For each 100 fissions of U235, around 243 high energy neutrons are released. Some of these high energy neutrons interact with the abundant U238 and convert them into Plutonium—a fissile element not found in nature. Plutonium is the potent and feared “weapon” grade atom. However, in light water reactors (LWR) such as Bushehr, the Plutonium atoms themselves undergo further fission and generate energy. In fact about a third of the cycle energy in LWR comes from fission of the Plutonium atoms. THE only way to retrieve the Plutonium before it undergoes fission is by shutting down the reactor, removing the reactor vessel dome (atop #5 in the figure), removing the fuel assemblies from the reactor (using #4 crane in the figure), removing the very hot and radioactive fuel rods from the fuel assemblies, and transporting the “deadly” radioactive fuel rods to a reprocessing plant, which amounts to a major task involving series of intense and highly visible activities not possible to conceal, particularly from IAEA resident inspectors. Furthermore, the depleted fuel is not of much use for weapon purposes at the end of the cycle either, because the fuel is depleted, hot, and radioactive that should only be moved to the spent fuel tank. It should be noted that even US with all its technological might does not reprocess spent fuel for weapons. Otherwise, all operating and decommissioned civilian nuclear power plants in US would have gladly and patriotically donated their entire spent fuel—which is currently seating in their spent fuel pool at great burden and cost–to the government.
1996: The National Academy of Sciences declares nuclear fuel reprocessing impractical and too costly for the country. See
this link.
http://www.juancole.com/2010/08/nakhai-bushehr-plant-going-hot.html
