Assessment of the Dose to a Representative Japanese Due to Stationary Release of Tritium to the Environment

Abstract

The computer program TriStat was applied to estimate the dose to a representative Japanese due to a stationaryrelease of tritium as HTO and/or HT to the atmosphere from nuclear facilities.In TriStat, the air tritiumconcentration is estimated by a Gaussian dispersion model.The tritium deposition to the soil was assumed to occurboth by dry and wet deposition processes of atmospheric tritium. The primary process of tritium transfer to humanbody is assumed to take place through a local food-chain in the contaminated area.
Tritium concentrations in soil, vegetables and forage were estimated as the tritium concentration per waterequivalent.The food chain was modeled by assuming a vegetable compartment and an animal-food compartment.
By using TriStat the annual dose to the representative Japanese was evaluated for stationary release of tritium asa function of the distance from a release point.The dose contribution from drinking water was neglected, since thedrinking water is generally supplied as tap water or as commercial bottled water.In the case of HT release, thecommitted dose due to tritium intake through breathing and skin absorption was found to be of minor importance.