ML20005E353

Forwards Response to Generic Ltr 89-10 Re safety-related motor-operated Valve Testing & Surveillance.Util Intends to Extend Existing IE Bulletin 85-003 Program to Cover motor- Operated Valves within Scope of Ltr

ML20005E353
Person / Time
Site:	Vermont Yankee
Issue date:	12/28/1989
From:	Murphy W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BVY-89-116, GL-89-10, IEB-85-003, IEB-85-3, NUDOCS 9001050100
Download: ML20005E353 (8)

Text

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x.- 6 TVbRMONT YANKEE

NUCLEAR POWER CORPORATION BVY 89-116 3 Ferry Road, Brattleboro, VT 05301 7002 ,,

) ENGINEERING OFFICE

d. 600 M AIN $TREET BoLTON. V A 0174D

($DB) 779 0711 December 28, 1989

.U,,S. Nuclear ~ Regulatory Commission i, Washington, D.C. 20555 '

! Attention: Document Control Desk L l C

References:

a) License No. OPR-28 (Docket No. 50-271) j b) Letter, USNRC to All Licensees of Operating Nuclear Power Plants and Holders of Construction Permits for Nuclear Power Plants, NVY 89-144, Generic Letter 89-10, dated 6/28,'89

! c) Letter, VYNPC to USNRC, BVY 89-050, dated 6/8/89

, d) Letter,'USNRC to All Holders of Nuclear Power Reactor L" Operating Licenses (OLs) or Construction Permits (cps) for

. Action, NVY 85-250 (IEB 85-03) dated 11/15/85 j

Subject:

Response to Generic Letter No. 89-20: Safety-Related Motor-Operated Valve Testing and Surveillance In November 1985, the NRC issued Bulletin 85-03 (Reference d)) to all  !

licensees requesting that they develop and implement a program to ensure that switch settings on certain safety-related motor-operated valves are selected, set, and maintained correctly to accommodate the maximum Differential Pressures (DPs) expected in these valves during both normal and abnormal events within the design basis. ,

i In response, Vermont Yankee developed the required program and submitted a report on the results of our review and demonstration of the operational readi-ness of each motor-operated valve in the High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) system (Reference c)).

By letter dated June 28, 1989 (Reference b)], the Office of Nuclear Reactor -

. Regulation requested licensees to extend the scope of the program outlined in NRC Bulletin 85-03 (Reference d)) to include all safety related motor operated valves. In accordance with the reporting requirements set forth in the subject Generic Letter, Vermont Yr.nkee herewith provides our response as Attachment I to this letter. The attachment responds to each of the Generic Letter recommen-1; dations. As described in the attachment, Vermont Yankee intends to extend the l ' existing IEB 85-03 program to cover all MOV's Vermont Yankee determines to be I

within the scope of Generic Letter 89-10.

9001050100 891228 i ADOCK 05000271 l

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. c VEZMONT YANKEE NUCLEAR POWER CORPORATION U.S. Nuclear Regulatory Commission December 28, 1989  !

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We trust that the information provided above and in the attachment to this letter is responsive to the requirements of the subject Generic Letter; however,

. should you have any questions or require additional information, please contact '

us.

Very truly yours,

(.. ,

VERMONT YANKEE NUCLEAR POWER CORPORATION dew-- W ~

Warren P. urph Vice President an ,

Manager of Operat n

/dm cc USNRC Regional Administrator, Region I USNRC Resident Inspector, VYNPS STATE OF VERMONT)

)ss WINDHAM COUNTY )

Then personally appeared before me, Warren P. Murphy, who, being duly sworn, did state that he is Vice President and Manager of Operations of Vermont Yankee Nuclear Power Corporation, that he is duly authorized to execute and file the foregoing document in the name and on the behalf of Vermont Yankee Nuclear Power Corporation and that the statements therein are true to the best of his knowledge and belief.

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I ATTACHMENT 1 VERMONT YANKEE RESPONSE TO L GENERIC LETTER 89-10 RECOMMENDED ACTIONS GENERIC LETTER ITEM "a" L

Review and document the design basis for the operation of each MOV. This documentation should include the maximum differential pressure expected.during

'; both the opening and closing of the MOV for both normal operations and abnormal  !

events, to the extent that these MOV operations and events are included in the existing approved design basis.

Response

The Vermont Yankee program for reviewing Motor Operated Valves (MOV) sub-ject to IEB 85-03 requirements considered all aspects of valve operation to i determine the highest maximum differential pressure (DP) each MOV would be required to operate against (including mispositioning).

Generic Letter 89-10, item "e", expands this design review to include other '

design basis information that could potentially have a significant influence on the amount of thrust required to operate a valve at a particular differential pressure.

INEL testing, noted within the Generic Letter, concludes that high flow is an additional contributor to the DP thrust requirement. Other factors such as 3 fluid temperature and valve position may also increase thrust requirements.

Even though MOV testing to date does not quantify these additional factors, future-testing may. Therefore, Vermont Yankee believes that establishing complete design basis criteria for each valve, under both normal and abnormal plant conditions, where that valve is or could be operated, provides a good starting point for determin'.1g MOV switch settings.

Vermont Yankee will establish the following normal and abnormal (open and closed) design basis criteria for each MOV determined to be within the scope of ,

Generic Letter 89-10.

1. Differential Pressure

2. Line Pressure

3. Fluid Flow

4. Fluid Temperature

5. Valve Orientation

6. Design Basis Minimum Voltage Available torque (thrust), considering minimum voltage and available L current, will subsequently be reviewed against the required torque (thrust)

, derived from the design conditions the valve must operate against.

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Attachment 1

, Page 2 GENERIC LETTER ITEM "b" L Using the results from Item a., establish the correct switch settings, f' This should include establishing a program to review and revise, as necessary, l' the methods for selecting and setting all switches (i.e., torque, torque bypass, t position limit, overload) for each valve operation (opening and closing). One purpose of this letter is to ensure that a program exists for selecting and setting valve operator switches to ensure high reliability of safety-related

i. MOV's.

r nesponse The Vermont Yankee final submittal [ Reference c)] for IEB 85-03 provides the Vermont Yankee methodology for selecting, setting and maintaining Motor Operator switches.

Vermont Yankee's program for selecting and setting switches to comply with Generic Letter item "b" will be a continuation of the program established for the valves within the scope of IEB 85-03.

GENERIC LETTER ITEM "c" Individual MOV switch settings should be changed, as appropriate, to those established in response to item b. Whether the switch settings are changed or not, the MOV should be demonstrated to be operable by testing it at the design-basis differential pressure and/or flow determined in response to item a.

Testing MOV's at design-basis conditions is not recommended where such testing

-is' precluded by the existing plant configuration. An explanation should be documented for any cases where testing with the design-basis differential pressure or flow cannot practicably be performed. This explanation should include a description of the alternatives to design-basis differential pressure testing or flow testing that will be used to verify the correct settings, p

NOTE: This letter is not intended to establish a recommendation for valve testing for the condition simulating a break in the line containing the MOV.

However, a break in the line should be considered in the analyses described I in items a., b., and c. if MOV operation is relied on in the design basis.

Each MOV should be stroke tested to verify that the MOV is operable at no-pressure or no-flow conditions even if testing with differential pressure or flow canot be performed.

Response

Differential pressure testing was performed to satisfy IEB 85-03 action item "c". This testing was specifically aimed at achieving a differential pressure reasonably close to that calculated to be the highest maximum differen- ,

tial pressure the valve could be subjected to. Few valves were available to l choose from that met this single requirement consistent with safe operation of

c. .

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Attachment 1 Page 3 )

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i the plant. The Generic Letter adds additional requirements (flow, temperature, )

etc.) to differential pressure, further reducing the valves to select from.  !

Safe in-plant testing at design basis conditions has shown to be severely  ;

limited at Vermont Yankee. Since no guidance exists for establishing acceptable '

parameter limits, no additional differential pressure testing is contemplated by Vermont Yankee. l The intent of items "c" and "f" for verifying that switch settings are j appropriate is fulfilled programmatically. The Vermont Yankee response

[ Reference c)) to IEB 85-03 contains DP testing results, demonstrating that the l methods used by Vermont Yankee for selecting appropriate torque switch (thrust) l

-setpoints is conservative.  ;

J Vermont Yankee uses a commercially available statistical database con-taining industry DP test results from valves other than "Walworth" valves. Most of the safety related valves at Vermont Yankee were manufactured by "Walworth". j Differential pressure testing performed by the USNRC (INEL and in Germany) indi-cates that "Walworth" valves require less thrust for a particular DP than other valves. Since Vermont Yankee uses a statistical database composed of few if 1 any "Walworth" valves, the resulting thrusts are inherently conservative when applied to Vermont Yankee's "Walworth" valves.

For non "Walworth" valves, Vermont Yankee's conservative application of the  ;

statistical database containing industry differential pressure test results pro-vides adequate assurance of MOV operability.

For MOV's determined to ba within the scope of Generic Letter 89-10, Vermont Yankee intends to extend the use of diagnostic equipment for setting or verifying switch settings during static testing.

GENERIC LETTER ITEM "d" Prepare or revise procedures to ensure that correct switch settings are determined and maintained throughout the life of the plant. These procedures should include provisions to monitor MOV performance to ensure the switch set-tings are correct. This is particularly important if the torque or torque bypass switch setting has been significantly raised above that required.

It eay become necessary to adjust MOV switch settings because of the '

effects of wear or aging. Therefore, it is insufficient to merely verify that the switch settings are unchanged from previously established values. The switch settings should be verified in accordance with the program schedule (see item J.). The ASME Code Section XI stroke-timing test required by 10CFR Part 50 is not or_iented toward verification of switch settings. Therefore, additional measures should be taken to adequately verify that the switch settings ensure MOV operability. The switch settings need not be verified each time the ASME Code stroke-timing test is performed.

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Response

Procedures and design drawings are estd for valves within the Vermont Yankee IEB 85-03 program [ Reference c)) to ensure switch settings are determined and maintained throughout the life of the plant. Vermont Yankee's conservative l method of determining switch settings adequately accounts for the effects of- i e normal wear and aging. These controls will be applied to valves determined to

!- be within the scope of Generic Letter 89-10.

Since the scope of'the Vermont Yankee MOV program will be significantly increased from the IEB 86-03 program, an MOV maintenance guideline will be deve+ ,

loped to direct work to applicable plant procedures and aid good maintenance  !

practices. Even though Vermont Yankee's maintenance personnel are highly

• experienced, this-will help ensure appropriate guidance and direction for con-sistent and complete application of testing, surveillance, repair and other i

maintenance activities.

GENERIC LETTER ITEM "e" Regarding item a., no change to the existing plant design besits is intended and none should be inferred. The design-basis review should not be restricted l to'n determination of estimated maximum design-basis differential pressure, but should include an examination of the pertinent design and installation criteria that were used in choosing the particular MOV. For example, the review should include the effects on MOV performance of design-basis degraded voltage, including the capability of the MOV's power supply and cables to provide the high initial current needed for the operation of the MOV.

Response -

L l The response to this item is included in the response to item "a".

t l 9ENERIC LETTER ITEM "f" l

Documentation of explanations and the description of actual test methods used for accomplishing item c. should be retained as part of the required records for the M0V.

~

It is also recognized that it may be impracticable to perform in situ MOV l- testing at design-basis degraded voltage conditions. However, the switch set-L tings established in response to item b, should at least be established to

account for the situation where the valves may be called on to operate at design-basis differential pressure, or flow, and under degraded voltage con-ditions. If the licensee failed to consider degraded voltage, power supply, or cable adequacy for MOV's in systems covered by Bulletin 85-03, the design review and established switch settings for those MOV's should be re-evaluated.

J V. .

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, Page 5 Alternatives to testing a particular MOV in situ at design-basis pressure or flow, where such testing cannot practicably be performed, could include a comparison with apropriate design-basis test results on other MOV's, either in situ or protetype. If such test information is not available, ana5ytical methods and extrapolations to design-basis conditions, based on the best data available, may be used until test data at design-basis conditions becor.e available to verify operability of the MOV. If this two-stage approach is followed, it should be accomplished within the schedule outlined in item 1. and would allow for NOV testing and surveillance to proceed without excessive delay.

Testing of the MOV's at design-basis conditions need not be repeated unless the MOV is replaced, modified, or overhauled to the extent that the licensee considers that the existing test results are not representative of the MOV in its modified configuration.

Response

A description of Vermont Yankee's method to verify operability is contained in the response to item "c"; based on this, the two-stage approach is not con-sidered applicable to Vermont Yankee at this time.

The Vermont Yankee program does not utilize a "two stage" alternative to in situ differential pressure testing. Rather, for the expanded scope of MOV's under Generic Letter 89-10, Vermont Yankee proposes to utilize the existing

. methodology for setting MOV switches that has been successfully implemented for IEB 85-03 val Ws and was outlined in Reference c). Vermont Yankee believes this method meets the intent of the Generic tetter based upon the conservative manner in which the maximum differential pressures are calculated, the conservatively applied statistical database thrusts and our differential pressure testing. We will, however, continue.to monitor industry and regulatory testing to ensure that the Vermont Yankee method of determining setpoints remains conservative.

Insufficient information exists today to determine if acceptable test data, from other valvus or prototypical valves, can be gathered or completed, analyzed and incorporated into the Vermont Yankee scope of valves within the 5 year sche-dule required oy item "f". Further, without sufficient guidance outlining the acceptability of data obtained by alternate methods, Vermont Yankee cannot esti- f mate or provide an alternative schedule, i

G_ENERIC LETTER ITEM "a"  !

A number of deficiencies, misadjustments, and degraded conditions were discovered by licensees, either as a result of their efforts to comply with (

Bulletin 85-03 or from other experiences A list of these conditions (including e

imrroper switch settings) is includ?d in Attachment A to this letter for licen- l l

see review and information. I

Response

i No response required by Vermont Yankee. l l

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Attacnment 1 Page 6 OENERIC LETTER ITEM h" Each MOV_ failure and corrective action taken, including repair, alteration, taa!ysis, test, and surveillance, should be analyzed or justified and docu-mented. The documentation should include the results and history of eech as-found deteriorated condition, malfunction, test, inspection, analysis, repair, h or alteration. All documentation should be retained and reported in accordance  !

u*.th-plaat requirements.

It is suggested that these MOV data be periodically examined (at least every 2 years or-after eacF refueling outage after program implementation) as  !

part of a monitoring and feeaback effort to establish trends of MOV operability.

These trends could provide the basis for a licensee revision of the testing fre-quency established to periodically verify the adequacy of MOV switch settings i (see items d. and J.). For this monitoring and feedback effort, a well-  ;

structured end component-oriented system [e.g., the Nuclear Plant Reliability  ;

Data System (NPROS)]'is needed to capture, track, and share the equipment history = 1 data. The NRC. encourages the use of the industry-wide, appropriately modified, l for this purpose in view of the multiple uses for these data. '

-Response Vermont Yankee reviews individual MOV failures when determining the appli-

-cable repair, corrective action, etc. Plant procedures an sently exist for the retention of documentation and the review of failures for reportability.

F r the current IEB 85-03 program, Vermont Yankee reviews applicable data on those values ~that are worked on as part of the surveillance interval or after maintenance or adjustments. This review will be extended to MOV's determined to be within the scope of Generic Letter 89-10.

GENERIC LETTER ITEM "1" Each licensee shall advise the NRC in writing, within 6 months of the date of this letter, that the above schedule and recommendations will be met. For any date that cannot be met, the licensee shall advise the NRC of a revised sche-dule and provide a technical justification in writing. For any recommendation that_it cannot meet or proposes not to meet, the licensee shall inform the NRC and provide a technical justification, including any proposed alternative action, in writing.

Response

The proposed schedele outlined within item "i" can be met with the excep- ,

tion of the two ;;rae approach delineated by item "f" as an alternative to in situ differential pressure testing.

The Vermont Yankee response to Item "f" provides an explanation of the program to be used as an alternative to in situ differential pressure testing and the two stage approach.

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