氢化锆高温氢释放的阻止方法研究

Research on Prevention Method of Hydrogen Release of Zirconium Hydride at High Temperature

氢化锆作为空间堆中的慢化剂,使用温度在650℃以上,H/Zr原子数比(H/Zr)在1.85左右的氢化锆会面临严重的氢释放风险,导致慢化能力下降,因而必须找到阻止其高温氢释放的方法。二氧化锆是一种潜在的阻止氢渗透的材料。通过设计氢释放对照实验,并利用X射线衍射(XRD)方法对氢释放实验前后氢化锆样品的H/Zr实现连续监测,验证阻氢方法是否有效。结果表明,在650℃下保温120h,普通的氢化锆样品及预氧化的氢化锆样品均发生了较严重的氢释放,H/Zr从1.85下降到1.66附近,且后者表面处还生成了Zr3O;而经过预氧化的氢化锆样品,在氦气和二氧化碳混合气氛下保温,其氢释放现象并不明显。由此可说明,氧化性的二氧化碳气氛能为二氧化锆提供支持,从而保证了较好的阻氢效果。

Zirconium hydride,as a moderator of the space reactor,working at temperature over 650 ℃,in which the initial H/Zr atomicity ratio（H/Zr）is about 1.85,will face a risk of hydrogen release and yield reduction of the moderation.Therefore,it＇s necessary to find a prevention method.ZrO2 is a potential material to prevent the hydrogen release.The verification of the prevention method was realized by the hydrogen release test and the XRD method which could minimize the variation of the H/Zr.The result indicates that both the plain sample and the pre-oxidized one lose a tremendous amount of hydrogen when they are placed in He atmosphere at 650 ℃ for 120 h,furthermore,a new substance Zr3 O comes into being on the surface of the latter.However,when it is in the gas mixture of He and CO2,the hydrogen release of the preoxidized sample is negligible.A conclusion can be draw that the CO2 sustains the ZrO2 structure and the method is available.