Dry cask storage is a method of storing high-level

radioactive waste Radioactive waste is a type of hazardous waste that contains radioactive material. It is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, nuclear decommissioning, rare-earth mining, and nuclear ...

, such as

spent nuclear fuel Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor (usually at a nuclear power plant). It is no longer useful in sustaining a nuclear reaction in an ordinary thermal reactor and ...

that has already been cooled in a

spent fuel pool Spent fuel pools (SFP) are storage pools (or "ponds" in the United Kingdom) for spent fuel from nuclear reactors. They are typically 40 or more feet (12 m) deep, with the bottom 14 feet (4.3 m) equipped with storage racks designed to hold ...

for at least one year and often as much as ten years.

Cask A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids ...

s are typically

steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

cylinders that are either welded or bolted closed. The fuel rods inside are surrounded by

inert gas An inert gas is a gas that does not readily undergo chemical reactions with other chemical substances and therefore does not readily form chemical compounds. Though inert gases have a variety of applications, they are generally used to prevent u ...

. Ideally, the steel cylinder provides leak-tight containment of the spent fuel. Each cylinder is surrounded by additional steel,

concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...

, or other material to provide radiation shielding to workers and members of the public. There are various dry storage cask system designs. With some designs, the steel cylinders containing the fuel are placed vertically in a concrete vault; other designs orient the cylinders horizontally. The concrete vaults provide the radiation shielding. Other cask designs orient the steel cylinder vertically on a concrete pad at a dry cask storage site and use both metal and concrete outer cylinders for radiation shielding. Until 2024/25, there was no long term permanent storage facility anywhere in the world, and most countries still don't have a facility; dry cask storage is designed as an interim safer solution than spent fuel pool storage. Some of the cask designs can be used for both storage and transportation. Three companies – Holtec International, NAC International and Areva-Transnuclear NUHOMS – are marketing Independent Spent Fuel Storage Installations (ISFSI) based upon an unshielded multi-purpose canister which is transported and stored in on-site vertical or horizontal shielded storage modules constructed of steel and concrete.

Usage

During the 2000s, dry cask storage was used in the United States, Canada, Germany, Switzerland, Spain, Belgium, the United Kingdom, Japan, Armenia, Argentina, Bulgaria, Czech Republic, Hungary, South Korea, Romania, Slovakia, Ukraine and Lithuania. A similar system is also being implemented in Russia. However, it is based on 'storage compartments' in a single structure, rather than individual casks. In 2017, France's

Areva Areva S.A. was a French multinational group specializing in nuclear power, active between 2001 and 2018. It was headquartered in Courbevoie, France. Before its 2016 corporate restructuring, Areva was majority-owned by the French state through t ...

introduced the NUHOMS Matrix advanced used nuclear fuel storage overpack, a high-density system for storing multiple spent fuel rods in canisters.

United States

In the late 1970s and early 1980s, the need for alternative storage in the United States began to grow when cooling pools at many nuclear reactors began to fill with stored spent fuel. As there was not a national nuclear storage facility in operation at the time, utilities began looking at options for storing spent fuel. Dry cask storage was determined to be a practical option for storage of spent fuel and preferable to leaving large concentrations of spent fuel in cooling tanks. The first dry storage installation in the US was licensed by the

Nuclear Regulatory Commission The United States Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the ...

(NRC) in 1986 at the Surry Nuclear Power Plant in

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

. Yucca Mountain, in Nevada, was expected to open in 2017. However, on March 5, 2009, Energy Secretary

Steven Chu Steven ChuYucca Mountain site was no longer considered an option for storing reactor waste. In 2012, The NRC estimated that many of the nuclear power plants in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

would be out of room in their spent fuel pools by 2015, necessitating alternate storage. The 2008 NRC guidelines call for fuels to have spent at least five years in a storage pool before being moved to dry casks. The industry norm is about 10 years. The NRC describes the dry casks used in the US as "designed to resist floods, tornadoes, projectiles, temperature extremes, and other unusual scenarios." Spent fuel is currently stored in dry cask systems at a growing number of power plant sites, and at an interim facility located at the

Idaho National Laboratory Idaho National Laboratory (INL) is one of the national laboratories of the United States Department of Energy and is managed by the Battelle Energy Alliance. Historically, the lab has been involved with nuclear research, although the labora ...

near

Idaho Falls, Idaho Idaho Falls is the fourth most populous city in Idaho and the county seat of Bonneville County. It is the state's most populous city outside the Boise metropolitan area. As of the 2020 census, the population of Idaho Falls was 64,818.2020 Cen ...

. As of the end of 2009, 13,856 metric tons of commercial spent fuel—or about 22%—were stored in dry casks. In the 1990s, the NRC had to “take repeated actions to address defective welds on dry casks that led to cracks and quality assurance problems; helium had leaked into some casks, increasing temperatures and causing accelerated fuel corrosion”. With the zeroing of the federal budget for the

Yucca Mountain nuclear waste repository The Yucca Mountain Nuclear Waste Repository, as designated by the Nuclear Waste Policy Act amendments of 1987, is a proposed deep geological repository storage facility within Yucca Mountain for spent nuclear fuel and other high-level radioact ...

in Nevada in 2011, more

nuclear waste Radioactive waste is a type of hazardous waste that contains radioactive material. It is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, nuclear decommissioning, rare-earth mining, and nuclear ...

began being stored in dry casks. Many of these casks are stored in coastal or lakeside regions where a salt air environment exists, and the Massachusetts Institute of Technology posited that corrosion in these environments could occur in 30 years or less, while the NRC was studying whether the casks could be used for 100 years as some hoped. According to the NRC's website in 2023, spent fuel placed in dry cask storage from the Diablo Canyon power plant in California shows no sign of corrosion after more than a decade of storage and appears to be capable of lasting for 1800 years before succumbing to corrosion. Company videos, covering the processes and remote handling, from the initial fuel loading to the removal and eventual dry-cask storage, are viewable on various video hosting domains.

Canada

In Canada, above-ground dry storage has been used.

Ontario Power Generation Ontario Power Generation Inc. (OPG) is a Crown corporations of Canada, Crown corporation and "government business enterprise" that is responsible for approximately half of the electricity generation in the province of Ontario, Canada. It is w ...

is in the process of constructing a Dry Storage Cask storage facility on its

Darlington Darlington is a market town in the Borough of Darlington, County Durham, England. It lies on the River Skerne, west of Middlesbrough and south of Durham. Darlington had a population of 107,800 at the 2021 Census, making it a "large town" ...

site, which will be similar in many respects to existing facilities at Pickering Nuclear Generating Station and

Bruce Nuclear Generating Station Bruce Nuclear Generating Station is a nuclear power station located on the eastern shore of Lake Huron in Ontario, Canada. It occupies 932 ha (2300 acres) of land. The facility derives its name from Bruce Township, Ontario, Bruce Township, the ...

. NB Power's Point Lepreau Nuclear Generating Station and Hydro-Québec's Gentilly Nuclear Generating Station also both operate dry storage facilities.

Germany

A centralized storage facility using dry casks is located at Ahaus. As of 2011, it housed 311 casks: 305 from the Thorium High Temperature Reactor, 3 from the Neckarwestheim Nuclear Power Plant, and 3 from the Gundremmingen Nuclear Power Plant. The transport from Gundremmingen to the Ahaus site met with considerable public protest and the power plant operators and the government later agreed to locate such casks at the powerplants. ''CASTOR'' () is a trademarked brand of dry casks used to store

(a type of

). CASTORs are manufactured by Gesellschaft für Nuklear-Service (GNS), a German provider of nuclear services. ''CONSTOR'' is a cask used for transport and long-term storage of spent fuel and high-level waste also manufactured by GNS. Its inner and outer layers are steel, enclosing a layer of

. A 9-meter

drop test A drop test is a method of testing the in-flight characteristics of prototype or experimental aircraft, experimental aircraft and spacecraft by raising the test vehicle to a specific altitude and then releasing it. Test flights involving powered ...

of the V/TC model was conducted in 2004; the results conformed to expectations.

Bulgaria

In 2008, officials at the Kozloduy Nuclear Power Plant announced their intention to use 34 CONSTOR casks at the Kozloduy NPP site before the end of 2010.

Lithuania

Spent fuel from the now-closed

Ignalina Nuclear Power Plant The Ignalina Nuclear Power Plant () is a Nuclear decommissioning, decommissioned two-unit RBMK-1500 nuclear power plant, nuclear power station in Visaginas Municipality, Lithuania. It was named after the nearby city of Ignalina. Due to the plant' ...

was placed in CASTOR and CONSTOR storage casks during the 2000s.

Russia

The Russian dry storage facility for spent nuclear fuel, the HOT-2 at Mining Chemical Combine in

Zheleznogorsk, Krasnoyarsk Krai Zheleznogorsk (), formerly known as Krasnoyarsk-26 (), is a closed town in Krasnoyarsk Krai, Russia, with a developed nuclear industry. The town has a population of History The town was established in 1950 for the production of Weapons-grade_nuc ...

in Siberia, is not a 'cask' facility per se, as it is designed to accommodate the spent nuclear fuel (both

VVER The water-water energetic reactor (WWER), or VVER (from ) is a series of pressurized water reactor designs originally developed in the Soviet Union, and now Russia, by OKB Gidropress. The idea of such a reactor was proposed at the Kurchatov Instit ...

and

RBMK The RBMK (, РБМК; ''reaktor bolshoy moshchnosti kanalnyy'', "high-power channel-type reactor") is a class of graphite moderated reactor, graphite-moderated nuclear reactor, nuclear power reactor designed and built by the Soviet Union. It is so ...

) in a series of compartments. The structure of the facility is made up of monolithic reinforced concrete walls and top and bottom slabs, with the actual storage compartments formed by reinforced concrete partitions. The fuel is to be cooled by natural convection of air. The design capacity of the facility is 37,785 tonnes of uranium. It is now under construction and in the process of commissioning.

Ukraine

In Ukraine, a dry storage facility has been accepting spent fuel from the six-unit Zaporizhzhia Nuclear Power Plant ( VVER-1000 reactors) since 2001, making it the longest-serving such facility in the former Soviet Union. The system was designed by the now-defunct Duke Engineering of the United States, with the storage casks being manufactured locally. Another project is underway with Holtec International (of the USA) to build a dry spent fuel storage facility at the 1986 accident Chernobyl Nuclear Power Plant ( RBMK-1000 reactors). The project was initially started with Framatome (currently

AREVA Areva S.A. was a French multinational group specializing in nuclear power, active between 2001 and 2018. It was headquartered in Courbevoie, France. Before its 2016 corporate restructuring, Areva was majority-owned by the French state through t ...

) of France, later suspended and terminated due to technical difficulties. Holtec was originally hired as a subcontractor to dehydrate the spent fuel, eventually taking over the entire project.

References

External links

NRC: Dry Cask StorageUnited States Nuclear Waste Technical Review Board, ''Evaluation of the Technical Basis for Extended Dry Storage and Transportation of Used Nuclear Fuel ''2010Locations of Independent Spent Fuel Storage Installations
{{DEFAULTSORT:Dry Cask Storage Radioactive waste Waste treatment technology Nuclear power plant components