Spent fuel rods how long

In its absence, the DoE continues to pay fines to the various nuclear power plants around the country for not providing storage for their waste—and the spent nuclear fuel piles up. Spent fuel At present, the nation's nuclear facilities store spent fuel on-site in pools or dry casks.

The glowing nuclear fuel rods rest beneath 40 feet 12 meters of pale blue water laced with boron to block stray neutrons, the uncharged atomic particles that initiate a nuclear reaction and slowly decay for a decade or more.

New reactors will be built with at least 18 years worth of spent fuel storage capacity, according to Ed Cummins, vice president of regulatory affairs and standardization at nuclear reactor—maker Westinghouse Electric Co.

But nearly all of the nuclear power plants in the U. In the absence of a long-term solution such as burying the waste deep inside Yucca Mountain , the nuclear industry has turned to so-called dry cask storage.

The encased rods still manage to emit roughly one millirem of radiation per hour and heat the outside of the plus ton concrete casing to as much as 90 degrees Fahrenheit 32 degrees Celsius. Some 9, metric tons of spent fuel rods are already stored encased in some such casks—the bulk of them stored vertically in concrete casks but some placed horizontally into concrete bunkers. But some environmentalists and other nuclear power critics contend that such dry casks present a tempting target for terrorists and a disaster for the environment if ever breached.

In fact, the San Luis Obispo, Calif. The solution may be one or many interim storage sites, centralized depots where such dry casks could be stored until a permanent repository is opened.

Recycling In General Electric Co. The U. Today, France, Japan, Russia and the U. The problem is that this is also how governments separate out plutonium for use in nuclear weapons —potentially creating a tempting target for theft. This DoE program proposes restarting the recycling of nuclear fuel in the U.

At the same time, the Energy Department has enlisted 21 nations, from Australia to Kazakhstan, to safely develop such reprocessing technology, in many cases by shipping any future spent fuel to this proposed U. The National Research Council , the research arm of the U.

National Academy of Sciences, notes, however, that such reprocessing is impractical and expensive. Eleven years later, the Council further declared that research and development of such technology under the GNEP should be halted, because the money could be better spent on other areas of nuclear power research, such as next-generation reactors. Several hundred fuel assemblies make up the core of a reactor.

In the reactor core the U isotope fissions or splits, producing a lot of heat in a continuous process called a chain reaction. The process depends on the presence of a moderator such as water or graphite, and is fully controlled.

Some of the U in the reactor core is turned into plutonium and about half of this is also fissioned, providing about one-third of the reactor's energy output or more than half in CANDU reactors.

As in fossil-fuel burning electricity generating plants, the heat is used to produce steam to drive a turbine and an electric generator. Through this process, a MWe unit provides over 8 billion kilowatt hours 8 TWh of electricity in one year. To maintain efficient reactor performance, about one-third of the spent fuel is removed every year or 18 months, to be replaced with fresh fuel. Typically, some 44 million kilowatt-hours of electricity are produced from one tonne of natural uranium.

The production of this amount of electrical power from fossil fuels would require the burning of over 20, tonnes of coal or 8. An issue in operating reactors, and hence specifying the fuel for them, is fuel burn-up.

Fuel burn-up is measured in gigawatt-days thermal per tonne and its potential is proportional to the level of enrichment. The benefit of increased burn-up is that operation cycles can be longer — around 24 months — and the number of fuel assemblies discharged as used fuel can be reduced by one third.

With metal fuels, the atomic percent metric is used, and a new light water reactor metal fuel is targeting 21 atomic percent burn-up when it is deployed in s. As with coal-fired power stations, about two thirds of the heat produced is released, either to a large volume of water from the sea or large river, heating it a few degrees or to a relatively smaller volume of water in cooling towers, using evaporative cooling latent heat of vaporization.

With time, the concentration of fission fragments and heavy elements in the fuel will increase to the point where it is no longer practical to continue using it. So after months the used fuel is removed from the reactor. The amount of energy that is produced from a fuel assembly varies with the type of reactor and the policy of the reactor operator. Used fuel will typically have about 1. When removed from a reactor, the fuel will be emitting both radiation, principally from the fission fragments, and heat.

It is unloaded into a storage pond immediately adjacent to the reactor to allow the radiation levels to decrease. In the ponds, the water shields the radiation and absorbs the heat, which is removed by circulating the water through external heat exchangers.

Used fuel is held in such pools for several months and sometimes many years. It may then be transferred to naturally-ventilated dry storage, generally on site. Depending on the policies of particular countries, some used fuel may be transferred to central storage facilities. Whilst there is a clear incentive for interim storage, used fuel must ultimately either be reprocessed in order to recycle most of it, or prepared for permanent disposal.

The longer it is stored, the easier it is to handle, due to decay of radioactivity. Reprocessing separates uranium and plutonium from waste products and from the fuel assembly cladding by cutting up the fuel rods and dissolving them in acid to separate the various materials. It enables recycling of the uranium and plutonium into fresh fuel, and produces a significantly reduced amount of waste compared with treating all used fuel as waste. For more information, see page on Processing of Used Nuclear Fuel.

The uranium recovered from reprocessing, which typically contains a slightly higher concentration of U than occurs in nature, can be reused as fuel after conversion and enrichment. The plutonium can be directly made into mixed oxide MOX fuel, in which uranium and plutonium oxides are combined.

In reactors that use MOX fuel, plutonium substitutes for the U in normal uranium oxide fuel. According to Areva, about eight fuel assemblies reprocessed can yield one MOX fuel assembly, two-thirds of an enriched uranium fuel assembly, and about three tonnes of depleted uranium enrichment tails plus about kg of waste.

It avoids the need to purchase about 12 tonnes of natural uranium from a mine. However, in a fast neutron reactor it is fissionable, as well as more importantly giving rise to plutonium, and is therefore potentially valuable. Waste from the nuclear fuel cycle is categorized as high-, medium- or low-level based on the amount of radiation that it emits.

This waste comes from a number of sources and includes:. After reprocessing, the liquid high-level waste can be calcined heated strongly to produce a dry powder, which is incorporated into borosilicate Pyrex glass to immobilize it. This means that after spent nuclear fuel is taken out of a reactor and 30 years have passed, only half of these short-lived fission products are leftover.

Other elements produced have long half-lives and require isolation from the biosphere for hundreds of thousands of years. Fission products vary in radioactivity, but the ones that pose a larger risk to human health and the environment are long-lived fission products.

It is time to consider alternative options to address the nuclear waste challenge by working alongside communities for mutually beneficial solutions. Deep Isolation, Inc. What is spent nuclear fuel? Spent Fuel Pool. Used fuel is stored at more than 70 sites in 34 U. Used fuel is safely transported across the United States Over the last 55 years, more than 2, cask shipments of used fuel have been transported across the United States without any radiological releases to the environment or harm to the public.

Used nuclear fuel can be recycled to make new fuel and byproducts. Nuclear Energy Basics. What is a Nuclear Microreactor?