ENS 44634
ENS Event | |
|---|---|
14:56 Nov 6, 2008 | |
| Title | Defect Found in Bussman Fuses |
| Event Description | On November 6, 2008, Nebraska Public Power District (NPPD) completed a reportability determination which concluded that a batch of Bussmann fuses with a date code of J47 contained an underlying fabrication vulnerability that could result in a premature failure of the fuse. NPPD has concluded this condition is reportable per 10 CFR Part 21, since the underlying vulnerability could create a substantial safety hazard. The fuses are Commercial Grade items dedicated by NPPD for use at the Cooper Nuclear Station (CNS). The fuses are shipped directly from an authorized Bussmann facility to CNS. The fuse purchasing description is as follows: FUSE ; 10 AMP ; 250VAC ; ONE-TIME ; 50KA I.R. ; GENERAL PUPOSE ; Manufacturer Part Number NON-10. These fuses, with batch code of J47, have been determined by independent analysis to contain a poor solder joint internal to the fuse.
These fuses are authorized by NPPD for use in both safety related and non safety related applications. The applicable dedication package identifies one of the safety functions as 'Fuses are required to conduct the design basis load current without interruption.' If the fuses were installed without the condition being detected and failed upon valid demand of associated circuit, the mission of the associated safety related equipment may not have been accomplished. However, since the fuses were found, the safety function of the installed fuses is maintained and the associated equipment remains operable based on specific instructions for maintaining the fuses in place until replacement. Therefore, this condition is NOT reportable under 10 CFR 50.72 or 50.73. However, installation could have occurred and remained undetected, thus introducing a common mode failure in certain applications, thus fulfilling the definition of a Substantial Safety Hazard as defined by 10 CFR Part 21. Based on independent analysis of fuse mode of failure, the defect may not be necessarily detected upon installation. Since the fuses were stocked in unrestricted spares for essential applications, 10 CFR Part 21 applies, and the condition is reportable under 10 CFR 21.21. The Responsible Corporate Officer has been notified of this condition per 10 CFR 21.21 (d)(3)(i) on November 6, 2008 at 08:56 AM, CST. Pursuant to 10 CFR 21.21 (d)(3)(ii) written notification is due to the NRC within 30 days of this notification. Forty fuses were in the defective lot of which 15 are still installed in plant systems: Circ Water, RCIC, Emergency Diesel Generator 2, air removal and 4160 VAC diesel start breaker circuitry. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Cooper  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 21.21 | |
| Time - Person (Reporting Time:+1.52 h0.0633 days <br />0.00905 weeks <br />0.00208 months <br />) | |
| Opened: | David Nelson Madsen 16:27 Nov 6, 2008 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Nov 6, 2008 |
| 44634 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 461652010-08-09T17:30:0009 August 2010 17:30:00
[Table view]10 CFR 21.21 4160 Vac Control and Transfer Breaker Switch Defect ENS 453342009-09-08T14:30:0008 September 2009 14:30:00 10 CFR 21.21 Defect Found in Bussmann Fuses ENS 446342008-11-06T14:56:0006 November 2008 14:56:00 10 CFR 21.21 Defect Found in Bussman Fuses 2010-08-09T17:30:00 | |