Utilisation of research reactors for fuel design and development

New fuel concepts which includes various advances carried out periodically in fuel design to improve safety or performance, require extensive testing before being adopted in power reactors. Research reactors have an important role in this and it usually involves fuel irradiation testing in dedicated test loops. The test loop has independent coolant system isolated from that of the main research reactor coolant to provide simulated power reactor coolant conditions. The test loop cooling system consists of pumps, heat exchanges, ion exchangers, heaters to control experiment temperature, and chemistry control systems. The test loop is also provided with instrumentation to continuously monitor and record the loop operating parameters and also an on-line failed fuel detection system to detect fuel failure if any at the earliest. As part of our power reactor fuel development programme, fuel irradiation tests in research reactors CIRUS and Dhruva have generated a large data-base on various design and manufacturing aspects. Fuel irradiation tests have been carried out on BWR, PHWR and AHWR types of fuel pin design and with different fuel materials and MOX compositions - UO₂, (U-Pu) MOX, ThO₂ and (Th-Pu) MOX. This paper brings out the experience of RED, BARC in the use of research reactors for design and development of different types of power reactor fuels and in validation of our fuel performance analysis codes