ML20141F369

Application for Amends to Licenses NPF-4 & NPF-7,revising Wording in Surveillance Requirement 4.7.1.7.2.a to Clarify Testing & Insp Methodology of Turbine Governor Control Valves.Clarification Also Provided in TS 3/4.7.1.7

ML20141F369
Person / Time
Site:	North Anna
Issue date:	05/14/1997
From:	Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20141F373	List: ML20141F369 ML20141F374
References
97-285, NUDOCS 9705210291
Download: ML20141F369 (11)

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. q WuisIA El.ECTRIC ANI) POWER COW %NY Riciistoso, hGINI A 23261 May 14, 1997 U.S. Nuclear Regulatory Commission Serial No.97-285 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 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 PROPOSED TECHNICAL SPECIFICATION CHANGE TURBINE CONTROL VALVE TESTING / INSPECTION CLARlFICATION Pursuant to 10 CFR 50.90, Virginia Electric and Power Company requests  ;

amendments, in the form of changes to the Technical Specifications, to Facility Operating License Numbers NPF-4 and NPF-7 for North Anna Power Station Units 1 and 2, respectively. The proposed changes will revise the current wording in Surveillance Requirement 4.7.1.7.2.a for both units to clarify the testing and inspection methodology of the turbine govemor control valves. The proposed changes also ,

provide clarification in Technical Specification Bases Section 3/4.7.1.7 for the Turbine Valve Freedom Testing of the turbine govemor control valves. -

A discussion of the proposed Technical Specifications changes is provided in Attachment 1. The proposed Technical Specifications changes are provided in Attachment 2. 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 basis for our determination that the changes do not involve a significant hazards consideration is provided in Attachment 3. The proposed Technical Specifications changes have been reviewed and approved by the Station Nuclear Safety and Operating Committee and the Management Safety Review Committee.

There are no commitments intended as a result of this letter. If you have any further questions, please contact us. ,

Very truly yours, .

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ff/0 Japes O' anion m l Senio ice President - Nuclear Attachments -

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9735210291 970514 h PDR ADOCK 05000338 R P PDR-

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Region II Atlanta Federal Center 61 Forsyth Street, SW Suite 23T85 Atlanta, Georgia 30323 NRC Senior Pesident inspector  ;

North Anna Power Station Commissioner Department of Radiological Health Room 104A 1500 East Main Street Richmond, VA 23219 1

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i COMMONWEALTH OF VIRGINIA )

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COUNTY OF HENRICO )  !

The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by M. R. Kansler, who is Vice President -

Nuclear Operations, for J. P. O'Hanlon, who is Senior Vice President - Nuclear, of Virginia Electric and Power Company. He has affirmed 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 l day of SQL, .19H.

My Commission Expires: March 31,2000.

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OO Notary Public 1

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', ATTACHMENT 1 l -

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9 DISCUSSION OF CHANGES i

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j VIRGINIA ELECTRIC AND POWER COMPANY i

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Discussion of Changes introduction i

Pursuant to 10 CFR 50.90, Virginia Electric and Power Company requests changes to Technical Specifications Surveillance Requirement 4.7.1.7.2.a for North Anna Power Station Units 1 and 2. The Technical Specifications (TS) surveillance requirements currently require testing and inspection of the Turbine Overspeed Protection System control valves to ensure their ability to prevent overspeeding of the turbine. The proposed change would clarify the Surveillance Requirement wording to reflect the Virginia Electric and Power Company's current valve testing and verification of valve movement methodology for cycling the valves through at least one complete cycle.

The proposed changes provide clarification to the testing and inspection requirements that each of the turbine control valves be cycled and movement verified through at least one complete cycle from the runnina cosition. Additionally, Technical Specification Bases Section 3/4.7.1.7 will be revised to clarify the testing requirements for the turbine governor control valves.

Clarification of the wording will also reflect the same wording in NUREG-0452,

" Standard Technical Specifications for Westinghouse Pressurized Water Reactors" I and Technical Specifications used by other utilities to demonstrate operability of the l Turbine Overspeed Protection System. The testing requirements are consistent with  ;

the current North Anna Periodic Test Procedures and Westinghouse Operating j Instructions. l The proposed changes to the North Anna Units 1 and 2 Technical Specifications will not adversely affect the safe operation of the plant. Additionally, the proposed wording j clarification will not result in an unreviewed safety question as defined in the criteria of )

10 CFR 50.59.

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B_ackaround Design / Licensing Basis:

The Westinghouse turbine is a conventional 1800 rpm tandem-compound unit consisting of one double-flow high pressure cylinder and two double-flow low pressure cylinders. The turbine is provided with four moisture separator reheaters located between the high-pressure and low-pressure cylinders.

Each high-pressure steam line to the high-pressure cylinder contains a stop-trip (throttle) valve and a governor control valve. A reheat stop valve and an intercept

-valve are provided in the crossover piping between each moisture separator reheater and low-pressure turbine cylinders.

Technical Specifications Surveillance Requirement 4.7.1.7.2.a ensures that the turbine speed control valves are OPERABLE to protect the turbine from excessive overspeed. A turbine overspeed condition significantly increases the probability of turbine missile generation relative to operation at normal speed due to the increased stress in the turbine rotor at higher operating speeds. The Turbine Overspeed Protection System trips the turbine to mitigate the potential for the generation of potentially damaging missiles from the turbine, in the event of a loss of a turbine speed control system or a transient. Regular testing and inspection of the turbine control valves reduce the probability of their failure and the probability of turbine overspeed.

Westinghouse technical manual operating instructions and Virginia Electric and Power Company periodic test procedures require all turbine control valves, used to stop steam flow to the turbine, to be tested from their operating position to their fully closed position. This testing is required to be performed on a scheduled basis to ensure continued reliability in service.

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Discussion  !

On April 11,1997, a question was presented conceroing the testing of the turbine  ;

I governor valves through one complete cycle of full travel required by the North Anna Power Station Technical Specifica3ons. Technical Specifications Surveillance Requirement 4.7.1.7.2.a requires the t asting of each turbine control valve "through one complete cycle of full travel." The defin, tion of " full travel" is not specifically provided in I the Technical Specifications. )

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- For turbine governor control valve #4, this surveillance requirement has been interpreted in the past to test the valve from its operating (running) position to the fully closed position. This test methodology is consistent with the Virginia Electric and Power Company's Periodic Test Procedures, Wat;r:ghouse Operating instruc+1ons,

NUREG-0452 " Standard Technical Specifications for Westinghouse P.cacurized s Water Reactors," and Technical Specifications utilized by other utilities.

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Westinghouse Electric Corporation was also contacted on April 11,1997 to evaluate l l the testing methodology baing performed. it was verified that our periodic test procedures, consistent with Westinghouse Operating instructions for turbine governor control valve #4, only test the valve from the operating position to fully closed. The

! valve is not tested from the fully open position. However, the evaluation results from Westinghouse, as agreed upon by our System Engineering, determined that deliberately opening the #4 governor valve during the test would likely result in an

, unstable valve configuration that furthermore would be irrelevant to the purpose of the testing which is to verify that the valves close from their normal position.

The proposed changes and the current test methodology is consistent with our Periodic Test Procedures, Westinghouse Operating Instructions, NUREG-0452,

" Standard Technical Specifications for Westinghouse Pressurized Water Reactors" Revision 4 and Technical Specifications used by other ut!!ities to demonstrate operability of the Turbine Overspeed Protection System. As the proposed wording to

. clarify the testing and inspection requirements of the turbine control valves represents current practice and understanding of the requirements, the proposed change does not increase the probability of the generation of missiles or the probability of damage to any plent s.tructures, systems, or components currently evaluated in the UFSAR.

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.. J Sp_qcific Chances ]

1 The following specific Technical Specifications changes apply to both Units 1 and 2:  !

• Clarify the test performance and verification of movement requirements for the i turbine overspeed protection system control valves by rewording Surveillance l Requirements 4.7.1.7.2.a as noted below-

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4.7.1.7.2 The above required turbine overspeed protection system shall be j demonstrated OPERABLE l i

EXISTING WORDING  :

a. By cycling each of the following valves through one complete {

cycle of full travel and verifying movement of each of the valves  ;

through one complete cycle by direct observation: j i

CHANGE WORDING TO

a. By cycling each of the following valves through at least one j complete cycle of-full-travel from the running position and j verifying movement of each of the valves through one complete cycle from the running position by direct observation.

Add the following clarification to Technical Specification Bases Section 3/4.7.1.6 and 3/4.7.1.7:  !

L The turbine governor valves are required to be tested through one complete  !

cycle from the running position, in normal operation, one or more governor j valves may be less than fully open. Based upon the Westinghouse Technical Manual Operating Instructions, these valves are tested from the operating j position to the' full closed position and back to their pretest position. The i

. deliberate opening of the last governor valve beyond its normal operating l position would likely result in an unstable valve configuration. The purpose of ,

the test is to verify that the governor valves will close from their normal operating i position to the fully closed position. l i

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i Safety Significance Virginia Electric and Power Company has reviewed these proposed Technical  ;

Specifications changes and determined that the changes would not involve an  !

unreviewed safety question.

1. The proposed changes would not increase the probability of occurrence or the consequences of an accident or malfunction of equipment important to safety l previously evaluated in the safety analysis report. The proposed changes have  ;

no adverse impact upon probability or consequences of any accident previously ,

evaluated. Only the wording of the e.,urveillance requirements for cycling and j inspecting of the turbine control vs.!ves are being changed for clarification  !

purposes to more specifically state the Westinghouse requirements and current practice. No new or unique accident precursors are introduced by this change in  ;

surveillance requirements.  !

L The verification of the operability of the turbine control valves will continue to provide adequate assurance that the turbine overspeed protection system will operate as designed, if needed. Therefore, the proposed change does not ]

involve a significant increase in the probability or consequences of any accident i previously evaluated.

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2. The proposed changes would not create the possibility for an accident or malfunction of a different type than any evaluated previously in the safety analysis report. Since the implementation of the proposed change to the surveillance requirements will require no hardware modifications (i.e., alterations to plant configuration), operation of the facilities with these proposed Technical Specifications does not create the possibility for any new or different kind of accident which has not already been evaluated in the Updated Final Safety Analysis Report (UFSAR).

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The proposed wording changes to the Technical Specifications will not result in any physical alteration to any plant system, nor would there be a change in the method by which any safety-related system performs its function. The design and operation of the turbine overspeed protection and turbine control systems are not being changed. Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. The proposed changes would not reduce the margin of safety as defined in the basis for any Technical Specifications. The design and operation of the turbine overspeed protection and turbine control systems are not being changed and the operability of the turbine control valves are being demonstrated in the same manner. In addition, the results of the accident analyses which are documented in the UFSAR continue to bound operation under the proposed changes, so that -

there is no safety margin reduction. The proposed changes represent a clarification to more specifically state current test practices and requirements.

Therefore, the proposed change does not involve a reduction in a margin of  !

safety.

Based on the above evaluation, the proposed changes to the Technical Specifications will not adversely affect the safe operation of the plant. Therefore, the proposed  !

changes for North Anna Units 1 and 2 do not result in an unreviewed safety question as defined in the criteria of 10 CFR 50.59. I l

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ATTACHMENT 2 a

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l PROPOSED TECHNICAL SPECIFICATIONS CHANGES I NORTH ANNA UNITS 1 AND 2 l

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VIRGINlA ELECTRIC AND POWER COMPANY e

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