ENS 50776

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v t e ENS Event
21:00 Jan 9, 2015
Title	Unanalyzed Condition While Cleaning the Catch Tray
Event Description	I. EVENT DESCRIPTION Scrap material resulting from various operations at B&W NOG-L's facilities is processed in the Low Level Dissolver (LLD) to reclaim as much of the uranium as possible. Since the material is scrap (e.g., filters, vacuum cleaner bags, etc.), it contains only small amounts of uranium bearing materials. On occasion during processing a slight amount of material will spill over the edge of the dissolver trays, filter bowls, or when hand-transferring material between the trays and filter bowls. These small spills collect on a large catch tray in the bottom of the enclosure. Periodically the catch tray is cleaned to limit the amount of material buildup. By procedure the solid material is to be scraped up and collected in a [less than or equal to] 2.5 liter container. During the cleanout the LLD process is shutdown. On January 9, 2015, the LLD process was shutdown and the enclosure was undergoing a routine cleanout. However on this occasion the operators scraped the material on the tray into several piles for subsequent collection into containers. The volume of most of the piles exceeded the 2.5 liter limit. However, the spacing between the piles was greater than the 15 inch limit, and the net weight of any single pile was less than the 7 kg limit for a 2.5 liter volume containing an unknown amount of U-235 . NDA [Non-Destructive Assay] measurements later determined the U-235 content of the piles ranged from 6.5 to 20.8 grams. There was no risk of a criticality accident. The accident scenarios for [less than or equal to] 2.5 liter containers of an unknown amount of U-235 were reviewed to analyze the event. At that point in time it was concluded the performance requirements of 10 CFR 70.61 were maintained. At 0900 EST on January 28, 2015, during discussion with the NRC as part of a regularly scheduled NCS inspection the applicability of these scenarios to the event came into question. The scenarios assume the material is containerized rather than in piles. Some of the IROFS [item relied on for safety] were therefore considered not available in this particular situation. II. EVALUATION OF THE EVENT The cleanup process as analyzed assumed the material was scraped up and collected in [less than or equal to] 2.5 liter containers. The scraping of the material into piles for subsequent collection into containers is a different process than what had been analyzed. The scenarios for the handling of materials containing an unknown amount of U-235 assume the material is containerized rather than in piles. Some of the IROFS credited in these scenarios were therefore not available for the collection of the material in piles. Although the as-found condition presented no safety concern, the scenarios as documented in the ISA [Integrated Safety Analysis] did not demonstrate the performance requirements of 10 CFR 70.61 were maintained. There was no immediate risk of a criticality or threat to the safety of workers or the public as a result of this event. Ill. 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. IV. 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. * * UPDATE FROM TONY ENGLAND TO JOHN SHOEMAKER AT 0908 EST ON 2/11/15 * * * I. EVENT DESCRIPTION On January 28, 2015 B&W NOG-L notified the NRC of an unanalyzed condition that occurred during the cleanup of residual solids from the Uranium Recovery Low Level Dissolver that failed to meet the performance requirements of 10 CFR 70.61. As part of the subsequent investigation of the event an Extent of Condition Review was performed. During the Extent of Condition Review of cleanup of residual solids from the High Level Dissolver, a similar potential condition was identified at 10:00 a.m. EST on February 10, 2015. A cleanup activity was not in process at the time of discovery. II. EVALUATION OF THE EVENT The Uranium Recovery High Level Dissolvers process scrap fuel materials. Undissolved residual solids collect in the Dissolvers' recirculation columns over time. These solids contain some amounts of U-235 that did not go into solution. The Dissolvers periodically undergo cleanup operations during inventory or contract changes. During this cleanout a small amount of solids are emptied from the horizontal recirculation columns onto drip pans and then transferred to a favorable volume less than or equal to 2.5 liter container. Although a cleanup was not in process at the time of the Extent of Condition Review, it could not be readily determined that the performance requirements of 10 CFR 70.61 would be met if a cleanup operation were to be performed. There was no immediate risk of a criticality or threat to the safety of workers or the public. No actual event occurred. Ill. NOTIFICATION REQUIREMENTS B&W is revising Event Report #50776 dated January 28, 2015. A potentially unanalyzed condition was identified that could not be demonstrated as meeting the performance requirements. B&W is making this 24 hr. 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. IV. 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. No cleanouts of the High Level Dissolvers' recirculation columns will occur until it can be demonstrated the performance requirements of 10 CFR 70.61 are met for this maintenance task. The licensee has notified the NRC Resident Inspector. Notified R2DO (Nease), NMSS EO (Rahimi), Fuels Group, and NMSS Events Notification via email. * * UPDATE FROM TONY ENGLAND TO HOWIE CROUCH AT 1619 EDT ON 3/16/15 * * * On February 11, 2015 Babcock & Wilcox (B&W) revised Event Report #50776 dated January 28, 2015. An Extent of Condition Review identified an unanalyzed condition associated with the cleanout of a High Level Dissolver (HLD) recirculation column. Although a cleanup was not in process at the time, it could not be readily determined that the performance requirements of 10 CFR 70.61 would be met if a cleanup operation were to be performed. There was no immediate risk of a criticality or threat to the safety of workers or the public. B&W amended the initial Event 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. The HLDs process scrap fuel materials. Undissolved residual solids collect in the Dissolvers' recirculation columns over time. These solids contain some amount of U-235 that does not go into solution. The Dissolvers periodically undergo cleanup operations during inventory or contract changes. During this cleanout a small amount of solids are emptied from the horizontal recirculation columns onto drip pans and then transferred to a favorable volume less than or equal to a 2.5 liter container. Further evaluation has determined that a criticality resulting from the cleanout of a recirculation column is not credible. This determination was made utilizing the guidance found in NUREG 15-20 which defines 'not credible' in part as: 'A process deviation that consists of a sequence of many unlikely human actions or errors in which there is no reason or motive... ' or 'Process deviations for which there is a convincing argument, given physical laws, that they are not possible, or any unquestionably extremely unlikely... ' The inherent design and process intent of the trough dissolvers, the nature of the chemical reactions involved, and the number of unlikely human errors that would have to occur to accumulate a sufficient amount of fuel and have it collect with a low enough packing fraction and entrained water, combine to make a criticality on the drip pans not credible. Although the facility was in a state that was not analyzed, was improperly analyzed, or different from that analyzed in the Integrated Safety Analysis, a criticality was not credible. Therefore, B&W is correcting Event Notification #50776 in accordance with 10 CFR 70.74(a)(4) and withdrawing the 10 CFR 70, Appendix A, (b)(1) notification of February 11, 2015. The licensee will notify the NRC Resident Inspector. Notified R2DO (Shaeffer), NMSS EO (Araguas) and FUELS OUO Group (email).

ENS 50776 +/-
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:+451.37 h18.807 days <br />2.687 weeks <br />0.618 months <br />)
Opened:	Kenny Kirby 16:22 Jan 28, 2015
NRC Officer:	John Shoemaker
Last Updated:	Mar 16, 2015
50776 - NRC Website
v • d • e

v t e Emergency Notification System
B&W Nuclear Operating Group, Inc. with Part 70 App A (B)(1)
WEEKMONTHYEAR2016-06-09T17:30:00 [Table view]
[ENS list for B&W Nuclear Operating Group, Inc.]

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