On January 17, 1995, a radiological control inspector (RCI) at the H-Canyon facility at the Savannah River Site tested positive for plutonium-238 on two consecutive bioassay samples. Facility personnel calculated the 50-year Committed Effective Dose Equivalent (CEDE) to be 691 millirem and estimated the activity of plutonium to be 1.76 nano-curies. As required by Article 522.7 of DOE/EH-0256T, Radiological Control Manual, facility management placed the inspector on administrative duty to limit radiation exposure pending an investigation. (ORPS Report SR--WSRC-HPIH-1995-0001)

The RCI participates in a semi-annual bioassay sampling program provided for personnel at the H-canyon facility. The frequency of sampling is based on the individual's work location and the type of contamination present at that location. If a worker's routine sample reads above a specified level, then a second sample is taken for confirmation. If the second sample is also positive, then the worker is placed on a special bioassay schedule and duties are changed to minimize radiation exposure. In this event, the inspector's second sample indicated a higher level of plutonium contamination.

Health physics personnel performed an extensive review of the RCI's work history and previous bioassay sample results. They determined that the RCI may have received two intakes; one in October 1994 and the other in December 1994. Facility investigators have not determined the cause and the exact dates of the intakes. They estimated that for two one-week periods, the RCI had performed approximately 45 jobs and surveys. Some required a respirator and some did not.

At H-canyon, a respirator is required in areas where the airborne plutonium concentration exceeds 0.1 derived air concentration (DAC). In areas where levels of transferable surface contamination are present and air sampling indicates airborne levels to be less than 0.1 DAC, the need for a respirator is determined based on the type of work performed, type of radioactive material, and length of time of the work activity.

A health physics investigator indicated that facility personnel are investigating two possible areas of concern in the radiological controls program. One area may involve incorrect application of approved practices by workers using respiratory protection. Facility management will have the RCI undergo respirator fit testing and other exercises to attempt to identify any incorrect methods. Health physicists are reviewing the criteria used to determine when respiratory protection is required. They also are reviewing the frequency of bioassay sampling against the current respiratory protection criteria to determine if the frequency is sufficient to protect workers.

Facility personnel are continuing the investigation to determine the cause of the intakes, to develop corrective actions, and to define the lessons to be learned.

NFS will provide additional information in a future OE Weekly Summary when details concerning the causes, corrective actions, and lessons learned become available.