ML20202C328

Application for Amends to Licenses NPF-4 & NPF-7,modifying Testing Requirements for Reactor Trip Bypass Breaker

ML20202C328
Person / Time
Site:	North Anna
Issue date:	02/03/1998
From:	Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20202C333	List: ML20202C328 ML20202C338
References
98-067, 98-67, NUDOCS 9802120220
Download: ML20202C328 (10)

Text

J V1HOIN1A ELiternic awn Pownin ( @ANY llH'HMOND,VIHU1NIA 200 08 February 3. 1998 U.S. Nuclear Regulatory Commission Serial No. 98 067 Attention: Document Control Desk NL&OS/GSS/ETS R0 Washington, D.C. 20555 Docket Nos. 50 338 50 339 License Nos. NPF-4  !

NPF-7 j Gentlemen:

YlRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITC 1 AffD_2 PROPOSED _ TECHNICAL SPEGEiCATION CHANGE REACTOR TRIP BYPASS BREAKER SEQUENCE CHANGE Pursuant to 10 CFR 50.90, Virginia Electric and Power Corppany requests i amendments, in the form of changes to the Technical Specifications and to Facility I Operating License Numbers NPF-4 and NPF 7 for North Anna Power Station Units 1 l and 2, respectively. The proposed changes will modify the testing requirements for the reactor trip bypass breaker. A discussion c? the proposed Technical Specifications changes is provided in Attachment 1.

The proposed Technical Specifications changes have been reviewed and approved by the Station Nuclear Safety and Op6: sting Committee and the Management Safety Review Committee. It has been determined that the proposed Technical Specifications changes do not involve an unreviewed safety question as defined in 10 CFR 50.59 or a significant hazards consideration as defined in 10 CFR 50.92. The proposed Technical Specifications changes are provided in Attachment 2. The basis for our determination that the changes do not involve a significant hazards consideration is provided in Attachment 3.

If you have any further questions, please contact us.

Very truly yours, dtt/ i James P. O'Hanlon i U l Senior Vice President - Nuclear

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in ti A'Itachinents

- 1. Discussion of Changes

2. Proposed Technical Specification Changes

3. Significant Hazards Consideration Determination Commitments made in this letter:

, 1. There are no commitments in this letter cc: U.S. Nuclear Regulatory Commission Region ll Atlanta Federal Center 61 Forsyth Street, SW Suite 23T85 b Atlanta, Georgia Sr303

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a Mr. M. J. Morgan NF:C Senior Resident inspector North Anna Power Station Commi:,sh a Departmem of Radiological Health Room 104A g 1500 East Main Street Pichmond, VA 23219 I

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' COMMONWEAL 1 H'OF VIRGINIAL .

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COUNTY OF HENRICO _ ):

The foregoing document was acknowledged before me, in and for the County and Commonwealthiaforesaid, today by _J.. P., O'Hanlon,-:who is-Senior Vice  ?

President - Nuclear, of Virginia Electric.and Power Company. He has_ affirmed .

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before' me that he is duly authorized to execute and file the foregoing document' in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief.-

Acknowledged before me this day of MldOALH,:19 .

My Commission Expires: March 31,-2000.

4 Notary Public m 'k " "

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s ATTACHMENT 1 DISCUSSION OF CHANGES VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA UNITS 1 AND 2 l

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f. Dist,ussion of Change:

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Pursuant to _10 CFR 50.90,-Virginia Electric and Power Company requests changes to

i. Technical Specifications Surveillance Requirement 4.3.1.1.1, Table 4.3-1, " Reactor Trip 1 1 System Instrumentation Surveillance Requirements," item 21.B,- Reactor; Trip Bypass -

' Breakers for North Anna Power Station Units;1 and 2.eThe test soquence specified in

. the Periodic Test Procedures currently requires the Reactor Trip Bypass Breakers to be .

racked to the test position, tested, and then retumed to the racked-in (connect) position. .

The proposed changes will allow;the _ bypass breakers to Latested in the racked-in

'positioni:In addition, changes are being made to the operability. and requirements for-itheL: reactor trip bypass breakers toielimirrte potential compliance: issues. - These changes ~ will continuef to; ensure the operabilityf 'of = the? breakers and eKminate tunnecessary movement caused by racking the breakers, thus, reducing the wear and

. tear'on the breakers and the possibility of a reactor trip.-

The operation of the Reactor Protection System as well as the reactor trip and reactor -

t bypass breakers is not being changed. The operability clarifications do not change the operability or testing requirements of the reactor trip or bypass breakers. The proposed changes in the test sequence for the reactor trip bypass breakers continue to -

provide assurance that the reactor trip bypass breakers will operate as designed.5The

breakers are designed to mitigate the consequence of any unsafe or improper reactor toperation during steady state or transient power operations when the_ bypass breakers arelplaced in service for- reactor. trip system testing;or trip breaker maintenance.

LTherefore, the proposed changes to the reactor trip bypass breaker surveillance testing.

. sequence do not create an unreviewed safety question.1

' Background 1 Current Licensing Basis "I'n response to the 1983 ATWS event at the Salem Nuclear Generating Station, the

. NRC issued Generic Letter GL 83-28, " Required Actions Based on Generic Implications of Salem ATWS Events." ltem 4.3 of this letter became the subject of NRC Generic J Letter GL 85-09, " Technical Specifications for Generic Letter 83-28, item 4.3," which

. required the industry to enhance the netitenance and testing of the reactor trip and reactor trip bypass' breakers.

As a' result of a letter dated April 12,1985, as modified by letter dated September 9, 1985, Virginia Electric and Power Company submitted propos d Technical

- Specifications changes in accordance with the guidance of GL 85-09. These changes

' revised the operability and surveillance requirements to ensure appropriate actions for inoperable breakers or trip devices and for complete testing of the breakers. The NRC approved the changes on June 9,1986, with the issuance of Amendments 81 and 69 for Unit 1 and Unit 2, respectively.

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Design" Basis The reactor trip circuit breakers and their associated switchgear are designed to channel electricity to the rod control cabinet. The reactor trip switchgear consists of four circuit breakers in a series / parallel arrangement. A bypass breaker is connected in parallel with its respective reactor trip breaker. The bypass breakers are interlocked so that only one bypass breaker can be closed at a given time, and permit online testing of the reactor trip breakers without shutting down the reactor.

The safety related function of the reactor trip and bypass breakers is to interrupt power to the control rod drive mechanisms (CRDM) on command from a reactor trip signal.

Interruption of power to the CRDMs causes the control rods to fall by gravity into the reactor core causing the reactor to shut down.

The reactor trip circuit breaker elements are Westinghouse Type DB 50 horizontal drawout, 600 volt,1600 ampere frame power air circuit breakers. The breaker interfaces electrically with the switchgear cell components through its six. primary disconnecting contacts and its secondary contact assembly. Each element has three designated positions (Disconnect, Test, and Connect) in the switchgear cell.

Discussion item 21 of Table 4.3-1 requires the staggered train 62 day Channel Functional Test of the reactor trip and the reactor trip bypass breakers. Noto 8 for Unit 1 and Note 9 for Unit 2 to this table state that a local manual shunt trip is required prior to placing the bypass breaker in service. On October 10,1996, a compliance issue was identified c conceming the testing sequence of the reactor trip bypass breakers. It was identified .

that the periodic tost proceduras did not verify the manual shunt trip prior to closing the bypass breaker, From approximately June 9,1986 until the verbatim interpretation issue was identified on October 10,1996, the reactor trip bypass breaker manual shunt trip was tested immediately after closing the normally racked-in breaker.

Prior to October 10,1996, the reactor trip bypass breakers were normally racked-in and open. Only during sun /eillance or maintenance was a reactor trip bypass breaker closed. The local manual shunt trip test of the reactor trip bypass breaker was performed with the breaker racked-in, thus, when the breaker was closed to perform the local shunt trip test the breaker was actually in service for that very short period of time.

This testing sequence was identified in Deviation Report N 96-2304 as not being in compliance with the Technical Specification Surveillance Requirement Table 4.3-1, item 21, Notations (8) for Unit 1 and (9) for Unit 2, which require a local shunt trip of the breaker prior to placing the bypass breaker in service. LER N1-96-009-00 dated November 6,1996 and Non-cited Violation 50-338,339/96012-02 were also issued to address this issue.

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. in response to the verbatim compliance issue with Technical Specifications, North Anna modified the test sequence. The modified test saquence requires the reactor trip bypass breaker to be racked from its normal racked in position (connect) to the test position. The breaker is then closed and tripped locally with the shunt trip device, and then retumed to the racked in position, whereby the bypass breaker is placed in service (closed) for testing or maintenance to commence. This current test sequence requires racking the breakers to the test position, which increases the wear and tear on the reactor trip bypass breakers.

The proposed changes to the Technical Specifications notations will retum the test sequence to thr initial testing sequence (prior to October 10,1996) for the reactor trip bypass breakers. The proposed notations will also clarify that the reactor trip bypass breaker functional test is coordinated with the reactor trip breaker functional test b ensure that the bypass breaker is tested prior to the testing of the reactor trip breaker.

These changes will continue to assure the operability and eliminate unnecessary movement (racking the breaker) for testing; thus, reducing the wear and tear of the reactor trip bypass breakers and alignment problems experienced when racking the breakers in and out.

The circuit breaker elements are approximately 340 pounds and are awkward to move on the breaker cell rails. Mishandling of the braaker elements can cause severe damage to the equipment. Damages reported by the Westinghouse Vendor Technical Manual have included bent cell positioning stop brackets, breaker element positioning levers, breaker release latches, miscellaneous brackets, pins and stops as well as misalignments of the cell rails and the breaker elements to the cells. Proper and limited handling of the circuit breaker elements will increase the longevity of the equipment and will contribute directly to its reliable operation.

Additionally, the prevailing interpretation before the compliance issue was based upon the application of the associated action statements. Table 3.3-1, " Reactor Trip System Instrumentation" Item 21 A, allows a reactor trip breaker to be bypassed by closure of the associated bypass breaker, for two hours for surveillance testing. Thus, the reactor trip breaker is effectively inoperable and in Action as soon as the bypass breaker was closed. Since the bypass breaker will be immediately tested upon closure by verifying that the electrical shunt trip causes it to trip, Note 8 for Unit 1 and Note 9 for Unit 2, were believed to be fully satisfied. UFSAR Section 7.2.2.2.1.7 also substantiated this interpretation such that the detailed testing sequence in the UFSAR matched that in the initial periodic test surveillance procedures.

The reactor trip switchgear consists of four circuit breakers in a series / parallel arrangement. A bypass breaker is connected in parallel with its respective reactor trip breaker. The bypass breakers are interlocked so that only one bypass breaker can be closed at a given time. In addition to the interlock, procedural controls have been established to prevent closing both reactor trip bypass breakers at the same time for testing or maintenance. To eliminate a potentici verbatim compliance issue, we are Page 3 of 6

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[ changing the. minimum channials operable requirement from two to one for the reactor; t' rip b%ess breakers in item 21B in Table 3.31, .

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i The proposed testing sequence of the: reactor trip bypass breakers starting.with the-breakers in their normal racked-in position _(connect) is as follows:

e ::- Close the bypass breaker

Immediately trip.the bypass breaker using the local shunt trip m_echanism (Immediately is intended to be as soon as reasonably practicable,:without 1 delay after closing the bypass breaker) -

e - Close' the bypass brealfer, commence reactor: trip - system. testing _ or trip -

^ breaker maintenance-oThis _ testing: sequence adequately establishes the operability of the breaker and

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eliminates the unnecessary movement of the bypass breakers. -

Specific Changes in order to. accomplish the test in this' manner and clarify the notations,'the Technical-Specifications will be revised as noted below:

. . Revise ^ Notation L (8) " Reactor Trip System - Instrumentation Surveillance -

Requirements" in Table 4.3 _1 for Unit 1 as noted below:

n(8) " Local manual shunt trip the= reactor trip bypass breaker immediately_-

lafter placing the. bypass breaker into service, but prior to commencing -

t reactor trip system testing or reactor trip breaker maintenance."

. . Revise ? Notation (9) " Reactor Trip System Instrumentation Surveillance.- y L Requirements" in Table 4.3-1 for Unit 2 as noted below:

J (9)'-- Local manual shunt trip the reactor (rip bypass breaker immediately s +- after placing the bypass breaker into service, but prior to commencing 4 reactor trip system testing or reactor trip breaker maintenance." <

<The_ following1changey in the operability requirements for the reactor trip bypass

~. breakers is being made to eliminate a potential compliance issue:

. . Table 3.3-1_ Item 21B, Reactor Trip Bypass Breakers - The minimum channel operable requirements is being changed from two to one.

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. Safety _ Significance The proposed change in test sequence for the reactor trip bypass breakers continues to provide assurance that the reactor trip bypass breakers will operate as designed to mitigate the consequence of any unsafe or improper reactor operation during steady state or transient power operations when the bypass breakers are placed in service for reactor trip system testing or trip breaker main;enance, a) Operation and testing of the reactor trip breakers does not increase the probability of an accident or malfunction of equipment important to safety previously evaluated in the safety analysis report.

The testing sequence will continue to ensure that the reactor trip system will be operable to mitigate the consequences of any unsafe or improper reactor operation during steady state or transient power operations. - Although the breaker is placed in service for a very short time before it is tested, the breaker is tested as soon as practicable to reestablish operability prior to performing testing of the reactor trip system or maintenance on the reactor trip breakers. During the short period of time the breaker is closed before the local shunt trip device test, the operability of the breaker is established based on satisfactory breaker testing conducted during the previous surveillance interval. Changing the minimum channels operable requirement for the reactor trip bypass breakers does not affect the operation of the reactor trip system since only one reactor trip bypass breaker can be placed inservice for testing or maintenance of thc reactor protection system.

Therefore, the proposed test sequence does not increase the probability of occurrence or the consequences of any previously analyzed accident.

b) The proposed Technical Specifications do not create the possibility of an accident or malfunction of a different type than any evaluated previously in the safety analysis report.

The proposed test sequence change does not alter the actual test performed to establish operability of the reactor trip bypass breakers. The bypass breakers will be proven operable prior to reactor trip system testing or reactor trip breaker maintenance. Although the breaker is placed in service before it is tested, the breaker is tested as soon as practicable to reestablish operability prior to performing testing of the reactor trip system or maintenance on the reactor trip breakers. During the short period of time the breaker is closed before the local shunt trip device test, the operability of the breaker is establlshed based on satisfactory breaker testing conducted during the previous surveillance interval. Changing the minimum channels operable requirement for the reactor trip bypass breakers does not affect the operation of the reactor trip system since only one reactor trip bypass breaker can be placed inservice for testing or maintenance of the reactor Page 5 of 6