Bayoumi T A, Reda S M, Saleh H M
Radioisotope Department, Nuclear Research Center, Atomic Energy Authority, Dokki 12311, Giza, Egypt.
Appl Radiat Isot. 2012 Jan;70(1):99-102. doi: 10.1016/j.apradiso.2011.09.016. Epub 2011 Sep 29.
Radioactive waste generated from the nuclear applications should be properly isolated by a suitable containment system such as, multi-barrier container. The present study aims to evaluate the isolation capacity of a new multi-barrier container made from cement and clay and including borate waste materials. These wastes were spiked by (137)Cs and (60)Co radionuclides to simulate that waste generated from the primary cooling circuit of pressurized water reactors. Leaching of both radionuclides in ground water was followed and calculated during ten years. Monte Carlo (MCNP5) simulations computed the photon flux distribution of the multi-barrier container, including radioactive borate waste of specific activity 11.22KBq/g and 4.18KBq/g for (137)Cs and (60)Co, respectively, at different periods of 0, 15.1, 30.2 and 302 years. The average total flux for 100cm radius of spherical cell was 0.192photon/cm(2) at initial time and 2.73×10(-4)photon/cm(2) after 302 years. Maximum waste activity keeping the surface radiation dose within the permissible level was calculated and found to be 56KBq/g with attenuation factors of 0.73cm(-1) and 0.6cm(-1) for cement and clay, respectively. The average total flux was 1.37×10(-3)photon/cm(2) after 302 years. Monte Carlo simulations revealed that the proposed multi-barrier container is safe enough during transportation, evacuation or rearrangement in the disposal site for more than 300 years.
核应用产生的放射性废物应通过合适的包容系统（如多屏障容器）进行妥善隔离。本研究旨在评估一种由水泥和粘土制成、包含硼酸盐废料的新型多屏障容器的隔离能力。这些废料被（137）铯和（60）钴放射性核素标记，以模拟压水反应堆一回路产生的废物。在十年期间跟踪并计算了两种放射性核素在地下水中的浸出情况。蒙特卡罗（MCNP5）模拟计算了多屏障容器的光子通量分布，该容器分别含有比活度为11.22KBq/g和4.18KBq/g的（137）铯和（60）钴放射性硼酸盐废料，模拟时间分别为0、15.1、30.2和302年。球形单元半径为100cm时，初始时刻的平均总通量为0.192光子/cm²，302年后为2.73×10⁻⁴光子/cm²。计算得出，将表面辐射剂量保持在允许水平内的最大废物活度为56KBq/g，水泥和粘土的衰减系数分别为0.73cm⁻¹和0.6cm⁻¹。302年后的平均总通量为1.37×10⁻³光子/cm²。蒙特卡罗模拟表明，所提出的多屏障容器在运输、疏散或处置场重新安置过程中300多年内足够安全。
