Iodine-129 in water samples collected adjacent to a spent nuclear fuel reprocessing plant in Rokkasho, Japan

The spent nuclear fuel reprocessing plant in Rokkasho, Japan, has been undergoing final testing since March 2006. The concentrations of I-129 in environmental water samples collected around the reprocessing plant were measured from 2005 to 2012. The I-129 concentrations in water samples of the brackish lake adjacent to a plant from 2006 to 2008 which the spent fuel rods were cut and chemically processed, was higher than the background level. The major source of I-129 in the lake was dominated by the direct deposition of I-129 from the atmosphere than that from the ocean.