An important element in the Three Mile Island Unit 2 defueling systems design program was a consideration of the radiation sources to be encountered during the defueling effort. A comprehensive radiation analysis program was developed to assess the radiological impacts to be expected during all defueling operations. This analysis was used to ensure adequate radiation protection of defueling operators and to minimize the collective doses expended to accomplish the defueling effort. The analytical program was accomplished in conjunction with the design process. In this way, it was ensured that the designs could incorporate important radiation protection features.