Uncertainties in recorded photon radiation doses at Sellafield

Individual monitoring for external radiation has been carried out on the Sellafield Site using film badges since 1950 with the results recorded in external dose records for about 20,000 workers. This paper considers the likely uncertainties in the recorded photon doses taking into account the main characteristics of the types of film badge used on the site and their performance in the radiation fields found in the workplace. Overall, it is concluded that the recorded cumulative annual photon doses should be within a factor of 2 of the true dose in comparison to the response of an ideal dosemeter, while the recorded annual dose is more likely to be an overestimate rather than an underestimate noting the possible influences of limit of detection of the badge, storage dose and the entry of notional doses onto the record.