ML20137B907
| ML20137B907 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 03/14/1997 |
| From: | Terry C TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-96-05, GL-96-5, TXX-97055, NUDOCS 9703240100 | |
| Download: ML20137B907 (8) | |
Text
a Nmmer Log # TXX-97055
""" =
File # 10035 L
2 Ref. # 10CFR50.54(f)
GL 96-05 1UELECTRIC' March 14, 1997 C. Lance Terry Gmur Mce Perndent U. S. Nuclear Regulatory Commission Attn.:
Document Control Desk Washington, D.C.
20555-0001
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NOS. 50-445 AND 50-446 UNITS 1 AND 2 RESPONSE TO GENERIC LETTER 96-05, " PERIODIC VERIFICATION OF DESIGN-BASIS CAPABILITY OF SAFETY-RELATED MOTOR-0PERATED VALVES" REF:
1, TV Electric letter logged TXX-96503 from Mr. C. Lance Terry, to NRC dated November 15, 1996 2.
TU Electric letter logged TXX-97068 from Mr. C. Lance Terry, to NRC dated March 14, 1997 3.
TV Electric letter logged TXX-95260 from Mr. C. Lance Terry to NRC dated November 27, 1995 4.
TU Electric letter logged TXX-96371 from Mr. C. Lance Terry to NRC dated June 3, 1996 On September 18, 1996, the NRC issued Generic Letter (GL) 96-05, " Periodic Verification of Design-Basis Capability of Safety-Related Motor-0perated Valves."
Pursuant to Section 182a of the Atomic Energy Act of.1954, as amended, and 10 CFR 50.54(f). this letter provides TU Electric's response to Required Response Item 2 in the subject generic letter.
The response to Item 1 was submitted via reference 1.
1 Additionally, via this letter TU Electric is amending the time frame stated in Reference 1 for implementation of GL 96-05 recommendations from:
the sixth refueling outage for CPSES Unit 1 and the third refucling outage fer CPSES Unit 2, to: the seventh refueling outage for CPSES Unit 1 and the fourth refueling outage for CPSES Unit 2.
This extension is required to enable development of the MOV periodic verification program described below.
Because of the extensive nature of the current GL 89-10 program (as described in Section 1.0 below). TV Electric considers this extension is acceptable.
Section 1.0 describes features of the present program.
9703240100 970314 PDR ADOCK 05000445.
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P. O. Box 1002 Glen Rose Texas 76043 l
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Page 2 of 8 BRC GL 96-05 Reauested Actions:
Each addressee of this generic letter is requested to establish a program, or to ensure the effectiveness of its current program, to verify on a periodic basis that i
safety-related Motor Operated Valves (MOVs) continue to be i
capable of performing their safety functions within the current licensing bases of the facility.
The program should ensure that changes in required performance resulting from degradation (such as those caused by age) can be properly 1dentified and accounted for. Addressees that have developed periodic verification programs in response to GL 89-10 should i
review those programs to determine whether any changes are 1.
appropriate in light of the information in this generic l
letter.
NRC GL 96-05 Reauired Resoonse:
All addressees are required to submit the following written response to this generic letter:
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1.
Within 60 days from the date of this generic letter, a written response indicating whether or not the addressee 2
will implement the action (s) requested herein.
If the addressee intends to implement the requested action (s),
i the addressee shall submit a schedule for completing implementation.
If an addressee chooses not to i
imalement the requested action (s), the addressee shall l
suamit a description of any proposed alternative course of action, the schedule for completing the alternative course of action (if applicable), and the safety basis i
for determining the acceptability of the planned alternative course of action.
i 2.
Within 180 days from the date of this generic letter, or l
upon notification to NRC of completion of GL 89-10 l
2 (whichever is later), the addressee shall submit a written summary description of its MOV periodic verification program established in accordance with the 4
i Requested Actions paragraph or the alternative course of 1
action established by the addressee in response to item 1 above.
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I TXX'97055 Page 3 of 8 TU Electric Resoonse:
Item 1:
TU Electric intends to implement the actions requested in GL 96-05. The program will be implemented during the seventh refueling outage for CPSES Unit 1 and the fourth refueling outage for CPSES Unit 2.
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i Item 2 i
i A summary description of the MOV periodic verification program established l
in accordance with the Requested Actions is as follows:
MOV Periodic Verification Proaram k
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1.0 Backaround NRC Generic Letter (GL) 89-10 recommended that each nuclear power i
plant establish a program to demonstrate that safety-related motor-
[
operated valves (MOVs) are capable of performing their design basis i
j functions.
In response CPSES developed a program which included (1) analysis of MOV design basis conditions and performance i
requirements. (2) testing to determine and confirm correct MOV operation and switch settings, including margins for performance degradations, and (3) improved maintenance, periodic diagnostic testing, and performance monitoring of MOVs to ensure that MOV a
l operability is maintained throughout the life of the plant.
I 4-Although GL 89-10 included recommendations for long term periodic verification of MOV performance. GL 96-05 provides current NRC guidance." It is TV Electric's understanding that GL 96-05 i
supersedes GL 89-10 and its supplements with regard to MOV periodic verification.
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The CPSES M0V periodic verification program addresses MOV periodic j
testing intervals, potential actuator and valve performance degradation, assurance of operational readiness over the periodic l
test interval MOV performance monitoring, and preventative i
maintenance.
2.0 Procram Scog The CPSES GL 96-05 program MOV scope is the same as the previously developed GL 89-10 program MOV scope.
3.0 Testina 3,1 Static Testing The periodic verification methodology at CPSES is typically a static diagnostic test in which operational readiness under maximum design basis DP conditions is demonstrated by satisfying established i
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j TXX'97055 Page 4 of 8 i
acceptance criteria.
The magnitudes of Rate of Loading factors, valve factors, and other factors are consistent with the results of extensive baseline testing performed in response to GL 89-10 under both static and dynamic conditions.
Maximum postulated valve 4
2 factors have been determined by statistical means for each group of rising stem M0Vs. Valve groups were determined in the GL 89-10 1
program and are based on being of the same manufacturer, model and size. Additional margins will be provided for degradation to increase the valve factors beyond the maximum postulated values.
j 3.2 Dynamic Testing
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1 The CPSES M0V program has accounted for the factors necessary to i
enable periodic MOV diagnostic testing under static conditions to i
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verify the continued operational readiness of MOVs under design l
basis DP conditions.
However, CPSES will perform periodic dynamic j
testing of a sample of MOVs to obtain additional data to ensure I
assumed MOV performance bounds actual M0V performance.
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Several GL 96-05 MOVs will be selected for periodic dynamic testing.
i The valves selected will be a mixture of both Unit I and Unit 2 l
i MOVs.
The selection is based on:
4 (1) the ability to perform the dynamic tests without creating an undue risk to plant safety.
(2) the performance of the individual MOV relative to
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similar MOVs in previous tests, and (3) the safety significance of the MOV.
4 Dynamic test results will be extrapolated to all valve groups.
If periodic dynamic test results reveal no significant changes in valve i
performance, periodic dynamic test requirements will be reevaluated.
Data collected within the first five years will be used to validate assumptions made in justifying periodic static test intervals greater than five years. Data collected during and after the first i
five years will also be used to provide continued confirmation of i
the adequacy of the overall program.
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3.3 Stroke Time Testing 1
Please refer to TU Electric Relief Request V-8 submitted for i
approval under TV Electric letter (Reference 2). Per relief request i
V-8 TV Electric proposes to perform (1) periodic static M0V 1
diagnostic testing to the frequencies identified in Section 4.0 and (2) exercising of the MOV once per cycle in lieu of the ASME Section 1
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XI required stroke time testing.
Leak rate testing requirements of 10CFR50 App. J and the CPSES IST Program Plan will continue unchanged.
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TXX*97055 l
Page 5 of 8 i
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3.4 Joint Owners Group Testing Program t
i TV Electric is participating in a joint MOV testing program with the Boiling Water Reactor (BWR) and Westinghouse Owners Groups and will use, if appropriate, results of that program.
4.0 Periodic Static Verification Test Freauency The maximum interval between static verification tests is determined in two steps:
Step 1. A relative risk assessment will categorize the MOVs into either of two groups: "more safety significant" or "less safety significant." The more safety significant components (MSSC) will be assigned a six' year " Maximum Static Test Interval" between diagnostic tests, and the less safety significant components (LSSC) will be assigned a 10 year
" Maximum Static Test Interval" between diagnostic tests.
The risk assessment methodology is described in Ref 3 and'4 which I
were submitted as part of the pilot plant project on Risk Informed IST.
i Step 2.
A deterministic consideration of design margins will_
l take place. This step accounts for factors such as.
diagnostic instrumentation uncertainties, actuator repeatability, maximum postulated valve factors, margin for degradation, minimum postulated motor capability to deliver l
torque to the valve stem, and maximum postulated stem factor changes over the interval between diagnostic tests. The maximum test interval will be reduced from the 6 year or 10 year limit as needed to accommodate the more restrictive design margin.
5.0 Performance Monitorino Proaram j
For each GL 96-05 M0V. CPSES will use MOV performance parameters collected during static diagnostic testing (and dynamic diagnostic testing for those MOVs which are tested under dynamic conditions) to monitor MOV performance.
In addition to monitoring the values of performance parameters, several relationships between performance parameters may be useful in detecting and isolating performance changes, and will also be monitored.
The MOV will be monitored for changes in its ]erformance from baseline tests Each MOV's performance will se compared with the typical performance range for similar MOVs.
Corrective actions will be taken as appropriate, Values of the measured parameters and their relationships will be compared with the values used in the MOV design calculation.
If test results indicate a revision of the calculation is necessary, the revised calculation will be used to verify that the previously
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1 TXX 97055 Page 6 of 8 implemented switch settings and the motor capabilities of all affected MOVs continue to be acceptable for the test interval.
The' periodic test interval will be changed if necessary. -These program requirements will provide assurance that the design calculation is appropriately maintained, and that the intervals between periodic verification tests are appropriate for the as-left settings and motor capability.
6.0 MOV Preventative Maintenance Proaram i
Actuator refurbishment including grease changes will be scheduled to ensure grease degradation and component wear are not excessive.
The adequacy of the maintenance program for actuators, packing, i
valves, and their power supplies will be monitored.
Improvements will be made where practicable to increase the reliability of the l
MOVs.
For example, valve seat and guide maintenance, butterfly valve elastomer seat and bearing maintenance, packing maintenance.
l stem thread lubrication maintenance, actuator gearbox and limit i
switch grease maintenance, and M0V power supply (MCC) maintenance j
will be adjusted as needed to maintain a high level of confidence in the operational readiness of the MOVs.
If valves are disassembled (such as to replace a body-bonnet gasket), the internals will typically be inspected. Such inspection is intended to identify damage, degradation, or sharp leading edges i
of the gate guides, gate seats, or body seats. Any sharp leading edges will be dulled as a standard maintenance activity.
The frequencies of the preventive maintenance ' activities are based i
l on vendor recommendations, industry data, and CPSES specific data.
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7.0 EPRI MOV Performance Prediction Methodoloav As an alternative to dynamic testing, GL 96-05 states that under certain conditions the EPRI MOV Performance Prediction Program i
Methodology provides bounding results and may be used in conjunction with static testing alone to meet the recommendations of GL 96-05.
At this time CPSES has not adopted the EPRI MOV Performance Prediction Methodology to determine the required thrusts or torques of installed MOVs, as CPSES performed sufficient dynamic testing of each MOV type during GL 89-10 baseline" testing.
CPSES has grouped similar valves, statistically analyzed the test results, and applied the bounding results of the analyses to all of the valves in the group.
However. CPSES may elect to use the EPRI methodology at a later date.
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TXX'-97055 Page 7 of 8 If you have any questions. please contact Obaid Bhatty at (817) 897-5839.
Sincerely, C. 0, ' %erry C. L. T By:
M Rog'er (T. Walker Regulatory Affairs Manager OB/ob Attachment cc:
Mr. J. E. Dyer. Region IV Mr. J. I. Tapia. Region IV Mr. T. J. Polich NRR Resident Inspectors CPSES
Att'achment I to TXX-97055 Page 1 of 1 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of
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Texas Utilities Electric Company
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Docket Nos. 50-445
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and 50-446 (Comanche Peak Steam Electric
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Station, Units 1 & 2)
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Roger D. Walker being duly sworn, hereby deposes and says that he is the Regulatory Affairs Manager for Comanche Peak Steam Electric Station of TV Electric. the licensee herein; that he is duly authorized to sign and file with the Nuclear Regulatory Commission this Response to Generic Letter 96-l 05, " Periodic Verification of Design-basis Capability of Safety-Related Motor-0perated Valves".: that he is familiar with the content thereof: and l
that the matters set forth therein are true and correct to the best of his knowledge, information and belief.
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- m s&.sWh Rof(rD. Walker j
Regulatory Affairs Manager STATE OF TEXAS
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COUNTY'0F wes
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Subscribed and sworn to before me, on this I
day of WOMJU j
- 1997, i
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D CAROLYN L COSENTW3 EIEYl$fM2l8 l W a )' b h 4
Notary PuhTlic
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