Thursday, 01 April 2010 07:05
Milestone announcement was made by Candu designer Atomic Energy of Canada Ltd (AECL) that fuel bundles containing recovered uranium from used fuel had been inserted into Qinshan Phase III unit 1. Over the next six months, another 24 of the 'natural uranium equivalent' (NUE) bundles will be used in two of the reactor's fuel channels.
If successful over a one-year trial, this practice could help China get more energy from its imported uranium and reduce stocks of highly-radioactive used nuclear fuel at the same time.
Mainstream light-water reactors, of which China has nine in operation, use uranium fuel enriched to 3-5% uranium-235.
After spending around three years producing power in the reactor core the level of enrichment drops to nearer the natural level of about 0.7% and is removed. However, this fuel is still mostly composed of unaltered uranium capable of producing power in a pressurized heavy water reactor, like AECL's Candu model. Instead of using enriched fuel, these increase reactivity in the core by employing a heavy-water neutron reflector.
To make this first batch of NUE fuel, Qinshan managers collaborated with AECL, the Nuclear Power Institute of China and China North Nuclear Fuel Corporation. Fuel that had previously been used was processed to recover unspent uranium and this was mixed with some depleted uranium to achieve a mix with the same overall characteristics as natural uranium. Technical challenges in doing this included the highly-radioactive nature of the used fuel and achieving the right blend of depleted uranium and the recovered stocks still enriched up to around 1.6%.
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