Estimation of whole body dose in an unusual event: spillage of radioactive material on the chair

The personnel monitoring in India is done using thermoluminescence dosimeters worn at chest level. In research institutions and in nuclear facilities where radiation sources are processed in dispersible forms, a remote possibility exists that radiation source entering in the area where installed monitor does not exist and the source may get spilled on chair and causing exposure to persons sitting on the chair. In such case TLD may not give the correct exposure as there is shielding of individuals body. An attempt is made to find out a factor for estimating the whole body dose by knowing the TLD badge dose or by measuring the gonad dose. Experiments are performed using TLDs and also measurement by teletector. Monte Carlo simulations are also done. It is observed that a factor of 8 to TLD Badge dose will give whole body dose if worker has received dose only on said chair or by applying a factor of 0.23 to dose measured at gonad level will give whole body dose. (author)