The following was received via email.
Between 2/27/19 and 2/28/19, an autoclave (13 inches long with 1.25 inches width) ruptured in room 2BR136 of Building 20620, at Wright Patterson Air Force Base (AFB) OH. Nobody was present at the time of the rupture. Scientists were working with unlicensed materials (potassium niobate and potassium hydroxide) at the time of the event. This autoclave originally came from Hanscom AFB .
During the investigation, the installation Radiation Safety Officer found affixed to the inside of the autoclave canister non-removable thorium-232 (31,235 dpm/100 cm2) and a significantly lesser amount of removable thorium-232. Besides the material on the autoclave, no other contamination was present. Thorium contamination might be from the raw materials used in the autoclave and/or Hanscom AFB might have used thorium in the autoclave. The licensee are investigating and conducting additional gamma spectroscopic analysis of the interior of the ruptured autoclave.
This was a historical incident that the licensee was made aware of, and is still uncertain if it is reportable. The licensee had a discussion with NRC Region IV regarding this event. After the discussion, the licensee chose to report to the NRC Operations Center in accordance with 10 CFR 40.60. To the best of the licensee's knowledge, nobody had radiation exposure or radioactive material uptake.
The licensee will provide the follow-up written report within 30 days.
The Thorium-232 Appendix B annual limit on intake is 3E-3 microCuries.
The licensee contacted Region IV.