ML20059G762
| ML20059G762 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 01/14/1994 |
| From: | Richard Anderson NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9401250273 | |
| Download: ML20059G762 (3) | |
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Northem States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401 1927 Telephone (612) 330-5500 January 14, 1994 10 CFR Part 2 Appendix C U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT j
Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Response to Notice of Violation NRC Inspection Report Nos. 282/93012(DRS) and 306/93012(DRS)
Corrective Action Related to Motor Operated Valve Testino Your letter of December 2, 1993, which transmitted Inspection Report No. 50-282/93012(DRS) and 50-306/93012(DRS), required a response to a Notice of violation. The response due date was extended to January 14, 1994, as a result of discussion with Region III representatives.
Following is our r
response.
Violation 1
During an NRC inspection conducted on September 27 through November 15, 1993, a violation of NRC requirements was identified.
In accordance with the " General Statement of Policy at. ' Procedure for NRC Enforcement Actions," 10 CFR Part 2, Appendix C, che violation is listed belows i
10 CFR 50, Appendix B, Criterion XVI requires, in part, that measures shall be established to assure that conditions adverse to quality, auch as failures, malfunctions, deficiencies, deviations, defective material I
and equipment, and nonconformances are promptly identified and corrected.
contrary to the above, as of September 27, 1993, corrective action had j
not been taken to evaluate 2nd document the functionality of motor operated MV32132, 32135, 32141, 32147, 32150, 332153, 32156 and 32387 in-response to the results of dynamic tests of similar-valves (same size and manufacturer) performed in July 1993. Those tests indicated that it would be necessary to use a valve factor of 0.75 in the calculation of torque switch settings in order to ensure those valves would be capable
-l of operating at design basis differential pressure and flow conditions (50-282/93012-03; 50-306/93012-03(DRS).
l This is a severity Level IV violation (Supplement I).
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i Nodhem States Power Company US N'RC
- January 14, 1994 Page 2 1
l Response to the violation Backoround Conservative thrust requirement calculationa for the subject valves, done in 1991, lii '.icated that larger actuators and yoses should be installed to meet AOV nw thu'alogy that required additional operating margin to assure continued operab'14) /.
Receipt of the new parts was complete in the spring of 1993.
The first of the new actuators and yokes were installed in July 1993, followed by static and dynamic testing of tha modified valves. Test results indicated a scatter of valve factors from 0.49 to 0.75.
Original thrust requirement calculations had used a valve factor of 0.50.
Using the higher valve factor, the design margin of the unmodified MOV's was significantly reduced. Given the operating flexibility of the containment cooling system, an informal evaluation indicated the valves were still operable, but no documentation of this evaluation was produced.
As a result of discussions with NRC inspectors during this inspection, the operability evaluation was formalized.
Reason for Violation Reasons for the violation are 1) insufficient formal guidance in procedure H5, Motor Operated Valve Program, and 2) a lack of sensitivity to the need to consider the implications of dynamic test data on similar valves.
Corrective Steos that have been taken and Results Achieved We had recognized the shortcomings in procedure H5, Motor Operated Valve Program, and had revised the procedure just prior to the inspection. The revision provides guidance during diagnostic test evaluation to' consider "the effects on similar valves, opposite unit valves, and parallel train valves" 1
whenever non-conservative test results are encountered, but the new guidance had not yet been implemented at the time a higher valve factor appeared to be appropriate.
Subsequent to the NRC inspection, Safety Evaluation No. 365, Operability Assessment of Fan-Coil Unit MOV's, was prepared to formally document operability of the valves until all modifications are complete in June 1994.
Increased sensitivity to non-conservative test results was demonstrated in two instances during the recent Unit 2 outage.
In the first instance, higher than expected. valve factors were discovered on two gate valves. An operability assessment was made for the similar Unit 1 valves resulting in static diagnostic testing and a change in their setpoints..Four other same size and model number valves in other applications were checked and setpoints were determined to be acceptable.
In the second instance, a higher-than-expected bearing load on a Unit 2 butterfly valve was discovered. This valve was l
replaced with a new valve. The opposite train valve was statically and dynamically tested and determined to be acceptable.
Similar Unit 1 valves were then tested'etatically and determined to be acceptable, with dynamici testing scheduled for the next Unit 1 outage.
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Northern States Power Company
.US N'RC l
' January 14, 1994 Page 3 Corrective Steps to Prevent Further Violations Procedure revisions are being considered to improve engineering guidance for evaluation of diagnostic test results for different valve types (e.g.,
butterfly valves).
Date When Full Compliance will be Achieved I
Full compliance has been achieved.
We have made no new NRC commitments in this letter. Please contact' Jack Leveille (612-388-1121, Ext. 4662) if you have any questions related to our response to the subject inspection report.
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Ro er O Anderson Director I
Licensing and Management Issues ca. Regional Administrator III, NRC Senior Resident Inspector, NRC NRR Project Manager, NRC J E Silberg P
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