The U.S. Nuclear Regulatory Commission (NRC) has been notified of a nuclear material event that occurred on May 1 at Walter Reed Army Medical Facility in Washington, D.C., involving improper storage of a 2 Ci molybdenum-99 (Mo-99) generator for two days.

The Mo-99 generator was delivered to the Walter Reed Army Medical Facility on May 1. An unauthorized person signed for the package and stored it in an improper location. The package was located on May 3 at the facility.

The licensee has now stored the package in proper location and is conducting dosage calculations for any individuals who may have been in the vicinity of the package where it was improperly stored, the report said.  

Since the nuclear material event contained "less than IAEA category 3 " level of radioactive material it is very unlikely to cause permanent injury to individuals, according to the report.