Measurement of the radiation dose distribution in EAST hall based on thermoluminescence dosimeter

Abstract

The spatial distribution of relative intensity of neutron dose and gamma-ray dose in the Experimental Advanced Superconducting Tokamak (EAST) machine hall were measured by multiple thermoluminescence dosimeters (TLDs) during second experimental campaign of 2019. This activity has been performed twice, the first measurement lasted 5 days and adopted 64 pieces of dosimeters, the second time lasted 10 days and employed 100 pieces of dosimeters. These dosimeters were arranged on the ground plane outside the tokamak device with different positions to obtain the radiation dose distribution of the deuterium plasma and activated radionuclide. Generally speaking, the radiation dose decreased with the increase of radial distance. However, the measurement results of TLDs showed that the variation trends of normalized neutron dose and normalized gamma-ray dose with the increase of radial distance were unsymmetrical and not always under the attenuation law in the radial distribution of EAST ports. Some large scale of equipment and the thick concrete shielding wall had significant effect on the dose distribution. Both radiation intensity of neutron and gamma-ray raised slightly near the equipment and shielding wall in generally. Furthermore, statistics of measurements from multiple dosimeters showed that there was a certain correlation between the normalized gamma-ray dose and normalized neutron dose.