Radiation dose distribution to CEGB workers in 1978

The ICRP system of dose limitation requires that few if any workers are exposed at the dose limit of 5 rem per year. The dose limit was fixed on the assumption that risks would be acceptable if doses were distributed among classified workers in a manner comparable with a reference log-normal distribution published by the United Nations Scientific Committee on the Effects of Ionizing Radiation. Although it is well-known from earlier publications that the doses to classified workers at CEGB nuclear sites are low, a further analysis shows that they are distributed according to a log-normal function with parameters showing a distribution of risks considerably better than those considered acceptable by ICRP. In 1978 the collective dose to 6,856 classified workers on CEGB nuclear sites was 1,635 man-rem. The mean individual dose was 0.24 rem, corresponding to 0.41 man-rem per MW. The log normal distribution of individual doses shows a median dose of 0.15 rem, compared with a median dose of 0.5 rem in the UNSCEAR reference distribution. (author)