ML20215K232
| ML20215K232 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna, 05000000 |
| Issue date: | 10/17/1986 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 86-276A, IEB-85-003, IEB-85-3, NUDOCS 8610280054 | |
| Download: ML20215K232 (6) | |
Text
VINGINIA ELucTHIC ann Pownn CourANY HicnMoxn,Vinoix A unuGI
,,6 0CT 20 A 9 : 5 2 0
W t. STEWART VICE I'.Est DEMT sm.... o,. non.
October 17, 1986 Dr. J. Nelson Grace Serial No.
86-276A Regional Administrator N0/DJB:vlh Region II Docket Nos.
50-280 U.S. Nuclear Regulatory Commission 50-281 Suite 2900 50-338 101 Marietta St., N.W.
50-339 Atlanta, Georgia 30323 License Nos. DPR-32 DPR-37 NPF-4 NPF-7
Dear Dr. Grace:
VIRGINIA ELECTRIC AND POWER COMPANY SUPPLEMENTAL RESPONSE TO IE BULLETIN 85-03 MOV COMMON MODE FAILURES DURING PLANT TRANSIENTS DUE TO IMPROPER SWITCH SETTINGS As requested by IE Bulletin 85-03, the Virginia Electric and Power Company has developed a plan and program to ensure that motor operated valves (MOV) in the ~ high pressure safety injection and emergency feedwater systems have correct valve operator switch settings.
This letter supplements our original IEB response of May 13, 1986, Serial Nos.86-275 and 86-276, and provides more specific data and. information (Attachment I) with regard to our program at Surry Unit No. 1.
Specifically, this letter addresses the questions from your staff and provides updated information on our differential pressure calculations.
The company is evaluating and plans to use a program similar to the maintenance and test program proposed by Motor Operated Valve Analysis and Test System, Inc. (MOVATS) and described in a briefing to the NRC in Bethesda on September 4,1986 (the Blue Book approach). This program will include pressure testing of selected valves.
We have completed the review of the maximum differential pressure calculations for the Bulletin valves referenced in our previous letters.
The updated tables are provided in attachment II.
If additional information is required, please contact me.
Very truly yours, gil a
8610280054 861017 v
A W. L. Stewart PDR ADOCK 05000280 i
PDR G
Attachments un h~
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Mr. L. Reyes, Acting Director 1
Division of Reactor Projects
'NRC Region II f
Mr. Lester S. Rubenstein, Director PWR Project Directorate No. 2 Division of PWR Licensing-A l
t Mr. J. L. Caldwell l
NRC Senior Resident Inspector North Anna Power Station i
i Mr. Leon B. Engle NRC North Anna Project Manager
'PWR Project Directorate No. 2 Division of PWR Licensing-A l
i 3
Mr. W. E. Holland NRC Senior Resident Inspector.
Surry Power Station Mr. Chandu P. Patel NRC Surry Project Manager q
PWR Project Directorate No. 2-Division of PWR Licensing-A 1
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Attachment I
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IE BULLETIN 85-03 MOV TEST PROGRAM SURRY UNIT NO.1 A.
Determination of MOV Parameters and Correct Switch Settings Company engineers are working with our Architect Engineer (Stone and Webster), Limitorque, and the valve manufacturers to analytically determine the correct settings for the valve operator torque switches (including bypass), the limit switches, and the thermal overloads.
Calculations are being performed for each of the MOVs identified in our IEB 85-03 response to determine the minimum operator thrust necessary to open and close the valve under maximum differential pressure conditions.
The-thrust calculation included conservative j
summation of the valve stem thrust, the packing load, and the stem load; an additional 10% (approximate) was added to the total calculated thrust to compensate for measuring / test equipment accuracy j
and torque switch setting tolerances. GDC-17 calculations were also examined for applicable MOVs to ensure that adequate - thrust is developed under reduced voltage conditions. In addition, the maximum a
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thrust value is also determined with information from the l
manufacturers of the valve and operator to ensure MOV components are not damaged. These calculations have been completed for each of the twenty-five Surry Unit No. 1 Bulletin MOVs.
To further ensure that the MOVs travel to their Engineered Safeguards Function (ESF) position, the torque switches will be bypassed during a portion of valve. travel to the ESF position by utilizing an installed spare limit switch rotor. For Surry Unit No.1, the~ torque switches are bypassed for approximately.85% of valve travel to the ESF position.
Where only 2 trains of limit switches are installed-l (no spare rotors), the torque switch was bypassed during valve ESF positioning.
Two Surry Unit No. I two rotor bulletin MOVs, which close for ESF positioning, are double disc gate valves and utilize the limit switches to close in accordance with the de' sign of the valve and the manufacturer's recommendations.
When the torque switch is
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bypassed, the limit switches remain adjusted to indicate proper full open and closed valve position (IE Notice 86-29).
Bypassing of the torque switch protection to ensure ESF positioning of the'. valve is
-in accordance with the philosophy set forth in Regulatory Guide 1.106.
i We believe that the probability of valve blockage or interference in.
i these ESF systems, which may render the MOV inoperable, is remote; tripping of the torque switch is'a more likely possibility, which is the reason for bypassing the torque switch during ESF positioning.
We are continuing our. review of torque switch bypass setting for i
Bulletin MOVs.
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Proper limit switch setiings are verified with the Motor Operated Valve Analysis and Test System (M0 VATS) equipment.
Backseating of i
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I the valve, for example, is not permitted and is verified not to occur during testing with the use of the MOVATS equipment.
The thermal overloads in the Motor Control Center electrical circuit breaker for the MOV are sized to ensure M0V operation without degrading MOV electrical systems. The Surry Unit No. 1 thermal overloads were set to time delay trip at approximately 50% of the M0V locked rotor current, but less.than 300% of full load current.
The MOV breaker itself will continue to provide thermal and short circuit protection for the electrical distribution system.
B.
Ensuring Correct Switch Settings Are Made To correlate the Limitorque operator torque switch settings with the actual stem thrust value, M0 VATS equipment was utilized on Surry Unit No.
1 Bulletin MOVs. Surry Unit No. 2 MOVs will be tes'ted this fall, i
and North Anna Unit Nos.
I and 2 during the 1987 refueling outages.
The MOVATS testing will include signatures of the torque and limit l
switch action, and Belleville spring pack deflection with the thrust measuring device (TMD), analysis of the motor power and current, and l
the installation of a calibrated load cell on various rising stem i
valves to measure actual operator thrust for specific torque switch
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settings. The torque switches were calibrated using the MOVATS test equipment, and linear graphs of torque switch settings vs. actual thrust are being developed from the data. The "as Icft" torque switch settings, and therefore thrust, will be. verified to exceed the calculated thrust required to ensure MOV operation under full a
differential pressure conditions.
In addition,. the MOV torque switches will be appropriately bypassed to facilitate valve ESF positioning.
We are planning to integrate the signature tracing techniques into our periodic inservice testing programs.
These programs will be utilized to indicate changes in MOV operability characteristics such as aging, inadequate adjustment or maintenance, etc.,
and will therefore ensure that the MOVs are fully operable.
The MOVATS equipment is a part of our Predictive Analysis Program.to ensure that adequate margins to failure are maintained. During the recent Surry Unit No. 1 outage, we performed signature analysis on 38 MOVs, and are using this baseline data in our program to ensure MOV operability.
C.
Full Differential Pressure Testing of IEB Valves In our original IEB 85-03 response, dated May 13, 1986, we committed to perform MOVATS signature analysis on over half of our Surry Unit 1 Bulletin MOVs and to stroke test at least 3 of the Bulletin valves at the maximum differential pressure to verify our program and methodology.
Twenty-two of,the the twenty-five Surry Unit No. 1 Bulletin MOVs were tested with MOVATS for signature analysis, and actual valve stem thrust was measured during valve operation with our calibrated load cell.
In addition, three of the above mentioned i
twenty-two Bulletin MOVs were successfully stroke ' tested at the maximum differential pressure, prior to Surry~ Unit No. I restart.
During the upcoming Surry Unit No. 2 outage we hope to complete the
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remainder of our IEB 85-03 MOV s'ignature testing at Surry Power Station.
We are confident that our program will demonstrate full operability of our MOVs on a continuing basis.
The "as left" torque switch settings are verified by measuring actual valve stem thrust during our torque rwitch calibrating procedures, and demonstrating that this thrust value exceeds the minimum calculated thrust required under full differential pressure conditions.
Signatures are also taken during full differential pressure valve testing to verify our methodology and calculations.
In addition, torque switches are bypassed during ESF positioning of the valve, as described above.
We plan to perform differential pressure testing on certain Bulletin valves at Surry Unit No. 2 and apply the analysis to similar MOVs to verify our program. For example, only one of the six Auxiliary Feedwater MOVs will be tested under differential pressure conditions, since all six can be pressurized to 1184 psi, are 3 inch Walworth globe valves, and have Limitorque SMB 00 actuators installed.
The IEB 85-03 MOVs will be MOVATS tested to verify our calculations and methodology, and to ensure full operability of our MOVs.
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Attachment-II r
MOV DATA
SUMMARY
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SURRY UNITS 1 AND 2 P
Design Valve Valve Function Basis AP
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LCV-1115B, D RWST.to high-head SI pump isclation 27 psi LCV-2115B, D 27' psi
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1 LCV-1115C, E VCT to charging pump isolation 84 psi i
LCV-2115C, E 84 psi t
1267A, B Low-head'SI to high-head SI isolation 145 psi j
2267A, B 145 psi 1269A, B 145 psi l
2269A, B 145 psi.
1 1270A, B 145 psi 2270A, B 145 psi I
i 1286A, B, C Charging pump to normal charging isolation 2630 psi l
2286A, B, C 2630 psi I
1289A, B 2630 psi' 2289A, B 2630 psi 1867C, D High-head SI to cold leg isolation 2630 psi i
I 2867C, D 2630 psi FW-151A-F Auxiliary feed pump to steam generator 1184' psi
- i FW-251A-F isolation 1184 psi
- t FW-160A, B Aux feed cross-connect isolation 1193 psi
- FW-260A, B 1193 psi
- t Updated Pressure r
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MOV DATA
SUMMARY
NORTH ANNA UNITS 1 AhT 2 Design Valve Valve Function Basis AP 1115B, D RWST to high-head SI pump isolation 35 psi 2115B, D 35 psi
.1115C, E VCT to charging pump isolation 80 psi 2115C, E 80 psi 1267A, B Low-head SI to high-head SI isolation 180 psi 2267A, B 180 psi 1269A, B 180 psi 2269A, B 180 psi 1270A, B 180 psi 2270A, B 180 psi 1286A, B, C Charging pump to normal charging isolation 2635 psi 2286A, B, C 2635 psi 1289A, B 2635 psi 2289A, B 2635 psi 1867A, B, C, D High-head SI to cold leg isolation 2867A, B, C, D
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2635 psi 2635 psi FW-100B, D-Auxiliary feed pump to steam generator 1302 psi
- FW-200B, D isolation 1302 psi *
- Updated Pressure l
-