In Korea, Wolsong Tritium Removal Facility (WTRF) is scheduled to begin operation in 2005 to reduce the amount of tritium generated in the moderator and coolant. The objective of this study is to evaluate the environmental impact of tritium released from WTRF in the postulated accident. In order to achieve this, a computer code was developed at KAIST (Korea Advanced Institute of Science and Technology). This code can be used to evaluate the individual and public dose with the source term. This source term can represent not only the concentration of tritium that will be stored at the long term tritium storage vault located in the underground of WTRF building but also may be released to the environment from the WTRF online system by variously postulated accidents. To validate this code, calculated results were compared with the previous reference under the same assumption. Even if the most severe postulated accident that the tritium may be released through the fracture of the storage vault was occurred, the result of individual dose at the exclusion area boundary is turned out to be within the radiation dose limit.