Re-evaluation of a method for monitoring airborne radioiodine discharge and its contribution to development of an advanced method

Koarashi, Jun   ; Mikami, Satoshi   ; Miyauchi, Toru; Kozawa, Tomoyasu*; Yokota, Tomokazu*; Nakada, Akira ; Akiyama, Kiyomitsu; Momose, Takumaro  

The current methodology for monitoring airborne radioiodine at the Tokai reprocessing plant (TRP) was reviewed, and some investigations were made to re-evaluate collection and measurement techniques in the methodology. The investigations focused particularly on: (1) in situ collection efficiency of an iodine sampler for I and its dependence on sampling flow rate; (2) evaluation of I and I activities collected in an activated charcoal cartridge; (3) I collection capacity of an activated charcoal cartridge under reprocessing off-gas conditions; and (4) real-time monitoring system for I in airborne effluent. The results obtained gave not only the validity of the TRP's monitoring method, but also technical aspects required for establishing a more reliable and effective monitoring method for radioiodine isotopes.