Isotope exchange reaction between gaseous hydrogen and tritium on Li2TiO3 grain surface
Isotope exchange reaction between gaseous hydrogen and tritium on Li2TiO3 grain surface
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DOI：
10.13182/fst02-a22743
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发表时间：
2002-05-01
影响因子：
0.9
通讯作者：
Nishikawa, M
中科院分区：
文献类型：
--
作者：
Nakashima, N;Beloglazov, S;Nishikawa, M
通过锂陶瓷材料如Li 2 O、LiAlO 2、Li 2 ZrO 3、Li 4SiO 4和Li 2 TiO 3。被认为是D-T聚变堆包层增殖材料的候选材料，但增殖氚在这些固体增殖材料中的释放行为尚未完全了解。本文指出，要估算稳态条件下均匀固体增殖包层中的氚存量，必须了解氚在颗粒中的扩散、颗粒体中的吸水和颗粒表面的吸水等传质步骤，以及两种类型的同位素交换反应。本研究以CEA、KHI和NFI的Li_2TiO_3小球为例，对Li_2TiO_3上的同位素交换反应速率进行了定量研究，发现在高温氢气氛中，Li_2TiO_3上的同位素交换反应速率比其它固体增殖材料小2 ~ 3个数量级。还观察到，Li 2 TiO 3的颜色随着反应速率的降低而变为黑色。在京都大学反应堆增殖氚释放实验中观察到，即使在吹扫气体中加入100 Pa的氢气，氚的化学形式在高温下也变成HTO，这可以用同位素交换反应速率的降低来解释，本文还讨论了不同条件下Li_2 TiO_3包层中氚的存量。
Though litium ceramic materials such as Li2O, LiAlO2, Li2ZrO3, Li4SiO4, and Li2TiO3. are considered as the candidates for breeding materials in the blanket of a D-T fusion reactor, the release behavior of the bred tritium in these solid breeder materials has not been fully understood yet. We have pointed out that it is essential to understand such mass transfer steps as diffusion of tritium in the grain, absorption of water in the bulk of grain, and adsorption of water on the surface of grain, together with two types of isotope exchange reactions for estimation of the tritium inventory in a uniform solid breeder blanket under the steady-state condition. The rate of isotope exchange reaction-1 on Li2TiO3 is quantified in this study, where pebbles of Li2TiO3 from CEA, KHI, and NFI are used.It is observed in this study that the rate of isotope exchange reaction on Li2TiO3 becomes 2similar to3 order smaller than other solid breeder materials when it is placed in the hydrogen atmosphere at high temperature. It is also observed that the color of Li2TiO3 changed to black in accordance with decrease of reaction rate. The observation obtained at the release experiment of bred tritium performed in Kyoto University Reactor that chemical form of tritium becomes HTO at the high temperature even when hydrogen of 100 Pa is added to the purge gas can be explained by decrease of isotope exchange reaction rate.Tritium inventory in the Li2TiO3 blanket in various conditions are also discussed in this paper.