Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Hirouchi, Jun; Takahara, Shogo; Yoshimura, Kazuya
Journal of Environmental Radioactivity, 232, p.106572_1 - 106572_6, 2021/06
Times Cited Count：1 Percentile：5.8(Environmental Sciences)Information on the radioactivity distribution inside and outside houses is useful for indoor external dose assessments. In this study, we collected both soil samples around the target houses and house material samples (i.e., of the floor, inner wall, ceiling, outer wall, and roof). The radioactivity of the samples was measured using a high-purity germanium detector. The surface contamination densities of the floor, inner wall, ceiling, outer wall, and roof relative to the ground were 3 
10
7 10
, 6 10
4 10
, 7 103 10, 2 101 10, and 4 102 10
, respectively. The relative surface contamination densities varied depending on the material, its location, and the orientation of the surface.
Shimada, Taro; Ishigami, Tsutomu; Seki, Masaya; Mukai, Masayuki
no journal, ,
Nuclear Safety Research Center is developing a safety evaluation code system for exposure dose of public and workers at the stage of decommissioning nuclear facilities from planning to site release. ESRAD program for estimation of spatial radioactivity distribution based on kriging was developed to support confirmation survey for site release. ESRAD has functions such as estimation of radioactivity concentration distribution in the region from some measured points considering spatial correlation, calculation of estimated mean value and variance comparable to the criterion by mean kriging, and calculation of a minimum numbers of measured points to satisfy the estimated mean value with the criterion including uncertainty. In addition, ESRAD calculated the Cs-137 concentration distribution of sea bottom soil at the port of Fukushima Daiichi Nuclear Power Plant as an application example.
Shimada, Taro; Nabekura, Nobuhide*; Miwa, Kazuji; Takeda, Seiji
no journal, ,
It is required to confirm that dose of public using the land after site release for is less than the criteria by dose evaluation based on the contamination distribution obtained by site survey before the completion of the decommissioning of nuclear facilities. Therefore JAEA is developing the methodology to evaluate public dose. We studied estimating methods for contamination distribution based on the data from the scoping survey and the final sampling measurement with errors using external drift kriging. As a result, it is indicated that estimated distribution by external drift kriging using scoping survey results with measurement errors is the same as that without measurement error. Estimation variance was increased with measurement errors. Therefore the evaluation method will be applied to determine the radioactivity distribution with uncertainty.
Shimada, Taro; Miwa, Kazuji; Sasaki, Toshihisa*; Takeda, Seiji
no journal, ,
The authors are developing a methodology for confirming that public dose using the site after site release will be in compliance with the dose criteria based on the radioactivity distribution at the termination of the decommissioning of nuclear facilities. In a previous study, it was confirmed that kriging with external drift combined with scoping survey and representative measurement could evaluate the radioactivity distribution. However, the issue that evaluated distribution should be validated from the viewpoint of sufficiency on points of representative measurement remained. Therefore, we developed the method for the validation, that mean absolute error (MAE) between each measured value and evaluated value is less than a reference value of MAE between an average of measured values and each measured value. The method was applied to supposed distributions and it was confirmed that some of the evaluated distributions were validated.
