ENS 49258
ENS Event | |
|---|---|
17:00 Aug 9, 2013 | |
| Title | Storage Racks Determined to Be in an Unanalyzed Condition |
| Event Description | EVENT DESCRIPTION:
At B&W's NOG-L [Nuclear Operations Group - Lynchburg] facilities, scrap and waste material is generated during fuel bearing operations. Certain streams are collected in favorable volume less than or equal to 2.5 liter containers and eventually transferred to the Drum Count Area for U-235 assay. Because the U-235 content of such containers is not known until they have been assayed, they are referred to as 'unknowns' and are subject to a bulk weight limit. These containers are limited to a maximum of 7,000 grams net weight (approximately 15 pounds). The unknowns are stored on designated less than or equal to 2.5 liter container storage racks. The construction of the storage racks controls the spacing between storage locations and the distance from the floor. The racks' materials of construction are credited as a fixed neutron poison. Some of the unknown racks are fitted with an additional poison plate which allows the rack-to-rack spacing to be reduced. On August 9, 2013, at approximately 1:00 p.m., a contract Nuclear Criticality Safety (NCS) engineer working with B&W's NCS staff identified a safety concern. While working to consolidate information in several Safety Analysis Reports, it was determined that the poisoned less than or equal to 2.5 liter storage racks fitted with a horizontal poison plate were improperly analyzed. EVALUATION OF THE EVENT: The NCS evaluation of the poisoned less than or equal to 2.5 liter storage racks fitted with a horizontal poison plate was completed in October of 2000. The analysis was based on an evaluation of a poisoned transport cart completed earlier the same year. However, a review by the B&W NCS staff indicated the conclusions of this earlier analysis were not properly applied to the analysis of the poisoned less than or equal to 2.5 liter storage racks fitted with a horizontal poison plate. The racks were improperly analyzed. The requirement of 10 CFR 70.61 (d) states in part: '...the risk of nuclear criticality accidents must be limited by assuring that under normal and credible abnormal conditions, all nuclear processes are subcritical, including use of an approved margin of subcriticality for safety.' Further evaluation of the poisoned less than or equal to 2.5 liter storage racks fitted with a horizontal poison plate indicated that under optimal moderation the keff exceeds the safety limit of 0.95 in NRC License SNM-42. Therefore the performance requirement of 10 CFR 70.61 (d) was not maintained. NOTIFICATION REQUIREMENTS: B&W is making this 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> report in accordance with 10 CFR 70, Appendix A, (b)(1) - 'Any event or condition that results in the facility being in a state that was not analyzed, was improperly analyzed, or is different from that analyzed in the Integrated Safety Analysis, and which results in failure to meet the performance requirements of 70.61.' There was no immediate risk of a criticality or threat to the safety of workers or the public as a result of this event. A portion of the storage locations in the poisoned less than or equal to 2.5 liter storage racks fitted with a horizontal poison plate were removed from service. This action was taken to restore compliance with the performance requirements of 10 CFR 70.61. STATUS OF CORRECTIVE ACTIONS: An investigation of the root causes of this event is ongoing. Corrective actions will be determined as a result of the investigation. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
| B&W Nuclear Operating Group, Inc. Lynchburg, Virginia (NRC Region 2) | |
| License number: | SNM-42 |
| Reporting | |
| Part 70 App A (B)(1) | |
| Time - Person (Reporting Time:+-0.67 h-0.0279 days <br />-0.00399 weeks <br />-9.17766e-4 months <br />) | |
| Opened: | Kenny Kirby 16:20 Aug 9, 2013 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Aug 9, 2013 |
| 49258 - NRC Website | |
B&W Nuclear Operating Group, Inc. with Part 70 App A (B)(1) | |
WEEKMONTHYEARENS 519982016-06-09T17:30:0009 June 2016 17:30:00
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