Design of a protective shield for a radiological emergency intervention using Monte Carlo simulation and an anthropomorphic phantom.

Abstract

Due to the increasing use of radioactive sources, new challenges appear for the protection of humans and the environment against ionizing radiation. Thus, organizations handling these sources must be endowed with plans how to react in case of any radiological emergency situations. Monte Carlo simulations are among the most widely employed methods used for the management and reconstruction of radiological incidents and accidents. In this work, results of a Monte Carlo simulation study with the Geant4 simulation toolkit using a digital anthropomorphic phantom are reported. The investigated scenario included an emergency intervention carried out inside the ionization cell of the National Institute of Agronomic Research (NIAR) of Tangier/Morocco, which houses a 60Co gamma irradiator. In this scenario, a radiological incident was assumed where the source cage of the gamma irradiator is stuck in the guide tube and not completely inserted into its storage container. The objective of this work was to design a radiation shield to protect an operator during the emergency intervention and make sure that any radiation exposure is below the recommended dose limits, taking into account the date of occurrence (which determines the activity of the source at the time of the emergency situation) of the accident and economic aspects of shielding design. In this work, the maximum time available for the operator to accomplish the operation intervention while remaining protected is calculated. The results obtained show that the shielding prototype developed gives the operator a time between 3 and 300s, depending on shielding design. It is concluded that shielding of the type investigated in the present study will allow any facility to manage the assumed emergency scenario, should it occur.