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The following information was obtained fro … The following information was obtained from the regulatee via facsimile:</br>At 0845, on 04-23-04, the Plant Shift Superintendent was notified of a violation of Nuclear Criticality Safety (NCS) controls associated with storage of waste drums in the C-335 building. Two Spacing Exempt waste drums were identified to have been characterized utilizing erroneous results from the Q2 drum monitor in violation of Nuclear Criticality Safety Evaluation (NCSE) 091. The characterization is based on it being unlikely that the drum monitor will give an erroneous result. The purpose of the requirements is to ensure the mass in an NCS Spacing Exempt waste drum is below the (DELETED) 235U limit.</br>The waste drums have been independently sampled and demonstrated to be below the (DELETED) 235U limit.</br>The NRC Resident Inspector has been notified of this event.</br>SAFETY SIGNIFICANCE OF EVENTS:</br>While the (DELETED) 235U limit was not exceeded for these two drums, both legs of double contingency were lost and the potential exists for waste drums to be non-conservatively characterized using the Q2 drum monitor.</br>POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S)) OF HOW CRITICALITY COULD OCCUR:</br>In order for a criticality to occur, two or more waste drums containing above the (DELETED) 235U limit would have to be accumulated to exceed a critical mass with no spacing and be moderated.</br>CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.):</br> Double contingency is maintained by implementing two controls on mass.</br>ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): </br>Each drum contains less than (DELETED) 235U at an enrichment of less than 1.5 wt% 235U.</br>NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES:</br>The first leg of double contingency relies on it being unlikely for the Q2 drum monitor to provide an erroneous result. The drum monitor measurement gave a non-conservative erroneous result, which was used to characterize the drum. Therefore, the unlikely statement was violated. However, the drums were subsequently sampled with the result being below the (DELETED) 235U limit for each drum. Therefore, the parameter was maintained.</br>The second leg of double contingency relies on it being independently unlikely for the Q2 drum monitor to provide an erroneous result. The independent drum monitor measurement gave a non-conservative erroneous result, which was independently used to characterize the drum. Therefore, the independent unlikely statement was violated. However, the drums were subsequently independently sampled with the independent result being below the (DELETED) 235U limit for each drum. Therefore, the parameter was maintained.</br>Although the parameter was maintained, double contingency is based on two controls on one parameter. Therefore, double contingency was not maintained.</br>CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED:</br>1. Characterize waste drums (PF-04-7258 and PF-03-5051) using the independent sample results. Completed 04/23/04.</br>2. Complete the 'extent of condition' examination prior to making a determination for removal of the ropes and postings.</br>The Q2 drum monitor requires a density of material input to properly characterize drum material. Sodium fluoride (NaF) density was used instead of uranyl fluoride (UO2F2) which resulted in a non-conservative characterization. The drum contained both materials.</br>Plant personnel have imposed spacing requirements on all other drums in the immediate area that have questionable characterizations until they can be properly analyzed.</br>To prevent re-occurrence, plant management has issued orders and mandates to verify drum contents utilizing two different and distinct sampling methods (i.e. monitoring and laboratory sampling).(i.e. monitoring and laboratory sampling).
13:45:00, 23 April 2004 +
40,700 +
04:46:00, 24 April 2004 +
13:45:00, 23 April 2004 +
The following information was obtained fro … The following information was obtained from the regulatee via facsimile:</br>At 0845, on 04-23-04, the Plant Shift Superintendent was notified of a violation of Nuclear Criticality Safety (NCS) controls associated with storage of waste drums in the C-335 building. Two Spacing Exempt waste drums were identified to have been characterized utilizing erroneous results from the Q2 drum monitor in violation of Nuclear Criticality Safety Evaluation (NCSE) 091. The characterization is based on it being unlikely that the drum monitor will give an erroneous result. The purpose of the requirements is to ensure the mass in an NCS Spacing Exempt waste drum is below the (DELETED) 235U limit.</br>The waste drums have been independently sampled and demonstrated to be below the (DELETED) 235U limit.</br>The NRC Resident Inspector has been notified of this event.</br>SAFETY SIGNIFICANCE OF EVENTS:</br>While the (DELETED) 235U limit was not exceeded for these two drums, both legs of double contingency were lost and the potential exists for waste drums to be non-conservatively characterized using the Q2 drum monitor.</br>POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S)) OF HOW CRITICALITY COULD OCCUR:</br>In order for a criticality to occur, two or more waste drums containing above the (DELETED) 235U limit would have to be accumulated to exceed a critical mass with no spacing and be moderated.</br>CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.):</br> Double contingency is maintained by implementing two controls on mass.</br>ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): </br>Each drum contains less than (DELETED) 235U at an enrichment of less than 1.5 wt% 235U.</br>NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES:</br>The first leg of double contingency relies on it being unlikely for the Q2 drum monitor to provide an erroneous result. The drum monitor measurement gave a non-conservative erroneous result, which was used to characterize the drum. Therefore, the unlikely statement was violated. However, the drums were subsequently sampled with the result being below the (DELETED) 235U limit for each drum. Therefore, the parameter was maintained.</br>The second leg of double contingency relies on it being independently unlikely for the Q2 drum monitor to provide an erroneous result. The independent drum monitor measurement gave a non-conservative erroneous result, which was independently used to characterize the drum. Therefore, the independent unlikely statement was violated. However, the drums were subsequently independently sampled with the independent result being below the (DELETED) 235U limit for each drum. Therefore, the parameter was maintained.</br>Although the parameter was maintained, double contingency is based on two controls on one parameter. Therefore, double contingency was not maintained.</br>CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED:</br>1. Characterize waste drums (PF-04-7258 and PF-03-5051) using the independent sample results. Completed 04/23/04.</br>2. Complete the 'extent of condition' examination prior to making a determination for removal of the ropes and postings.</br>The Q2 drum monitor requires a density of material input to properly characterize drum material. Sodium fluoride (NaF) density was used instead of uranyl fluoride (UO2F2) which resulted in a non-conservative characterization. The drum contained both materials.</br>Plant personnel have imposed spacing requirements on all other drums in the immediate area that have questionable characterizations until they can be properly analyzed.</br>To prevent re-occurrence, plant management has issued orders and mandates to verify drum contents utilizing two different and distinct sampling methods (i.e. monitoring and laboratory sampling).(i.e. monitoring and laboratory sampling).
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00:00:00, 24 April 2004 +
GDP-1 +
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23:41:29, 24 November 2018 +
04:46:00, 24 April 2004 +
0.626 d (15.02 hours, 0.0894 weeks, 0.0206 months) +
13:45:00, 23 April 2004 +
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