Process and engineering developments in production of ceramic grade uranium oxide

For well over 3 decades, Nuclear Fuel Complex (NFC), Hyderabad has been manufacturing natural Uranium-di-oxide fuel for all the PHWRs in India. Ammonium Di-Uranate (ADU) route is followed for Uranium Oxide (UO2) powder production for its PHWRs. The fuel is in the form of high-density UO2 pellets, clad in zircaloy tubes. The raw material for production of UO2 powder is Magnesium Diuranate (MDU), which, after dissolution in commercial nitric acid is purified and precipitated to form ADU. This material is then subjected to 'dry' operations involving filtration, drying, calcination, reduction and stabilisation to get nuclear grade UO2 powder, suitable for pellet fabrication. Uranium Oxide Plant was set up at NFC in 1971 having production capacity of 120 TPY with indigenously developed process at BARC, Mumbai. In the initial stage, the plant had conventional process equipment for carrying out various processes. Almost all the operations were manual or semi-continuous with extensive dependence on manual labour. Over the period, production had to be scaled up to meet the increased fuel demand. While augmenting production capacities, actions were initiated for the development of better processes and modifications in the equipment with an aim to reduce strain to the personnel and also to improve productivity, quality, recovery, health and safety. The paper covers the details of these modifications and developments successfully implemented for industrial scale production of uranium dioxide powder and pellets