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24 May 2012

Answer to Question #11 Submitted to "Ask the Experts"

Category: Instrumentation and Measurements — Personnel Monitoring (PM)

The following question was answered by an expert in the appropriate field:

Which materials must have a criticality dosimeter and why? Must it contain Rh?

I doubt that I fully understand the question, but let me offer the following: Criticality accident dosimeters (also referred to as nuclear accident dosimeters) should be used where there is potential for personnel to be exposed to radiation from accidents involving critical masses of fissionable material. While Rh has been used as a component in some such dosimeters, other materials (e.g., Au, S, In, Cu) are common.

Biological dosimetrical techinques including blood sodium activation, hair sulfur activation, and chromosome aberration are also available. Guidance can be found in ANSI Standard N13.3 , which was originally issued in 1969 and reaffirmed in 1981. The Department of Energy also has limited guidance on this subject contained in 10 CFR 835 (section 1304).

To learn more about dosimetry details, see "Dosimetry for Criticality Accidents," IAEA Technical Report Series No. 211 (1982) and/or "Nuclear Accident Dosimetry Intercomparison Studies," Health Physics, 57:439-448; 1989.

C. S. Sims
Office of Radiation Protection
Oak Ridge National Laboratory

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