Probability of plutonium intakes and doses exceeding estimates from personal air sampling

A method assuming Poisson distribution of particles in space and a log-normal distribution of aerosol size to evaluate the probability distribution of intake from a single measurement of activity on a personal air sampler (PAS) filter has been extended to apply over the practical range of activities collected in PAS monitoring, and simple algebraic expression derived to approximate the probability of a man's intake exceeding the estimated value by given factors. This is used to study the effect of aerosol size distribution. A new composite parameter to characterise aerosol size distributions is suggested. The expression is also used to assess effect of particle density and specific activity on sampling statistics, to enable the analysis to be applied to an aerosol where each particle is a mixture of a 239Pu compound (or other radionuclide) and a non-radioactive material. Similar expressions for the probability of exceeding estimated committed dose equivalents and committed effective dose equivalents are derived, taking into account the effects of solubility classification. Short computer programs are provided to evaluate these probabilities. The results' radiological implications are discussed. (author)