HTR-10一回路放射性核素在石墨上的吸附及其微观机理研究
Study of Adsorption on Graphite and Its Mechanism of Radionuclides in Primary Circuit of HTR-10 With Ab initio Theory
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摘要: 通过巨正则系综方法与第一性原理计算，研究了100～900 ℃下，134Cs、137Cs、90Sr、110Agm、131I 5种重要核素在石墨上的吸附率随温度、压强等参数的变化，并根据工程实际参数，推算他们在HTR-10一回路中反射层、石墨碳砖以及石墨粉尘上的吸附量。研究表明，Cs和Sr倾向于吸附在石墨的H位，而Ag和I倾向于吸附在石墨的T位，且他们的吸附能也有所差异。此外，核素粒子数密度与吸附率呈线性关系，而温度与吸附率呈指数关系。最后，通过研究5种核素在HTR-10一回路中的吸附情况，发现其中的放射性主要来自于核素134Cs、137Cs和131I，而90Sr和110Agm的贡献较少，这与唯象模型的保守估计结论一致。Abstract: The adsorption behavior on graphite and its relationship with temperature and atomic densities of radionuclides 134Cs,137Cs,90Sr,110Agm and 131I were studied with grand canonical ensemble and ab initio methods. Furthermore, with the engineering parameters of HTR-10, the amounts of these radionuclides adsorbed on reflector, carbon bricks and graphite dusts were also calculated. It is shown that the Cs and Sr are likely to be adsorbed on the H point of graphite, which is different from the adsorbed points and adsorption energies of I and Ag. The linear function of adsorption rate-temperature and exponent function of adsorption rate-atomic densities were also obtained. At last, it is found that the major amounts of adsorbed radioactivity in primary circuit of HTR-10 are contributed by 134Cs, 137Cs and 131I, which consists with the conservational evaluations obtained by traditional model.
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