Criticality Accident Dosimetry: An International Intercomparison at the Silene Reactor

In criticality accident dosimetry, specialised techniques, which differ markedly from those used in routine radiological protection, are used to measure separately the gamma ray and neutron components of dose. In order to improve these techniques and to evaluate the performance of their dosimetry systems, fifteen laboratories participated in an international intercomparison at the SILENE reactor, Valduc, France. The physical techniques used in criticality dosimetry are first described, for personnel and installed dosemeters, and for the initial sorting of those exposed. The SILENE reactor is briefly described together with a review of the dosimetry and spectrometry techniques used to characterise the radiation field at a reference position and to study the uniformity of the field on an arc around the source. The experimental arrangements of the participants' dosemeters for the intercomparison irradiations (in free-air and on phantoms) are given, followed by a summary of the doses measured by the participants. From an overall analysis of this intercomparison, it is concluded that the participant's results are in good agreement with the reference measurements for both the neutron and gamma ray components of dose.