Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 46120 | 24 June 2010 19:00:00 | 10 CFR 20.2201(a)(1)(ii) | Calibration Source Discovered Missing During Inventory | This is a 30-day notification to inform the NRC of missing licensed material in accordance with 10 CFR 20.2201 (a)(l)(ii). On June 24, 2010, while conducting the quarterly inventory of radioactive sources in accordance with Humboldt Bay Power Plant (HBPP) Unit 3 Radiation Control Procedure RCP-6D, 'INVENTORY AND CONTROLS FOR RADIOACTIVE SOURCES,' it was discovered that source number 498 was missing from the count room. This source is for the calibration of gamma detectors, but had not been used for that purpose this year. The source is a filter, mixed gamma source with an activity of 1.025 microCi as of July 1, 2008. The radionuclide mix of the source is as follows: Gammas/second Activity (Ci) 10 CPR 20 Appendix C (Ci) Am-241 7.02e+02 5.20e-08 1.00e-09 Cd-109 9.80e+02 7.12e-07 1.00e-06 Co-57 5.10e+02 1.61e-08 1.00e-04 Ce-139 7.10e+02 2.39e-08 1.00e-04 Hg-203 1.61e+03 5.63e-08 1.00e-04 Sn-113 1.01e+03 4.19e-08 1.00e-04 Cs-137 6.29e+02 2.00e-08 1.00e-05 Y-88 2.42e+03 6.99e-08 1.00e-05 Co-60 1.18e+03 3.18e-08 1.00e-06 The above radionuclide composition yields an aggregate quantity of missing licensed material of 53 times the quantity specified in 10 CFR 20 Appendix C, which exceeds which exceeds the 30-day reporting criterion of 10 times the quantity specified in Appendix C. An extensive search has not been successful in locating the source to date, and thus PG&E is making this 30-day notification in accordance with the requirements of 10 CFR 20.2201(a)(1)(ii). PG&E is continuing to investigate the cause of this event using the Technical Review Group (TRG) process and will provide a written report within 30-days in accordance with the requirements of 10 CFR 20.2201(b)(1)(a). This material was last accounted for on 4/8/10. The licensee informed NRC Region IV staff. THIS MATERIAL EVENT CONTAINS A "LESS THAN CAT 3" LEVEL OF RADIOACTIVE MATERIAL Sources that are "Less than IAEA Category 3 sources," are either sources that are very unlikely to cause permanent injury to individuals or contain a very small amount of radioactive material that would not cause any permanent injury. Some of these sources, such as moisture density gauges or thickness gauges that are Category 4, the amount of unshielded radioactive material, if not safely managed or securely protected, could possibly - although it is unlikely - temporarily injure someone who handled it or were otherwise in contact with it, or who were close to it for a period of many weeks. For additional information go to http://www-pub.iaea.org/MTCD/publications/PDF/Pub1227_web.pdf This source is not amongst those sources or devices identified by the IAEA Code of Conduct for the Safety & Security of Radioactive Sources to be of concern from a radiological standpoint. Therefore is it being categorized as a less than Category 3 source | ||
| ENS 41430 | 22 February 2005 22:25:00 | 10 CFR 20.2201(a)(1)(ii) | Report of Missing Special Nuclear Material | The following details were provided by the licensee via email after the telephonic notification: This is a non-emergency Event Notification in accordance with 10 CFR 20.2201(a)(1)(ii) to inform the NRC of missing special nuclear material (SNM) (up to approximately 0.15 grams of U235). The missing SNM consists of one complete and three partial in-core detectors. Since June 2004, Pacific Gas and Electric (PG&E) has been performing an investigation and search for three missing 18-inch rod segments at the Humboldt Bay Power Plant (HBPP) (reference NRC Event Notifications 40877 and 40963). The investigation also included a verification of the inventory of all SNM, including fuel and non-fuel SNM. As a result of the investigation, plant personnel identified HBPP records that indicate 54 in-core detectors should be in the spent fuel pool (SFP). In-core detectors were used inside in-core assemblies during plant operations to measure reactor power level. There were three in-core detectors contained inside each in-core assembly. The in-core assemblies were segmented for storage, and the in-core detectors from a total of 18 in-core assemblies (containing 54 in-core detectors) should be onsite. Each in-core detector is approximately 2-1/2 inches long. Depending on design, an in-core detector contains as much as 0.04 grams of U235, to slightly less than 0.002 grams of U235. PG&E personnel performed a search in the SFP for the in-core detectors from December 2004 through February 2005. On February 4, 2005, PG&E determined that not all 54 in-core detectors could be located and informed the NRC. PG&E is submitting this Event Notification in accordance with 10 CFR 20.2201(a)(1)(ii) that requires a telephonic report and an Event Notification to be made within 30 days from February 4, 2005. PG&E will be issuing a press release tomorrow that includes this issue. PG&E's search for in-core detectors is complete. PG&E has determined that 50 complete and three partial in-core detectors are in the SFP. Therefore, one complete and three partial in-core detectors are missing. The partial in-core detectors appear to have been cut when the in-core assemblies were cut to be shortened for SFP storage in the mid-1970s or mid-1980s. Most probable locations for the missing in-core detectors are licensed, monitored and restricted radiological control areas, therefore the public health and safety has not been adversely affected. PG&E will issue licensee event report (LER) 2005-001-00, 'Missing In-core Detectors,' dated February 22, 2005, to be submitted in accordance with 10 CFR 20.2201(b)(2)(ii) (Reference PG&E Letter HBL-05-002). Information pertaining to the missing in-core detectors is also included in the HBPP SNM Control and Accountability Project Interim Reports, to be submitted February 22, 2005 (Reference PG&E Letter HBL-05-001). NRC personnel at headquarters and in Region IV have been notified of the status of this issue. | ||
| ENS 40963 | 17 August 2004 15:30:00 | 10 CFR 20.2201(a)(1)(ii) 10 CFR 74.11(a) 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | "Report of Missing Special Nuclear Material | This is a non-emergency Event Notification in accordance with 10 CFR 74.11 to inform the NRC of missing special nuclear material of low strategic significance. On July 16, 2004, Pacific Gas, and Electric (PG&E) notified the NRC of a material accountability discrepancy involving a portion of a spent fuel rod used at the Humboldt Bay Power Plant (HBPP) Unit 3 (reference NRC Event Notification 40877). The discrepancy in plant records called into question the location of three approximately 18-inch segments that were cut from a single spent fuel rod in a used fuel assembly (A-49) in 1968. PG&E initiated a comprehensive search of the on-site HBPP spent fuel pool (SFP), a review of plant and nuclear materials shipping records, and interviews with present and former employees and contractors to resolve the material accountability discrepancy and locate the unaccounted for fuel segments. On August 17, 2004, at 08:30 PDT, the HBPP Plant Staff Review Committee (PSRC) reviewed the results of the search of the SFP to-date and concluded that the search of the most likely locations for the unaccounted for fuel segments (storage containers within the SFP) and all easily accessible spaces in the SFP was thorough and complete and that the search had not located the unaccounted for fuel segments in the SFP. The PSRC also reviewed the results to-date of the in-progress review of plant records, interviews, and nuclear material shipping records and concluded that the relevant information obtained did not definitively identify the on-site or off-site location of the unaccounted for fuel segments. Though it remains probable that the unaccounted for fuel segments will ultimately be found in the SFP or shown to have been shipped to a facility licensed to reprocess or store nuclear materials, PG&E is conservatively considering these segments as missing and making this 1-hour non-emergency event notification in accordance with 10 CFR 74.11. PG&E will be issuing a press release later today describing the current status of this issue. PG&E has embarked upon a 'phase II' search of the remaining less-accessible SFP areas and will continue its review of plant records, nuclear materials shipping records (plant and waste repository records), and interviews of plant personnel to definitively locate the missing fuel segments. A supplemental LER will be provided to the NRC when the segments are located or when the phase II search is concluded. No evidence has been uncovered to support the possibility of theft or diversion of the unaccounted for fuel segments. Due to the high radioactivity of the material, to be handled safely, the segments would have to be encased in a heavy shielded container that would have to be moved with special handling equipment designed for this purpose, precluding an abrupt loss. Since plant start-up, HBPP has been equipped with a system of radiation monitors for the refueling building (where the SFP is located) with alarm setpoints that are capable of alerting plant personnel of the movement of highly radioactive material should the fuel segments have been removed from the SFP without being in a shielded container. This could not have occurred casually without plant staff or security personnel observing the movement. Because the three approximately 18-inch segments are not readily identifiable in the SFP, three possible scenarios exist. The highest probability is that the fuel segments are in a SFP area that is not readily accessible, and will be located during a more detailed search of these locations. The second highest probability is that the fuel segments were shipped offsite to an appropriately controlled and restricted facility for either analysis or reprocessing. The least probable location, but not yet capable of being ruled out, is that the fuel segments were inadvertently included in a shipment to a licensed, monitored, and restricted LLRW facility. Since these possible locations are licensed, monitored and restricted radiological control areas, the public health and safety has not been adversely affected. For additional information, refer to licensee event report (LER) 2004-001-00,'Three Missing Fuel Rod Segments,' dated August 16, 2004, and submitted in accordance with 10 CFR 20.2201(b)(2)(ii), (Reference H BL-04-020). NRC personnel at headquarters and in Region IV have been notified of the status of this issue. |