熔盐堆冷却盐回路剂量场分布与设备屏蔽  

Calculation for Dose Distribution and for Equipment Shielding of Molten Salt Reactor Cooling Circuit

作　　者：李长园[1] 夏晓彬[1] 蔡军[1] 张志宏[1] 王建华[1] 钱治成 陈德锋 谢贵英[1] LI Changyuan;XIA Xiaobin;CAI Jun;ZHANG Zhihong;WANG Jianhua;QIAN Zhicheng;CHEN Defeng;XIE Guiying(Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China)

机构地区：[1]中国科学院上海应用物理研究所,上海201800

出　　处：《原子能科学技术》2022年第11期2422-2430,共9页Atomic Energy Science and Technology

基　　金：中国科学院战略性先导科技专项(XDA02050000);中国科学院青年创新促进会项目(2021256)。

摘　　要：液态燃料熔盐堆采用熔盐作为冷却剂,熔盐换热器置于反应堆堆芯内,冷却盐流经堆芯熔盐-熔盐换热器时被堆芯中子活化产生放射性,放射性核素随冷却盐从堆芯流出进入冷却盐回路工艺房间对周围环境和设备产生辐射影响。对冷却盐活化过程进行分析,给出相应的计算公式,采用公式给出的计算结果与ORIGENS程序计算结果的相对偏差最大为2.92%,两种方法计算结果相吻合,表明对冷却盐回路活化产生的放射性核素的计算推导过程合理可行。冷却盐工艺房间辅助设备所在位置屏蔽前最大吸收剂量率为45.7 mGy/h,不能满足设备整个寿期300满功率天耐辐照剂量低于50 Gy的限值要求,通过在辅助设备与冷却盐主泵回路之间设置30 cm厚的混凝土屏蔽墙可将辅助设备所在位置的吸收剂量率降低至7 mGy/h以下,从而满足辅助设备的辐射防护要求。LiF-BeF_(2)-ZrF_(4)-UF_(4) and LiF-BeF_(2) have been employed as fuel salt and coolant in liquid fueled molten salt reactor,respectively.A heat exchanger containing both fuel salt and cooling salt is placed inside the reactor vessel to dissipate the heat produced by the reactor.A molten salt-to-air heat exchanger outside the reactor vessel is used to cool the molten salt,and a molten salt pump is used to drive the circulation of the entire circuit of coolant system.As of the molten salt,LiF-BeF_(2) coolant,flows through the molten salt heat exchanger located inside the reactor vessel,nuclides in the coolant are activated by ^(19)F(n,α)^(16)N,^(19)F(n,γ)^(20)F,and ^(19)F(n,p)^(19)O reactions with neutrons in the reactor core,and thus radionuclides such as ^(16)N,^(20)F and ^(19)O are produced.These radionuclides have radiation impact on the surrounding environment and equipment if they enter the rooms where equipment for molten salt coolant circuit locate.According to the flow process and distribution law of the cooling salt,theoretical calculation formulas to calculate the amount of radionuclide were given.Using theoretical formulas,calculated radioactivities of the three most important radionuclides ^(16)N,^(20)F and ^(19)O per unit volume of cooling salt are 9.05×10~6,8.33×10~6 and 2.69×10~5 Bq/cm~3 at the outlet of the molten salt heat exchanger,while the radioactivities of the three radionuclides at the same location calculated by ORIGENS program are 8.98×10~6,8.58×10~6 and 2.76×10~5 Bq/cm~3,respectively.The results calculated by the formulas are in good agreement with the data of the ORIGENS program,and the maximum relative deviation between the results of the two methods is 2.92%,indicating that applying the derived formulas to carry out cooling salt activation analysis is reasonable and feasible.These radionuclides,16N,20F and 19O,produced in the cooling salt of molten salt reactor release high-energy gamma rays as they decay.The total gamma emissivities of the cooling salt in equipment and pipelin

关 键 词：冷却盐回路 中子活化 剂量率分布 屏蔽设计 

分 类 号：TL72[核科学技术—辐射防护及环境保护]