Identification of Iodine Species Released from Fuel Using a Commercial Volatile Radioiodine Species Sampler
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Abstract
Experiments have been carried out to verify the manufacturer's claims (1) for an "iodine species" sampler which differentiates between 12, CH31 and HOI, the main volatile forum of iodine expected in nuclear installations after radioactive releases from fuel. This sampler consists of five components: a filter paper to retain particulates ; Cd12 on a matrix of chromosorb-P to retain I and I2; iodophenol on a matrix of activated alumina to retain HOI; 30-50 mesh silver zeolite for CH31; and lastly 40-50 mesh TEDA-impregnated (5%) charcoal to capture any iodine which escapes the preceding filter elements.
Calibration experiments used radioactively labelled CH31 and 12. 95.4% of the methyl iodide was trapped in the silver zeolite, and 87% of the I2 in the Cd12. These figures are almost identical to those of the manufacturer.
The sampler has been used to measure the iodine species released during oxidation in air of irradiated U02 fuel fragments, and Pickering elements. The identification of I2 as the volatile form of iodine seems certain and logical since >93% of the released iodine was trapped in the first element of the sampler and little penetration occurred beyond this.
The only fission products ever observed downstream of a sampler have been the noble gases, and even these are trapped up to 50% by the charcoal back-up cartridge operating at room temperature.
In conclusion, the iodine species sampler performs very well and up to specifications for separating I2 and CH31. It has been found extremely useful in preventing radioactive iodine releases from apparatus during destructive oxidation of fuel in hot cells.
Calibration experiments used radioactively labelled CH31 and 12. 95.4% of the methyl iodide was trapped in the silver zeolite, and 87% of the I2 in the Cd12. These figures are almost identical to those of the manufacturer.
The sampler has been used to measure the iodine species released during oxidation in air of irradiated U02 fuel fragments, and Pickering elements. The identification of I2 as the volatile form of iodine seems certain and logical since >93% of the released iodine was trapped in the first element of the sampler and little penetration occurred beyond this.
The only fission products ever observed downstream of a sampler have been the noble gases, and even these are trapped up to 50% by the charcoal back-up cartridge operating at room temperature.
In conclusion, the iodine species sampler performs very well and up to specifications for separating I2 and CH31. It has been found extremely useful in preventing radioactive iodine releases from apparatus during destructive oxidation of fuel in hot cells.
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