Radiation air dose rates near the Fukushima Daiichi Nuclear Power Plant (FDNPP) have been steadily decreasing over the past eight years since the release of radioactive elements in March 2011. Currently, the radiation monitoring program is expected to transition to long-term monitoring after most of the remediation activities are completed. The main long-term monitoring objectives are to (1) confirm the continuing reduction of contaminant and hazard levels, (2) provide assurance for the public, (3) accumulate the basic datasets for scientific knowledge and future preparation, and (4) detect changes or anomalies in contaminant mobility (if they occur), or any unexpected processes or events. In this work, we have developed a methodology for optimizing the monitoring locations of radiation air dose-rate monitoring. Our approach consists of three steps in order to determine monitoring locations in a systematic manner: (1) prioritizing the critical locations, such as schools or regulatory requirement locations, (2) diversifying locations that cover the key environmental controls that are known to influence contaminant mobility and distributions, and (3) capturing the heterogeneity of radiation air-dose rates across the domain. For the second step, we use a Gaussian mixture model to identify the representative locations among multiple environmental variables, such as elevation and land-cover types. For the third step, we use a Gaussian process model to capture and estimate the heterogeneity of air-dose rates across the domain. Employing an integrated dose-rate map derived from Bayesian geostatistical methods as a reference map, we distribute the monitoring locations in such a way as to capture the heterogeneity of the reference map. Our results have shown that this approach allows us to select monitoring locations in a systematic manner such that the heterogeneity of air dose rates is captured by the minimal number of monitoring locations.

自2011年3月释放放射性元素以来，过去八年来，福岛第一核电站（FDNPP）附近的辐射空气剂量率一直在稳步下降。目前，预计辐射监测计划将在大多数情况下过渡到长期监测的修复活动已完成。长期的主要监测目标是（1）确定污染物和危害水平的持续降低；（2）为公众提供保证；（3）积累用于科学知识和未来准备工作的基本数据集；（4）进行检测。污染物迁移率的变化或异常（如果发生），或任何意外的过程或事件。在这项工作中，我们开发了一种用于优化辐射空气剂量率监测位置的方法。我们的方法包括三个步骤，以便系统地确定监视位置：（1）确定关键位置的优先级，例如学校或法规要求的位置，（2）覆盖已知影响污染物的关键环境控制的位置的多样化迁移率和分布，以及（3）捕获整个域内辐射空气剂量率的异质性。第二步，我们使用高斯混合模型来识别多个环境变量（例如海拔和土地覆盖类型）中的代表性位置。对于第三步，我们使用高斯过程模型来捕获和估计整个域中的空气剂量率的异质性。使用从贝叶斯地统计方法得出的综合剂量率图作为参考图，我们以捕获参考地图异质性的方式分布监视位置。我们的结果表明，这种方法使我们能够以系统的方式选择监测位置，以便通过最少数量的监测位置来捕获空气剂量率的异质性。