval tests for EPAs in accordance with this guidancefor performing channel functional to test EPAs during power operation. The will eliminate the requirement elimination of this testing during power operation will reduce the possibility for challenges to safety systems. The implementation inadvertent trips and improvement will produce a net benefit for of this line-item TS

safety.

- *^s LIST OF RECENTLY ISSUED GENERIC LETTERS

Generi c

• Date of Letter No. Subject Issuance Issued To

91-08 REMOVAL OF COMPONENT LISTS 05/06/91 ALL HOLDERS OF OLs FROM TECHNICAL SPECIFICATIONS OR CPs FOR NUCLEAR

POWER REACTORS

91-07 GI-23 "REACTOR COOLANT PUMP 05/02/91 ALL POWER REACTOR

SEAL FAILURES" AND ITS LICENSEES AND

POTENTIAL IMPACT ON STATION HOLDERS OF CPs BLACKOUT

91-06 RESOLUTION OF GENERIC ISSUE 04/29/91 ALL HOLDERS OF OLs A-30, *ADEQUACY OF SAFETY-

RELATED DC POWER SUPPLIED,"

PURSUANT TO 10 CFR 50.54(f)

91-05 LICENSEE COMMERCIAL-GRADE 04/09/91 ALL HOLDERS OF OLs PROCUREMENT AND DEDICATION AND CPs FOR NUCLEAR

PROGRAMS POWER REACTORS

91-04 CHANGES IN TECHNICAL SPECIFI- 04/02/9l ALL HOLDERS OF OLs CATION SURVEILLANCE INTERVALS OR CPs FOR NUCLEAR

TO ACCOMMODATE A 24-MONTH FUEL POWER REACTORS

CYCLE

91-03 REPORTING OF SAFEGUARDS 03/06/91 ALL HOLDERS OF OLs EVENTS OR CPs FOR NUCLEAR'

POWER REACTORS AND

ALL OTHER LICENSED

ACTIVITIES INVOLVING

A FORMULA QUANTITY

OF SPECIAL NUCLEAR

MATERIAL (SNM)

91-02 REPORTING MISHAPS INVOLVING 12/28/90 ALL OPERATORS OF

LLW FORMS PREPARED FOR LOW-LEVEL RADIO-

DISPOSAL ACTIVE WASTE (LLW)

DISPOSAL SITES,

WASTE PROCESSORS,

& ALL HOLDERS OF

LICENSES FOR NUCLEAR

FUELS, NUCLEAR

MATERIALS & NUCLEAR

POWER REACTORS

91-01 REMOVAL OF THE SCHEDULE FOR 01/04/91 ALL HOLDERS OF OLs THE WITHDRAWAL OF REACTOR OR CPs FOR NUCLEAR

VESSEL MATERIAL SPECIMENS POWER PLANTS

FROM TECHNICAL SPECIFICATIONS

90-09 ALTERNATIVE REQUIREMENTS FOR 12/11/90 ALL LIGHT-WATER

SNUBBER VISUAL INSPECTION REACTOR LICENSEES

INTERVALS AND CORRECTIVE AND APPLICANTS

ACTIONS

June 27, 1991 TO: All HOLDERS OF OPERATING LICENSES FOR BOILING-WATER REACTORS

SUBJECT: MODIFICATION OF SURVEILLANCE INTERVAL FOR THE ELECTRICAL PROTECTIVE

ASSEMBLIES IN POWER SUPPLIES FOR THE REACTOR PROTECTION SYSTEM

(Generic Letter 91-09)

This generic letter provides guidance for requesting a license amendment to modify the surveillance interval for electrical protective assemblies (EPAs)

used in power supplies for the reactor protection system (RPS). The current standard technical specifications (STS) for boiling-water reactors (BWRs)

require the licensee to perform channel functional tests of EPAs at a 6-month interval. The modification of EPA test interval provided by this generic letter is to change the TS to state that the test shall be performed each time the plant is in cold shutdown for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, unless the test was performed in the previous 6 months.

In a proposal on December 15, 1988, for Nine Mile Point Nuclear Station (NMP),

Unit 2, the Niagara Mohawk Power Corporation provided a justification that this TS change benefits plant safety. During the recent review of this TS change for Dresden Nuclear Power Station, Units 2 and 3, the U.S. Nuclear Regulatory Commission (NRC) staff noted that this change from the guidance of the BWR STS

had been implemented in the TS issued with 9 of the last 14 BWR operating licenses. The staff concludes that the TS change applies generically for BWRs as a line-item TS improvement. The enclosure provides guidance for preparing a license amendment request to implement this line-item TS improvement.

Licensees are encouraged to propose TS changes for BWR facilities that are consistent with the guidance provided in the enclosure. The NRC project manager for the facility will review amendment requests conforming to this guidance. Please contact the NRC project manager or the contact identified below if you have questions on this matter.

This letter does not require any licensee to propose changes to its plant TS.

Therefore, any action taken in response to the guidance provided in this generic letter is voluntary and is not a backfit under 10 CFR 50.109.

Sincerely, James G. Partlow Associate Director for Projects Office of Nuclear Reactor Regulation Enclosure: As stated cc: See attached Distribution:

See attached *See previous concurrence.

OTS Ebb Tech Editor OTSB:DOEA C:OTSB:DQ 1 C:OGCB:DOEA a TGD t :tgd JMain* FMReinha w / IGrime CHBerlinger J (

06/le291 06/12/91 06/12-/91 '06/It /91 06//e/91 7 Concurrence continued on next page.

_,Holders of Operating Licenses for BWRs -2 -

cc w/enclosures:

J. Sniezek F. Miraglia Division Directors, NRR

Associate Directors, NRR

Project Directors, NRR

Regional Administrators J. Conran, CRGR

C. Berlinger, DOEA

S. Treby, OGC

Distribution: (GL 91-09)

PDR (N49-e DOEA R/F

OTSB R/F

Central Files TGDunning

_-- 1 NOTE: This generic letter was reviewed during the CRGR meeting of June 11,

1991, and the CRGR had no objection to it being issued. A copy of the generic letter, the memorandum distributing it to project managers, and the generic safety evaluation report were provided to the CRGR staff. Subsequently, J. Conran, CRGR staff, noted that all CRGR comments have been addressed by the final versions of these documents.

Contact: Tom Dunning, NRR/OTSB /V,_,.' A. 7otf aA"-e0 ,C

(301) 492-1189  ? ~,~

OFFICIAL RECORD COPY A; C-/T AFv

_1 ,nt{

CONCURRENCE CONTINUED-" 91 07- a I M60_7__

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06/1 7191 /91 06V/91