福島第一原子力発電所事故の考証

（２）実測データに基づく耐圧ベントの除染効果

抄録

The dose rate field data recorded at Fukushima Daiichi site shows the effect of radioactivity release by hardened vents at 1F3 was 1/100~ 1/1,000 compared with the effect of direct radioactivity release from 1F2 PCV. That causes were clarified by the evaluation of hardened vent, that is,the steam containing a large amount of radioactivity in 1F3 PCV was decontaminated by scrubbing in the suppression pool (below 1/10) and diluted with a large quantity of steam generated by pressure reduction boiling(~1/35). The scrubbing effect and the dilution effect acted synergistically. The hardened vents performed twise at the early stage of ore damage of 1F3 were estimated to be highly effective for transferring low boiling point radioactive products such as I,Cs and CsI to the suppression pool. The preliminary dynamic analysis with TRAC code suggested the enthalpy loss of steamemmitted through the vent piping line to atomospheric environment was very small. The study will be continued.