快堆乏燃料干法后处理技术与发展思考

Progress and Development Thinking of Dry Reprocessing Technology for Spent Nuclear Fuel from Fast Reactor

  • 摘要: 乏燃料干法后处理是指在非水介质中处理乏燃料,回收铀钚等锕系元素,并妥善处理放射性废物的一种化工过程。干法后处理是闭式燃料循环快堆核能系统的关键环节,也是快堆乏燃料后处理的现实技术选择。美、俄均已掌握快堆乏燃料干法后处理技术,分别建立了适合本国快堆核燃料循环策略的干法后处理工艺流程,已经过工程规模热试验验证,正在开发工程化技术。我国干法后处理技术路线选择遵循国际先进技术和我国快堆燃料循环整体策略,重点发展了熔盐电解技术,可兼容处理氧化物和金属等多种类型的快堆乏燃料,正处于关键技术攻关阶段。本文概述了快堆乏燃料干法后处理技术典型流程和发展趋势,总结了国内围绕快堆乏燃料干法后处理研发取得的最新进展,分析了干法后处理技术面临的挑战,并结合我国快堆核能系统发展战略,提出了我国快堆乏燃料干法后处理技术发展急待突破的关键科学和技术问题。

     

    Abstract: Dry reprocessing of spent fuel refers to a chemical process that involves treating spent fuel in non-aqueous media, recovering actinide elements such as uranium and plutonium, and properly disposing of radioactive waste. It is a key step in closed fuel cycle of fast reactor nuclear energy systems and a practical technical choice for spent fuel reprocessing from fast reactors. Both the United States and Russia have mastered the dry reprocessing technology for spent fuel in fast reactors, and have established dry reprocessing process flows suitable for their own fast reactor nuclear fuel cycle strategies. After engineering scale hot testing verification, engineering technology is being developed. The selection of China’s dry reprocessing technology route follows international advanced technology and the overall strategy of China’s fast reactor fuel cycle, with a focus on the development of molten salt electrolysis technology, which is compatible with the treatment of many types of fast reactor spent fuel, such as oxides and metals. It is currently in a critical stage of technological research and development. An overview of the typical process and development trends of dry reprocessing technology for spent fuel in fast reactors was provided in this paper. The latest progress made in the research and development of dry reprocessing technology for spent fuel from fast reactors in China was summarized. The challenges faced by the dry reprocessing technology were analyzed, and the key scientific and technical issues urgently needed to be addressed in the development of dry reprocessing technology of fast reactor spent fuel in China were proposed in combination with the development strategy of fast reactor nuclear energy system in China. Based on the fact that transmutation of minor actinides is one of the main functions for the fast reactors in China, the dry reprocessing technological process needs to consider the recovery of all actinides, including minor actinides. At the same time, it is also necessary to consider the treatment of both metallic and oxide spent fuel. Thus, the molten salt electrorefining technology has been selected to meet the requirements. At present, the conceptual design of the dry reprocessing demonstration plant has been completed, and key technology research has been carried out. Minor actinides are recovered simultaneously in the main process, meeting the requirements of the full actinide cycle in the fast reactors. The flow sheet of dry processing was established with the recovery rates of 99% for uranium, 99.5% for plutonium and minor actinides. With the recycle of the molten salt, 90% of the salts can be reused.

     

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