Effect of Cs and Sr separation on occupied area reduction in current nuclear energy system and its evaluation by CAERA index
Effect of Cs and Sr separation on occupied area reduction in current nuclear energy system and its evaluation by CAERA index
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Cs、Sr分离对现有核能系统占用面积减少的影响及CAERA指数评价
DOI：
10.1080/01496395.2019.1577897
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发表时间：
2019
影响因子：
2.8
通讯作者：
K. Takeshita
中科院分区：
文献类型：
--
作者：
T. Okamura;K. Kawai;E. Minari;M. Nakase;H. Asano;K. Takeshita
从高放废液中分离铯和锶有助于减少高放废物地质处置库中的热产生，并相应地最大限度地减少所需的空间。为了最大限度地减少处置库占用面积的Cs和Sr分离的影响，有必要考虑核能系统的前端和后端阶段。因此，我们定量调查的因素，可能会影响减少占用面积-即，所需的面积处理一个废物包-当引入Cs和Sr分离。通过使用“减少处置区域效果综合分析”（CAERA）指数进行的评估，我们发现，在六所村后处理厂目前的运行条件下，排放后的乏核燃料（SNF）冷却期为15年，对于具有Cs和Sr分离的25和30wt%废物负载的玻璃化废物，实现了占用面积的最大减少30%。在这种情况下，根据日本地质处置概念的当前参考案例（所谓的H12报告），需要分离70%以上的Cs和Sr。此外，Cs和Sr的分离，以减少占用面积的有效性急剧下降，如果排放后的冷却期延长超过15年，例如，玻璃化废物与超过40年的冷却期显示几乎没有减少占用面积。这是因为随着冷却时间的延长，241钚的β衰变产生的241 Am的量以及241 Am对玻璃化废物中发热的贡献增加。结果表明，SNF的冷却时间、玻璃化废物的废物装载量、Cs和Sr的分离率以及废物的占地面积是影响Cs和Sr分离效果的关键因素。
ABSTRACT Separation of Cs and Sr from high-level liquid waste (HLLW) contributes to reducing heat generation and correspondingly to minimizing the required use of space in geological disposal repositories for high-level radioactive waste. To maximize the impact of Cs and Sr separation on reducing the occupied area of a repository, it is necessary to consider both the front-end and back-end stages of the nuclear energy system. Therefore, we quantitatively surveyed factors that potentially affect the reduction in the occupied area – that is, the area required for disposal of one waste package – when introducing Cs and Sr separation. From an evaluation using the Comprehensive Analysis of Effects on Reduction of Disposal Area (CAERA) index, we found that in case of a 15-year cooling period of spent nuclear fuel (SNF) after discharge, which is the current operational condition at the Rokkasho Reprocessing Plant, a maximum reduction of 30% in occupied area was achieved for 25 and 30 wt% waste-loaded vitrified waste with Cs and Sr separation. In that case, separation of more than 70% of Cs and Sr was required based on the current reference case for the Japanese geological disposal concept (the so-called H12 Report). In addition, the effectiveness of Cs and Sr separation for reducing the occupied area was drastically decreased if the cooling period after discharge was extended beyond 15 years; for instance, vitrified waste with a more than 40-year cooling period showed almost no reduction in occupied area. This was because the amount of 241Am, which is generated from the beta decay of 241Pu, and the contribution of 241Am to heat generation in vitrified waste increased as the cooling period became longer. The results suggested that the cooling period of the SNF, the waste loading of the vitrified waste, the Cs and Sr separation ratio and the occupied area of the waste were key factors governing the effectiveness of Cs and Sr separation for geological disposal area reductions.