初始腐蚀产物对水冷聚变堆源项影响的研究

The Study of the Influence of Initial Corrosion Products on the Source Term of Water-cooled Fusion Reactors

水冷聚变反应堆在首次临界之前,会经历一段时间的热工水力和水化学参数的调试,称为预运行阶段。在此期间,冷却回路的金属材料与高温高压且非中性的冷却剂接触过程中,会被氧化而产生初始的腐蚀产物。这些腐蚀产物会沉积在回路内表面,在反应堆物理启动后被中子活化形成活化腐蚀产物(简称ACPs),进而影响反应堆正式运行期间的放射性源项。本文首先依托ACPs源项分析程序CATE和ITER包层冷却回路例题,对初始腐蚀产物的影响进行了定量分析,结果表明:初始腐蚀产物含量越多,反应堆运行相同时间后产生的ACPs比活度越大;与非辐照区的初始腐蚀产物相比,辐照区的初始腐蚀产物对ACPs影响更大。随后,基于经典的浓度差驱动模型,推导了ACPs比活度与初始腐蚀产物的解析关系式,揭露了不同区域初始腐蚀产物对ACPs的影响机理,得到以下定性分析结论:辐照区与非辐照区的初始腐蚀产物对ACPs比活度有一定影响,但影响程度不同,验证了数值解的结论。

Water-cooled fusion reactor will experience a period of time for adjustment of the thermal-hydraulic and hydrochemical parameters before the first criticality,which is called pre-conditioning stage. During this period,the metal material of cooling loops in the reactor will be oxidized by the coolant with high temperature,high pressure and non-neutrality and the initial corrosion products will be produced. Those corrosion products will deposit on the inner surface of the loop,and then will be activated to the activation corrosion products（ACPs）by neutron after the physics start-up of the reactor,which will affect the radioactive source term during the formal operation stage of the reactor. In this paper,the following quantitative analysis of the influence from the initial corrosion products was made based on ACPs source term analysis program CATE and ITER blanket cooling loop model. The results show that：ACPs specific activity during the formal operation stage of the reactor increases with the quantity of the initial corrosion products;comparing with the out-of-flux area,the initial corrosion products in the in-flux area have larger influence on ACPs specific activity. Then,the analytic expression of the relationship between ACPs specific activity and initial corrosion products was deduced based on the classical concentration difference driving theory,and reveal the impact mechanism about different regions of the initial corrosion products for ACPs,the qualitative conclusion was derived ：the initial corrosion products in the in-flux area and out-of-flux area have some influence on ACPs specific activity,but the influence degree is different,the conclusion of numerical solution was verified.