Chromosome aberrations scoring for biological dosimetry in a criticality accident

During an international intercomparison of dosimetry systems for the simulation of a criticality accident which took place at the SILENE Reactor (Valduc, France), whole blood was exposed to reference pulses of mixed gamma and neutron irradiation. This was done with specimens supported free-in-air and attached to a phantom. Each blood sample was shared between the NRPB and IPSN laboratories, cultured and scored for chromosomal aberrations. Each laboratory made estimates of the neutron and gamma components of dose by reference to their own pre-existing in vitro calibration curves. It was necessary to have an estimate of the ratio of the neutron to gamma dose for this purpose. Good agreement was obtained between the results from both laboratories and with the reference doses. The conclusion is that biological dosimetry using peripheral lymphocytes gives credible estimates of personal doses in criticality accidents.