The fast reactor core designs so far have been mainly pursuing the breeding performance as seen in the so-called fast breeder reactor from the viewpoint of ensuring future energy sources. In the twenty-first century, significant growth of energy demand is expected mainly in developing countries. On the other hand, the issues of wasting natural resources and environmental destruction have recently become obvious. It has become internationally recognized that the world must go toward sustainable development with resource conservation and consideration of environmental issues as well as assurance of stable energy sources.

Japan, for example, has only small amounts of natural resources. It is essential to develop technologies which save resources, do not emit greenhouse gases, and lead to small loads on waste disposal. The FBR cycle was selected as one such technology. A high capacity for energy supply and the technologies for burning transuranium elements (TRU: Pu, Np, Am, Cm) have been devel­oped for the FBR. The FBR must have high economy which is competitive with other power generation methods while ensuring safety as a major premise. Also, non-proliferation must be considered according to the world political situation. From this background, consideration of a concrete scenario for deploying the FBR cycle has been started in Japan. Japan’s activities are attracting the world’s rapidly increasing interests in FBR deployment, and international corroborations are strongly desired.

Taking Japanese experience as an example, it is important to develop, in the early stage, the FBR cycle which has international competitiveness by improv­ing the performance of waste management and proliferation resistance and that goes toward a rational transition from the LWR cycle to the FBR cycle. This will contribute to sustainable development.

In the Fast Reactor Technology Development (FaCT) Project of Japan, the indexes of design targets are set from viewpoints of: safety; sustainability (environmental protection, waste management and resource efficiency); econ­omy; and proliferation. Furthermore, they are determined in consideration of consistency to requirements of international collaborative programs that have already taken place such as GEN-IV*1 and INPRO*2.

GEN-IV is the fourth generation nuclear power plant system. The first generation indicates the early prototype reactors such as at Shippingport (PWR) and Dresden (BWR). The second generation indicates the following commer­cial reactors i. e. PWR, BWR, CANDU and VVER, RBMK. The third genera­tion is the improved designs of the second generation systems. ABWR, APWR and EPR mainly pursue economy by scaling up. The reactors with the passive safety system such as AP1000 and ESBWR are also third generation. The fourth generation will follow the third generation and is assumed to have the following characteristics: (i) economically competitive with natural gas ther­mal power plants; (ii) higher proliferation resistance; (iii) higher safety; and

(iv) minimum load for waste management.

*2 INPRO (International Project on Innovative Nuclear Reactors and Fuel Cycles) is one of the IAEA programs to help prepare infrastructures aimed toward deployment of innovative nuclear systems which have safety, economy, proliferation resistance, etc.