加速器質量分析装置を用いた東海再処理施設周辺10km圏内における土壌中I-129分布調査

Survey of I concentration in soil within 10 km radius from the Tokai Reprocessing Plant using accelerator mass spectrometry

國分 祐司 ; 横山 裕也; 藤田 博喜; 中野 政尚 ; 住谷 秀一 

Kokubun, Yuji; Yokoyama, Hiroya; Fujita, Hiroki; Nakano, Masanao; Sumiya, Shuichi

AMS法を用いて、東海再処理施設周辺10km圏内の土壌中Iの水平分布及び施設南西約2km地点における深度分布を測定した。その結果、再処理施設からの大気放出に起因するI濃度が観測されたものの、拡散計算による計算値と良い相関を示しており、拡散計算の妥当性が10km圏内で確認された。また、深度分布試料の測定結果からIは撹拌層と推察される深さまでほぼ一定の値を示し、それ以下の深さで急激に減少した。

The horizontal distribution of I in soil within 10km radius from Tokai Reprocessing Plant (TRP) as well as the vertical distribution at 2 km southwest from TRP were measured using the Accelerator Mass Spectrometry (AMS) method. As a result, the small amounts of I were observed due to the atmospheric discharge from TRP. It was good agreement with the predicted concentrations in safety assessment. The validity of the diffusion calculation was confirmed in the 10 km radius. Moreover, the results of vertical distribution of I show equivalent value to be a churning layer and decreased rapidly in the depth more than it.