ENS 46105
ENS Event | |
|---|---|
19:07 Jul 17, 2010 | |
| Title | 24 Hour 91-01 Bulletin Report on Loss of One of Two Criticality Control Contingencies |
| Event Description | At 1407 CDT, on 07/17/2010 the Plant Shift Superintendent was notified that cracks had been discovered in the C-400 Spray Booth containment pan by Quality Control Inspectors. The floor pan for the spray booth storage tanks, near the hand tables, was found to be inadequate and would allow solution to leak directly onto the concrete floor, in violation of NCSE (Nuclear Criticality Safety Evaluation) 015. The floor pan is a Safety Related Item that is intended to prevent solution from leaking to the concrete floor beneath the floor pan and accumulating in or creating an unsafe geometry/volume.
Since one leg of double contingency was lost, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC Bulletin 91-01 Supplement 1. The process conditions relied upon for double contingency for this scenario are mass and geometry. The first leg of double contingency is based on the mass of uranium in solution form that leaks out of the system. The analysis credits both the integrity of the Spray Booth system and the fact that the tanks and piping are inspected for leakage. Small leaks will be identified and fixed before they have leaked enough uranium mass, in solution form, to be a concern. This control was not violated. The second leg of double contingency relies on the integrity of the floor pan to prevent accumulated liquids from leaking to the underlying concrete floor and accumulating in unfavorable geometries that may be present or created under the containment pan. Because a portion of the floor pan was discovered to have a hole, the Safety Related Item was violated; therefore, this control was violated. Pressure was placed on the Spray Booth floor pan in the area around the crack. Based on this inspection, there are no indication of unsafe geometry voids being present or having been created under the floor pan. Because the integrity of the floor pan was not maintained, this leg of double contingency is conservatively being considered as having been lost. Double contingency is conservatively considered to have been lost since the integrity of the spray booth storage tank floor pan was lost. In order for a criticality to be possible, greater than a safe mass of fissile material, in solution form, would have to leak out of the system undetected, leak under the floor pan, dissolve the concrete floor, and accumulate in an unsafe geometry. While the intended safety function of the Safety Related Item was violated, there was no significant uranium solution leak from the Spray Booth system. Additionally, there are no indications of unsafe geometry voids under the floor pan. The NRC Senior Resident Inspector has been notified of this event. The crack was characterized as through-wall and approximately 9 inches long. Since the pan is flush to the concrete floor it is mounted on, the licensee does not believe that any material has accumulated under the pan. A preliminary inspection of the pan did not reveal any indication of voiding under the pan. The licensee still has not determined if the pan will be lifted to inspect underneath. The crack was found during an annual inspection of the pan. The cause of the cracking is still under investigation. |
| Where | |
|---|---|
| Paducah Gaseous Diffusion Plant Paducah, Kentucky (NRC Region 2) | |
| License number: | GDP-1 |
| Reporting | |
| Response | |
| Time - Person (Reporting Time:+18.98 h0.791 days <br />0.113 weeks <br />0.026 months <br />) | |
| Opened: | Kevin Beasley 14:06 Jul 18, 2010 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Jul 18, 2010 |
| 46105 - NRC Website | |
Paducah Gaseous Diffusion Plant with Response | |
WEEKMONTHYEARENS 483982012-10-10T18:05:00010 October 2012 18:05:00
[Table view]Response Double Contingency Control for Empty Cylinders Not Maintained ENS 479112012-05-08T21:16:0008 May 2012 21:16:00 10 CFR 76.120(c)(2), Response Autoclave High Pressure Isolation System Failure ENS 474832011-11-28T15:30:00028 November 2011 15:30:00 Response 24-Hour Report Concerning a Localized Loss of a Geometry Criticality Control Contingency ENS 473102011-09-30T13:54:00030 September 2011 13:54:00 Response 24-Hour Nrc Bulletin 91-01 Report Involving a Loss of One Leg of Double Contingency ENS 471762011-08-19T13:15:00019 August 2011 13:15:00 Response 24-Hr Loss of Criticality Control Report Required Under Bulletin 91-01, Supplement 1 ENS 465922011-02-03T15:30:0003 February 2011 15:30:00 Response 24 Hour Notification Under Bulletin 91-01 Concerning Leakage of Moderating Liquid ENS 463122010-10-06T16:06:0006 October 2010 16:06:00 Response 24 Hour Notification Under Bulletin 91-01 Concerning Cooldown Verification of Uf6 Cylinders ENS 461052010-07-17T19:07:00017 July 2010 19:07:00 Response 24 Hour 91-01 Bulletin Report on Loss of One of Two Criticality Control Contingencies ENS 454922009-11-12T17:15:00012 November 2009 17:15:00 Response Violation of a Nuclear Criticality Safety Control ENS 450422009-05-04T10:07:0004 May 2009 10:07:00 Response 24 Hour 91-01 Bulletin Report on Loss of One of Two Criticality Control Contingencies ENS 445582008-10-09T20:37:0009 October 2008 20:37:00 Response 24-Hours Bulletin 91-01 Report Involving Failure to Visually Inspect Storage Cylinders ENS 442232008-05-18T22:21:00018 May 2008 22:21:00 Response Violation of a Nuclear Criticality Safety Approval - 24-Hour Report ENS 441512008-04-17T21:44:00017 April 2008 21:44:00 Response 24-Hour Nrc Bulletin 91-01 Report Involving an Excessively Large Container Found in a Fissile Control Area ENS 441002008-03-26T19:57:00026 March 2008 19:57:00 Response 24 Hour Report of Degraded Criticality Control ENS 440562008-03-11T19:57:00011 March 2008 19:57:00 Response Two Cylinders Identified with Weight Change Prior to Wash ENS 432322006-09-23T03:00:00023 September 2006 03:00:00 Response Reported Under Nrc Bulletin 91-01 24 Hour Notification ENS 421652005-11-22T18:05:00022 November 2005 18:05:00 Response Improper Criticality Spacing for Waste Drum ENS 411582004-10-29T14:45:00029 October 2004 14:45:00 Response Criticality Control Report ENS 410202004-09-04T18:45:0004 September 2004 18:45:00 Response Violation of Nuclear Criticality Safety Control in the Process Building ENS 408732004-07-14T18:00:00014 July 2004 18:00:00 Response Criticality Control 24-Hour (Bulletin 91-01) Report ENS 408602004-07-08T20:50:0008 July 2004 20:50:00 Response 24 Hour Nrc Bulletin 91-01 Loss of Criticality Control ENS 407232004-05-03T21:00:0003 May 2004 21:00:00 Response Criticality Control 24-Hour (Bulletin 91-01) Report ENS 407002004-04-23T13:45:00023 April 2004 13:45:00 Response Criticality Control 24-Hour (Bulletin 91-01) Report ENS 408052004-04-23T10:53:00023 April 2004 10:53:00 Response Paducah Gaseous Diffussion Plant - Response Bulletin 91-01 24 - Hour Report ENS 406412004-04-04T19:30:0004 April 2004 19:30:00 Response 24-Hour Nrc Bulletin 91-01 Loss of Criticality Control Notification ENS 404552004-01-16T21:27:00016 January 2004 21:27:00 Response 24 Hour Notification for Bulletin 91-01 Loss of Criticality Safety Controls Involving Waste Drum ENS 404472004-01-13T19:00:00013 January 2004 19:00:00 Response 24 Hour Notification for Bulletin 91-01 Loss of Criticality Safety Controls Involving Waste Drum ENS 403562003-11-25T09:45:00025 November 2003 09:45:00 Response 24 Hour Nrc Bulletin 91-01 Notification Regarding Loss of Double Contingency Protection ENS 401512003-09-11T13:45:00011 September 2003 13:45:00 Response Double Contingency Was Not Maintained for Non-Fissile Nams. ENS 401392003-09-07T12:50:0007 September 2003 12:50:00 Response Criticality Controls Degradation at Paducah ENS 401092003-08-27T14:00:00027 August 2003 14:00:00 Response Procedural Deficiency Omission 2012-05-08T21:16:00 | |