The general methods used to calibrate the dosimeters are given in the National
Bureau of Standards Special Publication 633, Procedures for Calibrating Neutron
Personnel Dosimeters (Schwartz and Eisenhauer, 1982). Two laboratories
conduct the performance test irradiations for the DOELAP and NVLAP
programs: Pacific Northwest National Laboratory of Richland, Washington, and
the Radiological and Environmental Sciences Laboratory (RESL) of Idaho Falls,
Idaho. Dosimeters are submitted for testing to the performance testing
laboratories in specified categories. If the dosimeter passes certain accuracy and
tolerance testing criteria, a team of dosimetry experts visit the processor and/or
site and assess the operation of the dosimetry program, including dosimetry
records and data retrieval systems, before the dosimeter processor or DOE site is
accredited. DOE requirements are given in the U. S. Department of Energy
Standard Laboratory Accreditation Program for Personnel Dosimetry Systems,
DOE STD-1095- 95 (DOE 1995h). At present, both whole body personnel
dosimeters and extremity dosimeters are being tested, with extremity dosimeter
testing currently being voluntary. DOE will formalize the extremity dosimetry
accreditation program in the near future.
Doses to the extremities from plutonium processing and handling can involve
significant exposures to the skin of the hands and forearms. Doses over small
areas of the skin are discussed in Section IV.B.2. of Implementation Guide.
External Dosimetry Program (DOE, 1999e) and will not be discussed here. That
Section discusses skin contamination including hot particles, and the
determination of skin dose from these events.
Highly accurate measurement of the dose to the hands and forearms is especially
difficult because of the low-energy photons (L x-rays and 60-keV photons from
241Am). Small variations in shielding, such as differences in the thickness of
gloves used in glove boxes or non-uniform distribution of plutonium oxide dust
on the surface of gloves, can produce large variations in the dose rate. Examples
of these variations were given previously.