05000416/LER-2009-003
| Docket Numbersequential Revmonth Day Year Year Month Day Year N/Anumber No. N/A | |
| Event date: | 07-22-2009 |
|---|---|
| Report date: | 08-21-2009 |
| 4162009003R00 - NRC Website | |
On July 22, 2009, at 1733 hours0.0201 days <br />0.481 hours <br />0.00287 weeks <br />6.594065e-4 months <br /> Central Daylight Time (CDT), Grand Gulf Nuclear Station (GGNS) was in Mode 1 operating at approximately 100 percent power. During performance of the annual physical inventory of special nuclear material (SNM), the determination was made that an unirradiated local power range monitor (LPRM) detector [IG-DET] serial number 01S22029 was not in its expected storage location. While the investigation concluded that the LPRM was shipped to a licensed disposal facility, this condition is being reported in accordance with 10 CFR 20.2201(a)(1)(ii) as a loss of licensed material of a quantity greater than ten times the quantity specified in Appendix C to 10 CFR Part 20. Telephone notification was made on July 22, 2009, to the NRC Emergency Notification System (ENS) pursuant to 10 CFR 20.2201(a)(1)(ii). This written report is being submitted within 30 days of the telephone notification in accordance with the requirements of 10 CFR 20.2201(b).
B. DESCRIPTION OF LICENSED MATERIAL INVOLVED
LPRM detector 01S22029 was originally received on site on April 2, 2002. The LPRM subsequently failed testing and was never put into service (i.e., unirradiated). It was determined that the unirradiated detector was placed into storage until it was shipped offsite to a disposal facility as an SNM discard on February 18, 2005. The LPRM detector is a sealed fission chamber containing uranium oxide material. Based on the original Shipper's Certification for Radioactive Material, dated March 25, 2002, the LPRM detector contained an estimated maximum total activity of 5.84 microcuries of Uranium-234 (U-234) and Uranium-235 (U-235) combined.
C. CIRCUMSTANCES UNDER WHICH THE LOSS OCCURRED
In September 2002, LPRM detector 01S22029 was moved to core location 26-35A during Refueling Outage 12 (RF12). Subsequently, it was discovered that the LPRM had failed testing. Prior to drywell closeout during RF12, the unirradiated defective detector was moved from the core to a temporary SNM storage area in the auxiliary building and placed into an Intermediate Range Monitor (IRM) / Source Range Monitor (SRM) detector canister.
In January 2003, LPRM 01S22029 was discovered in the SNM storage area in the auxiliary building. Prior to discovery of the detector, it was thought to have been moved to the Spent Fuel Pool (SFP) (reference: CR GGN-2003-00070). The LPRM was stored in a canister designed to contain IRM and SRM detectors which was not typical of the normal storage method for LPRMs (i.e., to place them in specifically designed LPRM canisters). This atypical storage method was a result of the detector not being irradiated. After discovery, the IRM/SRM canister containing LPRM 01S22029 was moved from the SNM storage area to a drum in the SFP which contained multiple canisters containing IRMs, SRMs, and LPRMs. Movement of the LPRM to the SFP drum was noted on the SNM Tracking Sheet STS-1-13-04.
A SFP cleanup campaign was conducted in February 2005 under the authorization of SNM Tracking Sheet STS-1-14-21, which described the staging of detectors into a shipping cask for disposal. During this campaign, the SFP drum was emptied of shippable items (i.e., items with specific activity not excessively high, including all IRM/SRM canisters), and these items were loaded into a shipping cask and shipped to the Barnwell, South Carolina, facility for disposal. No LPRM canisters were shipped offsite at this time. LPRM 01S22029 continued to appear in the SNM inventory database because it was incorrectly assumed to be stored in an LPRM canister in the SFP drum.
NRC FORM 366AA U.S. NUCLEAR REGULATORY COMMISSION (9-2007) During performance of the 2009 annual SNM physical inventory in July 2009, under the authorization of SNM Tracking Sheet STS-1-17-16, the SFP drum was emptied of LPRM can;sters. The LPRM canisters were transferred to specially designed holders that allowed each LPRM canister to reside in an individual fuel rack location in the SFP. During this activity, a discrepancy between the SNM database and physical inventory was discovered regarding the location of LPRM detector 01S22029 (reference: CR-GGN-2009-03729).
Review of the 2005 SNM Tracking Sheet STS-1-14-21 determined that the steps in the STS were vague and did not specifically document detector serial numbers. The STS referred to all detectors stored in the SFP drum, which was all detectors (IRM, SRM, LPRM, and Traversing Incore Probe (TIP)) in the SFP at that time.
The STS also contained the note "All detectors except LPRMs in canisters," indicating that all detectors except LPRMs in canisters were removed from the SFP drum and loaded into the shipping cask. Based on interviews with personnel performing the cask loading and review of STS-1-14-21, it was concluded that LPRM 01S22029 was loaded into the cask since the LPRM was contained in an IRM/SRM canister in the SFP drum and all IRM/SRM canisters had been shipped offsite in 2005. The contents of the IRM/SRM canister had not been positively identified because the canister was not accessible to perform serial number or piece count verifications of contents. The LPRM remained in the SNM inventory database because it was thought to be stored in an LPRM canister. The investigation concluded that LPRM 01S22029 was shipped offsite as an SNM discard in Grand Gulf Shipment No. 2005-0205 on February 18, 2005.
D. DISPOSITION OF LICENSED MATERIAL INVOLVED
Based on the investigation, review of inventory results, and interviews with responsible personnel, it was concluded that LPRM detector 01S22029 was shipped offsite to the Barnwell, South Carolina, facility as SNM discard. The 2009 SNM inventory sheets have been reconciled with the physical SNM inventory, and appropriate notifications and reporting are in progress.
E. EXPOSURES OF INDIVIDUALS TO RADIATION
LPRM detector 01S22029 contained a maximum total activity of approximately 5.84 microcuries of U-234 and U-235 combined. The licensed material in the detector that could not be accounted for was in a container that was properly handled as a device containing radioactive material. Since the detector containing the licensed material was maintained in the controlled waste process stream (i.e., packaging, transportation, and disposal of radioactive materials), no unregulated exposures occurred to persons in unrestricted areas. In addition, given that the detector was unirradiated, its contribution to the dose received by any radiation workers involved in the waste handling process was negligible.
F. ACTIONS TAKEN TO RECOVER THE MATERIAL
A thorough inspection of potential detector storage locations within the SFP Item Control Areas was conducted, interviews with persons previously involved in performing SNM physical inventories were conducted, and historical SNM related documentation was reviewed. Based on the investigation, it was concluded that LPRM detector 01S22029 was shipped offsite to the Barnwell, South Carolina facility and disposed of as an SNM discard. The 2009 SNM inventory sheets have been reconciled with the physical SNM inventory, and appropriate notifications and reporting are in progress.
NRC FORM 366A� U.S. NUCLEAR REGULATORY COMMISSION (9-2007) I� SEQUENTIAL� I
G. PROCEDURES OR MEASURES TAKEN OR WILL BE ADOPTED TO ENSURE AGAINST
RECCURRENCE
Condition Report GGN-2009-03729, initiated on July 22, 2009, will address any additional actions to preclude recurrence of similar events. A root cause evaluation was performed to thoroughly analyze the event and recommend corrective actions, identify process improvements, and ensure appropriate management involvement in issue resolution. This evaluation determined that the primary cause of the event was insufficient procedural guidance related to properly storing atypical SNM in identifiable containers.