氟盐冷却高温堆氚输运特性数值研究

Numerical Analysis of Tritium Transport Characteristics in Fluoride-salt-cooled High-temperature Reactor

  • 摘要: 氚的控制是限制氟盐冷却高温堆(FHR)发展的关键问题,欲实现氚的有效控制,首先需明确氚在熔盐堆一回路中的输运行为。本文阐明了氚在熔盐堆一回路中的输运特性,包括氚的产生及存在形态的分化、石墨对氚的吸附、氚在熔盐中的溶解与扩散以及氚在管壁材料中的渗透等。针对氚在熔盐堆一回路中的输运行为,建立了数学物理模型,基于FORTRAN语言开发了适用于FHR的氚输运特性分析程序TAPAS。通过将实验数据与程序计算结果对比,说明了TAPAS程序计算的合理性和准确性。利用TAPAS对模块化移动式氟盐冷却高温堆(TFHR)中氚的输运特性进行了分析。计算表明,TFHR的初始产氚率约为5.54×10-8 mol/s,一回路中的氚主要以T2形式存在,腐蚀反应主要发生在热管段入口处。反应堆运行25 EFPD(等效满功率天)后,石墨吸附氚达到限值。反应堆稳态运行时,T2向管壁表面的渗透速率可视为常数,其值为8.35 μmol/EFPD。本研究可为FHR的研究设计和辐射防护提供参考。

     

    Abstract: Tritium control is one of the most critical issues which limit the development of fluoride-salt-cooled high-temperature reactor (FHR). In order to control tritium effectively, the transport characteristics of tritium in fluoride salt must be known. In this paper, the transport characteristics of tritium in the primary loop of FHRs were expounded, including tritium production and speciation, the absorption and desorption by graphite, dissolution and diffusion in molten salt and permeation through structural materials. A series of reasonable mathematical and physical models were established for tritium transport characteristics analysis of TFHR and the TAPAS code for FHRs was developed based on FORTRAN code. The preliminary verification of the code was conducted by comparing calculation results with experiment data, and the results prove the fidelity and accuracy of TAPAS. The tritium transport characteristics in TFHR were analyzed by TAPAS. The initial tritium production rate of TFHR is 5.54×10-8 mol/s. Tritium in the primary coolant loop is mainly in the form of T2. The corrosion reactions always occur at the entrance of hot legs. After 25 EFPD operation, tritium absorption by graphite attends its limiting value. When the reactor operates at steady state, the permeation rate of T2 can be regarded as a constant, which is 8.35 μmol/EFPD. This study can contribute to the design and radiation protection of FHR.

     

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