nuclear fuel cycle

(redirected from Nuclear fuel chain)

nuclear fuel cycle

[′nü·klē·ər ¦fyül ‚sī·kəl]

Nuclear fuel cycle

The nuclear fuel cycle typically involves the following steps: (1) finding and mining the uranium ore; (2) refining the uranium from other elements; (3) enriching the uranium-235 content to 3–5%; (4) fabricating fuel elements; (5) interim storage and cooling of spent fuel; (6) reprocessing of spent fuel to recover uranium and plutonium (optional); (7) fabricating recycle fuel for added energy production (optional); (8) cooling of spent fuel or reprocessing waste, and its eventual transport to a repository for disposal in secure long-term storage. See Nuclear fuels

Steps 6 and 7 are used in Britain, France, India, Japan, and Russia. They are no longer used in the United States, which by federal policy has been restricted to a “once through” fuel cycle, meaning without recycle. Belgium, China, France, Germany, Japan, and Russia, with large and growing nuclear power capacities, use recycled plutonium. Disposal of highly enriched uranium from nuclear weapons is beginning to be undertaken by blending with natural or depleted uranium to make the 3–5% low-enrichment fuel. Similarly, MOX (mixed oxides) fuel capability can be used to dispose of plutonium stockpiled for nuclear weapons. This option is being planned in Europe and Russia, and is beginning to be considered in the United States.

Nuclear reactors produce energy using fuel made of uranium slightly enriched in the isotope 235U. The basic raw material is natural uranium that contains 0.71% 235U (the only naturally occurring isotope that can sustain a chain reaction). The other isotopes of natural uranium consist of 238U, part of which converts to plutonium-239, during reactor operation. The isotope 239Pu also sustains fission, typically contributing about one-third of the energy produced per fuel cycle. See Nuclear reactor

Various issues revolve around the type of nuclear fuel cycle chosen. For instance, the question is still being argued whether “burning” weapons materials in recycle reactors is more or less subject to diversion (that is, falling into unauthorized hands) than storing and burying these materials. Another issue involves the composition of radioactive wastes and its impact on repository design. The nuclear fuel cycles that include reprocessing make it possible to separate out the most troublesome long-lived radioactive fission products and the minor actinide elements that continue to produce heat for centuries. The remaining waste decays to radiation levels comparable to natural ore bodies in about 1000 years. The shorter time for the resulting wastes to decay away simplifies the design, management, and costs of the repository.

References in periodicals archive ?
Using kinesthetic learning, the students simulated nuclear fuel chain reactions, tossing ping pong balls representing neutrons.
All people should be informed about the risks of uranium, nuclear weapons and the whole nuclear fuel chain."
However, the processes in the nuclear fuel chain such as mining, enrichment and waste management does emit radioactive waste, which can pose a threat to the environment and is dangerous for humans, plants and animals.
In such a day Iranian scientists managed to complete nuclear fuel cycle and include Iran in the list of few countries with complete nuclear fuel chain.
Concerns over the entire nuclear fuel chain have also been part of the opposition's positioning.
The new JV will sell enriched uranium using TENEXa[euro](tm)s supply and Toshibaa[euro](tm)s nuclear fuel chain.
Stewart understates nuclear power's land-use by about 43-fold by omitting all land used by exclusion zones and the nuclear fuel chain. Conversely, he includes the space between wind or solar equipment--unused land commonly used for farming, grazing, wildlife, and recreation.
Finally, it is argued that nuclear power has the most minimal impact on global warming as there are no carbon dioxide and other greenhouse gas emissions as by products of generation (although there are emissions associated with the earlier parts of the nuclear fuel chain, for example at the mining and milling stage).
Both measures--the elimination of nuclear weapons, and managing the intrinsic capacity of nuclear fuel chain facilities to produce fissile materials able to be used in nuclear weapons--are needed more urgently than ever to improve the prospects for human and planetary health and survival.
With regard to the statement "it seems impossible to pin down exactly how carbon-intensive the nuclear fuel chain is," I call attention to a study (now several years old) by the German Oko-Institut that estimated C[O.sub.2] emissions of 25-50 grams per kilowatthour.
"At each step of the nuclear fuel chain from uranium mining to the production of nuclear waste, nuclear power leaves a heavy toxic footprint that impacts our health and the environment."
Still, it seems impossible to pin down exactly how carbon-intensive the nuclear fuel chain is, and there is disagreement within the environmental community about nuclear energy's potential contribution to global warming.

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