ENS 44558
ENS Event | |
|---|---|
20:37 Oct 9, 2008 | |
| Title | 24-Hours Bulletin 91-01 Report Involving Failure to Visually Inspect Storage Cylinders |
| Event Description | The following information is provided without quotation for readability:
DESCRIPTION: On 10/09/08 at 1537 hours0.0178 days <br />0.427 hours <br />0.00254 weeks <br />5.848285e-4 months <br /> it was determined that procedure CP4-CU-CH6430, "In Storage Fissile Cylinder Inspection", does not fully meet the periodic inspection requirements of NCSA GEN-003. GEN-003 requires inspection every four years of all thick wall cylinders that contained fissile material since they were last washed on the inside of the cylinder. Only cylinders that were filled with fissile material on their last fill have been identified for inspection. Cylinders filled with fissile material, emptied and subsequently filled with non-fissile material and emptied, have not been inspected as required. Approximately 73 Cylinders that have contained fissile material since their last washing have not been inspected in violation of the requirement of NCSA GEN-003, these cylinders could contain residual nonvolatile material referred to as heel. Potentially the residual heel could contain fissile material. Double contingency is maintained by implementing two independent controls on one parameter (moderation). The first leg of double contingency relies on the design of the cylinder to ensure moderation control. Cylinders are designed to the requirements of ANSI N14.1 and ensure that it is unlikely for the cylinder wall to breach and allow water intrusion. This control on moderation was not violated. The second leg of double contingency relied on inspections every 4 years of the cylinder wall, valve, and plug for abnormal corrosion. This control ensures that in the event of a cylinder breach, it is unlikely that sufficient moderation to cause a criticality will enter the cylinder before it is identified and mitigated. Since the cylinders were not inspected within the 4 year time frame as required, this control on moderation was violated. The NRC Resident Inspector has been notified of this event. PGDP Problem Report No. ATRC-08-2918; PGDP Event Report No. PAD-2008-31; NRC Worksheet No. 44558. SAFETY SIGNIFICANCE OF EVENTS: Although a control requiring inspection of the cylinders every 4 years was violated, no cylinder breaches occurred. Later inspections identified no cylinder integrity issues, moderation control was lost and double contingency was not maintained. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR): In order for a criticality to be possible, more than 10kgs of water would have to enter a breach in a cylinder which contains more than a critical mass of material enriched to greater than 1.0 wt% 235U. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.): Moderation. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS) : There were 73 cylinders which were not inspected as required. These cylinders had at one time held fissile material. The cylinders were emptied except for a small residual heel and then filled with non-fissile material. The non-fissile material was then emptied leaving only the residual heel in the cylinder. Cylinder heels are typically less than 50 pounds. Assay is always less than 5.5% enrichment. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: NCSA GEN-003 requires cylinders containing material enriched to greater than or equal to 1.0 wt % 235U to be inspected every 4 years to identify significant signs of degraded cylinder wall, valve and plug. These cylinders were filled with fissile material, emptied and then subsequently filled with non-fissile material and then emptied again, but were not inspected within the four year requirement. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED : Cylinders have been inspected per the CP4-CU-CH6430 and the identified cylinders were found to comply with NCSA GEN-003.
On 10/10/08 at 1500 CDT, an additional 8 cylinders were discovered which had not been properly inspected. The additional cylinders were of a different size than the initial cylinders found, but fall under the same requirement. The additional cylinders have been inspected and all met the NCSA requirements. Notified R2DO (Shaeffer) and NMSS (McCartin). |
| Where | |
|---|---|
| Paducah Gaseous Diffusion Plant Paducah, Kentucky (NRC Region 2) | |
| License number: | GDP-1 |
| Reporting | |
| Response | |
| Time - Person (Reporting Time:+17.72 h0.738 days <br />0.105 weeks <br />0.0243 months <br />) | |
| Opened: | Billy Wallace 14:20 Oct 10, 2008 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Oct 10, 2008 |
| 44558 - 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 | |