The safe completion of the Fukushima Daiichi Nuclear Power Plant decommissioning projects requires that the long-term distributions of fission products (FPs) as well as fuel debris for the entire plant be understood. The fuel debris is going to be removed from the plant under the severe conditions of FPs being scattered during major decommissioning work, and then, the decommissioning projects are going to be terminated by storing safely the removed debris as recovered fertile materials or as materials for final radioactive waste disposal.

In order to determine the FP distribution in the plant for the long period from the accident occurrence to the termination of the plant decommissioning, procedures for analyzing short-, medium- and long-term FP behaviors has been proposed. The proposed procedures should be improved by applying the FP data measured in the plant and validated based on the fed-back data. Then, the accuracy-improved procedures should be applied to estimate FP distributions during each phase of the decommissioning projects.

First the paper outlines the short-, medium- and long-term FP transfer analyses. Then, their applicability and some examples of their validations based on dose rate data of the containment atmosphere monitoring system (CAMS) of Unit 1 are introduced.

(195 words)

福岛第一核电站退役项目的安全完成需要了解整个工厂的裂变产物（FPs）和燃料碎片的长期分布。燃料碎片将在重大退役工作期间FPs散落的严峻条件下从工厂中清除，然后，退役项目将通过将清除的碎片作为回收肥沃材料或作为最终材料安全储存来终止。放射性废物处置。

为了确定从事故发生到工厂退役终止的长时间内工厂中的 FP 分布，已经提出了分析短期、中期和长期 FP 行为的程序。应通过应用在工厂中测量的 FP 数据并根据反馈数据进行验证来改进提议的程序。然后，应该应用精度改进程序来估计退役项目每个阶段的 FP 分布。

首先，本文概述了短期、中期和长期 FP 转移分析。然后，介绍了它们的适用性和一些基于 1 号机组安全壳大气监测系统（CAMS）剂量率数据的验证示例。

(195 字)