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	Start date	Reporting criterion	Title	Event description
ENS 48398	10 October 2012 18:05:00	Response	Double Contingency Control for Empty Cylinders Not Maintained	At 1305 CDT, on 10-10-12 the Plant Shift Superintendent (PSS) was notified that during reviews of paperwork for a customer, it was discovered that four clean, empty cylinders used for transfer did not have a hydrocarbon test performed prior to filling, in violation of NCSA 360-005. NCSA 360-005 requires a test for never used non-USEC owned cylinders prior to filling to detect the presence of hydrocarbons. The presence of moderator in the cylinders could lead to either an 'explosion' that ruptures the cylinder and releases UF6 or criticality from moderation of greater than a safe mass of uranium. The controls ensure that double contingency exits to prevent filling a cylinder containing enough moderator to support criticality. Cylinders affected are GE0195, GE0191, JM0226, and GE0407 and were filled on 9/16/12 and 9/22/12. Since one leg of double contingency was lost, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC BL 91-01 Supplement 1. The NRC Resident Inspector has been notified of this event. PGDP Problem Report No. ATRC-12-2554; PGDP Event Report No. PAD-2012-06. Responsible Division: Production Support & Product Scheduling SAFETY SIGNIFICANCE OF EVENTS: A control relied upon for double contingency was violated. A cold pressure check and cylinder weight check performed prior to initial transfer of UF6 did not indicate the presence of moderator, and customer compliance with ANSI N14.1 also ensures that cylinders received at PGDP would not contain moderator. There was no indication of an adverse reaction noted during the filling of the cylinders. A cold pressure check performed after filling and cooldown did not indicate that an adverse reaction associated with UF6 and moderator had occurred. The introduction of UF6 eliminates the possibility of any residual moderator remaining in the cylinder; therefore, the cylinders are now in compliance with double contingency. POTENTIAL CRITICALITY PATHWAYS INVOLVED: In order for criticality to be possible, sufficient undetected moderator would have to be present in the cylinder prior to the initial transfer of UF6. Although a control was violated, the cold pressure check ensured the moderation parameter was not exceeded. CONTROLLED PARAMETERS: Double contingency for this scenario is provided by two controls on moderation. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL: 20,000 lbs. of UF6 at approximately 4.0% U235 enrichment. Plant limit is 5.5 wt.% U235 enrichment NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency is based on cylinder compliance with ANSI N14.1 and the performance of a cold pressure check prior to initial transfer of UF6. ANSI N14.1 compliance ensures that the cylinders are clean and free of moderator. The cold pressure check provides a positive indication that no moderator is present inside the cylinder. The cold pressure check was adequately performed prior to initial UF6; therefore, this control was not violated. The second leg of double contingency is based on performing a hydrocarbon test on the internal valve opening of the UF6 cylinder prior to initial transfer of UF6. The presence of hydrocarbon material in a UF6 cylinder could result in a cylinder rupture or criticality prior to initial transfer of UF6. The hydrocarbon test will give telltale signs that the inside of the cylinder may contain oil or other potential moderators. The hydrocarbon test was not performed; therefore, this control was violated. This leg of double contingency is considered to have been lost. Since double contingency for this scenario is based on two controls on one parameter and a control was violated, double contingency was not maintained. CORRECTIVE ACTIONS: None are needed.
ENS 47911	8 May 2012 21:16:00	10 CFR 76.120(c)(2) Response	Autoclave High Pressure Isolation System Failure	At 1616 CDT, on 05-08-12 the Plant Shift Superintendent (PSS) was notified that C-360 (Toll Transfer & Sampling Building) Autoclave #2 had a failure in the Autoclave High Pressure Isolation System (AHPIS). (AHPIS) is designed to: 1) prevent a cylinder failure inside the autoclave as a result of overheating; and 2) mitigate releases to the atmosphere from releases inside the autoclave. Autoclave containment is required to be operable per TSR 2.1.3.1 while the autoclave is in TSR modes 3 (containment), 4 (autoclave closed), and 5 (autoclave heating). On 5/08/12 at 1610 CDT an operator noticed water flowing from the autoclave head to shell sealing surface on the #2 autoclave in C-360 while a cylinder was being heated (TSR mode 5 - autoclave heating). The PSS was notified of the loss of containment at 1616 CDT and the (AHPIS) was declared inoperable. The steam cycle was interrupted and the autoclave was placed in a non-applicable TSR mode at 1657 CDT. No release of UF6 occurred due to the failure of the (AHPIS). This event is reportable as a 24 hour event in accordance with 10CFR 76.120(c)(2)(i). This is an event in which equipment is disabled or fails to function as designed when: a.) the equipment is required by a TSR to prevent releases, prevent exposures to radiation and radioactive materials exceeding specified limits, mitigate the consequences of an accident, or restore this facility to a pre-established safe condition after an accident; b.) the equipment is required by a TSR to be available and operable and either should have been operating or should have operated on demand; and c.) no redundant equipment is available and operable to perform the required safety function. The NRC Senior Resident Inspector has been notified of this event. PGDP Assessment and Tracking Report No. ATRC-12-1195; PGDP Event Report No. PAD-2012-02; Responsible Division: Operations * * UPDATE FROM BILLY WALLACE TO DONALD NORWOOD AT 1640 EDT ON 5/9/2012 * * * After further review the licensee determined that additional reportability criteria were met as described below: At 1616 on 05/08/2012, the PSS was notified that C-360 Autoclave #2 had water flowing from the autoclave head to shell sealing surface indicating a potential failure in the Autoclave High Pressure Isolation System (AHPIS) containment, which is relied on as an engineered control in NCSE 042 (SRI 5.5.3). The AHPIS is designed to minimize leaks to atmosphere from the autoclave under maximum pressures resulting from a UF6 release from the cylinder, valve or pigtail in the autoclave. The maximum acceptable leak rate for the autoclaves is 12 SCFM at a minimum test pressure of 90 psig or a 10 psi pressure drop in 1 hour. In order to determine if the AHPIS would have met its safety function, a pressure decay test will be performed. However, the pressure decay test will not be performed within 24 hours of discovery. Therefore, it is conservatively assumed that the leak discovered is greater than 12 SCFM or greater than 10 psi pressure drop in 1 hour; resulting in a 24 hour NCS reportable event. When the leak was noticed, the heat cycle was interrupted and the autoclave placed in a safe configuration. No release of UF6 had occurred in the autoclave when the leak out the autoclave was found. This event is reportable as a 24 hour event in accordance with 24-Hr. NRC BL 91-01 Supp. 1. This is a criticality safety event in which violations involving operations that comply with the double contingency principle and do not meet the criteria for a 4-hr report, but still result in a violation of the double contingency principle, such as, events where the double contingency principle is violated but control is immediately reestablished. Safety Significance of Events: --While an NCSA control was not maintained resulting in the potential autoclave leak rate being exceeded, a release of fissile material from a cylinder in the autoclave did not occur and therefore a criticality was not possible. Potential Criticality Pathways Involved: --In order for a criticality to be possible, a cylinder, valve, or pigtail of a fissile cylinder would have to fail and release greater than a safe mass of fissile material into the autoclave and the autoclave containment would have to fail allowing a large release to atmosphere of uranium and settle out in an unfavorable geometry with sufficient moderator present. Controlled Parameters: --The first leg of double contingency is based on mass. --The first leg of double contingency is based on administrative and design controls to ensure that it is unlikely to have a large release of UF6 from the cylinder, valve or pigtail in the autoclave while healing the cylinder. --The second leg of double contingency is based on geometry moderation. Estimated Amount, Enrichment, Form of Licensed Material: --No leakage of UF6 occurred. Nuclear Criticality Safety Control(s) or Control System(s) and Description of the Failures or Deficiencies: --The first leg of double contingency is based on mass. --The first leg of double contingency is based on administrative and design controls to ensure that it is unlikely to have a large release of UF6 from the cylinder, valve or pigtail in the autoclave while heating the cylinder. This control was maintained. --The second leg of double contingency is based on geometry / moderation. --Small leaks out of the autoclave to atmosphere are considered normal case and the Autoclave High Pressure Isolation System ensures containment to minimize a significant release to atmosphere if a release occurs in the autoclave during heating. The AHPIS ensures that the maximum leak rate from the autoclave will not exceed 12 SCFM or a maximum acceptable pressure drop of 10 psi in 1 hour. If the containment leak rate is maintained, only a small amount of uranium could leak to atmosphere and the uranium would form in thin layers on surfaces in a geometrically safe configuration. Also there would be insufficient uranium to leak outside of the building; therefore there would not be a sufficient source of moderation. Since this control is assumed to have failed, uranium could leak out of the autoclave to atmosphere if a large release of UF6 occurred in the autoclave and potentially deposit in geometrically unfavorable configurations in areas where sufficient moderators exist. Since the leak rate cannot be confirmed within 24 hours, it is conservatively assumed that the geometry moderation parameter was lost and double contingency was not maintained. Corrective Actions To Restore Safety Systems and When Each Was Implemented: --Perform a pressure decay test on Autoclave #2 according to procedures and if the leak rate is determined to be greater than 12 SCFM or 10 psi in one hour, repair AHPIS prior to heating another cylinder containing uranium. The NRC Resident Inspector has been notified of this event. PGDP Assessment and Tracking Report No. ATRC-12-1195; PGDP Event Report No. PAD-2012-03; Responsible Division: Operations. Notified R2DO (Freeman) and NMSS EO (Campbell). * * RETRACTION FROM DAVID PETTY TO DONG PARK AT 1403 EDT ON 5/15/2012 * * * Subsequent to the above notifications on May 10, 2012, autoclave no. 2 was subjected to a pressure decay test in the as-found condition. The test indicated that the High Pressure Isolation Safety System would have been capable of performing its intended safety function if called upon on May 8, 2012, during the heat cycle subject of the event reports. Thus, the event was not required to be reported under 10CFR 76.120(c)(2)(i) and the notifications may be retracted. Subsequent to the above notifications on May 10, 2012, autoclave no. 2 was subjected to a pressure decay test in the as-found condition. The test indicated that the High Pressure Isolation Safety System would have been capable of performing its intended safety function if called upon on May 8, 2012, during the heat cycle subject of the event reports. The pressure drop from the as-found test was less than the maximum allowable pressure drop for the system required for criticality safety. Thus, the event did not meet the criteria to be reported under 24-Hr. NRC BL 91-01 Supp. 1. The NRC Senior Resident Inspector has been notified of this event. Notified R2DO (Shaeffer) and NMSS EO (Guttmann).
ENS 47483	28 November 2011 15:30:00	Response	24-Hour Report Concerning a Localized Loss of a Geometry Criticality Control Contingency	At 0930 CST on 11-28-11, during annual inspection of the C-400/C-409 floor drains and sumps according to procedure CP4-CU-CH6021, a chemical operator identified that an eye wash drain was no longer properly sealed around the concrete base and would not prevent solutions from entering the drain if challenged. NCSA (Nuclear Criticality Safety Assessment) CHM-001 requires specific drains to be sealed to prevent the accumulation of fissile material in the unsafe geometry drain system. In violation of NCSA CHM-001, the poured concrete base surrounding the eye wash drain #147 in C-400 was discovered to be broken loose from the floor so that it could no longer provide a seal against spilled uranium solution getting into the drain system. SAFETY SIGNIFICANCE OF EVENTS Although the concrete block has broken loose from the floor, only a small crack exists at the base of the concrete block which would present a torturous solution path to the drain. Therefore, a large release will be prevented from transporting a significant amount of solution to the drain system. While the Safety Related Item failed, no fissile material was released onto the C-400 building floor and no fissile material entered the drain system through this drain. POTENTIAL CRITICALITY PATHWAYS INVOLVED In order for a criticality to occur a release of greater than a safe mass of uranium onto the floor of C-400 would have to occur. A solution containing greater than a safe mass would then have to migrate to the drain, leak into the drain system, and accumulate in an unfavorable geometry. CONTROLLED PARAMETERS The two process conditions relied upon for double contingency for this scenario are mass and geometry. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL Process is designed to handle uranium contaminated solutions with a maximum assay of 5.5 wt.% U235. NUCLEAR CRITICALITY SAFETY CONTROL AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES The first leg of double contingency is based on the mass of uranium in solution form that leaks out of the system. The analysis credits both the integrity of the system and the fact that the tanks and piping are inspected for leakage. Small leaks will be identified and fixed before they have leaked enough uranium mass in solution to be a concern. Since no leakage has occurred, this control was not violated. The second leg of double contingency relies on the integrity of the floor drain seals to prevent uranium solution from getting into the unsafe geometry drain system. Since a pathway from the floor to the drain system exists, this control was violated and the parameter was not maintained. Because the parameter was not maintained double contingency was not maintained. Double contingency was not maintained because the geometry parameter was not maintained. CORRECTIVE ACTIONS 1. Stop fissile solution operations in the vicinity of the eyewash drain. This was completed at 1000 CST on 11-28-11. 2. Restore the seal to this drain. Pending 3. Upon successful restoration of the seal for the eyewash drain #147, fissile solution operations may be resumed. Pending Since one leg of double contingency was lost, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC BL 91-01 Supplement 1. The NRC Resident Inspector has been notified of this event. PGDP Problem Report No. ATRC-11-3171 and PGDP Event Report No. PAD-2011-20.
ENS 47310	30 September 2011 13:54:00	Response	24-Hour Nrc Bulletin 91-01 Report Involving a Loss of One Leg of Double Contingency	Description: At 0854 CDT on 09-30-11, the Plant Shift Superintendent (PSS) was notified that water was observed in the #5 withdrawal position scale pit during the completion of the monthly test of the C-310 scale pit water detection system alarm module. The alarm module was being tested per procedure, when the module was found with the visual alarm (a red light) on at the local panel in the #5 withdrawal position room. In response to the alarm, the scale pit hatch was opened and the water detection sensor cable was observed to be at least partially submerged. Immediate investigation found the sump pump breaker to be tripped; when the breaker was reset the pump actuated and water was immediately removed. At the time of the occurrence, product withdrawal was in progress in the #3 and #4 withdrawal position room, and no cylinder was present in the #5 withdrawal position room. The source of the water was found to be a leaking steam condensate valve above the #5 withdrawal room ceiling. The water had drained to the concrete pad outside the building and then along the scale cart rails, eventually finding its way into the #5 scale cart pit where it gradually accumulated. Because the C-310 Scale Pit Water Detection Alarm did not function as credited, it is in violation of NCSE 032 (NCSA 310-004). Since one leg of double contingency was lost, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC BL 91-01 Supplement 1. The NRC Senior Resident Inspector has been notified of this event. PGDP Problem Report No. ATRC-11-2610; PGDP Event Report No. PAD-2011-17 SAFETY SIGNIFICANCE OF EVENTS: The safety significance of this event is low, even though the event made it possible for the level of pre-existing water to exceed the safe geometry limit. Although it is normal case for overall PGDP operations to have assay up to 5.5 wt.% 235U, the actual assay of product withdrawal operations during the period in question remained no higher than 2.0 wt. % 235U. At that actual assay, the depth of water necessary to support a criticality would have been more than 7.21 inches, which might have been credible but in itself would have remained a very unlikely possibility due to the slow ingress rate and high probability of detection and mitigation by personnel performing routine activities in that area. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR): In order for a criticality to happen, a significant breach in the process system integrity would have to occur. After the breach, fissile UF6 and its reaction products would have to react with pre-existing water to form fissile solution. There would have to be a sufficient depth of water in the pit to support a criticality (e.g. more than 3.68 inches of water at 5.5 wt. % 235U). CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.): The two process conditions relied upon for double contingency are mass and geometry. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): Product withdrawal assay at the time of the event was no higher than 2.0 wt% U235. However, no UF6 release occurred. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: Geometry is controlled in the second leg of double contingency by limiting the level of pre-existing water that might be present in the scale pit. Water accumulation is considered normal case in the NCSE by acute or by chronic sources. The NCSE credits the Scale Pit Water Detection Alarm to provide detection of chronic water accumulation in the scale pit. The alarm is set to actuate before the water level exceeds 2.5 inches in the pit. The geometry parameter limit is 3.68 inches assuming the worst-case possible enrichment of 5.5 wt.% 235U. The alarm is credited to provide early indication, and result in prompt mitigation, of water ingress to the pit before the NCS parameter limit is exceeded. Since the alarm was not functional, and the ingress rate was sufficiently slow that ingress was not easily detectable, there was no reliable means in place to detect and mitigate the ingress of water into the pit. The sensor and local panel light performed their intended function; however, it is the ACR audible and visible alarms that are controlled as AQ-NCS equipment and not the local panel light and buzzer. With the alarm out of service, continued ingress of water to the pit could have resulted in exceeding the geometry parameter limit for water depth before detection and mitigation. NCS entered the scale pit for inspection shortly after notification of the discovery and after the water had been drained. NCS observed that the water level at the lowest point in the pit may have reached 2.5 inches. Based on those inspections, it is likely that the water level remained below the 3.68-inch level, but there was no definitive way to prove the maximum height that might have occurred throughout the period of time when the alarm was not functional. Therefore, for conservatism it is assumed credible that the geometry parameter limit was violated during the lime the alarm was not functional. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: The sump pump was immediately activated by resetting its breaker, which restored the water level in the pit below the 2.5 inch administrative limit, thus removing the hazard of this incident. The #5 withdrawal position scale pit will be checked twice per shift beginning on 9-30-11 in accordance with procedure due to the ACR alarm being out-of-service.
ENS 47176	19 August 2011 13:15:00	Response	24-Hr Loss of Criticality Control Report Required Under Bulletin 91-01, Supplement 1	At 0815 CDT on 08-19-11, a Chemical Operations First Line Manager discovered that during disassembly of a single Seal Exhaust/Wet Air (SX/WA) pump, pump housing subcomponents (i.e. two piston slides and a cam) were placed within 2 feet of the internal oil separators. Nuclear Criticality Safety Approval (NCSA) GEN-011 requires a minimum 2-foot edge-to-edge spacing between pump housing subcomponents and internal oil separators. The purpose of this control is to ensure interaction between grossly contaminated fissile items is minimized during movement and storage. The Plant Shift Superintendent and the NCS group were notified and access to the area was controlled. Since one leg of double contingency was lost, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC BL 91-01, Supplement 1. The NRC Senior Resident Inspector has been notified of this event. PGDP Problem Report No. ATRC-11-2161 PGDP Event Report No. PAD-2011-13 POTENTIAL CRITICALITY PATHWAYS INVOLVED: In order for a criticality to be possible, the components would have to be grossly contaminated and brought together in a geometry capable of supporting a criticality and an additional spacing violation would have to occur before a criticality is possible. CONTROLLED PARAMETERS: Double contingency is maintained by implementing controls on geometry and interaction. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL : Uranium contaminated oil. Product withdrawal assay at the time of the event was less than 4.95 wt% U235. The pump components were not grossly contaminated. 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 geometry of the seal exhaust/wet air pump components. The pump components are controlled as safety related items. This control was not violated. Therefore, this leg of double contingency was maintained. The second leg of double contingency relies on minimizing interaction between internal oil separators and pump housing subcomponents. Interaction is controlled by maintaining a minimum 2-foot edge-to-edge spacing between pump internal oil separators and pump housing subcomponents. The pump housing subcomponents were placed within 2 feet of the internal oil separators in violation of this control. The interaction parameter was not maintained; therefore this leg of double contingency was not maintained. Double contingency was not maintained because the interaction parameter was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: 1. Control Access to the area. This was completed at 0845 CDT on 08/19/11. 2. Move one item at a time such that the spacing between the pump housing subcomponents and the internal oil separators is always increasing until a minimum 2-foot edge-to-edge spacing has been established. This was completed at 1445 CDT on 08/19/11. 3. Upon establishing the proper spacing between the pump housing subcomponents and the internal oil separators, the exclusion zone may be removed. This was accomplished at 1450 CDT on 08/19/11.
ENS 46592	3 February 2011 15:30:00	Response	24 Hour Notification Under Bulletin 91-01 Concerning Leakage of Moderating Liquid	At 0930 CST on 02-03-11, the Plant Shift Superintendent (PSS) was notified that a steam condensate line broke above the C-310 withdrawal room and water leaked through the ceiling into the withdrawal room on the ground floor. Water accumulated greater than 0.5 inch in depth in the diked area above the withdrawal room in violation of NCSA (Nuclear Criticality Safety Approval) 310-004. NCSA 310-004 requires that open containers with volumes greater than 5.5 gallons shall not contain pre-existing moderator greater than 0.5 inches in depth. During the walk down, it was discovered that the sprinkler heads currently installed above the withdrawal room are rated at 160F in violation of the NCS (Nuclear Criticality Safety) limit. NCSE (Nuclear Criticality Safety Evaluation) 032 requires the minimum activation temperature to be no lower than 200F. The sprinkler system was taken out of service and drained at 2131 CST on 02-03-11 and the level of water accumulated in the diked area was verified to be less than 0.5 inches at 0426 CST on 02-04-11. Since one leg of double contingency was lost, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC BL 91-01 Supplement 1. The NRC Senior Resident Inspector has been notified of this event. SAFETY SIGNIFICANCE OF EVENTS The first leg of double contingency is based on preventing a release of fissile material greater than the safe mass of uranium. This event did not release fissile material greater than the safe mass of uranium. POTENTIAL CRITICALITY PATHWAYS (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR) In order for a criticality to be possible, a large UF6 release containing greater than a critical mass of uranium would have to occur and accumulate greater than the critical configuration. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.) The two process conditions relied upon for double contingency are mass and geometry. ESTIMATED AMOUNT, ENRICHMENT, FORM OF MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS) Product withdrawal assay at the time of the event was less than 4.95 wt% U235. However, no UF6 release occurred. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES The first leg of double contingency is based on preventing a release of fissile material greater than the safe mass of uranium. Since a UF6 release containing greater than the safe mass has not occurred, the mass parameter has maintained. The second leg of double contingency limiting moderating liquids in open containers to less than 0.5 inches and requiring the sprinkler head activation temperature to greater than 200F. Since the diked area above the withdrawal room did accumulate water level greater than 0.5 inches, the control was violated. Additionally, since the installed sprinkler heads activation temperature is less than 200F, a design feature of NCSE 032 was violated. Therefore, double contingency was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED Shiftly checks of the diked area above the withdrawal have been initiated to ensure water level is not accumulating. The condensate leak above the withdrawal room was repaired and solution level verified to be less than 0.5 inches (0426 (CST) on 2/4/11). The sprinkler systems associated with the sprinkler heads above the withdrawal room have been isolated until the sprinkler heads can be replaced with heads that comply with NCSE 032 (Systems isolated at 2131 (CST) on 2/3/11).
ENS 46312	6 October 2010 16:06:00	Response	24 Hour Notification Under Bulletin 91-01 Concerning Cooldown Verification of Uf6 Cylinders	At 1106 CDT, on 10/06/2010 the Plant Shift Superintendent was notified that the independent verification of cylinder cool down time had not been completed on the following Uranium Hexafluoride (UF6) Cylinders: PP5436, PP5453, PP5389, PP5435, PP5388, PP5424, PP5459, and PP5443 in accordance with NCSA GEN-003. NCSA GEN-003 requires that prior to movement of a cylinder from a liquid UF6 cylinder handling area it shall be determined, independently verified, and documented that the required cooling time has passed. The purpose of this requirement is to ensure the cylinder does not contain liquid UF6 before it is moved from a liquid handling area. Upon discovery of the violation, it was determined that the cylinders had, in fact, met the required cool down period prior to movement; however, the independent verification had not been completed. Since this independent verification was not completed, double contingency was not maintained. Therefore, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC BL 91-01 Supplement 1. SAFETY SIGNIFICANCE OF EVENTS Although an NCSA control was violated, cylinder integrity was maintained. POTENTIAL CRITICALITY PATHWAYS (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR) A solid UF6 cylinder would have to have been breached and sufficient moderator entered the cylinder in order to support a criticality. ESTIMATED AMOUNT, ENRICHMENT, FORM OF MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS) The assay of any material involved is less than or equal to 5.5 wt. % U235. The cylinders involved were 10 ton cylinders. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES Double contingency is maintained by implementing two independent controls on one parameter (moderation). The first leg of double contingency relies on it being unlikely that industrial grade cranes, forklifts, and cylinder haulers would drop an ANSI N14.1 designed cylinder in such a way that it would be breached. This moderation control was maintained. The second leg of double contingency relies on independent verification that the required cool down time has passed, prior to moving a cylinder from a liquid cylinder handling area. This control helps ensure that the cylinder does not contain liquid UF6 prior to movement. The independent verification was not performed or documented. Therefore, this moderation control was violated. Upon discovery of the violation, it was determined that the cylinders had, in fact, met the required cool down period prior to movement. Double contingency relies on two independent controls on the same parameter. Since one of the two independent controls on moderation was violated, double contingency was not maintained; however, the moderation parameter was maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED The cool down times for the identified cylinders have been independently verified thus bringing them back into compliance with double contingency. The NRC Resident Inspector has been notified of this event.
ENS 46105	17 July 2010 19:07:00	Response	24 Hour 91-01 Bulletin Report on Loss of One of Two Criticality Control Contingencies	At 1407 CDT, on 07/17/2010 the Plant Shift Superintendent was notified that cracks had been discovered in the C-400 Spray Booth containment pan by Quality Control Inspectors. The floor pan for the spray booth storage tanks, near the hand tables, was found to be inadequate and would allow solution to leak directly onto the concrete floor, in violation of NCSE (Nuclear Criticality Safety Evaluation) 015. The floor pan is a Safety Related Item that is intended to prevent solution from leaking to the concrete floor beneath the floor pan and accumulating in or creating an unsafe geometry/volume. Since one leg of double contingency was lost, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC Bulletin 91-01 Supplement 1. The process conditions relied upon for double contingency for this scenario are mass and geometry. The first leg of double contingency is based on the mass of uranium in solution form that leaks out of the system. The analysis credits both the integrity of the Spray Booth system and the fact that the tanks and piping are inspected for leakage. Small leaks will be identified and fixed before they have leaked enough uranium mass, in solution form, to be a concern. This control was not violated. The second leg of double contingency relies on the integrity of the floor pan to prevent accumulated liquids from leaking to the underlying concrete floor and accumulating in unfavorable geometries that may be present or created under the containment pan. Because a portion of the floor pan was discovered to have a hole, the Safety Related Item was violated; therefore, this control was violated. Pressure was placed on the Spray Booth floor pan in the area around the crack. Based on this inspection, there are no indication of unsafe geometry voids being present or having been created under the floor pan. Because the integrity of the floor pan was not maintained, this leg of double contingency is conservatively being considered as having been lost. Double contingency is conservatively considered to have been lost since the integrity of the spray booth storage tank floor pan was lost. In order for a criticality to be possible, greater than a safe mass of fissile material, in solution form, would have to leak out of the system undetected, leak under the floor pan, dissolve the concrete floor, and accumulate in an unsafe geometry. While the intended safety function of the Safety Related Item was violated, there was no significant uranium solution leak from the Spray Booth system. Additionally, there are no indications of unsafe geometry voids under the floor pan. The NRC Senior Resident Inspector has been notified of this event. The crack was characterized as through-wall and approximately 9 inches long. Since the pan is flush to the concrete floor it is mounted on, the licensee does not believe that any material has accumulated under the pan. A preliminary inspection of the pan did not reveal any indication of voiding under the pan. The licensee still has not determined if the pan will be lifted to inspect underneath. The crack was found during an annual inspection of the pan. The cause of the cracking is still under investigation.
ENS 45492	12 November 2009 17:15:00	Response	Violation of a Nuclear Criticality Safety Control	At 1115 CST on 11/12/09, abandoned cell piping was reported in C-331 and C-335 cell housings. The 16-inch abandoned piping is from the cell recycle line that was replaced in the mid 1970s. NCS (Nuclear Criticality Safety) controls require that equipment openings with unknown uranium deposits shall be covered with water-proof covers that are fire resistant. Since the piping contains an unknown uranium mass, and was discovered without water-proof covers, the NCS control was violated. Since moderation is the primary criticality control, and where double contingency cannot be re-established within 4 hours, this is being reported to the NRC as a 4-hour Event Report in accordance with NRC BL 91-01 Supplement 1. The NRC Resident Inspector has been notified of this event. PGDP Problem Report No. ATRC-09-2781; PGDP Event Report No. PAD-2009-19. Safety significance of events: Although the NCS control to cover the pipe openings was violated, it was not exposed to a liquid moderator. The geometry of the pipe is safe for a maximum enrichment that may be in the pipe. During the plant modifications that replaced the cell recycle lines, the maximum plant enrichment was 2.0 wt. % U235. There are no indications, based on quarterly NDA scans, that the piping contains greater than a safe mass of uranium. Therefore, the safety significance of the event is low. Potential criticality pathways involved: The maximum plant enrichment at the time the piping was in operation was a maximum 2.0 wt. % U235. The piping is contained in housing without fire suppression. The single parameter pipe diameter for that enrichment is greater than 16 inches. In order for a criticality to be possible, the pipe would have to contain greater than a critical mass. A large amount of moderator would have to enter the horizontal pipe opening. Greater than a critical mass would then have to be washed from the pipe due to the unlikely moderator release at the pipe opening. The washed material would then have to accumulate in an unsafe geometry. Controlled parameters: Moderation. Estimated amount, enrichment, form of licensed material: The assay of any material is less than or equal to 2.00 wt. % U235. Nuclear Criticality safety control(s) or control systems(s) and description of the failures or deficiencies: The first leg of double contingency relies on control of moderation. Moderator intrusion associated with sprinkler activation is controlled by limiting fire sprinkler head activation temperatures at the ceiling and bypass heights. The analysis also determined that significant moderator intrusion into open fissile piping due to inadvertent spills, RCW/oil line leaks, or other mechanism is unlikely. These controls were not violated and an unlikely moderator release event has not occurred at the pipe opening. The second leg of double contingency is also based on moderation. Piping exceeding 10.25 inches that contains an unknown or greater than safe mass deposit is required to have openings covered with fire resistant waterproof covers. Since the piping is nominal 16 inches in diameter, contains an unknown uranium mass, the NCS control was violated. Since the openings are not covered resulting in a loss of NCS control and there are two controls on one parameter, the process condition was not maintained. Corrective actions to restore safety systems and when each was implemented: Control access to the area. Exempt the pipe from NCS controls based on enrichment determination, cover the pipe openings, or quantify the uranium mass in the pipe.
ENS 45042	4 May 2009 10:07:00	Response	24 Hour 91-01 Bulletin Report on Loss of One of Two Criticality Control Contingencies	At 0507 CDT, on 05/04/09 the Plant Shift Superintendent was notified that a fissile sample buggy in C-331 Process Building was in violation of the 2-foot spacing requirement from a fissile HEPA vacuum. The buggy was pushed up against the HEPA vacuum spacing pan which resulted in approximately 21-inches of separation between the fissile material items. The situation has been remediated according to Nuclear Criticality Safety guidelines. Since one leg of double contingency was lost, this is being reported to the NRC as a 24-hour Event Report in accordance with NRC BL 91-01 Supplement 1. SAFETY SIGNIFICANCE OF EVENTS: There were approximately 21-inches of separation between fissile material items, therefore, although the minimum 24-inch (2-feet) spacing was violated, there was significant spacing provided. POTENTIAL CRITICALITY PATHWAYS INVOLVED: Even if the items had been configured with no spacing, an additional upset would be necessary in order for a criticality to be possible. CONTROLLED PARAMETERS: Geometry, interaction. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL: The assay of any material is less than or equal to 5.5 wt. % U235. NUCLEAR CRITICALITY SAFETY CONTROL AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency relies on maintaining a minimum of 2 feet edge to edge between the HEPA vacuum and other fissile material; this control was violated. The second leg of double contingency, which was not violated, relies on the geometry of the HEPA vacuum cleaner and demonstrates that a single spacing violation is subcritical. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: Control access to the area. Move the sample buggy in a direction away from the HEPA vacuum such that the spacing is always increasing until the minimum 2-feet edge to edge spacing has been re-established. Double contingency was re-established by 1300 hours on 5/4/09. The NRC Senior Resident Inspector has been notified of this event.
ENS 44558	9 October 2008 20:37:00	Response	24-Hours Bulletin 91-01 Report Involving Failure to Visually Inspect Storage Cylinders	The following information is provided without quotation for readability: DESCRIPTION: On 10/09/08 at 1537 hours 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. * * UPDATE AT 1750 EDT ON 10/10/08 FROM BILLY WALLACE TO STEVE SANDIN VIA FAX * * * 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).
ENS 44223	18 May 2008 22:21:00	Response	Violation of a Nuclear Criticality Safety Approval - 24-Hour Report	At 1721 hours on 5-18-08 the Plant Shift Superintendent was notified that violation of a nuclear criticality safety approval (NCSA) had occurred. At 1720 hours 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 hours 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 hours 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 hours on 5-18-08. Coolant system leak rate completed at 2100 hours on 5-18-08 confirmed 30" vacuum and holding to show the condenser and process cooler were leak-tight.
ENS 44151	17 April 2008 21:44:00	Response	24-Hour Nrc Bulletin 91-01 Report Involving an Excessively Large Container Found in a Fissile Control Area	An open and unattended Rad bag (greater than 5.5 gallon capacity), containing a valve stem fixture, was found in the C-400 G-17 valve disassembly FCA (Fissile Control Area) in violation of NCSA GEN-015. NCSA GEN-015 limits the volume of portable containers taken into an FCA to less than 5.5-gallons. The purpose of the requirement is to limit the accumulation of fissile waste to approved containers. Although NCSA GEN-029 allows the use of larger than 5.5-gallon containers for small equipment items, these containers are required to be fastened or taped closed or attended while open. This bag was not fastened / taped and was unattended. The valve stem fixture had been placed within the Rad bag for contamination control purposes while being transported into the area. The fixture contained no fissile material; there was no fissile equipment within the FCA; and no fissile work being performed within the FCA. The NRC Senior Resident Inspector has been notified of this event. PGDP Problem Report No. ATRC-08-1 147; PGDP Event Report No. PAD-2008-11.
ENS 44100	26 March 2008 19:57:00	Response	24 Hour Report of Degraded Criticality Control	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 hours 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
ENS 44056	11 March 2008 19:57:00	Response	Two Cylinders Identified with Weight Change Prior to Wash	Between 1979 and 1985, approximately 960 thin-walled cylinders were obtained by Paducah Gaseous Diffusion Plant (PGDP), transferred to Allied Chemical, and filled with near-normal assay material as part of a strategic feed reserve. These cylinders were transferred to Oak Ridge Gaseous Diffusion Plant (ORGDP) for storage. They were shipped back to PGDP beginning in the early 1990s. All but three of these cylinders have been fed. In early 2003, the Nuclear Criticality Safety Evaluation (NCSE) was revised to evaluate the washing of the heeled cylinders. At 1457 hours on 3/11/2008, the Plant Shift Superintendent was notified that two non-fissile cylinders were identified in the ORGDP strategic reserve category that had a weight change while stored at ORGDP in violation of the NCSE for the C-400 cylinder wash operation. One leg of double contingency is based on it being unlikely that cylinders in this category would be introduced into the process while stored at ORGDP. The weight change indicated that these cylinders were introduced into the process at ORGDP. The other leg of double contingency is based on two individuals independently verifying that the cylinder had no weight change while it was stored at ORGDP. This control was not violated. The NCSE concern associated with these cylinders entering the process is the potential to introduce fissile material into the cylinder while stored at ORGDP and subsequent washing at the non-fissile C-400 cylinder wash. Even though one leg of double contingency was lost, these cylinders were not washed. The cylinder heel of one cylinder is approximately 11 lbs. at 0.711 wt% U-235 in solid form and the other cylinder is approximately 39 lbs. at 0.7 wt% U-235 in solid form. The NRC Senior Resident Inspector has been notified of this event. PGDP Problem Report No. ATRC-08-0730; PGDP Event Report No. PAD-2008-06.
ENS 43232	23 September 2006 03:00:00	Response	Reported Under Nrc Bulletin 91-01 24 Hour Notification	On September 22, 2006, during a heavy rain storm, the water level in the C-310 position #4 scale pit reached 3 5/8 inches (3.625 inches). The scale pit liquid sensor alarm system did not function as credited, in violation of NCSA 310-004. The water was found by operators by visual inspection. NCSA 310-004 credits the liquid sensor alarm to provide notification of water in the pit in excess of 2.5 inches. At the time of the event, the water level was measured to be less than 3 5/8 inches (3.625 inches) deep. However, subsequent measurements accounting for slope in the scale pit floor show that the water could actually have been as deep as 4 3/8 inches (4.375 inches). The two process conditions relied upon for double contingency are mass and geometry. The first leg of double contingency is based on preventing a release of fissile material containing greater than a safe mass of uranium from getting into the scale pits. This is controlled through reliance on the integrity of the UF6 cylinder, liquid UF6 piping, pigtail, and liquid UF6 handling equipment. Since a UF6 release containing greater than a safe mass has not occurred, the mass parameter has been maintained Therefore, this leg of double contingency is maintained. The second leg of double contingency relies on the scale pit liquid sensor alarm system to provide notification of water in the pit in excess of 2.5 inches. Requiring the liquid sensor to alarm at 2.5 inches allows ample time to react and prevent the accumulation of more than 3.68 inches water. Although the alarm system did not function, operators performed a surveillance of the scale pits and identified water in the #4 scale pit in excess of 2.5 inches. NCSE 032 shows that the 'subcritical' slab height of UO2F2 solution in the C-310 scale pit is 4.1 inches at (deleted) wt% U235. The NCSE determined that an unsafe geometry slab height (is., greater than 4.1 inches) cannot form if the initial water height is less than 3.6 inches. The as-found water height corrected for the scale pit slope was determined to be as deep as 4 3/8 inches (4.375 inches). Therefore, the parameter limit specified in NCSE 032 was exceeded and double contingency was not maintained. The NRC Senior Resident Inspector has been notified of this event. PGDP Problem Report No. ATRC-06-3103; PGDP Event Report No. PAD-2007-01: NRC Worksheet No. SAFETY SIGNIFICANCE OF EVENTS: Although the scale pit liquid sensor alarm system failed to alarm when water in the pit exceeded 2.5 inches, an insufficient amount of water was available to achieve a criticality. The assay of the product withdrawal system at the time of the event was less than (deleted) wt%. Additional KENO and bucking calculations were included in design analysis calculation to illustrate the margin of conservatism. Those calculations show that the scale pit would have remained below the PGDP USL even for UO2F2 slab heights up to 7.75 inches at (deleted) wt%. In addition, a UF6 release containing greater than a safe mass did not occur. POTENTIAL CRITICALITY PATHWAYS INVOLVED: In order for criticality to be possible, a large UF6 release containing greater than a critical mass of uranium would have to form in the scale pit, and the pit would have to contain a sufficient amount of water. CONTROLLED PARAMETERS: The two process conditions relied upon for double contingency are mass and geometry. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL: Product withdrawal assay at the time of the event was less than (deleted) wt% U235. However, no UF6 release occurred. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: All C-310 scale pit sensor alarming systems have been repaired and verified to work properly and put back in service. The NRC Resident Inspector was notified of this report.
ENS 42165	22 November 2005 18:05:00	Response	Improper Criticality Spacing for Waste Drum	At 1205 CST, on 11-22-05 the Plant Shift Superintendent was notified that during waste drum remediation activities, a drum was discovered that was in violation of one leg of double contingency. Drum #39666W has been determined to contain up to (deleted) g (grams) U235 exceeding the allowed (deleted) gram limit for NCS Spacing Exempt drums. This drum was previously located in an NCS (Nuclear Criticality Safety) Spacing Exempt storage area in violation of NCSA WMO-001 requirements. The drum was moved to the C-335 storage area under an approved Remediation Guide which established a safety basis for the movement of drums that had been roped off and posted per earlier direction. This drum is currently stored in a Temporary Fissile Storage Area maintaining a minimum 2 foot edge-to-edge spacing under NCSA WMO-001, which maintains double contingency. SAFETY SIGNIFICANCE OF EVENTS While the (deleted) gram U235 limit was exceeded for this drum; DAC-832-2A1280-0001 demonstrates that drums containing less than (deleted) grams U235 in an NCS Spacing Exempt array are subcritical. The storage area is roped off and posted to prevent the addition of fissile material to the area; therefore another upset would be required before a criticality is possible. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR) This drum is currently stored in the Temporary Fissile Storage Area under NCSA WMO-001, meeting double contingency. In order for a criticality to occur, two independent, unlikely, and concurrent events would have to occur. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.) Double contingency is maintained by implementing two controls on mass. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS) The drum has been determined to contain (deleted) grams U235. Calculations performed demonstrate that drums containing less than (deleted) grams U235 each, in an NCS Spacing Exempt array are subcritical. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES Although the drum contains greater than the WMO-001 limit of (deleted) grams U235 for NCS Spacing Exempt drums, it has been shown to be less than (deleted) grams U235 based on independent sample results. Calculations performed demonstrate that drums containing less than (deleted) grams U235 each, in an NCS Spacing Exempt array, are subcritical. Therefore, an additional process upset (i.e., spacing upset) would be necessary in order to have a criticality. Therefore, while the drum contained greater than (deleted) grams U235 in the spacing exempt array, the array has been shown to be subcritical for drums containing less than (deleted) grams U235 thus maintaining one leg of double contingency. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED At the time of discovery, the drum was being stored according to NCS approved spacing controls. The drum will continue to be handled according to approved controls until the U235 mass can be reduced to meet the NCS Spacing Exempt criteria per NCSA WMO-001. The NRC Senior Resident Inspector has been notified of this event. See Related Event Report #40700. * * UPDATE 1802 EST ON 2/13/06 FROM K. BEASLEY TO S. SANDIN * * * At 1100 (CST), on 02-13-06 the Plant Shift Superintendent was notified that two additional waste drums were discovered that exceed the allowed (deleted) gram limit for NCS Spacing Exempt drums and had previously been located in an NCS Spacing Exempt storage area in violation of NCSA WMO-001. The drums are currently stored in a Temporary Fissile Storage Area under NCSA WMO-001, which maintains double contingency. The NRC Senior Resident Inspector has been notified of this event. Notified R2DO(Ayres) and NMSS (Camper). * * UPDATE ON 3/20/06 AT 1859 EST FROM B. WALLACE TO HUFFMAN * * * At 1430, on 03-20-06, the Plant Shift Superintendent was notified that an additional waste drum has been discovered that exceeds the allowed (deleted) gram limit for NCS Spacing Exempt drums and had previously been located in an NCS Spacing Exempt storage area in violation of NCSA WMO-001. The drums are currently stored in a Temporary Fissile Storage Area under NCSA WMO-001, which maintains double contingency. The additional drum was determined to contain (deleted) grams U235. Calculations performed demonstrate that drums containing less than (deleted) grams U235 each, in an NCS Spacing Exempt array are subcritical. The licensee notified the NRC Resident Inspector. R2DO (Ernstes) and NMSS EO (Pierson) notified. * * UPDATE ON 4/20/06 AT 1750 EDT FROM B. WALLACE TO HUFFMAN * * * At 1130, on 04-20-06 the Plant Shift Superintendent was notified that an additional waste drum has been discovered that exceeds the allowed (deleted) gram limit for NCS Spacing Exempt drums and had previously been located in an NCS Spacing Exempt storage area in violation of NCSA WMO-001. The drums are currently stored in a Temporary Fissile Storage Area under NCSA WMO-001, which maintains double contingency. The additional drum (#41663) was determined to contain (deleted) grams of U235. The licensee notified the NRC Resident Inspector. R2DO (Lesser) and NMSS EO (Janosko) notified. * * UPDATE ON 4/21/06 AT 2040 EDT FROM WALKER TO HUFFMAN * * * At 1333, on 4-21-06 the Plant Shift Superintendent was notified that seven additional waste drums had been discovered that exceed the allowed (deleted) gram limit for NCS Spacing Exempt drums and had previously been located in an NCS Spacing Exempt storage area in violation of NCSA WMO-001. The drums are currently stored in a Temporary Fissile Storage Area under NCSA WMO-001, which maintains double contingency. Seven additional drums (41160W,41161W,41162W,41158W,41159W,40605W.41681W) were determined to contain in excess of the (deleted) gram limit of U235 but less than the (deleted) gram safety limit. The licensee notified the NRC Resident Inspector. R2DO (Lesser) and NMSS EO (Janosko) notified. * * UPDATE ON 4/28/06 AT 1802 EDT FROM WALKER TO A. COSTA * * * At 1430, on 04-28-06 the Plant Shift Superintendent was notified that an additional waste drum has been discovered that exceeds the allowed (DELETED) gram limit for NCS Spacing Exempt drums and had previously been located in an NCS Spacing Exempt storage area in violation of NCSA WMO-001. The drum is currently stored in a Temporary Fissile Storage Area under NCSA WMO-001, which maintains double contingency. (This) one additional drum, # 43170W was determined to contain in excess of the (DELETED) gram limit of U235 but less than the (DELETED) gram safety limit. The licensee notified the NRC Resident Inspector. Notified R2DO (Landis) and NMSS EO (Giitter). * * UPDATE ON 10/11/06 AT 1551 EDT FROM WALLACE TO HUFFMAN * * * At 0900, on 10-11-06 the Plant Shift Superintendent was notified that an additional waste drum (#41470W) has been discovered that exceeds the allowed limit (but less than the safety limit) for NCS Spacing Exempt drums and had previously been located in an NCS Spacing Exempt storage area in violation of NCSA WMO-001. The drum is currently stored in a Temporary Fissile Storage Area under NCSA WMO-001, which maintains double contingency. The licensee notified the NRC Resident Inspector. Notified R2DO (Decker) and NMSS EO (Essig). * * UPDATE ON 10/24/06 AT 1130 EDT FROM K. A. BEASLEY TO MACKINNON * * * At 1000, on 10/24/06 the Plant Shift Superintendent was notified that an additional waste drum has been discovered that exceeds the allowed (Deleted) gram limit for NCS Spacing Exempt drums and had previously been located in an NCS Spacing Exempt storage area in violation of NCSA WMO-001. The drum is currently stored in a Temporary Fissile Storage Area under NCSA WMO-001, which maintains double contingency. The NRC Senior Resident Inspector has been notified of this event. Notified R2DO (Brain Bonser) and NMSS (Sandra Wastler). * * UPDATE ON 12/08/06 AT 1604 EST FROM K. A. BEASLEY TO KOZAL * * * At 1140 on 12/08/06 the Plant Shift Superintendent was notified that an additional waste drum (42171W) has been discovered that exceeds the allowed (Deleted) gram limit for NCS Spacing Exempt drums and had previously been located in an NCS Spacing Exempt storage area in violation of NSCA WMO-001. The drum is currently stored in a Temporary Fissile Storage Area under NCSA WMO-001, which maintains double contingency. The licensee notified the NRC Resident Inspector. Notified R2RDO (Lesser) and NMSS EO (Janosko). * * UPDATE ON 12/18/06 AT 1250 EST FROM B. W. WALLACE TO KOZAL * * * At 1250 on 12/18/06 the Plant Shift Superintendent was notified that 4 additional waste drums (39639W, 42118W, 42488W, & 43521W) had been discovered that exceeds the allowed (Deleted) gram limit for NCS Spacing Exempt drums and had previously been located in an NCS Spacing Exempt storage area in violation of NSCA WMO-001. The drum is currently stored in a Temporary Fissile Storage Area under NCSA WMO-001, which maintains double contingency. The licensee notified the NRC Resident Inspector. Notified R2RDO (Moorman) and NMSS EO (Ruland). * * UPDATE ON 3/23/07 AT 1602 EDT FROM C. PITTMAN TO JOE O'HARA * * * At 1345 on 3/23/07 the Plant Shift Superintendent was notified that an additional waste drum (43561W) had been discovered that exceeds the allowed (Deleted) gram limit for NCS Spacing Exempt drums and had previously been located in an NCS Spacing Exempt storage area in violation of NSCA WMO-001. The drum is currently stored in a Temporary Fissile Storage Area under NCSA WMO-001, which maintains double contingency. The licensee notified the NRC Resident Inspector. Notified R2RDO (Lesser) and FSME EO (Brach). * * UPDATE 1155 EDT ON 4/2/07 FROM CALVIN PITTMAN TO MARK ABRAMOVITZ * * * The following information was received as an update: UPDATE 4/02/07 at 0845, on 4/02/07 the Plant Shift Superintendent was notified that an additional waste drum (43557W) has been discovered that exceed the allowed (Deleted) gram limit for NCS Spacing Exempt drums and had previously been located in an NCS Spacing Exempt storage area in violation of NCSA WMO-001. The drum is currently stored in a Temporary Fissile Storage Area under NCSA WMO-001, which maintains double contingency. The licensee informed the NRC Resident Inspector. Notified R2DO(Henson) and FSME(Wastler).
ENS 41158	29 October 2004 14:45:00	Response	Criticality Control Report	At 0945 on 10/29/04, the Plant Shift Superintendent was notified that NCSE/A 3972-11 did not establish the necessary moderation controls for the sump in the C-360 elevator pit to ensure that double contingency is maintained if a UF6 release occurs in the transfer room. The sump is an unfavorable geometry. The C-360 basement transfer room is small and relatively air-tight once placed in containment resulting from a UF6 release. A credible UF6 release in the Transfer Room could consume all moisture in the room and leave gaseous UF6 available to react directly with pre-existing liquids in the elevator sump. Over an extended period of time this reaction could support a uranium concentration that results in a critical configuration. The current configuration of the sump does not prevent less than an always safe slab depth of 3.5 inches of solution in the sump. CORRECTIVE ACTIONS: Stop fissile operations in the C-360 transfer room until the necessary NCS controls for double contingency can be ensured for the sump in the elevator pit. The regulatee has notified the NRC Resident Inspector.
ENS 41020	4 September 2004 18:45:00	Response	Violation of Nuclear Criticality Safety Control in the Process Building	At 1345 (CDT), on 09-04-04 the Plant Shift Superintendent was notified of a violation of Nuclear Criticality Safety (NCS) control in the C-337 process building. During Inspection of the RCW (Recirculating Cooling Water) line to the RCW/ R114 Differential Pressure alarm switches (DP switches) for the C-337 #5 Low Speed P&E (Purge and Evacuation) Pump, Instrument Maintenance discovered that the instrument line boss was plugged. This condition rendered both Independent DP switches incapable of performing their intended safety, violating an SRI (Safety Related Item) in Nuclear Criticality Safety Evaluation (NCSE) 039. The SRI requires that both DP alarms are to be functional while the P&E pump is Isolated from the cascade process system. The purpose of the SRI is to alert an operator to take actions within a 28 hour timeframe to prevent high moisture R-114 from leaking into the process gas system. The DP alarms had likely been nonfunctional for more than 28 hours when discovered. Clarity of the Instrument line boss was subsequently re-established and both DP alarms were returned to service. The R-114 was sampled and determined to be dry (low moisture content) within 4 hours of discovery, thereby re-establishing double contingency. SAFETY SIGNIFICANCE OF EVENTS: While the R-114 was demonstrated to be dry, both OF alarms relied on for double contingency were disabled without the knowledge of the operators. CONTROLLED PARAMETERS: Double contingency Is maintained by Implementing two controls on moderation. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency is based on the DP switch alarming to alert the operator to take action to either verify the R-114 is dry or to isolate the RCW and remove the R-114 from the system in order to prevent water from leaking into the process gas system. This DP alarm was not maintained as functional. The DP alarm was put back In service and the R-114 was sampled and found to be dry. The SRI was not maintained and the control was violated but the process condition was maintained. The second leg of double contingency is based on the independent DP switch alarming to alert the operator to take action to either verify the R-114 is dry or to Isolate the RCW and remove the R-114 from the system in order to prevent water from leaking into the process gas system. The independent DP alarm was not maintained as functional. The independent DP alarm was put back in service and the R-114 was sampled and found to be dry. The SRI was not maintained and the control was violated but the process condition was maintained. This re-established double contingency. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: Both DP switches were returned to service and the R-114 was sampled and found to be dry within four hours time of discovery. PGDP Problem Report No. ATR-04-3602; PGDP Event Report No. PAD-2004-22 The Senior NRC Resident Inspector has been notified of this event.
ENS 40873	14 July 2004 18:00:00	Response	Criticality Control 24-Hour (Bulletin 91-01) Report	At 1300 (CDT) on 7/14/04, the Plant Shift Superintendent (PSS) was notified that a cylinder, which was to be washed, was determined to contain heel material. The cylinder had been filled a single time with natural material at Honeywell (2/2001) since its last wash in 8/1999. An examination of the associated Nuclear Material Control and Accountability (NCM&A) data and cylinder card indicated that the only other filling was in 9/1982 with depleted material at C-315. The cylinder was fed to the cascade in 9/2003 at C-337-A. A total of 4 gas over solid samples were taken of the cylinder and all indicated that the cylinder contains material. Nuclear Criticality Safety Evaluation 085 and Nuclear Criticality Safety Analysis 400-012 establish double contingency to ensure that a fissile cylinder is not washed in the non-fissile cylinder wash facility. The NRC Resident Inspector has been notified of this event. PGDP Assessment and Tracking Report No. ATR 04-2756; PGDP Event Report No. PAD 2004-019; Responsible Division: Operations. SAFETY SIGNIFICANCE OF EVENTS: NMC&A showed this cylinder contained a heel of around 8 lbs. Gas over solid sampling determined this non-fissile cylinder contained fissile material and could not be washed. Although the cylinder was not washed, an unlikely failure occurred that allowed fissile material to enter a cylinder controlled as non-fissile. CONTROLLED PARAMETERS: The process condition relied upon for double contingency for this scenario is enrichment. NUCLEAR CRITICALITY SAFETY CONTROL OR CONTROL SYSTEMS AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency relies on a gas over solid sample of the cylinder to demonstrate that the cylinder contains non-fissile material prior to washing. The second leg of double contingency relies on an argument that back- or cross-feeding at C-337A is unlikely to result in a significant amount of fissile material to be transferred to the cylinder. Since fissile material was found in the cylinder after it was fed at C-337A, this unlikely argument appears to have failed. However, the cylinder was not washed, maintaining this parameter. Although the parameter was maintained, double contingency is based on two controls on one parameter and one of the controls (unlikely argument) failed. Therefore double contingency was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: 1. Correct NMC&A database for this cylinder to show the correct assay in the cylinder and that the cylinder is fissile.
ENS 40860	8 July 2004 20:50:00	Response	24 Hour Nrc Bulletin 91-01 Loss of Criticality Control	At 1550, on 07-08-04 the Plant Shift Superintendent was notified that three centrifugal compressor impellers were received as part of a shipment from Portsmouth GDP. The existence of the impellers was not recognized as being part of this shipment and, as a result, applicable NCS (Nuclear Criticality Safety) controls were not implemented. NCSA GEN-20 requires receipt of documented NDA (Non Destructive Analysis) inspections of equipment prior to receipt (unloading) in the shipping/receiving area and completion of a second NDA prior to removing the equipment from the shipping/receiving area to a location within the plant. The purpose of this control is to ensure that equipment containing greater than a safe mass will not be received from offsite. The three centrifugal compressor impellers have subsequently been characterized as a group, by NDA, to be less than the safe mass assuming 100 wt.% 235U. SAFETY SIGNIFICANCE OF EVENTS: NDA measurements have been completed and the results indicate less than a safe mass of uranium. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR): In order for a criticality to be possible, greater than a critical mass of uranium would have to be present in the equipment in a configuration favorable for a criticality. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC): Double contingency is maintained by implementing two controls on mass. ESTIMATED AMOUNT ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): The group of equipment contains less than the safe mass assuming 100 wt.% 235U. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEMS) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency relies on the review of characterization results prior to receipt (unloading) at PGDP. Characterization results were not reviewed prior to receipt. The three centrifugal compressor impellers have subsequently been characterized as a group, by NDA, to be less than the safe mass assuming 100 wt.% 235U. Although, the NCS controls were violated, the parameter was maintained. The second leg of double contingency relies on an independent NDA measurement prior to release from the shipping/receiving area. NDA characterization did not occur prior to release from the shipping/receiving area. The three centrifugal compressor impellers have subsequently been characterized as a group, by NDA, to be less than the safe mass assuming 100 wt% 235U. Although, the NCS controls were violated, the parameter was maintained. Although the parameter was maintained, double contingency is based on two controls on one parameter. Therefore, double contingency was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED : 1. Post equipment according to CP2-MA-MT1034. Completed 07/09/04 The NRC Resident lnspector has been notified of this event. PGDP Problem Report No. ATRC-04-2682, PGDP Event Report No. PAD-2004-18; Event Worksheet #40860 Responsible Division: Maintenance
ENS 40723	3 May 2004 21:00:00	Response	Criticality Control 24-Hour (Bulletin 91-01) Report	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.
ENS 40700	23 April 2004 13:45:00	Response	Criticality Control 24-Hour (Bulletin 91-01) Report	The following information was obtained from the regulatee via facsimile: 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. The waste drums have been independently sampled and demonstrated to be below the (DELETED) 235U limit. The NRC Resident Inspector has been notified of this event. SAFETY SIGNIFICANCE OF EVENTS: 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. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S)) OF HOW CRITICALITY COULD OCCUR: 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. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.): Double contingency is maintained by implementing two controls on mass. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): Each drum contains less than (DELETED) 235U at an enrichment of less than 1.5 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 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. 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. Although the parameter was maintained, double contingency is based on two controls on one parameter. Therefore, double contingency was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: 1. Characterize waste drums (PF-04-7258 and PF-03-5051) using the independent sample results. Completed 04/23/04. 2. Complete the 'extent of condition' examination prior to making a determination for removal of the ropes and postings. 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. Plant personnel have imposed spacing requirements on all other drums in the immediate area that have questionable characterizations until they can be properly analyzed. 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).
ENS 40805	23 April 2004 10:53:00	Response	Paducah Gaseous Diffussion Plant - Response Bulletin 91-01 24 - Hour Report	At 1550 on 6-09-04, the Plant Shift Superintendent was notified of a failure of a Safety Related Item (SRI) relied upon in Nuclear Criticality Safety Evaluation (NCSE) 052 'Enrichment Cascade During Normal Operations at the Paducah Gaseous Diffusion Plant.' At 0553 hours on 4-23-04, when responding to alarms on Cell 6 in Building C-310, the second bank of motors could not be shut down using the manual motor trip system. Operators opened the Transformer Secondary Breaker (TSB) as an alternate means to shut down the motors. The manual motor trip system is credited to mitigate/minimize the consequences or extent of a Hot Metal Reaction (HMR). PGDP Problem Report No, ATRC-04-2299; PGDP Event Report No. PAD-2004-17; Event Worksheet (NRC Event Number): # 40805, Responsible Division: Operations. SAFETY SIGNIFICANCE OF EVENTS: Minimal. There are multiple methods capable of shutting down equipment suspected of undergoing a HMR. The compressor motors were shut down using one of these methods. The shutdown was accomplished within 2 minutes. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIOS) OF HOW CRITICALITY COULD OCCUR: In order for a criticality to occur, the equipment would have had to be involved In the initiating event of a HMR. There were no indications of a HMR. Additionally, the HMR event would need to have occurred with a significant inventory of UF6 present. The event was in the purge cascade having UF6 concentrations in the ppm range. Therefore, there is no credible pathway to criticality for this incident. CONTROLLED PARAMETERS (MASS, MODERATION. GEOMETRY, CONCENTRATION, ETC): This scenario is singly contingent based on moderation control. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): The event was in the purge cascade having UF6 concentrations in the ppm range at an enrichment of less than (DELETED) wt % 235U. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: This scenario is singly contingent based on moderation control. The scenario indicates that it is unlikely for a significant HMR to occur resulting in a cooler/cascade breach with subsequent sprinkler activation based on historical operations. The manual motor trip system is credited to mitigate/minimize the consequences or extent of a HMR. The credited trip failed to perform its intended function. Although the credited trip failed, alternative methods were used to shutdown the cell, thereby satisfying the intent of the administrative portion of the control. Also, no HMR, cell breach, or sprinkler activation occurred. Although the SRI failed, the moderation parameter was maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: The cell was shut down using alternate means within 2 minutes. The manual motor trip system was declared inoperable at 0700 on 4-23-04 and repaired. The NRC Resident Inspector has been notified of this event.
ENS 40641	4 April 2004 19:30:00	Response	24-Hour Nrc Bulletin 91-01 Loss of Criticality Control Notification	At 1430, on 04-04-04 the Plant Shift Superintendent was notified of a violation of Nuclear Criticality Safety (NCS) control in the C-333 process building. While preparing for start up of the C-333 #1 High Speed Purge and Evacuation (P & E) pump, operations discovered that the delta pressure (DP) alarm instrument line to the RCW supply was unattached and the isolation valve was closed. With the RCW instrument line not attached, both DP alarms for this pump were not functional and therefore not able to perform their safety function, violating a safety related item (SRI) in NCSE 039. The SRI requires that both DP alarms be functional while the P & E is isolated from the cascade. The purpose of the SRI Is to alert the operator to take actions within a 28-hour timeframe to prevent wet R-114 from leaking into the process gas system. The DP alarms had been nonfunctional for more than 28 hours when discovered. Both DP alarms were put back in service and the R-114 sampled and found dry within 4 hours of discovery, therefore, re-establishing double contingency. The Senior NRC Resident Inspector has been notified of this event. PGDP Problem Report No, ATR-04-1342; PGDP Event Report No. PAD-2004-09; Event Worksheet #40641 Responsible Division: Operations SAFETY SIGNIFICANCE OF EVENTS: While the R-114 was demonstrated to be dry, both DP alarms relied on for double contingency were disabled without the knowledge of the operators. POTENTIAL CRITICALITY PATHWAYS INVOLVED: In order for a criticality to occur, an unsafe mass uranium deposit would have to be present in the process gas system, an R-114 leak to the process gas system would have to occur, the R-114 would have to contain an unacceptable amount of moisture ( i.e., greater than 10 kg of water) and moderate the deposit. CONTROLLED PARAMETERS (MASS, MODERATION, G5OMETRY, CONCENTRATION, ETC): Double contingency is maintained by implementing two controls on moderation. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL: No known mass of licensed material exists in the #1 High Speed Purge and Evacuation pump. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency is based on the DP switch alarming to alert the operator to take action to either verify the R-114 is dry or to isolate the RCW and remove the R-114 from the system in order to prevent water from leaking into the process gas system. This DP alarm was not maintained as functional. The DP alarm was put back in service and the R-114 was sampled and found to be dry. The SRI was not maintained and the control was violated but the process condition was maintained. The second leg of double contingency is based on the independent DP switch alarming to alert the operator to take action to either verify the R-114 is dry or to isolate the RCW and remove the R-114 from the system in order to prevent water from leaking into the process gas system. The independent DP alarm was not maintained as functional. The independent DP alarm was put back in service and the R-114 was sampled and found to be dry. The SRI was not maintained and the control was violated but the process condition was maintained. This re-established double contingency. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: Both DP switches were returned to service and the R-114 was sampled and found to be dry on 04-04-04 at 1655. * * UPDATE 4/29/04 AT 1025 BEASLEY TO GOTT * * * Subsequent assay sample analysis of the Purge and Evacuation pump system indicates the system is non-fissile. The PGDP notified the NRC Resident Inspector. Notified NMSS (Torres) and R2DO (Ernstes)
ENS 40455	16 January 2004 21:27:00	Response	24 Hour Notification for Bulletin 91-01 Loss of Criticality Safety Controls Involving Waste Drum	At 1526 on 1-16-04, the Plant Shift Superintendent (PSS) was notified that a waste drum was not characterized and handled properly and handled as fissile waste. This is a continuation of PGDP Event Report No. PAD-2004-003, NRC Event Report 40447. During the investigation of ATRC-03-4095, container RFD# 215759-20, which had been characterized as NCS (nuclear criticality safety) spacing exempt based on the drum being heterogeneous material, it was identified that this waste drum contained spent alumina material violating NCSA (nuclear criticality spacing analysis) WM0-001. The purpose of this NCSA requirement is to determine if the waste drum requires two independent characterization results. Two independent characterization methods were not utilized for characterization of this drum. PGDP Assessment and Tracking Report No. ATR 04-0166; PGDP Event Report No. PAD-2004-004. NRC Event Worksheet 40455 Responsible Division: Production Support SAFETY SIGNIFICANCE OF EVENTS: The control for performing two independent analysis for determining the U235 mass was violated but one drum monitor analysis determined that the drum did contain less than the safe mass for spacing exempt waste drums. Since the process condition was maintained, the safety significance is low but double contingency was not maintained. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIOS) OF HOW CRITICALITY COULD OCCUR: In order for a criticality to be possible, two or more waste drums would have to contain greater than 120 grams U235 and not have the proper spacing maintained between the waste drum. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC The process condition relied upon for double contingency for this scenario is mass. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): The drum has been characterized to show that Uranium mass is less than 120g U235. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency is based on the requirement that uranium waste material must be characterized to show that the U235 mass of the waste drum is less than 120 grams. This control was not violated and the process condition of mass was maintained. The second leg of double contingency is based on the requirement that high density uranium homogeneous waste material be characterized using an independent analysis. Since the waste drum material was mistakenly identified as heterogeneous material, only one analysis was performed. Therefore, this control was violated. One drum monitor analysis determining that the waste drum contained less than 120 grams U235. Although the control was violated, the process condition was maintained. Since this scenario relies on two controls on one parameter and this control was violated, double contingency was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: Access to the area has been flagged off and access controlled until drums retagged and properly stored. The NRC Senior Resident Inspector has been notified of this event.
ENS 40447	13 January 2004 19:00:00	Response	24 Hour Notification for Bulletin 91-01 Loss of Criticality Safety Controls Involving Waste Drum	At 1300 on 01/13/04, the Plant Shift Superintendent (PSS) was notified that a waste drum was not characterized and handled properly as fissile waste. During the investigation of ATRC-03-4095, container RFD# 213439-01, which had been characterized as NCS spacing exempt based on the drum being heterogeneous material, it was identified that this waste drum contained solid uranium deposit material violating NCSA WMO-001. The purpose of this NCSA requirement is to determine if the waste drum requires two independent characterization results. Two independent characterization methods were not utilized for the characterization of this drum. SAFETY SIGNIFICANCE OF EVENTS: Safety significance of event Is low due to the fact that Nondestructive Assay characterization results of drum contents indicate a total U235 content of less than the safe mass limit for NCS Spacing Exempt waste. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR: More than two drums, all exceeding the safe mass limit, spaced less than minimum spacing requirements. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC): Double contingency is maintained by implementation of two controls on mass. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): The material in the drum is in a solid state. Uranium mass is less than 120g U235. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: Controls relied upon for maintaining double contingency are two Independent measurements to determine the U235 mass of the drum. Since there are two controls on one parameter, double contingency was not maintained since only one measurement was performed. Even though mass control was maintained, double contingency Is based on two controls on mass. Therefore, double contingency was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: Access to the area has been controlled and the drum has been spaced from other fissile material. The NRC Senior Resident Inspector has been notified of this event. PGDP Assessment and Tracking Report No. ATR 04-0111; PGDP Event Report No. PAD-2004-003, Responsible Division: Production Support
ENS 40356	25 November 2003 09:45:00	Response	24 Hour Nrc Bulletin 91-01 Notification Regarding Loss of Double Contingency Protection	At 0420 on 11/25/03, the PSS (Plant Shift Superintendent) was notified that contrary to NCSA (Nuclear Criticality Safety Assessment) CAS-011, 'Shutdown of the Cascade With or Without Inventory', M&TE (Measuring & Testing Equipment) pressure gauges, installed on the RCW( Recirculating Cooling Water) return side of the C-331 U/3 C/2 condenser, were removed prior to the RCW supply spool piece being removed. NCSA CAS-011 requires independent verification that the supply spool piece has been removed prior to removing the M&TE gauges. The purpose of these gauges is to monitor the condenser pressure to insure RCW pressure in the condenser does not exceed 17 psig in the event the RCW supply valve leaks with the return valve completely closed. As long as the 17 psig limit is not exceeded, RCW pressure can not over come the coolant pressure and leak into the coolant. Evolutions that occurred during the spool piece removal found that the RCW return valve to the condenser could not be completely closed. This provided an open flow path to pressure gauges installed on the RCW return header allowing for pressure readings to be taken that provides an indication of the pressure at the condenser. Pressure readings on the RCW return header indicate that the RCW return did not exceed the 17 psig as required in the NCSA. The NRC Senior Resident Inspector has been notified of this event. PGDP Assessment and Tracking Report No, ATRC-03-4076, PGDP Event Report No. PAD-2003-021, NRC Event Worksheet # 40356 Responsible Division: Maintenance SAFETY SIGNIFICANCE OF EVENTS: Double contingency was not maintained because independent verification that the supply spool piece had been removed before removing the M&TE pressure gauges was not performed. However, since the RCW return header did not exceed 17 psig, the process condition was maintained. This event was of low safety significance due to moderation control being maintained. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIOS) OF HOW CRITICALITY COULD OCCUR: Once the fluorinating environment is removed from the process cell, moisture that may leak into the process gas side could potentially moderate a uranium deposit that may be present. RCW pressures below 17 psig will prevent water from leaking into the coolant that could then leak into the process gas side. Sufficient water would have to leak into the process gas side from the coolant and moderate a critical mass of uranium. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC): Double contingency is maintained by implementing two controls on moderation. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDES PROCESS LIMIT AND % WORST CASE CRITICAL MASS): This system has a process limit of (DELETED). NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency is based on ensuring that a condenser tube leak will not introduce RCW (moderator) into the process gas side through the coolant. This is accomplished through monitoring the RCW return pressure to be 17 psig or less. Once the return RCW valve is closed the M&TE gauges, installed on the RCW return side of the condenser, provide indication that the condenser does not exceed 17 psig. The purpose of these gauges is to monitor the condenser pressure in the event the supply valve leaks with the return valve completely closed. Under these conditions, actions are required if the condenser pressure exceeds 17 psig. As long as the 17 psig limit is not exceeded, RCW can not over come the coolant pressure and leak into the coolant. Since the pressure gauges were removed prior to the spool piece being removed, this control was violated. However, due to the return valve leaking at the condenser, an open flow pathway is available to peak reading pressure gauges installed on the RCW return header that would provide an indication of the pressure at the condenser. Pressure readings from the RCW return header do not indicate the return pressure exceeded 17 psig. Therefore, the process parameter, moderation, was maintained. The second leg of double contingency is based on an independent verification that the supply spool piece has been removed prior to removing the M&TE pressure gauges. Since the gauges had been removed before the supply spool piece was removed, the independent verification requirement was violated. Though this control was violated, the process parameter was maintained due to the RCW return header pressure not exceeding 17 psig. 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: The M&TE pressure gauges were re-installed at approximately 0620 on 11-25-03. The licensee will notify the DOE Site Representative.
ENS 40151	11 September 2003 13:45:00	Response	Double Contingency Was Not Maintained for Non-Fissile Nams.	NRC BULLETIN 91-01 24 HOUR NOTIFICATION At 0845 on 9/11/03, it was discovered that non-fissile negative air machines (NAMs) were not verified by two individuals to contain approved and properly installed filters, as specified in NCSA GEN-09, "Operation and Maintenance of Negative Air Machines". Procedure CP4-GP-BG2108, "Negative Air Machine and in-place HEPA System Internal Inspection and Filter Replacement", did not adequately flowdown requirements specified in NCSA GEN-09 was revised to make non-fissile portable negative air machines (NAMs) readily available for fissile use in emergency situations. Contrary to requirements specific in NCSA GEN-09, procedure CP4-GP-BG2108 did not include requirements for two individuals to perform independent verification that approved filters are selected and properly installed. This control prevents mass loadings of fissile material that are outside the scope of that analyzed in NCSE KY/S-249. SAFETY SIGNIFICANCE OF EVENTS: Double contingency was not maintained for non-fissile NAMs because the second verification was not performed. However, the non-fissile NAMs were not used for fissile material releases. The non-fissile NAMs have been subsequently verified to contain approved and properly installed filters. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR: In order for a criticality to be possible, a non-fissile NAM would have to be used in a fissile material release and greater than a safe mass of uranium would have to accumulate within the NAM in a configuration favorable for criticality. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.): Double contingency for the accumulation of an unsafe fissile mass is maintained by implementing two controls on mass. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): This system has a process limit of (xx) wt% U235. NUCLEAR CRITICLITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency is based on one individual verifying and documenting that approved filters are selected and properly installed. This control prevents loadings of fissile material that are outside the scope of that analyzed in NCSE KY/S-249. This verification was performed, therefore, this control was maintained. The second leg of double contingency is based on a different individual verifying and documenting that approved filters are selected and properly installed. This control prevents loadings of fissile material that are outside the scope of the analyzed in NCSE KY/S-249. Because this verification was not performed, this control was lost. No events have occurred to introduce fissile material into any non-fissile NAMs. Therefore, though the control was violated, the parameter was maintained. Since double contingency is based on two controls on one parameter, and one control was violated, double contingency was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: 1. Non-fissile Nams verified to contain the correct filters and installed in the correct orientation. Completed 9/11/2003. 2. Procedure CP4-GP-BG2108 placed on hold pending revision to include independent verification requirements specific in NCSA GEN-09. Completed 9/11/2003. The NRC Senior Resident Inspector has been notified of this event.
ENS 40139	7 September 2003 12:50:00	Response	Criticality Controls Degradation at Paducah	At 0750 on 9/7/03, it was discovered that the Recirculating Cooling Water (RCW) Supply valve for C333 Unit 6 Cell 2 was not positioned correctly for the current condition of the cell, in violation of NCSA CAS-011. On 9/3/03, the cell was in a fluorinating environment with the Odd R-114 system drained and evacuated for leak repairs, Odd RCW valves closed, the Even R-114 system was not drained with the Even RCW valves open satisfying the conditions of CAS-002. It was determined that the cell needed to have a UF6 negative obtained for maintenance work. The UF6 negative was initiated without closing the Even RCW Supply valve, tagging both the Supply and Return valve, and without performing the independent checks for valve position, which violates NCSA CAS-002. Once the UF6 negative was obtained, the cell transitioned to NCSA CAS-011 without satisfying the RCW isolation controls of that NCSA. Both RCW isolation controls require that the RCW Supply valve be tagged closed and that the RCW Return valve be tagged open and both valves independently verified to be positioned correctly. The NRC Senior Resident Inspector has been notified of this event. SAFETY SIGNIFICANCE OF EVENTS: Since the process condition (lack of moisture in the coolant, and therefore in the process gas system) was maintained, the safety significance of this incident is low. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO OF NOW CRITICALITY OF HOW CRITICALITY COULD OCCUR): Once the fluorinating environment is removed from a process cell, moisture that may leak into the process gas system could potentially moderate any uranium that may be present. Sufficient water would have to leak into the process gas system and moderate a critical mass of uranium. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC Double contingency is maintained by implementing two controls on mass. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency is based on ensuring that a coolant condenser leak will not introduce RCW (moderator) into the process gas side of a cell through the coolant. This is accomplished by either maintaining a fluorinating environment in the cell or by restricting /isolating the RCW supply prior to removing the fluorinating environment. This restriction/isolation is accomplished by either removing a supply spool piece or closing and tagging the manual supply valve and tagging open the return valve. Neither of these two RCW alignments was maintained. The second leg of double contingency is based on an independent verification of the RCW alignment relied upon for the first leg of double contingency. The independent verification was not performed. Therefore, this control was lost, 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 IMPLEMPNTED: At 1010 on 9-7-03, the Even RCW Supply valve was tagged closed, the Odd RCW Return valve was tagged open, and both valves were independently verified. The coolant moisture content was checked and was less than minimum detectible moisture. These actions have placed the system back in compliance with NCSA CAS-011.
ENS 40109	27 August 2003 14:00:00	Response	Procedural Deficiency Omission	NRC BULLETIN 91-01 24 HOUR NOTIFICATION At 0900 on 8/27/03, it was discovered that the procedure for operation of the C-409 Uranium Precipitation System did not adequately address flowdown requirements specified in NCSA 409-001. NCSA 409-001 control 3.2.39 prevents introduction of organic material to the precipitation system by requiring verification that the solution originated from either the C-710 Laboratory, the C-409 Cylinder Wash, or the C-409 Uranium Precipitation System and that the solution does not contain organic material, as indicated by sampling. The control had been flowed down for solutions originating from the C-710 Laboratory and the C-409 Cylinder Wash, however was not flowed down for solutions originating from the C-409 Uranium Precipitating System. PGDP Assessment and Tracking Report No. ATR 03-2767, PGDP Event Report No. PAD-2003-017. SAFETY SIGNIFICANCE OF EVENTS: Double contingency was not maintained because the independent verification of the origination of solutions from the C-409 Uranium Precipitation System and the independent verification that the solution did not contain organic material had not been performed. However, no oil has been introduced to the operation. POTENTIAL CRITICALITY PATHWAYS INVOLVED OF HOW CRITICALITY COULD OCCUR: In order for a criticality to be possible, greater than a safe mass of uranium must be accumulated within the Uranium Precipitation System, facilitated by the presence of organic material and accumulate in the rotary drum filter. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.) Double contingency is maintained by implementing two controls on mass. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL: This system has a process limit of (xx) wt.% U235. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OF DEFICIENCIES: The first leg of double contingency is based on controlling the mass of uranium in the tanks. NCSA 409-001 requires that prior to placing solution in the Uranium Precipitation Operation the solution must be verified to be uranium salvage from C-710 laboratory, C-409 cylinder wash, or the C-409 Uranium Precipitation System and that the solution does not contain organic material. This control prevents the build-up of organic material at the top of the Uranium Precipitation System tanks. If organic material were to get in the tanks it would create a floating uranium/oil layer and result in non-representative sampling of the concentration, since sampling is conducted near the bottom of the tank. This may lead to an unsafe mass reaching the rotary drum filter. The C-710 solution currently in the system was independently verified to be free of organic material prior to initial introduction. However, since no verification was documented for the C-409 Uranium Precipitation system solution, this control was lost. Chemical Operations personnel have subsequently verified that no events have occurred to introduce organic material into the solution from the C-409 Uranium Precipitation System. The control was violated; however the parameter was maintained. The second leg of double contingency is based on mass. NCSA 409-001 requires that prior to placing solution in the Uranium Precipitation Operation, the solution be independently verified to be uranium salvage from C-710 Laboratory, C-409 Cylinder Wash or the C-409 Uranium Precipitation System and that the solution does not contain organic material. However, since no independent verification was documented for the C-409 Uranium Precipitation system solution, this control was lost. Chemical Operations personnel have subsequently independently verified that no events have occurred to introduce organic material into the solution from the C-409 Uranium Precipitation System. Therefore, this control was violated. Since there are two controls on one parameter, double contingency was not maintained. Since double contingency is based on two controls on one parameter, and the controls were violated, double contingency was not maintained. CORRECTIVE ACTIONS TO REESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: Chemical Operations revise procedure CP4-CU-CH2137 to include verification requirements specified in NCSA 409-001. Procedure change was initiated on 8-27-03. The NRC Senior Resident Inspector has been notified of this event by the licensee.

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