ML20011E264
| ML20011E264 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 02/01/1990 |
| From: | Frizzle C Maine Yankee |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CDF-90-18, GL-89-10, IEB-85-003, IEB-85-3, MN-90-15, NUDOCS 9002130022 | |
| Download: ML20011E264 (10) | |
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i February 1, 1990 MN-90-15 CDF-90-18 i
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f UNITED STATES NUCLEAR REGULATORY COMMISSION
. Attention: Document Control Desk Washington, DC 20555
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) USNRC IE Bulletin No. 85-03: Motor-Operated Valve Common Mode
-l Failures During Plant Transients Due to improper Switch Settings, dated November 15, 1985 (c) MYAPCo Letter to USNRC dated October 2, 1987 (MN-87-109) l (d) MYAPCo Letter to USNRC dated December 15, 1987 (MN-87-137)
(e) USNRC Bulletin No. 85-03, Supplement I dated April 27, 1988 (f) MYAPCo Letter to USNRC dated April 12, 1989 (MN-89-55) lated (g) MYAPCo Letter to USNRC dated June.12, 1989:
Safety-Re Motor-0perated Valve Testing and Surveillance (Generic letter 1
No. 89-10)
(h) USNRC Letter to MYAPCo dated June 28, 1989:
Safety-Related Motor-Operated Valve Testing and Surveillance (Generic Letter i
No. 89-10)
(1) 'USNRC Letter to MYAPCo dated May ll,1988
Subject:
Maine Yankee Motor-0perated Valve Testing and Surveillance - Response to Generic Letter No. 89-10 Gentlemen:
L The NRC issued Bulletin No. 85-03, Reference (b), requesting licensees develop Motor Operated Valve (MOV) switch setting programs to ensure the reliability of safety-class MOVs under design basis conditions.
In response to the Action Items of Bulletin No. 85-03, Maine Yankee identified the valves covered by the Bulletin, established the design basis for those valves, developed a switch setting )rogram, stroke tested the valves to verify their operability, and establisied procedures for the development and maintenance of switch settings.
Maine Yankee responded to Bulletin 85-03 with References (c) and (d), and later supplemented that response with References (f) and (g).
The NRC reviewed our activities associated with Bulletin No. 85-03 during an inspection at Maine Yankee in March of 1988. During that inspection, the NRC found our M0V program addressed the significant aspects of the Bulletin, and that our safety class valves covered by the program can perform their safety function during normal and abnormal n
operation, Reference (1).
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UNITED STATES NUCLEAR REGULATORY COMMISSION MN-90-15 Attention: Document Control Desk Page two r
NRC Generic Letter 89-10, Reference (h), has expanded the scope of valves.
covered by Bulletin 85-03 to include additional safety class MOVs, and position changeable MOVs. Maine Yankee's response to the action items of Generic Letter 89-10 is attached.
In general, Maine Yankee plans to build on our already acceptable MOV program to incorporate the additional measures of Generic Letter No. 89-10.
We trust this information is satisfactory.
Please contact us should you have any questions.
Very truly yours, Charles D. Frizzle President CDF:SJJ Attachment c:
Mr. William T. Russell Mr. Cornelius F. Holden Mr. Eric J. Leeds STATE OF MAINE Then personally appeared before me, Charles D. Frizzle, who being duly sworn did state that he is President of Maine Yankee Atomic Power Company, that he is duly authorized to execute and file the foregoing response in the name and on behalf of Maine Yankee Atomic Power Company, and that the statements therein are true to the best of his knowledge and belief.
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Attachment A Recommended Actions from NRC Generic letter 89-10 1
By this latter NRC extends the scope of the program outlined in Bulletin 85-03 and Supplement 1 of Bulletin 85-03 to include all safety-related MOVs as well as all position-changeable MOVs as defined below. The licensee's program should provide for the testing, inspection, and maintenance of MOVs so as to provide the necessary assurance that they will function when subjected to the design-basis conditions that are to be considered during both normal operation and abnormal events within the design basis of the plant. Although this program should address safety-related MOVs and position-changeable MOVs as a minimum, NRC envisions that, as part of a good maintenance program, other MOVs in the balance of plant should be considered for inclusion in the program, commensurate with the licensee's assessment of their importance to safety.
Any MOV in a safety-related system that is not blocked from inadvertent operation
- from either the control room, the motor control center, or the valve itself should be considered capable of being mispositioned (referred to as position-changeable MOVs) and should be included in the program. When determining the maximum differential pressure or flow for position-changeable MOVs, the fact that the MOV must be able to recover from mispositioning should be considered.
The program to respond to this letter should address items a. through h. below, items a., b., and c. and the first paragraph of d. are repeated, with limited changes, from Bulletin 85-03 or from Supplement 1 of that bulletin. The second paragraph of item d. and items e.,
f., g., and h. provide additional clarification and guidance.
NRC Recommended Action 1 Review and document the design basis for the operation of each M0V. 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.
Maine Yankee Response Generic Letter 89-10 expands the scope of valves in our Bulletin No. 85-03 MOV program to include additional safety class valves, position changeable valves and some support system valves, in response to this action item, Maine Yankee plans the folicwing:
1.
Identify the valves subject to Generic Letter 89-10.
We plan to complete this effort by October 1,1990.
i 2.
Document the design basis by identification of the intended safety function of the MOV during a design basis accident condition (e.g. those accidents described in Chapter 14 of Maine Yankee's FSAR).
Documentation of design basis is scheduled for completion by December 31, 1990.
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Identify those valves from above to be added to the MOV program.
This shall be done on a case-by-case basis considering each valve's f
capabilities and intended safety function.
This will be completed by startup from the 1991 refueling shutdown.
i-We expect that certain valves covered by Generic Letter No. 89-10 (for instance position changeable MOVs) were not designed or constructed to operate against accident temperatures and pressures.
NRC Recommended Action b Using the results from item a., establish the correct switch settings. This should include establishing a program to review and revise, as necessary, the methods for selecting and setting all switches (i.e., torque, torque bypass, 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 MOVs.
Maine Yankee Resoonse Maine Yankee developed its switch setting program in 1987 and submitted it to the NRC by letter dated December 15, 1987 (MN-87-137).
This program was subsequently reviewed and found acceptable by the NRC during an audit of our motor operated valve maintenance program (NRC Inspection Report No. 88-04). Two open items from that report are being addressed. We plan no further changes to our switch setting program as a result of Generic Letter 89-10. This program shall be used for establishing the correct switch settings for those valves added in response to item a.
NRC Recommended Action c Individual MOV switch settings should be changed, as appropriate, to those l
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 MOVs at design-basis conditions is not recommended where such testing is precluded by the existing plant configuration.
An explanation should be documented for any i
l 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.
Note: This letter is not intended to establish a recommendation for valve testing i
for the condition simulating a break in the line containing the M0V.
However, a break in the line should be considered in the analyses described 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 cannot be performed.
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Maine Yankee Response As part of existing post maintenance functional testing requirements, Maine Yankee's Discrepancy Reporting / Repair Order (DR/RO) procedures require testing or evaluation to determine functional acceptability of the component.
Procedures require that this functional testing include stroke testing motor operated valves, providing plant operating conditions permit.
Also, as discussed in response to item b above, Maine Yankee has an established t
MOV switch setting program and has in place procedures for adjusting switch setpoints..We intend to verify switch settings by tests.
Maine Yankee believes there are circumstances in which design basis differential pressure or flow tests are not practicable, i.e., cannot or should not be performed. The bulletin addresses two cases:
line breaks and where such testing is precluded by the existing plant configuration. Other cases would be where design basis testing would impose one of a few allowed severe duty cycles on a valve or its associated piping, supports, or other associated system components or where there is a family of valves in which design basis testing of one or several valves, in conjunction with other measures applied to all valves in the family can demonstrate the operability of all valves in the family. We intend to condu:t design basis tests on MOVs where practicable and necessary, and to provide written explanation for all cases where design basis testing cannot practicably be performed, including a description of the alternative testing to be used to verify proper switch settings.
NRC Recommended Action _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 M0V performance to ensure the switch settings are correct.
This is particularly important if the torque or torque bypass switch setting have been significantly raised above that required.
It may 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 setting should be verified in accordance with the program schedule (see item j). The AStiE Code Section XI stroke-timing test required by 10 CFR Part 50 is not oriented toward verification of switch settings. Therefore, additi d measures should be taken to adequately verify that the switch settings ensure tiOV operability.
The switch settings need not be verified each time the ASME Code stroke-timing test is performed.
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r Maine Yankee Resoonse t
4.
Maine Yankee currently has procedures for determining and monitoring correct switch settings throughout the life of the plant. Revisions to these.
j procedures will be necessary to reflect modified switch settings, and to.
provide the additional post maintenance testing requirements we consider i
necessary as a result of Generic Letter 89-10. These revisions will be completed within 5 years of the Generic Letter.
5.
Our MOV prograin will be developed to require consideration of programmatic post maintenance testing, periodic tracking of key parameters, and >eriodic baseline testing (initially every 5 years or 3 refuelin outages, w1ichever is longer) to maintain correct MOV switch settings.
(A so see response to Actions i and j.)
Changes to our MOV program will be completed within 5 years of the Generic Letter.
NRC Recommended Action e Regarding item a., no change to the existing plant design basis is intended and none should be inferred.
The design-basis review should not be restricted to a 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 M0V 3erformance of design-basis degraded voltage, including the capability of tie MOV's power supply and cables to provide the high initial current needed for the operation of the M0V.
Maine Yankee Response Maine Yankee does not plan to modify the original design basis of NOVs as a result of our MOV program. Maine Yankee recognized the importance of original design and installation criteria when developing our motor operated valve program. Our program currently considers the effects of degraded voltage conditions on MOV performance.
We believe our current MOV program adequately addresses this recommended action.
NRC Recommended Action f 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 MOV.
It is also recognized that it may be impracticable to perform in situ M0V testing I
at design-basis degraded voltage conditions. However, the switch settings 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 conditions.
If the licensee failed to consider degraded voltage, power supply, or cable adequacy for MOVs in systems covered by Bulletin 85-03, the design review and established switch settings for those MOVs should be reevaluated. Alternatives to testing a particular MOV in situ at design-basis pressure or flow, where such testing cannot CDF9018.LTR 4
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'a' practicably be performed, cou ld include a comparison with appropriate design-basis test results on other MOVs, either in situ or prototype.
If such test information is not availtble, analytical methods and extrapolations to design-basis conditions, based en the best data available, may be used until test data at design-basis conditions become available to verify operability of the M0V.
If this two-stage approach is 4110wed, it should be accomplished within the schedule outlined in item 1. and would allow for MOV testing and surveillance to proceed without excessive delay.
Testing of MOVs 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.
Maine Yankee Resportig Maine Yankee maintains documentation of our MOV tests conducted and results obtained.
As discussed in response to item e above, degraded voltage conditions, and design-basis flow and differential pressure are currently included in our MOV design basis and/or switch setting programs.
We believe our current program utilizes an optimal combination of plant test, evaluation and industry experience. This program has been in place for approximately three years during which time we have tested twenty one motor operated valves. As described in response to item a, with Generic Letter 89-10 we are now expanding the program to include additional safety class, position changeable and support system MOVs. We plan to use the same philosophy when deciding the degree of testing to be applied to the additional MOVs.
6.
The revised program will require (on a case-by-case basis) repeat testing of M0Vs at design basis conditions whenever the MOV is modified (to the extent the existing test results are not representative of the M0V in its modified configuration).
In some cases, modification of the valve operator can also be verified correct by performing a diagnostic baseline of the modified operator and applicable engineering analysis. Also, any replacement or overhaul cf the valve operator can also be verified by performing a diagnostic base line of the new operator and applicable engineering analysis.
This revised program will be completed within 5 years of the Generic Letter L
per item d above.
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NRC Recommended Action a L
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 improper switch settings) is included in Attachment A to this letter for licensee review and information.
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' - Maine Yankee Response This item does not request action.
FJC Reouested Action h Each MOV failure and corrective action taken, including repair, alteration,
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analysis, test, and surveillance, should be analyzed or justified and documented.
The documentation should include the results and history of each as-found i
deteriorated condition, malfunction, test, inspection, analysis, repair, or alteration. All documentation should be retained and reported in accordance with plant requirements.
It is suggested that these MOV data be periodically examined (at least every 2 l
years or after each refueling outage after program implementation) as part of a j
monitoring and feedback effort to establish trends of MOV operability.
These trends could provide the basis for a licensee revision of the testing frequency established to periodically verify the adequacy of MOV switch settings (see items
- d. and j.).
For this monitoring and feedback effort, a well-structured and component-oriented system (e.g., the Nuclear Plant Reliability Data System
[NPRDS]) is needed to capture, track, and share the equipment history data.
The NRC encourages the use of the industry-wide NPRDS, appropriately modified, for this purpose in view of the multiple uses for these data.
s Maine Yankee Response In general we believe Maine Yankee's various programs and procedures provide documentation of the types mentioned, and the documentation is retained and reported in accordance with Maine Yankee procedures. At Maine Yankee the Discrepancy Report and Repair Order (DR/RO) system identifies discrepancies and provides a vehicle for recording and. storing corrective actions taken.
This includes repair and component substitution alterations. Other alterations are performed using Maine Yankee's design change process. Analysis, test, or surveillance activities, when conducted, are generally recorded as part of their test or surveillance procedure or in EDCR packages.
Root cause evaluations are generally considered when the discrepancy is repetitive in nature.
Maine Yankee procedures do not require as found conditions to be recorded on routine maintenance or preventive maintenance activities.
Corrective maintenance (DR/R0) may not note any as found conditions beyond the discrepancy for which corrective action is being taken.
If it is planned or seems prudent, preventive maintenance may be performed on an M0V prior to any diagnostic testing.
"As E
found" conditions for MOVs may not reflect "each as-found deteriorated condition".
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l NRC Reauested Action i Each licensee with an operating license (0L) should complete all design-basis reviews, analyses, verifications, tests, and inspections that have been instituted in order to comply with items a. through h within 5 years or three refueling outages of the date of this letter, whichever is later.
Each licensee with a construction permit (CP) should complete these actions within 5 years of the date of this letter or before the OL is issued, whichever is later.
For plants with an i
OL, the documentation described in items 1. and 2. below should be available within 1 year or one refueling outage of the date of this letter, whichever is later.
For plants with a CP, the documentation outlined in items 1. and 2. should be available within one year of the date of this letter or before the OL is issued, whichever is later. The documents should include:
1.
The description and schedule for the design-basis review recommended in item
- a. (including guidance from item e.) for all safety-related MOVs and position-changeable MOVs as described, and 2.
The program description and schedule for items b. through h. for all safety-related M0vs and position-changeable MOVs.
Maine Yankee Response 7.
Maine Yankee's design-basis review is ongoing.
We expect this review will be completed within five years of the date of the letter.
Maine Yankee has developed a program description as a result of Bulletin 85-03.
This description is currently undergoing review and approval, and is available on site.
I NRC Recommended Action.i The program for the verification of the procedures outlined in item d., as well as other tests or surveillance that the owner may choose to use to identify potential MOV degradations or misadjustments, such as those described in Attachment A, should be-implemented after maintenance or adjustment (including packing adjustment) of each M0V, and periodically thereafter. The surveillance interval should be based on the licensee's evaluation of the safety importance of each MOV as well as its maintenance and performance history.
The surveillance interval should not exceed 5 years or three refueling outages, whichever is longer, unless a longer interval can be justified (see item h.) for any particular M0V.
Maine Yankee Response Maine Yankee's planned program to maintain correct switch settings for the life of the plant as outlined in response to Action Item d is, we believe, also completely consistent with this recommended action. We note, however, that since initiating a MOV program in 1984 and diagnostic testing in 1987, Maine Yankee has already accumulated significant M0V experience. This experience, when combined with additional monitoring and trending of M0V performance, n.ay justify expansion of surveillance intervals early in our MOV program.
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. NRC' Recommended Action k In recognition of the necessity for preplanning, refueling outages that-start l'
. within 6 months of the date of this letter need not be counted in establishing the m
schedule to meet the time limits recommended in items 1. and J.
Maine Yankee Response
-- This item does not apply to Maine Yankee.
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