加速器質量分析法で測定した東海再処理施設10km圏内における土壌中I及びI濃度

Concentrations of I and I in soil samples within 10km radius from the Tokai Reprocessing Plant measured by Accelerator Mass Spectrometry method

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

2006年3月の電気事業者との役務再処理の完遂を機に、AMS法による、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、安全審査で用いられた拡散計算による計算値とおおむね一致しており、安全審査で用いた拡散計算の妥当性が確認された。また、深度分布試料の測定結果からIは一旦土壌に吸着されると移動しにくく、数十年間はそこに留まっていることが示唆された。

Since the reprocessing contracts with electric power companies were completed in March 2006, the horizontal distribution of I in soil within 10 km 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 that the I remaining there for several decades that it will be hard to move soil is adsorbed.