The annual individual and collective doses to the thyroids of four age-dependent groups due to the in-take of I-131 released from the Younggwang nuclear power plant NU-1 & 2, Korea, are estimated using the model presented in ICRP 29. Sensitivity and robustness of the model are analyzed. In case of 0.12% fuel defect during normal operation, the collective dose is founded to be 3.05${ imes}10^{-3}$man-thyroid-Sv, which is higher than the value calculated by the GASPAR code, 2.3${ imes}10^{-3}$man-thyroid-Sv. The maximal individual annual doses resulting from an acute release are higher than those calculated under the assumption of continuous release by $1.4{sim}1.7$ times. The most important pathway to the infant is milk and, in contrast, that to child, teen and adult is ingestion of crops. The model used is the calculation appears to be influenced by the variables such as roubstness-index. The weighted committed dose equivalent obtained by the ICRP 29 model is slightly higher than that calculated by the three-compartment model.