Research on and economic evaluation of uranium enrichment by gaseous diffusion in Japan

Research and development on uranium enrichment by the gaseous diffusion process have been carried out by the Japan Atomic Energy Research Institute, the Institute of Physical and Chemical Research, and industries since 1965. The paper describes the two important keys to reducing the cost of uranium separation. One is the characteristics of barriers and the other is financing and/or political planning. The techniques of preparing a barrier with pore diameter 40A have been developed with polytetrafluoroethylene (PTFE), alumina and nickel. Experiments on corrosion behaviour have indicated that PTFE barriers are the most favourable. In the field of engineering research, the adiabatic efficiency of the axial compressor for UF6 was raised to as high as 90% by long-term operation tests. Based on these experimental data, technico-economic evaluation of a uranium enrichment plant was carried out for optimization of separation efficiency, number of steps and plant operating conditions. Sensitivity in the separation cost was calculated as a function of pore diameter, cost of uranium hexafluoride, plant capacity, cost of electric power, and annual expenditure of the plant. A finance plan must be such as to achieve: (a) maximization of debt in a percentage of total capital; (b) off-take contracts to utilities as security for financing; (c) minimization of risks to equity and achievable cost of capital. Therefore, the cash flow analysis and the schedule for construction and operation are very important for the economic feasibility of a uranium enrichment plant. To minimize the risk, the economic as well as the political environment is important. Government support and international agreements are necessary. (author)