Extremity Dosimetry - doe-std-1136-20040164

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiation Protection in Uranium Facilities

6.4.4 Extremity Dosimetry

Doses to the extremities from uranium processing and handling can involve significant

exposures to the skin of the hands and forearms. Doses over small areas of the skin, including those

from hot particles, are discussed in detail in DOE G 441.1-4 and will not be discussed here.

Measurement of the dose to the hands and/or forearms typically are made with TLD chips or TL

powder in finger rings or wrist dosimeters. Such devices do not allow for all of the sophisticated energy

discrimination just discussed. The non-homogeneity of beta radiation fields coupled with the angular

dependence of commonly-available extremity dosimeters can result in a probability of underestimating the

dose. However, by carefully considering the typical exposure conditions at the work site (handling metal

pieces, glove box work, etc.) and calibrating the dosimeters with appropriate sources (uranium plaque

sources, etc.), extremity doses can be measured with acceptable accuracy for protective purposes.

Care should be exercised in preventing "obvious" underestimations of extremity dose. For example,

finger rings worn on the "top" of the finger (opposite the palm side of the hand) will not measure the dose

received by the palm side when handling metal rods, etc. Dosimeters worn on the wrist have been shown to

underestimate the beta dose to the fingers and palm. Reference to the Bibliography information sources will

provide further information in current techniques and considerations.

The general methods used to calibrate dosimeters are given in the National Bureau of Standards

Special Publication 633, Procedures for Calibrating Neutron Personnel Dosimeters. Two laboratories

conduct the performance test irradiations for the DOELAP and NVLAP programs: Pacific Northwest

Nationa l Laboratory of Richland, Washington, and the Radiological and Environmental Laboratory

(RESL) of Idaho Falls, Idaho. Processors submit dosimeters for testing to the performance testing

laboratories in the categories listed in Table 6-9. If the dosimeter processor passes certain accuracy and

tolerance testing criteria, a team of dosimetry experts visit the processor and assess the operation of the

dosimetry program, including dosimetry records and data retrieval systems, before the dosimeter processor

is certified. These requirements are given in DOE STD-1111-98, Department of Energy Laboratory

Accreditation Program Administration (DOE 1998b) and its associated guidance documents.

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