Estimation of Effective Dose Equivalent from Inhalation of Thoron and its Daughter Products at a Thorium Plant

Thoron daughter products contribute to the inhalation dose to workers in a thorium processing plant. To demonstrate compliance with the annual effective dose equivalent (EDE) limit, the contributions from internal and external exposures must be summed. This paper describes the method used to estimate the EDE due to inhalation of thoron and daughters. The plant is divided into seven zones for air sampling purposes. The workers are categorised on the basis of the nature of their work. The occupancy period of the workers was calculated taking into account the number of batch operations in a year and the leave records of individual workers