Multi-term fission product (FP) analysis procedures were developed to determine FP distribution all over the Fukushima Daiichi nuclear power plant (F1) not only for analyzing accident propagation but also for planning its decommissioning projects. They should be validated based on the measured FP data. One of the useful tools for their validation was application of the dose rate data monitored by the containment atmosphere monitoring system (CAMS). However, in order to compare the data with different characteristics and dimensional units, e.g., FP distribution (kg, Bq) and dose rate (Sv/h), application of the conversion factors bridging them would be effective and useful. In order to prepare speedy, easy-to-handle and tractable procedures to calculate radiation dose rates at the CAMS detector locations, dose rate conversion factors were determined for major source locations and major radionuclides. The dose rates could be easily calculated by multiplying FP amounts obtained with the multi-term FP analysis procedures by the conversion factors.

This paper introduces the procedures to calculate the conversion factors based on a point kernel integral shielding calculation code, QAD-CGGP2. Then, the determined conversion factors for the 460 MWe BWR (1F Unit 1) and for the 780 MWe BWR (Units 2 and 3) are listed and the differences in those due to the reactor sizes are discussed.

开发了多项裂变产物 (FP) 分析程序，以确定整个福岛第一核电站 (F1) 的 FP 分布，不仅用于分析事故传播，而且用于规划其退役项目。它们应该基于测量的 FP 数据进行验证。用于验证的有用工具之一是应用安全壳大气监测系统 (CAMS) 监测的剂量率数据。但是，为了比较具有不同特征和维度单位的数据，例如, FP 分布 (kg, Bq) 和剂量率 (Sv/h)，应用连接它们的转换因子将是有效和有用的。为了准备快速、易于操作和易于处理的程序来计算 CAMS 探测器位置的辐射剂量率，确定了主要源位置和主要放射性核素的剂量率转换系数。通过将使用多项 FP 分析程序获得的 FP 量乘以转换因子，可以很容易地计算出剂量率。

本文介绍了基于点核积分屏蔽计算代码QAD-CGGP2计算转换因子的过程。然后，列出了确定的 460 MWe BWR（1F 机组 1）和 780 MWe BWR（机组 2 和 3）的转换系数，并讨论了由于反应堆尺寸而导致的差异。