Mixed-Field Neutron-Gamma Dosimetry with an Electronic Personal Gamma Dosimeter

Abstract

Handling radioisotope neutron sources may involve exposure to both neutron and gamma fields. Although the field of gamma dosimetry is well developed and reliable, challenges exist with personal neutron dosimetry. A number of gamma and neutron dosimeters were evaluated for their efficacy in providing personal dosimetry for radioisotope source manipulations. A commercial off-the-shelf electronic neutron dosimeter was observed to underestimate total operator dose when manipulating a 252Cf source. In this work, scaling factors were evaluated using both experimental results and Monte Carlo simulations to allow a measured electronic personal gamma dosimeter (EPGD) dose to be used to estimate the total neutron + gamma dose. The recommended scaling factor using an MGP SOR/R EPGD for free-field 252Cf is 18, and for shielded 252Cf the recommended scaling factor is 6. A conservative single scaling factor of 18 is appropriate for personal dosimetry estimates.