Comments by C.E.G.B

The 1981-82 intercomparison of radiation protection or personal dosemeters was organised by the Commission of European Communities and approximately 30 establishments participated. It was agreed that the CEGB Berkeley Nuclear Laboratories should be responsible for the exposures specified in low and medium doses of ISO 83keV X-radiation on a phantom. Since it was not appropriate that BNL should measure dosemeters exposed at BNL, dosemeters were prepared and despatched only for exposure at other establishments; i.e. using the radiations specified in low, medium and high doses of 60Co γ rays in air; low, medium and high doses of 60Co γ rays on a phantom; low and medium doses of ISO 83keV X-radiation in air; and low and medium doses of mixed 60Co and 83keV radiation in air. The dosemeter used was the Kodak Type 2 film in the standard NRPB/AERE holder, and 26 such dosemeters including control's and spares were dispatched on 18th September 1981. From the results is was apparent that if the standard formula of the NRPB is applied (Marshall et al., 1980) to these film badges when exposed solely to 83 keV photon radiation an overestimate of the dose is obtained. the question of angle of incidence is also of importance when the energy is decreased; the NRPB data assumes 35 deg. incidence. Suitable correction factors can be applied however, and the choice of 83 keV for the intercomparison demonstrates the need for this. In practice, one is seldom concerned with isolated energies of this value, and in the CEGB, the main source of radiation is from fission products of high mean energy, where the NRPB formula is adequate