ML20205T645
| ML20205T645 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 06/10/1986 |
| From: | Musolf D NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| References | |
| REF-PT21-86, REF-PT21-86-218-000 PT21-86-218, PT21-86-218-000, NUDOCS 8606160125 | |
| Download: ML20205T645 (3) | |
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SW Northern States Power Company 414 Nicollet Mall Minneapoks. Minnesota 55401 Telephone (612) 330 5500 June 10, 1986 Director Office of Inspection and Enforcement U S Nuclear Regulatory Commission Washington, DC 20555 MONTICELLO NUCLEAR GENERATING PLANT DOCKET NO. 50-263 LICENSE NO, DPR-22 Report of Defective Component (SSH-M-86/01)
The following information is reported in accordance with 10 CFR Part 21, Section 21.21(b)(3).
Northern States Power Company has determined that a component intended for use in the new Alternate Shutdown System (ASDS) being installed during the current refueling outage was manufactured with a defect which may have presented a substantial safety hazard.
The ASDS provides a redundant plant shutdown und cool down capability in the event of a fire in the control room or cable spreading room and is a requirement of 10 CFR Part 50, Appendix R.
The defective component was a control switch manufactured by the General Electric Company.
The component was purchased as a spare component for the ASDS control panel.
The fail-ure was detected following receipt inspection and acceptance by Northern States Power Company making this event repor-table under 10 CFR Part 21.
The following information is provided related to this defect:
1.
Name and Address of Individual Informing the Commission David Musolf, Manager Nuclear Support Services Northern States Power Company 414 Nicollet Mall Minneapolis, MN 55401 2.
Identification of the Facility and Defective Components Monticello Nuclear Generating Plant General Electric Type SBM Control Switch No. 10CN776 8606160125 860610 in PDR ADOCK 05000263 il S
PDR 8
P 1
Northem States Power Company Director of Inspection and Enforcement US Nuclear Regulatory Commission June 10, 1986 Page 2 3.
Identification of the Firm Supplying the Defective Components Supplied by United Controls, Inc., for NSP Project E-81N300A, Alternate Shutdown System, ASDS Panel C292.
The General Electric switch was supplied by United
- Controls, Inc., under Bechtel Purchase Order 10040-E-222(q) as a spare part.
4.
Nature of Defect The switch is a three-position control switch with a spring return to center.
The switch initially operated properly, but eventually malfunctioned when cycled repeatedly.
The spring return feature was lost with occasional jamming preventing return to center.
Exami-nation of the switch revealed that a spacer that main-tains the torsion spring in alignment with the spring actuator was missing.
Manipulation of the switch in various positions with some shaking of the assembly could intermittently cure the problem.
However, the malfunction could be recreated in any orientation.
This defect is considered a manufacturing assembly oversight and not a design defect.
5.
Date on Which Information Was obtained The malfunction was discovered by the Project Engineer while casually operating the switch in various posi-tions on April 17, 1986.
While originally intended as a spare part, the switch was being used to accommodate a late revision to the ASDS system by replacing an exis-ting switch.
The switch was disassembled to determine the cause of the intermittent operation and Nonconformance Report (NCR) No. 183 was issued on April 30, 1986.
Disposi-tion of the NCR on May 6, 1986 concluded that evalua-tion for reportability under 10 CFR Part 21 was re-quired.
Following an evaluation of this defect, a Technical Review Board concluded on June 6, 1986 that the defective switch may be reportable under 10 CFR Part 21.
NSP management was notified on June 9, 1986.
, r. /*
Northem States Power Company Director of Inspection and Enforcement US Nuclear Regulatory Commission June 10, 1986 Page 3 6.
Number of Components and Location There are a total of 19 similar switches used in ASDS Panel C292.
One switch was found to be defective.
These switches serve manual start functions for the RHR Pump, Core Spray Pump, and motor operated valves in these systems.
We are unable to determine the number and locations of similar switches provided to other facilities.
7.
Corrective Action Taken The defective switch was rejected and returned to the vendor.
All remaining switches (18) supplied by this vendor at Monticello were examined and found to have spacers in place and properly installed.
8.
Advice Related to Defect Given to Purchasers or Licensees Corrective Action Report M-36 was issued to United Controls, Inc., on May 10, 1986 requesting action be taken to prevent future delivery of defective switches.
As an end user and not a supplier, Northern States Power Company cannot offer direct information related to advice provided to other purchasers by the vendor.
Please contact us if you require additional information related to this defect.
Three copies of thie report are being provided.
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David Musolf Manager Nuclear Suppor Services t
c:
Administrator Region III, NRC Resident Inspector, NRC NRR Project Manager, NRC G Charnoff