•Recently, India loaded its long-delayed Prototype Fast Breeder Reactor (PFBR) vessel, coming to the cusp of stage II — powered by uranium and plutonium — of its three-stage nuclear programme.
•By stage III, India hopes to use its vast reserves of thorium.
•But the large-scale use of nuclear power is accompanied by a difficult problem: waste management.
•In a fission reactor, when uranium-235 (U-235) nucleus absorbs a neutron, it fission to barium-144, krypton-89, and 3 neutrons.
•If the ‘debris’ (barium-144 and krypton-89) constitute elements that can’t undergo fission, they become nuclear waste.
•Handling the spent fuel is the main challenge — it is hot and radioactive, and needs to be kept underwater for a few decades.
•Once cooled, U.S. had 69,682 tonnes (as of 2015), Canada 54,000 tonnes (2016), and Russia 21,362 tonnes (2014it is transferred to dry casks for longer-term storage.