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Hydrogen Transportation Behavior and its Control on the Water-Metal Boundary Using Pure Tritium

纯氚氢在水-金属边界的输运行为及其控制

基本信息

批准号：
17560737
负责人：
HAYASHI Takumi
金额：
$ 2.18万
依托单位：
Japan Atomic Energy Agency
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

In order to discuss detailed mechanism of hydrogen transferred from metal to water jacket at the water-metal boundary, a series of tritium permeation experiment has been performed at 423 K, using pure iron piping (4)10mm x 75mm^1 x 1mm^t) contained tritium gas (1 kPa, 7.4 GBq, >90% purity) under monitoring chemical species of tritium in the water jacket, which pressurized to 0.8MPa by He or 1%H_2 in He balance gases, by purging through ion chambers, water bubblers and oxidation catalyst bed. Surface of pure iron tube sample was mechanically polished initially. Also, samples with oxide layer, which grew in the water of 0.8MPa-He at 423K for more than 20 hours, were prepared. Sample surface was analyzed by SEM, XRD etc. The oxide layer consisted of inner fine part and outer porous part, and was magnetite (Fe_3O_4) not hematite (Fe_2O_3). The inner fine part of oxide grew 0.06~0.07 μm/h in the above condition. The main results are as follows1. The permeation amount through pure iron to water jacket was about 1/5 of the calculated value in this experimental condition.2. Even if surface oxide layer (fine and porous magnetite) grew, tritium permeation rate to water was not changed drastically.3. However, HT fraction of permeated tritium was 30% initially, then, it decreased drastically to about 1/50 after > 1.4μm of fine magnetite layer growth. It suggested the relation between the HT fraction decrease and oxide layer growth.4. Permeated species and amounts were not affected clearly by dissolved hydrogen amount difference between pure He and 1% H_2 in He balance purging under 0.8 MPa at 423 K.From the above results, it suggests that the tritium in pure iron would transfer to water by isotope exchange reaction through surface hydroxyl species of magnetite. On the other hand, if surface hydroxyl density is small, the tritium would permeate to water as hydrogen gas after surface recombination.

为了探讨水-金属界面上氢从金属向水套转移的详细机理，用纯铁管道(4)10 mm×75 mm^1×1 mm^t含氚气体(1kPa，7.4GBq和90%纯度)，在423K下进行了一系列氚渗透实验，监测水套中氚的化学形态，用氦或平衡气体中1%H_2加压至0.8 Mpa，通过电离室、水泡和氧化催化剂床吹扫。首先对纯铁管材进行了表面机械抛光。此外，还制备了具有氧化层的样品，这些样品在423K、0.8 Mpa-He的水中生长20小时以上。用扫描电子显微镜、X射线衍射仪等对样品表面进行了分析，氧化层由内部细小部分和外部多孔部分组成，氧化层为磁铁矿(Fe3O4)而不是赤铁矿(Fe2O3)。在此条件下，氧化物的内部细小部分生长0.06~0.07μm/h。主要研究结果如下：1。在本实验条件下，纯铁对水套的渗透量约为计算值的1/5。即使表面氧化层(细小、多孔的磁铁矿)生长，氚对水的渗透率也没有明显变化。然而，渗透出的氚中的HT含量最初为30%，然后在~gt；1.4μm的细小磁铁矿层生长后急剧下降到约1/50。这表明羟色胺组分的减少与氧化层的生长有关。在0.8 Mpa、423K的氦气平衡吹扫条件下，纯氢和1%氢气的溶氢量差异对渗透物种和渗透量没有明显影响。上述结果表明，纯铁中的氚可能通过磁铁矿表面羟基物种的同位素交换反应转移到水中。另一方面，如果表面羟基密度较小，氚在表面复合后会以氢气的形式渗入水中。