Radiation exposure at the Idaho Chemical Processing Plant

The Idaho Chemical Processing Plant (ICPP) is one of the few facilities which reprocess nuclear fuel and solidify liquid wastes. This paper summarizes the radiation exposure experience, dose trends, average doses received by workers, work groups receiving the highest doses, and activities which routinely give the highest doses. Because ICPP is a direct-maintenance facility, entry is required into process cells for decontamination and repair of equipment by ''hands-on'' maintenance. This type of operation generally results in higher personnel dose than does a remote-maintenance plant. New buildings and associated processes at ICPP are being designed and built to provide remote-maintenance capabilities in those areas and for equipment known from experience to require high maintenance. The work groups receiving the highest external doses are the maintenance, production and health physics personnel. Individual doses are kept as low as practicable by using pre-job planning and innovative techniques. An administrative guideline of 3 rem/year has been established. While penetrating doses are limiting on an annual basis, the non-penetrating doses are limiting on many jobs. The high non-penetrating fields from unshielded fission products occasionally encountered cause severe dosimetry problems. Internal doses are normally below a few per cent of the limit; however, several workers have received internal doses approaching 50% of the limit. The critical organ is often the lung, from the inhalation of insoluble particulate activity. Dose assessments are made from in vivo counting whenever possible. Bioassay samples are routinely collected to provide complete internal dosimetry information. Particularly when alpha and beta emitters are encountered, faecal and urine samples are collected and analysed to provide data necessary to evaluate lung doses