Description : | Radiation is a serious concern in medical diagnostic systems, nuclear power facilities, particle accelerator, synchrotron radiation sources, food sterilization plants, radiotherapy facilities, etc. Prolonged exposure and accumulation of such high energy ionizing radiations like X- rays, gamma-rays and particle emissions (alpha, beta, proton, electron and neutron) may result in cell mutations, genetic disorder, organ failure etc.To avoid the occupational hazardous of employees, public and environment from the radiation is a great concern. Commonly, lead based radiation shielding materials are widely used to attenuate high energy gamma and X-rays, because of its high atomic number (82), high density (11.34 g/cc), malleability and low cost. But, lead is highly toxic and contact with this toxic material could lead to severe health problem. Lead is known to interfere with a number of body functions and it is primarily affecting the central nervous, hematopoietic, hepatic and renal system producing serious disorders. Lead poisoning happens when too much lead gets into the body through the skin, inhalation, eating and drinking.
Apart from lead other materials like high atomic number based iron, tin, antimony, tungsten, Bismuth etc., filled polymer composites and thick walled heavy weight concretes are also used to attenuate high energy ionizing radiations. The high Z material incorporated polymer composites are expensive. Heavyweight concretes are used to fabricate by incorporating heavy density aggregates in cement matrix. But the concretes are not stable above 300C due to the breakage of C-S-H gel.
CSIR-Advanced Materials and Processes Research Institute (CSIR-AMPRI) was converted iron rich red mud (hazardous alumina industrial waste) into X-ray shielding tiles, which can be used to shield X-rays instead of toxic lead sheet and concretes in the X-ray diagnosis, computerized tomography scanner (CT scan) and Cath labs. The red mud tiles were made through ceramic route by adding 30 - 45 wt% of BaSO4/Bi2O3 and 5 - 10 wt% kaolin clay binder with it. The green tiles were fabricated by applying 300 kg/cm2 pressure in a hydraulic press and then sintered between 1050 - 1150C. The developed tile posses the flexural strength of 22 N/mm2. The 6.29 mm and 11.698 mm thick red mud:Bi2O3:kaoline clay tile and red mud:BaSO4: kaoline clay tile, respectively, possess the attenuation equivalent to 2 mm lead at 125 kVp X-ray. The developed tiles were accredited by Atomic Energy Regulatory Board of India and listed as an alternative material of toxic lead in their website.
The developed tiles were demonstrated in M/S Saideep Healthcare and Research Pvt. Ltd., Ahmednagar. Nearly 2500 ft2 joint free X-ray shielding tiles were fabricated and installed in two X-ray diagnoses, one CT scanner and one Cath lab of it, which is in operation since 2018.
This innovation will suppress the accumulation of hazardous red mud, which is underutilized (2-3% has been used in building sectors) and associated environmental problems like ground water, soil and air pollution. It will also reduce the usage of toxic lead sheet in hospitals and its import. |