ENS 46312
ENS Event | |
|---|---|
16:06 Oct 6, 2010 | |
| Title | 24 Hour Notification Under Bulletin 91-01 Concerning Cooldown Verification of Uf6 Cylinders |
| Event Description | At 1106 CDT, on 10/06/2010 the Plant Shift Superintendent was notified that the independent verification of cylinder cool down time had not been completed on the following Uranium Hexafluoride (UF6) Cylinders: PP5436, PP5453, PP5389, PP5435, PP5388, PP5424, PP5459, and PP5443 in accordance with NCSA GEN-003.
NCSA GEN-003 requires that prior to movement of a cylinder from a liquid UF6 cylinder handling area it shall be determined, independently verified, and documented that the required cooling time has passed. The purpose of this requirement is to ensure the cylinder does not contain liquid UF6 before it is moved from a liquid handling area. Upon discovery of the violation, it was determined that the cylinders had, in fact, met the required cool down period prior to movement; however, the independent verification had not been completed. Since this independent verification was not completed, double contingency was not maintained. Therefore, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC BL 91-01 Supplement 1. SAFETY SIGNIFICANCE OF EVENTS Although an NCSA control was violated, cylinder integrity was maintained. POTENTIAL CRITICALITY PATHWAYS (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR) A solid UF6 cylinder would have to have been breached and sufficient moderator entered the cylinder in order to support a criticality. ESTIMATED AMOUNT, ENRICHMENT, FORM OF MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS) The assay of any material involved is less than or equal to 5.5 wt. % U235. The cylinders involved were 10 ton cylinders. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES Double contingency is maintained by implementing two independent controls on one parameter (moderation). The first leg of double contingency relies on it being unlikely that industrial grade cranes, forklifts, and cylinder haulers would drop an ANSI N14.1 designed cylinder in such a way that it would be breached. This moderation control was maintained. The second leg of double contingency relies on independent verification that the required cool down time has passed, prior to moving a cylinder from a liquid cylinder handling area. This control helps ensure that the cylinder does not contain liquid UF6 prior to movement. The independent verification was not performed or documented. Therefore, this moderation control was violated. Upon discovery of the violation, it was determined that the cylinders had, in fact, met the required cool down period prior to movement. Double contingency relies on two independent controls on the same parameter. Since one of the two independent controls on moderation was violated, double contingency was not maintained; however, the moderation parameter was maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED The cool down times for the identified cylinders have been independently verified thus bringing them back into compliance with double contingency. The NRC Resident Inspector has been notified of this event. |
| Where | |
|---|---|
| Paducah Gaseous Diffusion Plant Paducah, Kentucky (NRC Region 2) | |
| License number: | GDP-1 |
| Reporting | |
| Response | |
| Time - Person (Reporting Time:+5.57 h0.232 days <br />0.0332 weeks <br />0.00763 months <br />) | |
| Opened: | Ron Dockery 21:40 Oct 6, 2010 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Oct 6, 2010 |
| 46312 - 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 | |