ML20057D146
| ML20057D146 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 09/27/1993 |
| From: | Frizzle C Maine Yankee |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CDF-93-141, GL-89-10, MN-93-88, NUDOCS 9310010177 | |
| Download: ML20057D146 (5) | |
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i YIaineYankee 5E @ B5 [ 5I55 5 5 Ty[.S M E 191)
J Charles D. Fnzzle Edson Drive Presdent and September 27, 1993 Augusta, Maine 04336 chef Executwe Offcer MN-93-88 CDF-93-141 (207) 622 4868 l
l UNITED STATES NUCLEAR REGULATORY COMMISSION Attention: Document Control Desk Washington, DC 20555
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) USNRC Letter to MYAPCo dated June 28, 1993: Inaccuracy of Motor-Operated Valve Diagnostic Equipment (Generic Letter 89-10, i
Supplement 5)
(c) MYAPCo Letter to USNRC dated February 1, 1990 (MN-90-15) i (d) MYAPCo Letter to USNRC dated July 21, 1993 (MN-93-70)
Subject:
Generic letter 89-10, Supplement 5, Inaccuracy of Motor-0perated Valve -
Diagnostic Equipment Gentlemen:
i Generic Letter 89-10, Supplement 5, requested licensees to provide information that will enable the NRC to verify whether the licensee is evaluating new information on the accuracy of MOV aiagnostic equipment.
Consistent with the reporting requirements of Reference (b), Maine Yankee's response to each requirement is as follows:
NRC Reportina Reauirement (1):
Within 90 days of receipt of this letter, all licensees are required to notify the NRC staff of the diagnostic equipment used to confirm the proper size, or to establish settings, for MOVs within the scope of GL 89-10.
Maine Yankee Response:
The types of diagnostic equipment used at Maine Yankee for MOVs within the scope of the GL 89-10 program are listed in Attachment A.
NRC Reportino Reauirement (2):
Within 90 days of receipt of this letter, licensees are required to report whether i
they have taken actions or plan to take actions (including schedule and summary of actions taken or planned) to address the information on the accuracy of M0V l
diagnostic equipment.
Maine Yankee Response:
The ITI-M0 VATS thrust measuring device (TMD) was used to estimate stem thrust for 14 out of 20 MOVs tested during the first (of three) GL 89-10 program refueling outages.
As a result of the identification of inaccuracies in the ITI-MOVATS TMD, Maine Yankee has either retested these MOVs with V0TES equipment or performed a design basis evaluation that the MOV will perform its safety function in light of the increased inaccuracy of the TMD.
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MN-93-88 September 27, 1993 i
The Liberty Technologies V0TES equipment was used during the first and second GL 89-10 refueling outages and is currently in use during the third (and last) outage. As a result of the Liberty Technologies Part 21 issued in October 1992, a design basis evaluation was conducted in December 1992 which concluded that a reasonable expectation existed that pertinent components met design basis and nuclear safety was not adversely affected.
When Maine Yankee received Generic Letter 89-10, we established goals, scope of work and committed in Reference (c) to completion of the Generic Letter 89-10 Program within five years of the Generic Letter or three refueling outages after December 28, 1989, whichever was later.
The scope of work was based on known technology at that time. By the end of the present (third) outage in October 1993, we will have completed that original scope of work. As requested by Reference (b), additional time will be required to reexamine the MOV program and to identify measures to account for uncertainties in properly setting valve operating thrust to ensure operability. Specifically, the following issues were identified by Maine Yankee as a result of the Liberty Technologies Part 21:
Issue No. 1 Some valves may exceed their weak link analysis value because past test methods underestimated measured thrust and reanalysis would be required.
Maine Yankee Resoonse This reanalysis was completed as part of the design basis evaluation discussed above.
Issue No, 2 The application of error using straight-line calibrations of the yoke strain i
gage is so restrictive that test data is not very useful for GL 89-10 application.
1 l
Maine Yankee Responso Reference (d) provided an interim 10CFR21 report relative to this issue.
Issue No, 3 A need to revise the V0TES test reports for the MOVs tested during the first and second outage.
Maine Yankee Response i
The rework consists of revising the test reports by using the new values of Elasticity (E) and Poisson's Ratio (NU) obtained from Liberty's testing and then changing the Torque Correction Factor (TCF) for calibrations performed on the threaded portion of the stem.
The threaded stem geometry is being field verified for this latter step. The revised test reports may indicate that some torque switches will need to be readjusted to obtain optimum performance which will require retesting the associated MOV. With an already full scope of work Lt\\CDF\\GLB930. SUS
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i y!YGHIC IBIMTC Page Three MN-93-88 September 27, 1993 for the third outage, there was only sufficient time to apply tho,Part 21 information to the originally scheduled third outage work.
The plan for revising the test reports of the previously tested MOVs is dependent on which outage they were previously tested as follows:
a.
The MOVs tested during the first outage used the V0TES version 1.0 software.
As the current version 2.31 software is not capable of correcting these test reports, we are waiting receipt of the V0TES version 2.32 software. Once received, we estimate these test reports will all be revised within six months.
b.
For the M0Vs tested during the second outage, the current V0TES version 2.31 software is capable of correcting these test reports.
For these MOVs, revised test reports will be generated (some MOVs have as many as 25 test reports with the average about ten) to obtain the new thrust, to compare the new thrust to the MOV's design basis and to ensure that the results of the design basis evaluation are conservative. We plan to revise these test reports by May 1, 1994.
Consistent with item m. of Generic Letter 89-10, we will notify the NRC in writing by July 28, 1994, that we have completed the original requirements of items
- a. through h. of the generic letter.
Two additional refueling outages will be required to finish revising the original test reports, determine any required changes and complete these changes during the outage of the M0V's next scheduled test.
We trust this information is satisfactory.
Please contact us should you have any questions.
Very truly yours, i
f1<
Charles D. Frizzle President and Chief Executive Officer WBD/ jag Attachment c:
Mr. Thomas T. Martin Mr. E. H. Trottier Mr. J, T. Yerokun Mr. Patrick J. Dostie STATE OF MAINE Then personally appeared before me, Charles D. Frizzle, who being duly sworn did state that he is President and Chief Executive Officer 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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MlillO1BlikCO ATTACHMENT A MN-93-88 TYPES OF DIAGNOSTIC EQUIPMENT Packmate:
Items Measured: Force in lbs. at various displacements.
(M0 VATS)
Determines spring pack K factor and dimensions.
Comparison with Limitorque data allows rejection of spring pack before it is reinstalled.
e Reduces work e
Provides basis for spring back relaxation measurement e
Alternate means of torque measurement Torquemate:
Items Measured: Displacement (Spring pack) vs. Torque (M0 VATS)
(MOVATS) Switch Settings (TSS).
Verifies Torque switch is balanced and slope of TSS vs.
displacement is consistent with design.
Provides increased confidence in tt.rque expectations for a given TSS.
NOTE:
A balanced torque switch will rarely remain balanced after installation.
Torque Test Stand:
Items Measured: Actuator output torque.
(M0 VATS)
If inputs like TSS, voltage, power, load rate, etc. are controlled and measured, then: 1)Thetorqueswitchcan be balanced; 2) Actuator design outputs can be verified against Limitorque design expectations; 3) Capability variance with voltage load rate can be determined; and
- 4) Relationship of power vs. torque output can be determined with measurement of possible variances with load rate and voltage.
Significantly reduces rework l
Significantly reduces diagnostic test time at valve because diagnostic performed on torque test stand Verifies actuator output capability L \\CDF\\GLB910.$U5
Midile'ntrilme ATTACHMENT A TYPES OF DIAGNOSTIC EQUIPMENT (Continued)
Motor Power:
Items Measured: 3-phase voltage and current and phase (LIBERTY) angle (power factor).
Derives: Instantaneous motor power.
Permits se.fsitive measurements to be made from MCC (i.e., no exposure).
Challenge is to correlate motor power quantitatively to required valve parameters.
Experience suggests that motor power will provide early detection of problems.
Difficulty is assigning engineering units and uncertainties to values of interest.
Definitely is a powerful qualitative tool.
Probably will be used as post packing or packing adjustment test. Early tests indicate good quantitative tool that might be suitable for periodic tests as well as situational.
2151:
Dual trace digital o' scope is the data collection (M0 VATS)
(M0 VATS) platform for this M0 VATS diagnostic system.
This platform can acquire only two signals simultaneously and is limited to 4,000 points per trace.
Sample rates are adjusted so that the event of interest can be captured in 4,000 points or less.
All adjustments available on sophisticated o' scopes are available on this machine. Several sensors can be used in conjunction with the 2151.
The primary sensor measures spring pack movement.
V0TES:
The major components of the V0TES 100 System are the (LIBERTY)
Computer, Signal Conditioner Box, and the Breakout Box.
These three components, used in conjunction with the V0TES Force Sensor and system peripherals such as switch and current probes, form the backbone of the V0TES 100 System.
The primary sensor (V0TES Force Sensor) measures yoke strain.
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