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| Entered date | Event description | |
|---|---|---|
| ENS 44608 | 28 October 2008 14:15:00 | At 0849 CDST, on 10-28-08 the Plant Shift Superintendent (PSS) was notified that an alarm was received for the C-337 Unit 1 Cell 2 UF6 Release Detection (PGLD) System. Operators responded and found that the READY and MANUAL lights for this system were not illuminated. This PGLD System contains detectors that cover C-337 Unit 1 Cell 2 and Section 1 of the cell bypass piping. At the time of this alarm, Unit 1 Cell 2 and some areas of Sections 1 of the cell bypass were operating above atmospheric pressure. TSR 2.4.4.1 requires that at least the minimum number of detector heads in the cell and in each defined section of the cell bypass are operable during steady state operations above atmospheric pressure. With the Unit 1 Cell 2 PGLD system inoperable, none of the required cell heads and only 2 of the required 3 heads in Sections 1 of the cell bypass were operable. This PGLD System was declared inoperable. TSR LCO 2.4.4.1.A.1 and 2.4.4.1.C.1 were entered and a continuous smoke watch was put in place within one hour. Engineering has determined that the system would not have been able to perform its intended safety function when this alarm came in. This event is reportable as a 24 hour event in accordance with 10CFR76.120(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. PGDP Event Report No. PAD-2008-033. The NRC Resident lnspector has been notified of this event. |
| ENS 44151 | 18 April 2008 14:45:00 | 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 43987 | 14 February 2008 14:10:00 | At 0207 CST, on 02-14-08 the Plant Shift Superintendent (PSS) was notified that an alarm was received in the C-333 Area Control Room for the C-333 Unit 5 Cell 8 UF6 Release Detection (PGLD) System. Operators responded to the local panel and verified the alarm was not due to a UF6 release, but local panel lights were flickering. Operators attempted to test the system and the system would not test fire. This PGLD System contains detectors that cover the C-333 Unit 5 Cell 8 cell housing roof and inter-cell housing and section 4 of the cell bypass housing. At the time of this alarm, C-333 Unit 5 Cell 8 and section 4 of the cell bypass were operating above atmospheric pressure. TSR 2.4.4.1 requires that at least the minimum number of detector heads in the cell housing roof, inter-cell housing, and section 4 of the cell bypass housing are operable during steady state operations above atmospheric pressure. With the Unit 5 Cell 8 PGLD System inoperable, none of the required 3 heads in the cell housing roof and inter-cell housing were operable and only two of the required 3 heads in the cell bypass housing were operable. This PGLD System was declared inoperable. TSR LCOs 2.4.4.1.B.1 and 2.4.4.1 .C.1 were entered and a continuous smoke watch was put in place within one hour. An investigation is ongoing to attempt to determine the cause of the failure. This event is being reported 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. |
| ENS 43903 | 14 January 2008 15:36:00 | At 1512 CST, on 01-13-08 the Plant Shift Superintendent (PSS) was notified that the C-333 Unit 6 Cell 7 UF6 Release Detection (PGLD) System failed to function when performing the twice per shift test firing. Test firing of the PGLD detector heads is required per TSR SR 2.4.4.1-1. TSR 2.4.4.1 also requires that at least the minimum number (three) of detector heads in the cell and in each defined section of the cell bypass are operable where UF6 systems are above atmospheric pressure. The C-333 Unit 6 Cell 7 PGLD System contains detectors that covers the cell and Sections 3 and 4 of the cell bypass piping. At the time of this failure some areas of Section 3 of the cell bypass were operating above atmospheric pressure. Since Unit 6 Cell 7 was operating below atmosphere, the cell was not in an applicable TSR mode. However, Section 3 of the cell bypass was above atmosphere and in an applicable TSR mode which required at least three operable PGLD heads. With the Unit 6 Cell 7 PGLD system inoperable only two of the required three heads in Section 3 of the cell bypass were operable. This PGLD System was declared inoperable, and system pressure in the affected operating area was reduced to less than atmospheric pressure within one hour, thus placing the operating system in a non-applicable TSR mode. This event is being reported 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 Resident Inspector has been notified of this event. PGDP Assessment and Tracking Report No. ATR-08-0122; PGDP Event Report No. PAD-2008-01; Worksheet No. 43903 Responsible Division: Operations The licensee is investigating the cause of the event, and will make appropriate notifications to the Department of Energy.
On January 13, 2008 the C-333 U/6 C/7 PGLD system failed during testing. This affected all the PGLD heads in the cell area and two of the four heads in section 3 of the cell by-pass. A review of operating pressures in the affected area determined that the cell was operating below atmospheric pressure, but that piping in section 3 of the cell by-pass was operating above atmosphere. Thus, three of four heads in section 3 of the Cell by-pass were required by the TSR to be operable. Given the recent failure in November and indications that the failure modes may be similar, the PSS reported the event to the NRC per 10CFR 76.120(c)(2)(i), In-Service Safety System Failure. Subsequent to the event, the pressures in C-333 U/6 CR, section 3 in the cell by-pass area associated with the event were reviewed. Using Engineering Notice EN-C-821-05-090, Rev, 3, it was determined that section 3 of the cell by-pass was actually not operating above atmosphere and thus, the PGLD system was not required to be operable at the time of the failure. Since the failure only affected detectors in an area operating in a non-TSR mode, the PGLD system is not required to be operable and reporting under 10 CFR 76.120(C)(2) is not required. The licensee notified the NRC Resident Inspector. The licensee made appropriate notifications to the Department of Energy. R2DO (Moorman) and NMSS EO (Kokajko) notified. |
| ENS 43385 | 24 May 2007 12:26:00 | A required 24-hour notification was made by Paducah Regulatory Affairs to EPA Region IV in Atlanta, GA at 0815, 5-24-2007. The notification was made concerning a PCB spill of greater than the agreed upon action level of 10 pounds of PCBs confined within a building. The approximate 3 gallon PCB oil spill was from an electrical capacitor located inside the C-333 Process Building. The oil spilled onto a concrete floor and was contained to the immediate area. The area was flagged and posted as a PCB spill area and clean up is in progress. This event is reportable as a 4 hour event as required by the NRC NUREG 1022, a specific report made to a government agency. PGDP Assessment and Tracking Report No. ATR-07-1362; PGDP Event Report No. PAD-2007-06; Worksheet No. 43385. The NRC Resident Inspector was notified of this event by the licensee. |
| ENS 43232 | 13 March 2007 15:44:00 | 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 42176 | 29 November 2005 23:36:00 | At 0845 CST, on 11/29/2005 the C-337 process building Criticality Accident Alarm System (CAAS) was being tested when a building horn control switch in C-300 Central Control Facility which supplies voltage to actuate the building CAAS evacuation horns was found to not be properly made up. This switch caused the building CAAS horns not to sound when a cluster was actuated. The test which revealed this problem, was the initial 'as found' test, which means the failure most likely occurred prior to today's testing. The C-337 CAAS system is a TSR system which is required to be operable in the current operating mode unless LCO actions are in place. The C-337 CAAS system was last tested on 11/05/2005 and indications are that the switch problem has existed since that time. During testing the CAAS alarm was received in C-300, but the evacuation horns did not automatically sound. Per procedure if a criticality alarm had occurred the C-300 operator would have actuated the horn switch manually which would have sounded the evacuation horns. To ensure that not only the C-337 switch was properly repaired, but also to verify all other building horn control switches were in the proper state, a plant wide LCO was implemented and switch outputs were checked to verify the proper voltage output. The NRC Senior Resident has been notified of this event. |
| ENS 41378 | 6 February 2005 17:28:00 | The licensee provided the following information via facsimile: At 1008, on 2-06-05, the Plant Shift Superintendent (PSS) was notified that at the C-360 Toll and Transfer Facility on autoclave 4, the vent line block valve, XV-434, failed to close when the control switch was operated to the closed position. A check of the valve indicator showed that the valve moved to approximately 75% of the closed position. This valve is a single isolation point (no redundant valve) for two TSR (Technical and Safety Requirements) systems: (1) The Autoclave Steam Pressure Control System and (2) The Autoclave Water Inventory Control System. The autoclave was in mode 5, an applicable TSR mode for both systems. The PSS declared the systems inoperable and TSR LCOs 2.1.3.3 and 2.1.4.3 were implemented to remove the autoclave from service and place it in mode 2 within one hour. This event is reportable as a 24 hour event in accordance with 10 CFR 76.120.c.2.i. It was 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 be 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. |
| ENS 40423 | 2 January 2004 10:03:00 | At 0230 on 01-02-04 the Plant Shift Superintendent (PSS) was notified of a failure of the C-360 #3 Autoclave High Pressure Isolation System. Steam was observed leaking from the autoclave head-to-shell interface between the eleven and one o'clock position shortly after initiating a cylinder heat cycle. At the time of discovery, the autoclave was in TSR (Technical Safety Requirements) mode 5 and the High Pressure Isolation System was required to be operable while in this mode. This system is designed to provide containment of the autoclave and prevent an external release of UF6 during a system breach while heating a UF6 cylinder. The PSS declared the system inoperable and TSR LCO 2.1.3.1.C1 actions were implemented to remove the autoclave from service and place it in Mode 2, "Out of Service". The event is reportable as a 24 hour event, as required by 10 CFR 76.120(c)(2)(i); An event in which equipment is disabled or fails to function as designed when 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. The equipment was required by TSR to be available and operable and no redundant equipment was available to perform the required safety function. The Senior NRC Resident Inspector has been notified of this event. |