ENS 44100
ENS Event | |
|---|---|
19:57 Mar 26, 2008 | |
| Title | 24 Hour Report of Degraded Criticality Control |
| Event Description | At 1410, on 3/26/08 the Plant Shift Superintendent was notified that a violation of a nuclear criticality safety approval (NCSA) had occurred. During a review of pre-removal NDA [Non destructive assessment] inspection in C-337 for the unit 3 cell 10 stage 2 converter inspection port, it was discovered that the NDA was performed on the wrong side of the converter (measurement taken on the east side of the converter, and the access hole was cut in the west side). The pre-removal NDA inspection was improperly performed resulting in a violation of NCSA GEN-10. The purpose of the requirement is to determine the initial handling category of the equipment.
Two independent post removal NDA measurements were performed on the adjacent system and two independent visual inspections were performed on the removed item that demonstrated the item and adjacent system were each UH [uncomplicated handling]. The results indicate the equipment was properly classified as UH based on the resulting mass. SAFETY SIGNIFICANCE OF EVENTS: Although a leg for double contingency was lost, the correct equipment handling category was used. Additionally, an independent verification of no visible uranium present on the removed item has been successfully performed in accordance with applicable procedures to NCS Exempt the item. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRIT!CALITY COULD OCCUR): The equipment contained less than a safe mass of uranium and the equipment was covered to prevent exposure to a moderator. The uranium mass would have had to exceed a critical mass. The equipment would then need to be exposed to sufficient moderator in order for a criticality to be possible. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY CONCENTRATION, ETC.): The process condition relied on for double contingency for this scenario is mass. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): The NDA measurement indicated less than 674 grams at 1.6679 wt% U-235. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency relies on mass. Prior to opening the system a pre-removal NDA is required to be performed to initially classify the handling category of the equipment. Since the pre-removal NDA was performed on the wrong side of the equipment potentially resulting in an improper handling categorization, this control was violated. The second leg of double contingency is based on mass by performing a post-removal NDA of the removed equipment and adjacent system within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to verify the handling category. This control was not violated. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: On 3/26/08, a second post removal NDA was completed on the adjacent system and a second visual inspection was performed on the removed item in order to verify the handling category is UH and re-establish double contingency. The NRC Senior Resident Inspector has been notified of this event. PGDP Problem Report No. ATRC-08-0906; PGDP Event Report No. PAD-2008-08 |
| Where | |
|---|---|
| Paducah Gaseous Diffusion Plant Paducah, Kentucky (NRC Region 2) | |
| License number: | GDP-1 |
| Reporting | |
| Response | |
| Time - Person (Reporting Time:+3.12 h0.13 days <br />0.0186 weeks <br />0.00427 months <br />) | |
| Opened: | Kevin Beasley 23:04 Mar 26, 2008 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Mar 26, 2008 |
| 44100 - 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 | |