ENS 44035
ENS Event | |
|---|---|
13:00 Mar 5, 2008 | |
| Title | Vacuum Daily Inspections Not Completed |
| Event Description | {{#Wiki_filter:Raschig Ring Vacuum Cleaners (RRVCs) are used within BWXT's Research and Test Reactors and Targets (RTRT) radiologically controlled area to collect floor scrubbing solutions. There are no fissile solutions present in the area. The RRVCs are checked daily to ensure the vessels are adequately filled with Raschig rings. According to the form used to document the inspection, the last time the level was verified it was noted as 'good.' However, the inspection was last performed on January 28, 2008. The RTRT foreman had recently been assigned to the area and was not aware of the requirement to perform the daily check. On the morning of March 5, 2008 the foreman realized the check had not been performed and proceeded to inspect the RRVC. The level of the rings within the vacuum cleaner was judged to be inadequate (the form does not contain specific acceptance criteria). The rings were approximately 5 inches below the level of the hose intake. There was a minimal amount of contaminated floor scrubbing solution in the vacuum cleaner at the time of discovery. Only solutions from floor scrubbing are collected with RRVCs in RTRT. Fissile solutions are not generated in the area. The RRVC was immediately removed from service pending the results of an investigation.
The initial filling of the vacuum cleaner with Raschig rings by an operator is an Item Relied on for Safety (IROFS). The vacuum cleaner was adequately filled with Raschig rings in September of last year during the semi-annual inventory. However, at the time of event the ring level was less than adequate, resulting in a degraded IROFS. The daily inspection of the Raschig ring level is a second IROFS to ensure an adequate ring level on an ongoing basis. The failure to perform this inspection is a failure of this IROFS. The remaining IROFS is the operator controls what is collected (and therefore the U235 concentration) with the RRVC. Only contaminated floor scrubbing solutions are vacuumed within in RTRT, not fissile solutions. There was no immediate risk of a criticality or threat to the safety of workers or the public as a result of this event. There was a portion of the RRVC that contained no rings, but there was only a minimal amount solution in the vacuum cleaner. However, with the degradation of one IROFS and the loss of a second, double contingency could no longer be assured. BWXT is making this 24 hour report in accordance with 10 CFR 70, Appendix A (b)(2), 'Loss or degradation of items relied on for safety that results in failure to meet the performance requirements of � 70.61.' The use of the RRVC in the RTRT area was immediately suspended by Nuclear Criticality Safety pending further investigation. The Licensee notified the NRC Resident Inspector.
As a result of the ongoing investigation supplemental information to this notification is being provided. The investigation identified that two other vacuum cleaners were not adequately filled with Raschig rings. One of these RRVCs is used within the Chemistry Lab. The ring level in this vacuum cleaner was approximately 3 inches below the level of the hose intake. The vacuum is used in the Chemistry Lab for floor scrubbing purposes. Although there are no fissile solutions in the lab, the NCS posting on the RRVC allows concentrations of up to 400 grams 235 to be collected. This is the same NCS posting on RRVCs in BWXT's Uranium Recovery facility. Although unlikely, it is possible that the Chem Lab RRVC could be transferred to Uranium Recovery and used to collect high concentration fissile solutions. The ring level of RRVCs used in Uranium Recovery is checked daily. Should the Chem Lab RRVC be moved to Uranium Recovery there are no documented controls to check the ring level before its use. Potentially, the Chem Lab RRVC containing an inadequate level of Raschig rings could have been used to collect a high concentration fissile solution. The filling of the vacuum cleaner with Raschig rings in accordance with American Nuclear Society Standard 8.5 is an Item Relied on for Safety (IROFS). The standard states, 'The level of the solution shall not exceed the level of uniformly packed rings.' The Chem Lab vacuum cleaner was not adequately filled with Raschig rings according to the standard. This IROFS was degraded. A second IROFS for the RRVC is the operator inspects the Raschig ring level according to ANS 8.5. The standard states, 'Raschig rings shall be inspected periodically to demonstrate their continued criticality control properties.' One of the required tests accounts for settling over time. The standard further states, 'If settling is detected, rings meeting specifications of this standard shall be added to restore full packing.' This second IROFS had failed given the level of the rings in the Chem Lab RRVC at the time of discovery. As such, no IROFS as documented in the Integrated Safety Analysis Summary remained. Double contingency had been lost. There was no immediate risk of a criticality or threat to the safety of workers or the public as a result of this event. There was a portion of the RRVC that contained no rings, but there was only a minimal amount of solution in the vacuum cleaner. However, with the degradation of one IROFS and the loss of a second, double contingency could no longer be assured. BWXT is making this 1 hour report in accordance with 10 CFR 70, Appendix A, (a)(4)(ii) - An event or condition such that no items relied on for safety, as documented in the Integrated Safety Analysis summary, remain available and reliable in an accident sequence evaluated in the Integrated Safety Analysis, to perform their function: Prevent a nuclear criticality accident. Notified R2DO (Hopper), NMSS (Easton) and Fuels OUO Group (e-mail). * * * UPDATE FROM B. COLE TO P. SNYDER ON 3/7/08 AT 1752 * * * The following "additional supplemental information is being provided to Event Notification #44035 as a result of the ongoing investigation. During the investigation of Event Notification #44035, a concern was expressed about the ability of a RRVC to suction solution above the level of the Raschig rings. It is BWXT's opinion that it is possible to collect solution above the level of the Raschig rings in the vacuum cleaner. The criticality safety of the RRVCs is based on American Nuclear Society Standard 8.5, 'Use of Borosilicate-glass Raschig Rings as a Neutron Absorber in Solutions of Fissile Material.' The standard states, 'The level of the solution shall not exceed the level of uniformly packed rings.' It is BWXT's opinion that it is credible for the solution to exceed the level of the Raschig rings in the RRVC. There is no immediate risk of a criticality or threat to the safety of workers or the public. It is BWXT's opinion that under certain conditions there is a potential for high concentration SNM bearing solutions to be collected above the level of the Raschig rings. According to internal spill procedures this condition is not likely, but is credible. As such, this potential condition is an unanalyzed condition where double contingency is lost. BWXT is making this 24 hour 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 use of all RRVCs at the BWXT facility was immediately suspended by Nuclear Criticality Safety pending further investigation. Notified R2DO (Hopper), NMSS (Easton), and Fuels OUO Group (E-mail). }} |
| Where | |
|---|---|
| Bwx Technologies, Inc. Lynchburg, Virginia (NRC Region 2) | |
| License number: | SNM-42 |
| Reporting | |
| Part 70 App A (B)(2) | |
| Time - Person (Reporting Time:+6.17 h0.257 days <br />0.0367 weeks <br />0.00845 months <br />) | |
| Opened:Some use of "" in your query was not closed by a matching "". | 19:10 Mar 5, 2008 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Mar 7, 2008 |
| 44035 - NRC Website | |
Bwx Technologies, Inc. with Part 70 App A (B)(2) | |
WEEKMONTHYEARENS 447112008-12-09T21:30:0009 December 2008 21:30:00
[Table view]Part 70 App A (B)(2) As-Built Depth of Low Level Dissolver System Dissolver Trays Exceeded Maximum Design Depth ENS 440352008-03-05T13:00:0005 March 2008 13:00:00 Part 70 App A (B)(2) Vacuum Daily Inspections Not Completed 2008-03-05T13:00:00 | |