Calibration of neutron personal dosimeters in a realistically simulated neutron irradiation room

We have evaluated neutron personal dose equivalents and neutron fluence-to-personal dose equivalent conversion coefficients using MCNPX transport calculations for a (252)Cf, a D(2)O-moderated (252)Cf, and an (241)Am-Be source in the neutron irradiation room of the Korea Research Institute of Standards and Science. The direction of the phantom surface normal was set so that it pointed to the source. The increment of the personal dose equivalent due to room-scattered neutrons for the (252)Cf source was 4.6, 4.9, 7.2, 12.6 and 23.2% for distances of 50, 75, 100, 150 and 200 cm, respectively. The personal dose equivalents of the D(2)O-moderated (252)Cf and the (241)Am-Be source also had a tendency to increase as the distance increased. These results suggest that the contribution of room-scattered neutrons to personal dose equivalents in a neutron irradiation room is not negligible and should be thoroughly studied prior to actual calibration in that setting. (C) 2010 Elsevier Ltd. All rights reserved.