ENS 44313
ENS Event | |
|---|---|
14:35 Jun 23, 2008 | |
| Title | Only One Safety Item Available for Safety for Greater than 8 Hours |
| Event Description | I. EVENT DESCRIPTION: In April of this year, BWXT replaced the recirculation columns on the High Level Trough Dissolvers in the Uranium Recovery Facility. The columns were processed out of the area according to standard waste handling procedures for disposal. An NMC technician raised a concern as the columns were checked by BWXT Security before placement into a SeaLand container. The technician believed the response of Security's monitor was overly sensitive compared to the assigned 235-U values based on calculations. NMC immediately placed a hold on the columns.
The columns were later moved into the Decon Area of BWXT's Waste Treatment Facility where they were stored for approximately three weeks. The Decon area is posted by Nuclear Criticality Safety for 100 grams of 235-U. NMC personnel conducted subsequent NDA field measurements of the columns and estimated an accumulation of approximately 695 grams 235-U in four of the columns. The Decon Area was immediately secured and a Radiation Work Permit (RWP) generated to clean and reevaluate the columns in the Uranium Recovery's Maintenance area. The four columns were relocated to the Recovery Maintenance area where they were cleaned according to the instructions in the RWP. NDA measurements of the columns and cleaning materials indicated a total 235-U content of 577 grams. The Limiting Condition for Operation (LCO) in the Decon Area is 400 grams. The Item Relied On For Safety (IROFS) for control of mass was degraded. II. EVALUATION OF THE EVENT: The safety basis for the Decon Area takes credit for two IROFS, control of mass and moderation. The control for mass was degraded. Although the LCO for 235-U mass was exceeded by 177 grams, this was less than the fully reflected, optimally moderated minimum critical mass of approximately 800 grams. A criticality was not credible in this scenario. There was no immediate risk of a criticality or threat to the safety of workers or the public as a result of this event. The amount of 235-U present in the columns was less than the minimum critical mass of approximately 800 grams. However, with the degradation of one IROFS and only one remaining, double contingency could no longer be assured. III. NOTIFICATION REQUIREMENTS: BWXT is making this 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> report in accordance with 10 CFR 70, Appendix A, (a)(5) - Loss of controls such that only one item relied on for safety, as documented in the Integrated Analysis Summary, remains available and reliable to prevent a nuclear criticality accident, and has been in this state for greater than eight hours. 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 will notify the NRC Resident Inspector. |
| Where | |
|---|---|
| Bwx Technologies, Inc. Lynchburg, Virginia (NRC Region 2) | |
| License number: | SNM-42 |
| Reporting | |
| Part 70 App A (A)(5) | |
| Time - Person (Reporting Time:+-3.12 h-0.13 days <br />-0.0186 weeks <br />-0.00427 months <br />) | |
| Opened: | Cheryl Goff 11:28 Jun 23, 2008 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | Jun 23, 2008 |
| 44313 - NRC Website | |
Bwx Technologies, Inc. with Part 70 App A (A)(5) | |
WEEKMONTHYEARENS 443132008-06-23T14:35:00023 June 2008 14:35:00
[Table view]Part 70 App A (A)(5) Only One Safety Item Available for Safety for Greater than 8 Hours 2008-06-23T14:35:00 | |