production of an economic high-density concrete for shielding megavoltage radiotherapy rooms and nuclear reactors

background: in megavoltage radiotherapy rooms, ordinary concrete is usually used due to its low construction costs, although higher density concrete are sometimes used, as well. the use of high-density concrete decreases the required thickness of the concrete barrier hence, its disadvantage is its high cost. in a nuclear reactor, neutron radiation is the most difficult to shield. a method for production of economic high-density concrete with appropriate engineering properties would be very useful. materials and methods: galena (pbs) mineral was used to produce of a high-density concrete. galena can be found in many parts of iran. two types of concrete mixes were produced. the water-to-concrete (w/c) ratios of the reference and galena concrete mixes were 0.53 and 0.25, respectively. to measure the gamma radiation attenuation of galena concrete samples, they were exposed to a narrow beam of gamma rays emitted from a cobalt-60 therapy unit. results: the galena mineral used in this study had a density of 7400 kg/m3. the concrete samples had a density of 4800 kg/m3. the measured half value layer thickness of the galena concrete samples for cobalt- 60 gamma rays was much less than that of ordinary concrete (2.6 cm compared to 6.0 cm). furthermore, the galena concrete samples had significantly higher compressive strength (500 kg/cm2 compared to 300 kg/cm2). conclusion: the galena concrete samples made in our laboratories had showed good shielding/engineering properties in comparison with all samples made by using high-density materials other than depleted uranium. based on the preliminary results, galena concrete is maybe a suitable option where high-density concrete is required in megavoltage radiotherapy rooms as well as nuclear reactors.