ENS 44223
ENS Event | |
|---|---|
22:21 May 18, 2008 | |
| Title | Violation of a Nuclear Criticality Safety Approval - 24-Hour Report |
| Event Description | At 1721 hours0.0199 days <br />0.478 hours <br />0.00285 weeks <br />6.548405e-4 months <br /> on 5-18-08 the Plant Shift Superintendent was notified that violation of a nuclear criticality safety approval (NCSA) had occurred.
At 1720 hours0.0199 days <br />0.478 hours <br />0.00284 weeks <br />6.5446e-4 months <br /> on 5-17-08, the coolant system for [DELETED] was evacuated using an R-114 evacuation pump. The recirculating cooling water (RCW) condenser for that cell had not been disconnected or vented before evacuation of coolant system vapor or air, in violation of NCSA CAS-21 Rev. 01, 'Operation and Shutdown of the Diffusion Cascade,' Control 3.2.3. That control states: 'The RCW condenser shall be disconnected or vented before coolant vapor is evacuated.' This control minimizes the amount of water that is available to moderate fissile material that might be present in the UF6 region of the process gas cooler. Coolant system leak rate testing results were logged as of 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> on 5-18-08 showing the coolant system to be evacuated to 30" vacuum and holding. At that pressure the system would be below the vapor pressure of water. Therefore, the coolant system being evacuated to that level and holding would indicate that no liquid water was present in the coolant system. The system being evacuated and holding proves that not only was the condenser free of any significant RCW to coolant leaks, but the process gas cooler was also essentially leak-tight. The NRC Senior Resident Inspector has been notified of this event. PGDP Problem Report No. ATRC-08-1471: PGDP Event Report No. PAD-2008-18; NRC Worksheet No. 44223 This violation represents a significant breach of NCS administrative controls for this operation: however, the safety significance of the as-found condition was quite low. The worst case enrichment [DELETED] at this location was just above the minimum fissile enrichment, so that a very large mass of optimally moderated uranium (more than [DELETED]) would have been needed for a criticality to be possible. Moderation would have required excessive water intrusion into the coolant system through condenser tube leaks, and subsequent water intrusion into the process gas region of the cooler/converter through a concurrent process gas cooler lube leak. Even though NCS Control 3.2.3 was violated, no significant water intrusion occurred. Although the as-found condition of the coolant system did not contain water, the parameter is considered lost since the typical condition of condenser tubes would be expect to result in water intrusion and would not represent a reliable barrier to in-leakage. Double contingency was re-established within four hours of discovery by confirming the coolant system was drained of any possible liquid. At 1615 hours0.0187 days <br />0.449 hours <br />0.00267 weeks <br />6.145075e-4 months <br /> on 5-18-08 the air evacuation pumps were isolated from [DELETED] coolant system, which is the last point at which any potential liquid would have been drained from the coolant system. The condenser venting was completed at 2050 hours0.0237 days <br />0.569 hours <br />0.00339 weeks <br />7.80025e-4 months <br /> on 5-18-08. Coolant system leak rate completed at 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> on 5-18-08 confirmed 30" vacuum and holding to show the condenser and process cooler were leak-tight. |
| 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: | Calvin Pittman 17:20 May 19, 2008 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | May 19, 2008 |
| 44223 - 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 | |