For the geological disposal system in Japan, a vitrified waste will be contained in a metal overpack, which, in turn, will be surrounded by a thick bentonite buffer. The overpack is aiming to prevent the contact of groundwater to vitrified waste during the high radioactivity and heat generation period of the first 1,000 years at least after emplacement. Within the Japanese program, consideration for overpack candidate materials has included carbon steel, copper–steel composite, and titanium–steel composite. Within the extensive safety assessment conducted in 2000, steel was selected. This selection was partly based on the manufacturability of carbon steel, as well as its well‐understood corrosion behavior. However, the understanding of copper corrosion and welding/manufacturing technologies have greatly progressed over the past two decades. In this study, we focus on the copper‐coated container developed by the Nuclear Waste Management Organization, because this technology is seemingly effective to maintain very long‐term containment of hundreds of thousands of years, with a low cost of manufacturing within the Canadian program. We are investigating the applicability of the copper‐coating technologies in terms of the corrosion allowance and mechanical design.

中文翻译：

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日本高放废物处置概念的铜包外包装设计

对于日本的地质处置系统，玻璃化废料将包含在金属外包装中，而金属外包装又将被厚的膨润土缓冲层包围。外包装的目的是至少在放置后的最初1000年内，在高放射性和高热量产生期间防止地下水与玻璃化废物接触。在日本计划中，考虑使用外包装候选材料包括碳钢，铜钢复合材料和钛钢复合材料。在2000年进行的广泛安全评估中，选择了钢材。这种选择部分是基于碳钢的可制造性及其公认的腐蚀行为。但是，在过去的二十年中，对铜腐蚀和焊接/制造技术的理解有了很大的进步。在这项研究中，我们重点研究了由核废料管理组织开发的镀铜容器，因为该技术似乎可以有效地保持数十万年的长期封存，并且在加拿大计划中的制造成本较低。我们正在从腐蚀余量和机械设计方面研究铜涂层技术的适用性。