ML20005E141

Responds to Generic Ltr 89-10, Motor-Operated Valve Testing & Surveillance. Thermal Overloads on Most safety-related motor-operated Valves Are Jumpered During Operation.Epri Developing Program to Calculate Valve Thrust Requirements

ML20005E141
Person / Time
Site:	Hatch
Issue date:	12/28/1989
From:	Hairston W GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-89-10, HL-869, NUDOCS 9001030391
Download: ML20005E141 (7)

Text

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a December 28, 1989-t U.S.-Nuclear Regulatory Commission 1 ATTN: , Document Coitrol Desk q;- <

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PLANT HATCH - UNITS 1, 2 ..

NRC DOCKETS 50-321, 50-366  :

> 4 -OPERATING !ICENSES DPR-57, NPF-5 l

-7 . RESPONSE TO GENERIC LETTER 89-10

. MOTOR-OPERATED VALVE TESTING AND SURVEILLANCE o

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~ Gentlemen:

0 -. On June >28,- '1989,1 the,'NRC issued Generic. Letter' (GL) 89-10,' l

• - Safety-Related : Motor-0perated Valve (M0V) Testing and Surveillance." The I

-GLE extended the recommendations outlined in' NRC Bulletin 85-03 and its- o supplement to all safety-related and " position-changeable" MOVs. ~The a

H  : whether Reporting atheRequirements recommendations (Item an1)d schedule centained in the GL would be-met.-requestel The letter. further requests that, for any recommendation which could not be l met,: the' licensee: > should present- technical justification along .with :l

alternative -' actions and/or - schedules. The enclosure- to this letter i provides.the requested information. '

Georgia Power.. Company (GPC) concurs with the need to increase the iM overall functional reliability associated with MOVs, and will extend its a f program for testing, inspection-and maintenance of safety-related M0Vs H < :above .that currently required by ASME Section XI. However, GPC has :1 concerns regarding.two -major issues associated with MOV testing and GL I

L 89-10. -The two major issues are:

L 1. Requiring utilities to consider inadvertent mispositioning of MOVs, i l-

' including those valves in safety-related systems which do not have  !

an active safety function, and I

[ 2. Requiring utilities to test MOVs at maximum differential pressure.

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l 9001030391 091228 F D bf .

PDR- ADOCK 05000321 O l Pi PDC 7 )

I I c0rgiaPOWor L U.S. Nuclear Regulatory Commission <

December 28.-1989 Page Two Item (1) clearly represents a backfit without supporting analysis justifying this new NRC position. Consequently we are hesitant to commit to this requirement until its impact has been determined for Plant Hatch. 1 The issue of differential pressure (dP) testing and valve performance at ,

full dP_ conditions is being evaluated by industry and the NRC. As such, we t will perform limited dP testing and. focus on the more defined areas used to assure valve functionality such as design . reviews, static (zero) dP diagnostic testing, and upgraded maintenance.

, Georgia Power Company understands that the Nuclear Management and Resources Council (NUMARC) is planning to meet with the Staff to discuss industry concerns associated with GL 89-10. In the past, guidance from .

NUMARC has been used to help formulate programs which are acceptable to the NRC. Unfortunately, because_ of the complex issues surrounding the GL, clear guidance on an acceptable program was not available prior to this submittal date. The enclosure provides the requested information; however, additional communications with the Staff will be required.

Our program,_ which was begun under NRC Bulletin 85-03, concentrates on ensuring the actuator / valve units are as electrically and mechanically sound as is reasonably achievable. At -this time, it is our-intent to complete -the design basis review and static ~(zero) differential pressure testing, in addition to some differential pressure testing, within five years or three refueling outages, whichever is later. We hope _the enclosed information is helpful in your review. Please contact this office if you have questions.

Sincerely,

+:z-4. 2. .

W. G. Hairston, III GKM/eb Enclosure i c: Georata Power Company Mr. H. C. Nix, General Manager - Nuclear Plant Mr. J. D. Heidt, Manager Engineering and Licensing - Hatch G0-NORMS ll,S. Nuclear Reaulatory Commission. Washinaton. D.C.

Mr. L. P. Crocker, Licensing Project Manager - Hatch U.S. Nuclear Reaulatory Commission. Reaion II Mr. S. D. Ebneter, Regional Administrator Mr. J. E. Menning, Senior Resident Inspector - Hatch

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E ENLLOSVRE L

PLANT HATCH - UNITS 1, 2 ,

NRC DOCKETS'50-321, 50-356' OPERATING LICENSES DPR-57,'NPF-5

, RESPONSE TO GENERIC LETTER 89-10 MOTOR-0PERATED VALVE TESTING AND SURVEILLANCE <

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-Introductiore In response to NRC Bulletin 85-03 and its supplement, Georgia Power Company

-(GPC) developed and implemented a comprehensive _ program for testing MOVs in

'the high. pressure coolant injection (HPCI) and reactor core isolation Leooling- (RCIC) systems. The program was based on a thorough design basis

" review, staticipressure testing, and analytically determined thrust / torque requirements at full flow and pressure. Only limited differential pressure (dP)~ testing was performed.

We -plan to extend the program to include additional safety-related MOVs, and - will-include more dP testing. Also, GPC intends to participate.in the ,.

BWROG committee on MOV testing, as was done in response to Bulletin 85-03.

Committee participation resulted in a consistent BWR design basis review i for the-HPCI and RCIC-systems, and the Staff was able to review and approve the methodology, (

Georgia. Power Company be'lieves an aggressive predictive / preventive-maintenance program is the key element in ensuring that M0V's-will operate- ,

on demand. Meticulous initial set-up utilizing diagnostic- equipment ,

'followed by regularly scheduled preventive maintenance will eliminate the ,

R . vast-. majority of problems which have been experienced throughout the industry involving MOV's. The Hatch program is based on this concept and has-been very successful to date.

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Recommended Actions A. A design basis review will be performed for each MOV covered by Generic Letter 89-10. 'The approach will be similar to that used in Bulletin 85-03, -and we are planning to participate in the BWR0G Committee which has been formed to address.GL 89-10. The design basis review will include as a minimum the- following.

1 L 1. Identification of all safety-related and position-changeable M0V's covered by the generic letter.

2. Determination of the maximum differential pressure (dP) for each MOV.

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& ENCLOSURE (Continued)-

RESPONSE TO GENERIC LETTER 89-10 MOTOR-0PERATED VALVE TESTING AND SURVEILLANCE l 3.. Calculation of ~the minimum required opening and closing thrust L s

and/or torque values for each MOV. .)

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'4. Evaluation of operator capability for-each MOV to determine the maximum: allowable. thrust and/or torque including consideration for 1 4 degraded voltage operation.

The generic letter states that any MOV in a safety-related system that is not blocked from. inadvertent operation must be capable of recovering i from an' inadvertent mispositioning. This is clearly beyond the existingo design basis for the plant. Safety-related M0V's may be requiredto. operate against dP'following mispositioning. Non-safety m M0V's, which are not designed to perform an active safety function (and L .which may not be included in the IST program), could also be undersized I to operate.. against higher dPs than originally designed. This new l 4 requirement' could~ result in the valves, which are. adequately sized to ,

b perform their safety -function, being undersized when considering ,

mispositioning.

) The implications of requiring position-changeable MOV's to be capable of' recovering-from an inadvertent mispositioning are being reviewed.

W L-Determining maximum dPs associated with an operator error scenario will

'be complex and time consuming. For valves which are required to

< operate against a higher dP- when recovering from mispositioning- than '

1 when performing their design basis functions, the potential exists. that p operators may- be undersized. GPC will evaluate the impact of requiring M0V.'s to recover from- inadvertent mispositioning and formulate a position with regard to this aspect of the generic letter as additional ,

• data becomes available. We also understand this is one of the topics t which will be discussed with-NUMARC.

B; A program will be established and will be similar to the existing program established at-Plant Hatch to comply with the requirements of NRC Bulletin 85-03 established procedures for setting torque, torque bypass, and position limit switches. These procedures, in combination with the minimum required thrust values calculated in the design basis review, will be utilized in setting up each M0V. The thermal overloads on most safety-related M0V's at Hatch are jumpered during operation.

For valves with thermal overloads not jumpered, an engineering review will be performed. ,

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ENCLOSURE (Continued)

L RESPONSE TO GENERIC > LETTER 89-10 MOTOR-0PERATED VALVE TESTING AND SURVEILLANCE C. . Motor-operated valves' covered by'.the generic 1etter will be set up-statically utilizing motor-operated valve test equipment. All switches will be set based.upon procedures established in item B. with  :

sufficient margins to ensure operability at maximum differential ,

pressure. We intend to perform selected dP testing to the extent

- practical and as further discussed under item F. An explanation will .

~ be documented in cases- where dP testing cannot practicably be "

,. performed.

D. Plant procedures were developed and/or revised to ensure that correct switch settings are determined and maintained to comply with the requirements. of NRC Bulletin 85-03. These procedures cover diagnostic testing as well:as electrical and mechanical maintenance. Maintenance -i activities involving M0V's covered by the generic letter will be .

controlled to ~ ensure that Maintenance Engineering reviews work

-performed and evaluates the need for testing to verify switch settings.

L Procedures will be revised as necessary based on the results of-activities performed in association with GL 89-10.

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't E. As stated'_in item A, a' design basis review will be performed for each MOV covered by the generic letter. This review will include an ,

evaluation of. operator capability at degraded voltage as well as re-verification-of the adequacy of the M0V's power supply and cables.

Item _

e. of the generic letter states that "no change to - the existing I,

design basis is-intended and r.9ne should be inferred". This appears to conflict with the statement "When determining the maximum dP or flow I for position-changeable M0V's, the fact that the MOV must be able to recover from 'mispositioning should be considered". As stated in l response to item A., the impact of requiring MOV's to recover from-l inadvertent mispositioning will be evaluated, g

F. Explanations and descriptions of actual test methods will be retained for each M0V. As stated in response to Recommendation A. ,' all M0V's 5 covered by the generic letter will be set up statically based on calculated values. The calculations will consider degraded voltage to ensure' that the switch settings selected are adequate to ensure i operability under degraded voltage conditions. No degraded voltage L testing is planned at this time. Georgia Power Company will perform MOV testing at dP conditions to the extent practical. In many cases, this dP will be less than the maximum dP determined from item A. The following paragraphs discuss the issues surrounding dP testing and highlight the fact that the issue is complex and by no means resolved technically.

0002 HL-869 E-3 P

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, 1 K , j g ENCLOSUR[ (Continued)

RESPONSE TO GENERIC LETTER 89-10 1

, MOTOR-0PERATED VALVE TESTING AND SURVEILLANCE 1 L

The generic , letter states'"i_t-is not clear that tests of an MOV at low

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or moderate -pressure differentials 'can ; be directly extrapolated to determine correct. switch settings at design-basis conditions using any-type of diagnostic equipment"' .This- statement implies that ~each valve

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s should be tested at maximum dP which is-neither possible nor practical.

The letter also states, " demonstrating operability in-situ- at

, design-basic conditions is not practical for~ some M0V's". The generic I letter concedes it-is not possible to test all valves at maximum dP but does not provide any guidance as to what would be an acceptd.'a 1 alternative.

The NRC workshops which were held to review the generic letter-have -

' raised ; additional questions . relative to dP testing and acceptable o alternatives'.- The Idaho National Engineering Laboratory (INEL) testing.

was discussed and the results of this testing seem to have caused the l

l, NRC to take a very conservative position with regard to demonstrating valve operability.

.Several issues need to be. considered relative to the INEL- testing, ,

, First, the testing was restricted to two valves operating -under simulated: - pipe break isolation conditions. Data based on test results-

. involving two valves operating at these extreme conditions should not-be- construed as being representative of the typical M0V. Second, the testing and subsequent data evaluation tock many months to perform

. under essentially ideal conditions and did not resolve the issue. For e an individual utility to undertake a research and development program of sufficient magnitude to address all- of . the outstanding questions relative to valve thrust . requirements would require a tremendous commitment of both time and money. An operating nuclear power' plant is not the proper environment for conducting a-program of this type.

EPRI is currently conducting a program to develop improved methodology to calculate and predict valve thrust requirements. As many as twenty parameters have been identified which may have some effect on 3 performance. Until has a clear

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valve / actuator the industry understanding of which parameters are significant and how they affect valve performance, an extensive program of in-situ dynamic testing '

would be premature. It is virtually impossible to simulate all design basis conditions when performing in-situ testing and without an approved methodology for extrapolating test conditions to design basis conditions the results are of limited value.

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l ENCLOSURE (Continued)

L RESPONSE TO GENERIC LETTER 89 i'

. MOTOR-OPERATED VALVE TESTING AND SVRVEILLANCE GPC will continue. to track and participate in - industry efforts addressing 'MOV ' issues. As additional data becomes available, it will-be factored into the Plant Hatch MOV program to ensure that the program i remains current and addresses the relevant issues, j n - G. -This item requires no response.

H. Each MOV failure and corrective action taken will be documented and .

' analyzed. Documentation will be retained and failures will be reported in accordance with existing requirements. Motor-operated valve. performance data will be periodically evaluated to establish trends of MOV operation. l l

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