基于cosRMC的同位素电池屏蔽计算研究  

Shielding Calculation of Isotope Battery Based on cosRMC

作　　者：王益祺 刘仕倡 靳程建 李锐 孙宁延 韩毅[2,3] 张显 陈义学 WANG Yiqi;LIU Shichang;JIN Chengjian;LI Rui;SUN Ningyan;HAN Yi;ZHANG Xian;CHEN Yixue(School of Nuclear Science and Engineering,North China Electric Power University,Beijing 102206,China;China Institute for Radiation Protection,Taiyuan 030006,China;Shanxi Key Laboratory for Radiation Safety and Protection,Taiyuan 030006,China)

机构地区：[1]华北电力大学核科学与工程学院,北京102206 [2]中国辐射防护研究院,山西太原030006 [3]辐射安全与防护山西省重点实验室,山西太原030006

出　　处：《原子能科学技术》2024年第3期622-629,共8页Atomic Energy Science and Technology

基　　金：国家自然科学基金(12175067);河北省自然科学基金(A2022502008);中国辐射防护研究院平台开放基金(ZFYFSFH-2022001);中央高校基本科研业务费专项资金(2022JG002)。

摘　　要：热电式同位素电池系统作为一种新型能源系统,在深空、深海探测任务中有广泛应用。钛酸锶热源中的放射性同位素90 Sr和90 Y会发射β射线,β射线与物质作用产生韧致辐射,韧致辐射具有很强的穿透力,需要为热源安装屏蔽层,以降低辐射剂量。当屏蔽层厚度超过一定值后,蒙特卡罗方法计算结果的统计误差显著增大,采用减方差技术可以提高热电式同位素电池屏蔽计算的准确性。同时,直接电子输运模拟耗时很长,可以通过厚靶韧致辐射模型处理电子产生的光子,从而提高计算效率。本文开展了cosRMC程序的减方差技术和厚靶韧致辐射模型在同位素电池屏蔽计算中的应用研究与验证,基于美国SNAP-21结构的设计方案,采用cosRMC程序对同位素电池进行了精细建模,通过改变外屏蔽层厚度分析其对表面剂量率的影响,并与MCNP结果进行比较。结果表明,在电池径向和轴向使用不同厚度的屏蔽层,cosRMC与MCNP计算的贫铀屏蔽层表面的剂量率的相对误差在±3σ区间内符合良好。采用栅元重要性减方差后,两程序统计误差均减小,且在电池径向5 cm处和轴向4 cm处,结果在±3σ区间内符合良好,进一步验证了cosRMC程序进行热电式同位素电池屏蔽计算的准确性。As a new type of energy system,thermoelectric isotope battery system is widely used in deep space and deep sea exploration missions.Strontium titanate fuel is used as the heat source for thermoelectric isotope batteries.The radioactive isotopes of 90 Sr and 90 Y in the strontium titanate heat source emitβray,which interact with substances to produce bremsstrahlung radiation.Due to the strong penetrating power of bremsstrahlung radiation,it is necessary to install a shielding layer on the surface of the isotope radioactive source strontium titanate to reduce the radiation dose of the thermoelectric isotope batteries.When the thickness of the shielding layer exceeds a certain value,the statistical error of the Monte Carlo method increases significantly.Variance reduction technique can be used to improve the accuracy of shielding calculation for thermoelectric isotope batteries.At the same time,the direct electron transport simulation takes a long time,which is much longer than the photon simulation,and the photons produced by the electrons can be processed by the thick target bremsstrahlung(TTB)model,thus improving the computational efficiency.In this paper,the variance reduction technology of cosRMC program and the application of TTB radiation model in the shielding calculation of isotope batteries were studied and verified.Based on the design scheme of SNAP-21 structure in the United States,the thermoelectric isotope battery is modeled by cosRMC program.The influence of depleted uranium on the surface dose rate was analyzed by changing the thickness of the radial and axial outer shielding layers of the thermoelectric isotope battery,and the calculated results were compared with those of MCNP program.The comparison of the two programs shows that the statistical error of dose rate of depleted uranium shield surface calculated by cosRMC and MCNP is in good agreement with±3σrange when different thickness shielding layers were used in radial and axial directions of thermoelectric isotope batteries.In order to reduc

关 键 词：同位素电池 屏蔽计算 MCNP cosRMC 减方差 

分 类 号：TL32[核科学技术—核技术及应用]