In-situ measurements for assessment of residual radiation field on incore structural components of research reactor Cirus

In-situ radiation field measurements on in-core components of Cirus reactor were carried out during the refurbishing outage of the reactor. The data aided in characterization studies for evaluation of residual activity in the structural components of the reactor after four decades of its operation. The study led to the generation of a database which served as a primary input in decision making for various refurbishing activities related to in-core components of the reactor. The measurements also helped in dose budgeting during the refurbishing activities. The radiation field measurements were repeated in near identical conditions to asses the decay pattern of the residual activity. It was observed that the reduction of 35-40% in radiation field over a period of ∼-1200 days can be correlated to the half-life of radionuclides produced by neutron activation of structural components. This paper describes, in detail, the radiation field measurements carried out and the measurement technique employed for in-situ measurements in generating a reliable database for planning of the future decommissioning activities of the reactor. (author)