A new barite-colemanite concrete with lower neutron production in radiation therapy bunkers

Abstract

The purpose of the current was to design a new high density concrete with low photoneutron production rate for radiation therapy bunker constructions. We used MCNPX Monte Carlo (MC) code for photoneutron productions in a radiation therapy bunker. The validated MC model of Varian Clinac 2100 C/D, 18 MeV photon beam and a radiation therapy bunkers made of barite was used for photoneutron calculations. Colemanite mineral with weight fraction of 5% and 10% was added to the barite concrete in bunker walls. Photoneutrons absorbed doses at beam isocenter and at the maze entrance door were calculated. The Barite-colemanite concretes with two different compositions were built and their linear attenuation coefficients were measured against Cobalt-60, 9 and 18 MeV photon beams. MC results showed that adding 5% and 10% Colemanite to Barite concrete reduces photoneutron production rate 7% and 16% respectively. However, experimental measurement of photon attenuation showed its lower photon attenuation coefficient and reduced mechanical properties. The results indicated that adding colemanite reduces photoneutrons received by the maze entrance door, but its photon attenuation and mechanical properties were compromised accordingly. Further studies on proposed concrete composition to enhance its mechanical properties are recommend. (C) 2012 Elsevier Ltd. All rights reserved.