Design and operation of the internal dosimetry program for the Chornobyl 'shelter implementation plan'.

The paper discusses the system of individual monitoring for internal exposure, deployed by the Ukrainian Radiation Protection Institute as an integral component of the Shelter Implementation Plan (SIP) at the Chornobyl industrial site. SIP anticipates involving of up to 10,00 workers of numerous SIP contractors. A typical daily shift comprises several hundred workers. Most of them have a direct contact with the irradiated nuclear fuel, fuel-contained aerosols and other contaminated materials on the industrial site. The hierarchical SIP individual monitoring program has been designed with consideration of peculiarities of SIP exposure conditions and aims at the timely and reliable identification of intakes, assessment of doses and initiation of measures for prevention of further intakes.