Distribution of uranium in Dounreay workers due to uptake from the environment

At Dounreay, there are a number of facilities in which the main radiological hazard is the intake of uranium. The hazard is managed through the implementation of controls and contamination surveys in order to reduce the risk of intake. In order to provide reassurance that radiological significant intakes are not taking place, a routine urine sample programme is in place. As well as being exposed to work place sources of uranium workers are also exposed to the intake of uranium from foodstuffs and water, which are not associated with their work at Dounreay. In order to characterise the intake of the radionuclides from the environment, urine samples were collected from a group of Dounreay personnel who are not exposed to uranium in their workplace. The distribution of the uranium isotopes 234U, 235U and 238U has been assessed for these workers. The distributions will be used to assess the likelihood of uranium detected in urine for a uranium worker being due to an intake in the workplace. The best match to distributions of 234U and 238U was found to be a combination of normal and lognormal distributions.