An uncertainty analysis of the ingestion dose following a discrete deposition from atmosphere

This paper presents the results of an uncertainty analysis of the committed individual ingestion dose equivalent arising from a discrete radioactive deposition to the terrestrial environment from atmosphere. In particular, the committed dose equivalent to the thyroid from 131I, and the committed effective dose equivalent from 137Cs, arising from the consumption of milk and green vegetables have been analysed. The sensitivity of the results to the statistical method used and the effects of correlations between some parameters have also been studied. It was found that the Latin Hypercube Sampling technique gave good results even with relatively small samples. Both observed and extreme correlation coefficients were employed within a sensitivity study of the effects of correlations, and were all found to have little effect on the assessed uncertainties. The contributions to the uncertainty from the foodchain, diet and dosimetry components of the models were also studied. Probability distributions for the committed dose equivalent to the thyroid per unit intake of 131I, and for the committed effective dose equivalent per unit intake of 137Cs, have been derived. The expectation values of the dose conversion factors were found to be in good agreement with the ICRP recommended values