Abstract: There is probability of fuel rods damage in PWR during operation. If the fuel rods damaged, the fission gases such as radioiodine will be released to the air of building, increasing the risk of internal exposure to personnel. According to the estimation of iodine hazard due to fuel rods damage for VVER unit, one damaged fuel rod can lead to air contamination of radioiodine as high as 84DAC. With reference to the practical NPP, radioiodine hazard control and protection measures such as the primary circuit purification, control of iodine releasing and diffusing to the air, air purification and personal protection are discussed, and some suggestions for similar situations are proposed.

Key words: fuel rod, damage, radioiodine hazard, estimation, protection