Event Notification Report for April 28, 2020

AGREEMENT STATE REPORT - STOLEN TROXLER MOISTURE DENSITY GAUGE

The following information was received from the state of California via email:

"On 4/30/2020, at approximately 1127 [PDT], the RSO [radiation safety officer] of RMA Group, RML Number 8055-19, contacted RHB [California Radiologic Health Branch] Brea concerning a moisture/density gauge, Troxler, model 3440, serial number 25671 (Cs-137, 0.3 GBq, Am-241, 1.50 GBq) that had been stolen from in front of a private apartment complex while the RMA employee was offloading his vehicle. The Troxler radioactive gauge was left on the sidewalk during offloading of the vehicle. [The RMA employee] forgot about the gauge he had left on the sidewalk as he then drove off to have his vehicle washed. When he returned from the carwash at approximately 1730 to 1800 on 4/28/2020, he realized that he had left the radioactive gauge in front of the apartment complex and that it was no longer there. The [RSA employee] finally reported the theft to the RMA RSO on 4/29/2020 at 1215, prior to reporting the theft to Los Angeles Police Department at the West Los Angeles office on 4/29/2020 at 1245. A copy of the theft report and the [employee's] statement has been sent to RHB Brea as part of this report. [The RMA RSO] will utilize local papers to attempt to retrieve the stolen gauge as well as notifying local servicing vendors of radioactive gauges to be alert of the serial number of the stolen gauge in case it turns up for any of their services.

"The investigation will continue to determine if the radioactive gauge can be recovered in a reasonable time frame. This is being reported to the NRC Operations Center as a 24-hour report under 10 CFR 20.220(a)(1)(i) since the radioactive gauge has been stolen with the source handle locked and the Type A transport container locked."

California Report Number 5010-043020


* * * UPDATE FROM DONALD OESTERLE TO DONALD NORWOOD AT 1516 EDT ON 5/4/2020 * * *

The gauge has been recovered intact. A formal closing report will be submitted later.

Notified R4DO (Drake), and via E-mail: NMSS Events Notifications E-mail group, ILTAB, and CNSNA (Mexico).

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

PART 21 REPORT - NON-CONSERVATIVE BWR/6 SIDE ENTRY ORIFICE LOSS COEFFICIENTS

The following is a summary of information received from GE Hitachi Nuclear Energy:

For core monitoring, Global Nuclear Fuel-Americas (GNF) applies different hydraulic loss coefficients to BWR/6 fuel bundles as a function of location. The Side Entry Orifice (SEO) loss coefficient varies in BWR/6 plants, depending on the orientation of the SEO relative to intersecting core support beams. The SEO loss coefficient for some bundle locations are under predicted, which results in a local over prediction of Minimum Critical Power Ratio (MCPR) margin. Specifically, the SEO loss coefficients for fuel bundle locations adjacent to Intermediate and Source Range Monitor (IRM/SRM) locations should be higher than the current "one beam" values that are applied. The MCPR effect on affected bundles under conditions where they are near limits can reduce margin by 0.02 in CPR. The condition is not a substantial safety hazard, but the MCPR effect is above the threshold that GNF applies for reportability.

GNF has completed its evaluation and concluded that this issue is a reportable condition under 10 CFR 21.21(d). The basis for reportability is that the change in MCPR associated with this issue could contribute to the exceeding of a safety limit, as defined in the technical specifications of a license for operation issued under 10 CFR Part 50.

US BWR Potentially Affected Plants:
Grand Gulf, River Bend, Clinton, and Perry.

There are currently no US ABWR plants in operation that would potentially be affected by this evaluation. The potential error in the core monitoring system does not affect the NRC certified design of the ABWR or the GEH ABWR design certification renewal application currently under review. The unique core support structure design of the BWR6 and ABWR is not shared by earlier BWR plants or the ESBWR.

Affected plants should review the following paragraph and contact their GNF account representative for schedule and delivery dates for updated core monitoring databanks. Updated core monitoring databanks for the affected BWR/6 plants are scheduled to be completed by July 10, 2020.

For affected plants that use GNF core monitoring software, the long-term corrective action is to implement an updated core monitoring databank with corrected SEO loss coefficient values. Affected plants should contact their GNF account representative for schedule and delivery dates. If necessary, a short-term corrective action such as an administrative MCPR penalty on IRM/SRM locations, should be applied to the core monitoring system. An effective short-term measure would be to assure that IRM/SRM locations are 0.02 less than the Maximum Fraction of Limiting CPR limit (e.g., MFLCPRlimit = 1.00). This condition is met if the core wide MFLCPR is 0.02 below the limit (e.g., MFLCPR < 0.98), because the IRM/SRM locations will be bounded. Note that this recommended short term or interim measure was developed on a standalone basis and does not supplant any existing MFLCPR limit reductions established for other purposes.

For non-affected plants, there are no recommended actions. GNF recognizes that other non-GNF fueled plants, safety analysis methodologies, and core monitoring systems may have different design bases and address SEO losses by other means.

For more information, please contact:
Michelle Catts
GE Hitachi Nuclear Energy
Safety Evaluation Program Manager
3901 Castle Hayne Road, Wilmington, NC 28401
Michelle.Catts@GE.com
(910) 200-9836