ویژگی حفاظتی پرتوهای گاما و نوترون در بتن با استفاده از پودرهای باریت و گرافیت

در این پژوهش ضریب تضعیف خطی پرتو گاما و سطح مقطع پراکندگی پرتو نوترون دو سری از نمونه‌های بتنی حاوی پودر باریت به عنوان جایگزینی از ماسه با و بدون پودر گرافیت تحت اشعه گاما با چشمهcs-137  و آشکارساز nai (tl) و تحت پرتو نوترون با چشمهam-be 241  و آشکارساز bf3 بررسی شد. مقاومت فشاری، مقاومت کششی و سرعت پالس اولتراسونیک نیز تعیین شد. تمام نمونه‌های بتن، به جز نمونه‌های کنترل، با مقدار 400 کیلوگرم در متر مکعب سیمان و نسبت آب به سیمان0.4 با جایگزینی 10 درصد میکروسیلیس در دو سری ساخته شده‌اند. در سری اول، پودر باریت با جایگزینی 10، 25، 50، 75 و 100 درصد جایگزین ماسه شد و در مرحله دوم، 10 درصد پودر گرافیت به نمونه‌های حاوی پودر‌های مختلف پودر باریت اضافه شده  است. نتیجه این پژوهش نشان داد که یک نمونه حاوی 10٪ پودر باریت به اضافه 10٪ پودر گرافیت می‌تواند به عنوان یک مقدار مطلوب برای بتن حفاظت شده در برابر اشعه های گاما و نوترون باشد. 

protective property of gamma and neutron beams in concrete using barite and graphite powders

today in the world, including in our country, the use of nuclear technology in various fields of power plants, industry, agriculture and medicine is expanding. one of the most important issues in nuclear technology is nuclear radiation protection to prevent harmful environmental, pathogenic and harmful effects on some of the precision measuring instruments. from the perspective of preservation, all the radiation and particles are not of the same importance, because their penetration and impact on different materials, such as living tissue, are not equal. in the discussion of conservation, neutron and gamma radiation is of particular importance because, due to its unloaded nature, they can pass relatively large thicknesses of the shield and contribute to raising the dose rate outside the shield. in addition to the many uses of radioactive waste, it should be noted that this radiation damages cells and living tissues and protection against it is essential and inevitable. in order to protect against radiation, absorbent materials should have a high density, high attenuation coefficient, and structural properties with high strength, easy to provide and cheap production. according to the above, the use of concrete is a suitable alternative for radiation protection. due to its high specificity and low cost, barite is widely used in the oil and gas drilling industry, coloring industry, pharmaceutical plastics (due to the absorption of radioactive wastes), chemicals and so on. so it can be a good option for gamma radiation protection. in this research gamma-ray linear attenuation coefficient and neutron beam dispersion cross-section of two series of concrete samples containing barite powder as a substitute of sand with and without graphite powder under gamma rays with cs-137 fountain and nai (tl) detector under neutron beam with the am-be 241 fountain and the bf3 detector. the compressive strength, tensile strength and ultrasonic pulse velocity were also determined. all concrete samples, with the exception of control samples, have been made with 400 kg / m3 cement and 0.4 water/cement ratio with 10% microsilicon replacement in two series. in the first series, barite powder was replaced with 10, 25, 50, 75 and 100% replacement of sand, and in the second, 10% of the graphite powder was added to samples containing various powdered barite powder. the result of this study showed that a sample containing 10% barite powder plus 10% graphite powder could be an optimal amount for a concrete protected against gamma and neutron rays.