Impact of a revision of nuclear decay data on internal dose coefficients for workers

Manabe, Kentaro   ; Endo, Akira   

The impact of revisions of nuclear decay data on internal dose coefficients for workers was studied using revised data of ICRP Publication 107 (ICRP107) and existing data of ICRP Publication 38 (ICRP38). At first, two sets of ingestion dose coefficients for workers based on ICRP107 and ICRP38 were calculated using the dose and risk calculation software DCAL for 876 chemical forms of 774 nuclides. Ingestion dose coefficients based on ICRP107 increased by over 10% compared with those based on ICRP38 in 61 chemical forms, and decreased by over 10% in 28 chemical forms. It was revealed that the differences in ingestion dose coefficients mainly originated from the revision of energy data as is the case in inhalation dose coefficients. And, the revisions of the proportion of energy of electrons to that of photons, decay modes and half-lives also resulted in changes in the dose coefficients. Then, the extent and causes of changes in ingestion and inhalation dose coefficients were also compared with each other in light of our previous work concerning inhalation dose coefficients. As a result of comparing the dose coefficients for ingestion and inhalation, it was found that the change in proportion of energy of electrons to that of photons impacted on dose coefficients in ingestion more significantly than in inhalation. On the other hand, the change in shape of energy spectrum, which was one of the causes of change in inhalation dose coefficients, did not impact on ingestion dose coefficients.