Concentration determination of I2 and I− formed by thermal and radiolytic decomposition of NaIO3

As a part of the evaluation of radioactive iodine behavior under the severe accident condition of nuclear power plant, we measured the concentrations of the volatile I 2 and non-volatile iodine formed by thermal and radiolytic decomposition of NaIO 3 . In UV–VIS spectrophotometry, the calibration curves of I − concentrations were not affected by pH in the range of 3–13. Even though I 2 captured in toluene was evaporated slightly with toluene, most of the evaporated I 2 was captured again in the second capture solution. ICP-MS was used to measure the non-volatile I concentration, because the UV–VIS absorption of IO 3 − in the range of 190–275 nm completely overlaps with that of I − .