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Vaporization Behavior of Tritium Breeding Candidate Materials in Reducing Atmosphere at High Temperatures

氚增殖候选材料在高温还原气氛中的汽化行为

基本信息

批准号：
03808027
负责人：
ASANO Mitsuru
金额：
$ 1.15万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

Tritium release behavior from solid breeding materials in fusion reactors is very influenced by the composition of a sweep gas. Lower oxygen potential is essential for larger desorption rate and leads to good compatibility between the breeding materials and stainless steel claddings. For this reason, gas species including oxygen and their partial pressures in equilibrium with many breeding candidate materials existing with graphite were studied by a mass-spectrometric Knudsen effusion method. In addition, the chemical stability of the breeding materials was studied thermodynamically in the reducing atmosphere with the coexistence of graphite. The results are summarized as follows.1. Enthalpies of formation for Li_2ZrO_3, Li_6Zr_2O_7 and Li_8ZrO_6 in the Li_2O-ZrO_2 system were determined from the data of partial pressures over them. Generally, complex oxides with less Li_2O content are more stable in the Li_2O-MO_X(M=Al, Fe, Mo, Si, Sn, Ti and Zr).2. The enthalpy of formation for Li_2SnO_3 from constituent oxides is greater than that for Li_2SiO_3; it seems that the value increases in keeping with the atomic number in the IVB group. On the contrary, in the IVA group the enthalpy of formation for Li_2ZrO_3 is smaller than that for Li_2TiO_3.3. Computer simulation shows that under the reducing condition the ratio of T_2O/T_2 released from the breeding materials becomes small, leading to the large desorption rate. Furthermore, reactions between the breeding materials and the claddings are suppressued markedly.4. The oxygen partial pressure in the Li_2ZrO_3-graphite system is eight orders of magnitude lower than that in the Li_2ZrO_3-platinum system; that is, the presence of graphite is very useful for the reduction of the oxygen partial pressure.

氚在聚变反应堆中从固体增殖材料中释放的行为很大程度上受到扫气组成的影响。较低的氧势对于较大的脱附速率是必不可少的，并导致繁殖材料与不锈钢包层之间的良好相容性。为此，用质谱Knudsen渗出法研究了包括氧在内的气体种类及其与石墨存在的许多繁殖候选材料的平衡分压。另外，在石墨共存的还原性气氛中，对繁殖材料的化学稳定性进行了热力学研究。结果总结如下：1。根据Li_2ZrO_3、Li_6Zr_2O_7和Li_8ZrO_6在li_2zro_2体系中的分压数据测定了它们的生成焓。一般来说，Li_2O含量越少的复合氧化物在Li_2O- mo_x （M=Al, Fe, Mo, Si, Sn， Ti和Zr）中越稳定。组成氧化物生成Li_2SnO_3的焓大于Li_2SiO_3的焓；这个值似乎随着IVB族原子序数的增加而增加。相反，在IVA基团中，Li_2ZrO_3的生成焓小于Li_2TiO_3.3的生成焓。计算机模拟结果表明，在还原条件下，从繁殖材料中释放的T_2O/T_2之比变小，导致脱附速率变大。此外，育种材料与包层之间的反应被明显抑制。li_2zro_3 -石墨体系的氧分压比li_2zro_3 -铂体系的氧分压低8个数量级；也就是说，石墨的存在对于氧分压的降低是非常有用的。