NIST contamination event results in radiation exposure

The National Institute of Standards and Technology (NIST) has reported a contamination event in one of its laboratories that has resulted in an internal radiation exposure from americium-241 (Am-241) to at least one radiation staff member. Initial bioassay testing appears to show that the employee received a dose above the annual regulatory limit for radiation workers; additional testing is underway to acquire more dose estimate data.

The staff member has received appropriate medical treatment based on guidance provided by specialists in radiation exposure care.

On Aug. 18, 2017, NIST radiation safety personnel discovered Am-241 contamination in a laboratory used to prepare radioactive samples. The source of the contamination was traced to a small glass ampoule of Am-241 that had shattered within its lead-lined container inside a larger protective storage box. Contamination was also found in a nearby laboratory where other samples stored in the box were measured.

NIST radiation safety personnel then identified other radioactive sources that could cause a similar hazard and relocated them to individual reinforced containers.

Bioassay testing for additional staff members is underway. Those tests and a confirmed dose estimate for the exposed staff member are expected to take several weeks to months to complete.

Following Nuclear Regulatory Commission (NRC) protocols, NIST self-reported the contamination event to the NRC on Aug. 19, 2017, and followed up with a self-report of the one staff member's positive bioassay results on Sept. 6, 2017.

Additional surveys of the building in which the contamination was found identified two non-laboratory spaces with low levels of Am-241 contamination that do not pose a health concern. NIST reached out to the Department of Energy National Nuclear Security Administration's Radiation Emergency Assistance Center/Training Site (REAC/TS) and its Radiological Assistance Program (RAP). REAC/TS and RAP provided expert personnel and equipment to assist NIST. A full survey of the building was completed and did not find additional Am-241 contamination.

Radiation safety teams from NIST and the NRC have begun inquiries to determine why the ampoule shattered, how the contamination spread, and to provide recommendations for preventing similar events.

Provided by National Institute of Standards and Technology