The nuclear facilities sites handling radioactive materials are contaminated due to accidents or its activities. Since the experimental reactor was operated in Idaho, USA in 1951, nuclear power and its related activities were carried out in many countries. Thus, the legacy sites in which radioactive materials have been deposited are a matter of public concern. As a result of the operation of facilities related to the use of nuclear energy, it is faced with the restoration of the environment containing radioactive wastes. In particular, the activities carried out in the early years caused its contamination of the sites and areas with significant releases of fission products and natural radioactive wastes adventitiously or intentionally due to the lack of its technology and the unclear radiation risks. In addition, nuclear weapons tests conducted in the 1950s and 1960s and the Chernobyl power plant accident in 1986 caused radioactive contamination in the Pacific Ocean and extensive territories in Europe. Accordingly, the IAEA discussed the restoration of the contaminated areas at the conference on the radiation legacy of the 20th Century in terms of environmental restoration (RADLEG-2000) held at Moscow, Russia in October 2000 and its cases from the former Soviet Union and Eastern Europe were reported. Also, the Nuclear Energy Agency (NEA) has discussed the potential issues on the legacy sites occurring radioactive materials and suggested that these sites should be managed in an open, transparent and consistent manner in order to build sustainable solutions with trust. However, there is currently no overall regulatory system for the management of legacy sites in Korea. The TRIGA Mark-II research reactor, which was commissioned in 1962, was decontaminated and dismantled in 1997. As such, it is necessary to consider the regulatory system related to the existing legacy site. Most of all, the legacy site management and regulatory standards of facilities that have operated in the past and are not currently operating or that deal with natural radioactive materials should be established. Also, the dismantling of NK’s nuclear facilities and management of related radioactive waste, particularly NK’s uranium mines and refining facilities particularly at Pyongsan and Bakcheon in NK are one of the key issue on the North Korea’s denuclearization. In this study, the international standards on the reuse of the legacy site after dismantling are analyzed, and its regulatory considerations used for domestic application are suggested.