Event Notification Report for April 17, 2025

POSSIBLE OVEREXPOSURE DUE TO LOSS OF CONTROL OF LICENSED MATERIAL

The following information was provided by the licensee via phone and email:

"At 1518 EDT on April 8, 2025, the radiation safety officer (RSO) was informed about an incident that happened during routine Sr-82 production and waste activities. Four workers were performing waste and remediation activities for a Sr-82 production hot cell. The work was performed under a job-specific radiation work permit and direct supervision of health physics staff. Two of the workers (Worker 1 and Worker 2) entered the waste collection space (basement) located underneath the hot cell to repair a clog in the solid waste duct and replace the liquid acid waste transfer container. Worker 1 and Worker 2 were wearing positive air pressure respirators (PAPRs) which are the appropriate personal protective equipment for work being performed and electronic dosimeters. Worker 2 surveyed the working area upon entry and the shielded waste container using a RadEye [survey meter]. Worker 2 found a partially unshielded area in the waste container reading 930 mR/hr (highest reading recorded during survey).

"Worker 1 and Worker 2 proceeded to disconnect the solid waste duct to remove a potential clog and inspected the waste container. The solid waste container was empty. While inspecting the solid waste duct, a liquid acid waste line disconnected from the bottom of the hot cell. There was no liquid in the line. Worker 1 moved the solid waste cask out of the way of the work area. Worker 1 and Worker 2 then focused on the liquid acid waste container. Worker 1 and Worker 2 moved the shielded acid waste container to the entry of the waste area and removed the lid of the container. Worker 2 removed the plastic bag from the waste container and placed it away from the working area. Worker 1 then replaced the liquid acid waste bucket.

"Worker 1 and Worker 2 returned to the solid waste chute to inspect and unclog the chute. The second liquid waste line broke at this time and fell to the floor. Worker 1 and Worker 2 returned to the entry way and communicated the problem to Worker 3 and Worker 4. It was requested that Worker 3 attempt to lift the waste plate inside the hot cell to reconnect the waste lines and lower the lines back into the waste area. A survey of the hot cell was requested prior to starting this work. Worker 3 opened the hot cell and found the working area to read between 1.5 R/hr to 5 R/hr. Worker 3 unsuccessfully tried to open the connection plate between the hot cell and the solid waste duct. Worker 1 and Worker 2 positioned the shielded waste cask under the hot cell to reconnect it to the hot cell. Worker 1 and Worker 2 noted the dose alarms (100 mrem threshold) on their dosimeters at this time. When they were unsuccessful in lifting the shielded cask into position, they abandoned the work and exited the waste collection space. Upon exiting, their electronic dosimeters were alarming. Worker 1 and Worker 2 noted that their electronic dosimeters were alarming and recorded doses of 4.399 rem for Worker 1 and 2.924 rem for Worker 2.

"Worker 2 escalated the incident to the RSO immediately. The RSO secured the area and instructed Worker 4 to survey the space between the hot cell and the solid waste plate that connects the solid waste duct. Worker 4 found the exposure rates to be 75 mR/hr. As a post-incident follow-up, the RSO instructed Worker 3 to enter the waste collection space to confirm the exposure rates. Worker 3 found exposure rates of 2 R/hr at the entry point, 25 R/hr next to the working location and a waste bucket opposite to the working area that saturated the detector (>1,000 R/hr on contact). Worker 3 electronic dosimeter recorded a dose of 457 mrem. Worker 1 exhibited a maximum of 25,000 disintegrations per minute (dpm) on their left hand. Worker 4 exhibited a maximum of 1,200 counts per minute (120 dpm) on his shirt. Preliminary urinalysis results for Worker 1 did not identify count rates above background levels (no intake).

"The RSO initiated a stop work for production waste activities. As a post-incident follow-up, the director of the radiation safety office and RSO immediately reviewed the dose to date in 2025 and found that Worker 1 total dose was 5.604 rem, exceeding the dose limit set forth in 10 CFR 20.1201. The RSO and director of the radiation safety office initiated a formal investigation."

The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:

Discussions with the licensee revealed that the report is being submitted pursuant to 10 CFR 20.2202(b)(1)(i) for an individual potentially exceeding a total effective dose equivalent of 5 rem within 24 hours due to a loss of control of licensed material. Additionally, a 30-day report will be submitted pursuant to 10 CFR 20.2203(a)(2)(i) for an adult receiving an annual occupational total effective dose equivalent in excess of 5 rem.

THEFT OR LOSS OF LICENSED MATERIAL

The following is a summary of the information provided by the licensee via phone:

During a shipment from Wilmington, Delaware to Albuquerque, New Mexico, a 0.63 millicurie iron-55 (Fe-55) source was lost or stolen in transit. The last known location was Wilmington, Delaware. The source was shipped on March 27, 2025, and was identified as lost on April 10, 2025. The shipping package was delivered to the intended recipient, but the shipping package was compromised with the source missing. The shipper and the common carrier are investigating.

Model Number: FE5VZ29120005M
Serial Number: NK772

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