ENS 40723
ENS Event | |
|---|---|
21:00 May 3, 2004 | |
| Title | Criticality Control 24-Hour (Bulletin 91-01) Report |
| Event Description | At 1600 on 5-03-04, the Plant Shift Superintendent was notified of a violation of SRI 5.4.1 of NCSE 052. The oil seals and bearing housing for the C-310 cell 6 stage 2B pump failed allowing significant quantities of oil to be accessible for entry to the cascade through a failed process seal in violation of SRI 5.4.1 in NCSE 052. Also, greater than 3.7 gallons (5.1 [measured]) of oil was found inside the pump casing in violation of the unlikely arguments which limit the amount of oil that will enter the process side of the pump.
The NRC Senior Resident Inspector has been notified of this event. SAFETY SIGNIFICANCE OF EVENTS: While the moderation parameter of 3.7 gallons of oil was exceeded, NDA measurements showed the pump contained less than a safe mass of uranium and double contingency has been established under NCSA GEN-010. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR: In order for a criticality to occur, greater than a critical mass of uranium would have to be in the pump and greater than 3.7 gallons of oil would have to enter the process side of the cell and moderate the uranium deposit in a critical configuration. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.): Double contingency is maintained by implementing two controls on moderation. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): The pump contains less than the [DELETED] 235U process limit at an enrichment of less than 5.5 wt %235U. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency relies on the oil seals and bearing housing to limit the amount of oil that may be accessible for entry to a failed process seal to less than 3.7 gallons. This SRI failed; therefore double contingency was not maintained. The second leg of double contingency relies on shutting down the affected equipment as soon as practical after discovery of a catastrophic process seal failure to make it unlikely to continue to operate for any appreciable length of time with wet air inleakage. Since the cell was shut down in accordance with control 3.2.2, but significant wet air inleakage continued for a period of time which allowed greater than 3.7 gallons of oil to enter the process side of the pump, the unlikely argument was violated. Since greater than 3.7 gallons of oil entered the process side of the cell, double contingency was not maintained. Since double contingency is based on two controls on one parameter, double contingency was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: NDA measurements showed the pump contained less than a safe mass of uranium and double contingency has been established under NCSA GEN-010. NUCLEAR CRITICALITY SAFETY CONTROLS INVOLVED AND THEIR IMPACT ON DOUBLE CONTINGENCY: Double Contingency Double contingency is maintained by implementing two controls on moderation. The first leg of double contingency relies on the oil seals and bearing housing to limit the amount of oil that may be accessible for entry to a failed process seal to less than 3.7 gallons. This SRI failed; therefore double contingency was not maintained. The second leg of double contingency relies on shutting down the affected equipment as soon as practical after discovery of a catastrophic process seal failure to make it unlikely to continue to operate for any appreciable length of time with wet air inleakage. Since the cell was shut down in accordance with control 3.2.2 but significant wet air inleakage continued for a time period which allowed greater than 3.7 gallons of oil to enter the process side of the pump, the unlikely argument was violated. Since greater than 3.7 gallons of oil entered the process side of the cell, double contingency was not maintained. Since double contingency is based on two controls on one parameter, double contingency was not maintained. The NCS parameter of moderation was not maintained. Potential Critical Pathways: In order for a criticality to occur, greater than a critical mass of uranium would have to be in the pump and greater than 3.7 gallons of oil would have to enter the process side of the cell and moderate the uranium deposit in a critical configuration. Safety Significance: While the moderation parameter of 3.7 gallons of oil was exceeded, NDA measurements showed the pump contained less than a safe mass of uranium and double contingency has been established under NCSA GEN-010. |
| Where | |
|---|---|
| Paducah Gaseous Diffusion Plant Paducah, Kentucky (NRC Region 2) | |
| License number: | GDP-1 |
| Reporting | |
| Response | |
| Time - Person (Reporting Time:+17.17 h0.715 days <br />0.102 weeks <br />0.0235 months <br />) | |
| Opened: | Eric Walker 14:10 May 4, 2004 |
| NRC Officer: | Arlon Costa |
| Last Updated: | May 4, 2004 |
| 40723 - 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 | |