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AN INSIDER’S VIEW Nuclear Cycle

What is the Cycle? Once enriched, fuel is formed into reactor, and then stored. In other countries, fuel pellets. These pellets are loaded into the fuel cycle is closer to a closed loop, , the fuel used by sealed metal tubes, called fuel rods. The since the used fuel is recycled. In the once- plants to produce electricity, is a naturally fuel rods are grouped together to form through cycle, the cooled fuel assemblies occurring element in the earth’s crust. The assemblies to hold them in place inside are prepared for dry storage on-site and process of extracting uranium and using it the reactor. Each fuel assembly spends then indefi nite storage in a deep geologic to generate electricity is called the nuclear 5 to 6 years in the reactor before it must repository. In the closed-loop cycle, the fuel cycle. be removed and replaced with fresh fuel. fuel is sent to a recycling facility, where How Does the Fuel Cycle Work? Once removed from the reactor, the fuel the assemblies are broken down and the assemblies are moved to a storage pool to uranium pellets recycled. The pellets The uranium goes through a series of cool. are processed to remove the unwanted steps from being mined as a raw material byproducts of fi ssion. The remaining fuel through its life as a useful source of Once-Through or Recycled? are then made into new fuel pellets and beyond. First, uranium At this point, the fuel will continue through for another turn in the reactor. Only the ore is mined and milled. Then, the either the once-through cycle or the byproducts are sent to long-term storage. concentrations of desirable isotopes closed-loop cycle. In the , are increased in a series of steps called we currently use the once-through cycle, enrichment. meaning that the fuel is used once in the

Once-Through Cycle Storage of Used Nuclear Fuel 235 The U in UF6 is enriched via centrifuge/ diffusion/laser isotope enrichment. This enrichment process raises the concentration of 235U to 3-6% The natural form of uranium to make the fuel work in the nuclear The gaseous, enriched

in the earth’s crust is an oxide reactor. Uranium-235 is the only nuclide UF6 product is processed existing in nature that is fi ssile to form (U3O8), and most of the uranium in it is the isotope uranium-238 with thermal . (UO2), which is pressed (238U. In order for the uranium to be and sintered into a ceramic used in a reactor, it must be enriched pellet. The ceramic pellet in another isotope it contains, is designed to wear in 235 the reactor environment. uranium-235 ( U). The U308 is converted to uranium hexafl uoride

(UF6), a gas, before it can be enriched.

Fuel is loaded and milling of into the reactor. Each fuel to produce “yellow assembly spends 5 to 6 years cake” (U O ). 3 8 in the reactor before it must be removed and replaced with fresh fuel.

Cooled Closed-Loop Cycle fuel is Recycling of Used Nuclear Fuel reprocessed Used fuel leaves the reactor and into new fuel. goes to pool storage. Cooled fuel is conditioned and sent to long-term disposal. Nuclear Fuel Cycle

Why is the Closed Fuel Cycle Important?

Benefi ts of the Closed Fuel Cycle By recycling the used nuclear fuel, we make more effi cient use of the uranium resources. As a result: • the amount of used fuel to be stored is greatly reduced. • less uranium needs to be mined to produce the same amount of electricity. Source Energy Equivalents • more energy is extracted per unit mass of fuel, which means uranium 1 Uranium Fuel Pellet, without being reprocessed and recycled, resources are extended for many has about as much energy available in today’s light reactor as... years.

3 Barrels of Oil 2,000 lbs of 17,000 Cubic Feet of Uranium Fuel Pellet (42 gal. each) (actual size) Coal Natural Gas

Center for Nuclear Science and Technology Information 555 North Kensington Ave. La Grange Park, IL 60526-5592 708-352-6611 telephone [email protected] e-mail AN INSIDER’S VIEW 2017 www.NuclearConnect.org