In this work we present the results of two spent nuclear fuel leaching experiments in simulated granitic groundwater, saturated with hydrogen under various pressures. The results show a large impact of the dissolved hydrogen already at 1 bar H₂ and room temperature on the release of both the uranium and of the fission products contained in the fuel matrix. Based on the results of this study and on published data with fuel from the same rod, the importance of the oxidative dissolution of spent fuel under repository conditions as compared to its non-oxidative dissolution is discussed. The XPS-spectra of the fuel surface before the tests and after long-term leaching under hydrogen are reported and compared to reduced UO₂ and SIMFUEL surfaces. The overall conclusion is that in spite of the unavoidable air contamination, hydrogen pressures of 1 bar or higher counteract successfully the oxidative dissolution of the spent nuclear fuel. The stability of the 4d-element metallic particles during fuel leaching under such conditions is also discussed, based on data for their dissolution. The metallic particles are also stable under such conditions and are not expected to release their component metals during long-term fuel leaching.

在这项工作中，我们介绍了在不同压力下被氢饱和的模拟花岗岩地下水中的两次乏核燃料浸出实验的结果。结果表明，已经在1 bar H ₂和室温下溶解的氢对燃料基质中所含铀和裂变产物的释放均具有很大的影响。基于这项研究的结果以及来自同一杆的燃料的公开数据，讨论了在储存条件下乏燃料的氧化溶解与其非氧化溶解相比的重要性。报告了在测试之前和在氢气中长期浸出之后燃料表面的XPS光谱，并将其与减少的UO _{2进行了比较。}和SIMFUEL表面。总的结论是，尽管不可避免的空气污染，但1 bar或更高的氢气压力仍能成功抵消乏核燃料的氧化溶解。基于其溶出数据，还讨论了在这种条件下燃料浸出过程中4d元素金属颗粒的稳定性。金属颗粒在这样的条件下也是稳定的，并且在长期的燃料浸出期间不会释放它们的成分金属。