Print View Posted on: 17 July 2025
On April 8, 2025, two workers were performing waste handling activities in a hot cell basement of a cyclotron facility that produces strontium-82 from metallic rubidium targets. One worker removed a high-level liquid waste container from a shielded barrel and placed the unshielded container on the ground adjacent to the work area, where activities continued for approximately 15 minutes. Both workers’ electronic dosimeters alarmed for high dose soon after the container was removed from shielding; however, neither worker noticed these alarms because of the personal protective equipment they had donned, including respirators. Radiation surveys were performed upon entry to the area and prior to removing the container from shielding, but not again until after the workers left the area and noticed the excessive doses recorded on their electronic dosimeters. Radiation dose rates on contact with the waste container exceeded 9.99 Sv/hr (999 R/hr), which was the upper limit of available instrumentation. The licensee later determined that on the day of the event, the waste container contained over 7.77 TBq (210 Ci) of rubidium radionuclides. A dose reconstruction concluded that as a result of this event, Worker 1 received a total effective dose equivalent (TEDE) of 0.124 Sv (12.4 rem) and a shallow dose equivalent (SDE) of 2.4 Sv (240 rem) to the skin of the lower extremities, and that Worker 2 received a TEDE of 0.096 Sv (9.6 rem). The TEDE of both employees exceeded the U.S. regulatory limit for annual whole body dose of 0.05 Sv (5 rem). The SDE of Employee 1 exceeded the U.S. regulatory limit for annual dose to the skin of the extremities of 0.5 Sv (50 rem). EN57657