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 I2 and non-volatile iodine formed by thermal and radiolytic decomposition of NaIO3. In UV–VIS spectrophotometry, the calibration curves of I− concentrations were not affected by pH in the range of 3–13. Even though I2 captured in toluene was evaporated slightly with toluene, most of the evaporated I2 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 IO3− in the range of 190–275 nm completely overlaps with that of I−.