ML20057D594
| ML20057D594 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/30/1993 |
| From: | Rainberry J SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-89-10, NUDOCS 9310050023 | |
| Download: ML20057D594 (3) | |
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Southem Califomia Edison Company 23 PARKER GTf4EET IFIVtNE, CALIFORNIA 92718 September 30, 1993 JL " ^ *NF BERRY TELEPHONE PLANT LICEN51NG MANAGER (714; eS4-4SS2 '
SAN ONCWME NUCL E AN GE.NE MATfNG STATION U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C.
20555 Gentlemen:
Subject:
Docket Nos. 50-361 and 50-362 Response to Generic Letter 89-10, Supplement 5, " Inaccuracy of Motor-Operated Valve Diagnostic Equipment" San Onofre Nuclear Generating Station Units 2 and 3
Reference:
Generic Letter 89-10, Supplement 5, " Inaccuracy of Motor-0perated Valve Diagnostic Equipment," dated June 28, 1993 This letter provides the Southern California Edison (SCE) response to Generic Letter (GL) 89-10, Supplement 5 (referenced above). As requested by the NRC in this GL supplement, SCE has reexamined our Motor-0perated Valve (M0V) program and identified measures to account for uncertainty in setting valve operating thrust to ensure operability. Also as requested, we have evaluated the schedule to consider the new information, both in GL 89-10, Supplement 5 and any information reasonably available to us, on M0V diagnostic equipment inaccuracy.
MOV DIAGNOSTIC EQUIPMENT The diagnostic equipment used in the San Onofre M0V program currently includes the following MOVATS 3000/3386 Diagnostic System M0 VATS Thrust Heasuring Device (TMD) including a Load Cell y
Stem Mounted Strain Gages supplied by Teledyne
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Yoke Mounted Strain Gages supplied by Micro-Measurements l
B&W Nuclear Technologies, Inc. ' Spring Pack Tester i
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SETTING M0V OPERATING THRUST TO ENSURE OPERABILITY Rising stem MOVs that have been set up and tested in the GL 89-10 program utilizing the M0 VATS TMD and Load Cell Methodology have been evaluated for the inaccuracy concerns referenced in GL 89-10, Supplement 5.
An as-left. thrust setting evaluation for these valves has been performed using MOVATS Engineering Report (ER) 5.2, path 2, to determine potential operability 010075 gg7 I o 9310050023 930930 I[
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Qocume'nt Control Desk concerns.
This evaluation is documented in SCE design calculation M-8910-ER52-SP-001.
Additionally, beginning with the Unit 2 Cycle 7 refueling outage, SCE utilizes stem mounted strain gages, where practical, to determine thrust on rising stem MOVs in the GL 89-10 program. Our setpoint calculations incorpcrate an instrument accuracy within 10%. Based on preliminary results of the calculations, use of the stem mounted strain gages with the MOVATS 3000/3386 system will meet this accuracy tolerance.
SCE has a testing program to determine accuracies of stem and yoke-mounted strain gages for measuring stem thrust. The results of this testing are to be used as the basis for Total Loop Uncertainty (TLU) calculations.
Preliminary results from the testing program indicate that the uncertainties associated with yoke-mounted strain gages are generally higher than those associated with stem-mounted strain gages.
When an MOV is set and tested using a M0 VATS TMD, a MOVATS ER 5.2 evaluation will be performed to account for the uncertainties associated with the TMD.
For uncertainties associated with other diagnostic systems, including thrust measurement using strain gages, SCE will ensure that the uncertainty of those systems will be less than the value for diagnostic system uncertainties used in the GL 89-10 setpoint calculation.
Starting with the Unit 2 Cycle 7 outage, calibrated spring packs are being installed in GL 89-10 MOVs, including in MOVs with stem mounted strain gages.
These spring packs are being calibrated on site utilizing the B&W Nuclear Technologies, Inc. Spring Pack Tester, and are used to estimate actuator output torque. The inaccuracies associated with this B&W Spring Pack Tester and with the transducer (s) used to measure spring pack deflection have,been applied to torque values used to reconcile calculation and test results.
SCHEDULE FOR CONSIDERING THE NEW INFORMATION ON MOV DIAGNOSTIC EQUIPMENT INACCURACY A TLU calculation will be performed to determine stem and yoke-mounted strain gage thrust measurement uncertainties. A MOVATS ER 5.2 evaluation of MOVs which have been set and tested using the TMD has been completed.
For MOVs set and tested using the TMD during future refueling Outages, a M0 VATS ER 5.2 evaluation will Se completed prior to returning the MOVs to service.
In addition, by the end of the Unit 3 Cycle 8 refueling outage, SCE will complete documentation and validation of new information on M0't diagnostic equipment inaccuracy and evaluations to account for uncertainty in setting operating thrust to ensure operability for all MOVs in the San Onifre Units 2 and 3 GL 89-10 program.
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Docum6nt Control Desk If you have any questions or would like additional information, please let me l
know.
Respectfully submitted,
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B. H. Faulkenberry, Regional Administrator, NRC Region V NRC Senior Resident Inspector's Office, San Onofre Units 1, 2 & 3 M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3 l
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before On personally appeared d. L G nEtX /ry
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to me to be the person whose name is subicribed to the within instrument and, acknowledged to-me that he. executed the same in his authorized capacity, and that by his signature on the
' instrument the. person or the entity upon behalf of which the i
person acted, executed the instrument.
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Witness myi hand and official seal.
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