Current and 2050 energy perspectives in India. Opportunities for materials scientists and technologists

Nuclear technology can provide an essentially inexhaustible supply of energy to meet the world energy needs in an environmentally sustainable manner. In order to utilise the available uranium resources effectively, India has been successfully pursuing the construction and operation of Pressurized Heavy Water Reactors (PHWRs) and Liquid Metal (sodium) Cooled Fast Breeder Reactors (FBRs). In PHWR systems, the main factors responsible for shortening the life of in-core components are irradiation damage, in-reactor creep and growth, stress corrosion cracking and hydrogen pick up during service life. The materials used for manufacturing fuel tubes, pressure tubes and calendria tubes must meet stringent requirements of various properties in order to perform reliably in nuclear reactor environments. While Zirconium alloys have proven to be successful in their designed usage, a desire for longer life time of components and duty cycle puts more demand on the development of newer compositions for zirconium alloys, their processing and fabrication, and their evaluation for critical applications. In the next two decades, the progress made in the development and operation of PHWRs will depend on how well the performance of the existing structural materials can be improved under the extreme conditions prevailing in the reactor. The crucial constraint in the development of FBRs is the need for high temperature structural materials for reactor structural components, primary heat exchanger tubes, steam generator tube sheets and piping, and radiation resistant high temperature materials for reactor core components. For economic viability of FBRs, the target fuel burn-ups required are more than 20 atom % of heavy metal (200,000 MWd/t), and this can be achieved only by the availability of materials resistant to void swelling, irradiation creep and irradiation embrittlement, as well as satisfying the high temperature mechanical properties. All these issues have been overcome by developing Ti-Ta-Nb alloys for dissolver tanks and evaporators of fuel reprocessing plants. Safe operating window for processing, corrosion and weldability characteristics for these materials have been established. The future challenge is to develop nuclear technologies to meet energy needs through emissions-free production of electricity and in the longer-term transportation fuels such as hydrogen. High temperature reactors hold promise in this regard. The paper high lights the technologies, processes, and materials research relevant to PHWR and FBR programmes in India. Thorium based reactors and Fusion Reactors are important for energy security beyond 2050. Materials challenges in fusion reactors are briefly outlined. India's dream of self sufficient in energy can be realized by expeditions and efficient harvesting of her limited uranium and vast thorium resources. (orig.)