ML20076K817
| ML20076K817 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 10/26/1994 |
| From: | Richard Anderson NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-89-10, NUDOCS 9411020127 | |
| Download: ML20076K817 (3) | |
Text
er Northern States Power Company Prairie Island Nuclear Generating Plant 1717 Wakonade Dr. East Welch, Minnesota 55089 October 26, 1994 U S Nuclear Regulatory Commission Attn:
Document Control Desk Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Additional Information Related to Inspection Followup Items NRC Inspection Report Nos. 50-282/93012(DRS) and 50-306/93012(DRS)
Motor-Operated Valve (MOV) Testinz and Surveillance This letter refers to the Generic Letter 89-10 motor operated valve inspection conducted September 27 through November 15, 1993. Your letter of December 2, 1993, which transmitted Inspection Report No. 50-282/93012(DRS) and 50-306/93012(DRS), required responses to each of 3 inspection followup items.
Our letter of February 4, 1994 provided responses to those items. This letter provides additional information related to Inspection Followup Item 2.
Statement of Inspection Followup Item 2 The preliminary assessment of Limitorque's May 13, 1993, Part 21 report regarding high ambient temperature effects on MOV motor output torque assumed that there would be no net loss of torque and assigned a date of March 1994 for completion.
The licensee assumed that torque output losses due to high temperature would be offset by gains due to Limitorque's allowance to use an application factor of 1.0 in certain instances instead or' the 0.9 originally used.
This assumption was questioned by the inspectors and found to be invalid.
In rasponse to the inspectors' concerns, the licensee performed calculations for some of the most affected MOV's and showed that the worst case torque reduction would be 4.7%.
These MOV's were shown to have sufficient margin to compensate for the loss in torque; however, a more thorough initial review should have been done to preclude operability concerns.
The licensee will request additional information from Limitorque in order to evaluate some MOV motors and detailed calculations will be performed for each MOV effected by the Part 21.
This is considered an inspection followup item that will be evaluated in a future inspection (50-282/93012-02; 50-306/93012-02(DRS)).
9411020127 941026
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US NRC NORTHERN STATES POWER COMPANY October 26, 1994
'Page 2 February 4.
1994 Response to Insgection Followup Item 2 A review of MOV's for which we have data has been completed.
Six MOV's still need review upon receipt of motor curve and torque derate data from Limitorque. The results indicate that all the MOV's reviewed retain sufficient margin to compensate for the torque capability changes arising from the Part 21 report. Results of the review are summarized below.
1) 104 of 1.0 MOV's which have had their torque switches set diagnostica11y with either VOTES or MOVATS have been verified to have sufficient margin to compensate for the torque capability changes.
The 6 remaining MOV's were not addressed in the Part 21 report.
Limitorque was contacted by letter dated 10/15/93, and numerous followup calls, requesting motor curve and torque derate data.
To date this data has not been recaived.
Upon receipt of the requested motor data from Limitorque, the remaining 6 MOV's shall be reviewed.
Based on current margins, no operability concerns are expected.
2)
Of the remaining Generic Letter 89-10 MOV's:
Six of the M0V's (not the same six as in 1 above) are not motor stall limited, and remain as such after application of the Part 21 report. The Part 21 report has no impact on these valves.
The remaining MOVS are non-environmentally qualified and therefore have a maximum temperature of 130 degrees F when required to operate during an accident.
The resulting torque capability increase due to Limitorque's allowance to use an application factor of 1.0 instead of 0.9 more than offsets any torque loss at this temperature. Torque capability increases for these MOV's as a result of the Part 21 report.
The results of this Part 21 review of MOV's will be incorporated into the next revision of the Site Engineering Manual HOV target thrust calculations (ENG-ME-046). The complete implementation of this revision will be completed 30 days after receipt of the remaining motor data from Limitorque, l
The italicized sentences above represent commitments which we have made.
However, we did not complete the revision of the Site Engineering Manual
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US NRC NORTHERN STATES POWER COMPANY October 26, 1994 Page 3 within 30 days after receipt of the remaining motor data from Limitorque as we had committed. The data was received prior to our Unit 1 refueling outage last spring and the data was factored into the test program for all valves tested after receipt of the information.
The Site Engineering Manual was not revised until recently. A decision had been made that use of the proper motor data met the intent of the commitment. When this decision was brought to the attention of plant management, it was determined that we, indeed, had not met the letter of the commitment regardless of whether or not we met the intent.
We revised the manual and notified the Senior Resident Inspector of the situation.
We do recognize the significance of commitments made to the NRC and intend to complete them as stated. We believe that our commitments are generally fulfilled as promised, this instance was not typical. We apologize for any inconvenience this oversight may have caused.
Please contact Jack Leveille (612-388-1121, Ext. 4662) if you have any questions related i.e our response to the subject inspection report.
Mb e-Rogec 0 Anderson Director Licensing and Management Issues c: Regional Administrator III, NRC Senior Resident Inspector, NRC NRR Project Manager, NRC J E Silberg