Nuclear flask

Last updated
Wagon with transport cabin containing a nuclear waste flask, at Bristol Nuclear waste flask train at Bristol Temple Meads 02.jpg
Wagon with transport cabin containing a nuclear waste flask, at Bristol

A nuclear flask is a shipping container that is used to transport active nuclear materials between nuclear power station and spent fuel reprocessing facilities.

Contents

Each shipping container is designed to maintain its integrity under normal transportation conditions and during hypothetical accident conditions. They must protect their contents against damage from the outside world, such as impact or fire. They must also contain their contents from leakage, both for physical leakage and for radiological shielding.

A typical SNF shipping cask mounted on a railroad car Shipping Cask 01.jpg
A typical SNF shipping cask mounted on a railroad car

Spent nuclear fuel shipping casks are used to transport spent nuclear fuel [1] used in nuclear power plants and research reactors to disposal sites such as the nuclear reprocessing center at COGEMA La Hague site.

International

United Kingdom

Nuclear flask train near the Sellafield nuclear spent fuel reprocessing facility in the UK Railway Line - geograph.org.uk - 596522.jpg
Nuclear flask train near the Sellafield nuclear spent fuel reprocessing facility in the UK

Railway-carried flasks are used to transport spent fuel from nuclear power stations in the UK and the Sellafield spent nuclear fuel reprocessing facility. Each flask weighs more than 50 tonnes (110,000 lb), and transports usually not more than 2.5 tonnes (5,500 lb) of spent nuclear fuel. [2]

Over the past 35 years, British Nuclear Fuels plc (BNFL) and its subsidiary PNTL have conducted over 14,000 cask shipments of SNF worldwide, transporting more than 9,000 tonnes of SNF over 16 million miles via road, rail, and sea without a radiological release. BNFL designed, licensed, and currently own and operate a fleet of approximately 170 casks of the Excellox design.[ citation needed ] BNFL has maintained a fleet of transport casks to ship SNF for the United Kingdom, continental Europe, and Japan for reprocessing.

In the UK a series of public demonstrations were conducted [3] in which spent fuel flasks (loaded with steel bars) were subjected to simulated accident conditions. A randomly selected flask (never used for holding used fuel) from the production line was first dropped from a tower. The flask was dropped in such a way that the weakest part of it would hit the ground first. The lid of the flask was slightly damaged but very little material escaped from the flask. A little water escaped from the flask but it was thought that in a real accident that the escape of radioactivity associated with this water would not be a threat to humans or their environment.

For a second test the same flask was fitted with a new lid, filled again with steel bars and water before a train was driven into it at high speed. The flask survived with only cosmetic damage while the train was destroyed. Although referred to as a test, the actual stresses the flask underwent were well below what they are designed to withstand, as much of the energy from the collision was absorbed by the train and in moving the flask some distance. This flask is on display at the training centre at Heysham 1 Power Station.

Description

Introduced in the early 1960s, Magnox flasks consists of four layers; an internal skip containing the waste; guides and protectors surrounding the skip; all contained within the 370-millimetre-thick (15 in) steel main body of flask itself, with characteristic cooling fins; and (since the early 1990s) a transport cabin of panels which provide an external housing. Flasks for waste from the later advanced gas cooled reactor power stations are similar, but have thinner steel main walls at 90-millimetre-thick (3.5 in) thickness, to allow room for extensive internal lead shielding. The flask is protected by a bolt hasp which prevents the content from being accessed during transit. [4]

Transport

All the flasks are owned by the Nuclear Decommissioning Authority, the owners of Direct Rail Services. A train conveying flasks would be hauled by two locomotives, either Class 20 or Class 37, but Class 66 and Class 68 locomotives are increasingly being used; locomotives are used in pairs as a precaution in case one fails en route. Greenpeace protest that flasks in rail transit pose a hazard to passengers standing on platforms, although many tests performed by the Health and Safety Executive have proved that it is safe for passengers to stand on the platform while a flask passes by. [5]

Safety

1980s Old Dalby Test Track test against a flask in its most vulnerable position. Video footage is available on various hosting services. Old Dalby nuclear flask test-by-Brian-Robert-Marshall.jpg
1980s Old Dalby Test Track test against a flask in its most vulnerable position. Video footage is available on various hosting services.

The crashworthiness of the flask was demonstrated publicly when a British Rail Class 46 locomotive was forcibly driven into a derailed flask (containing water and steel rods in place of radioactive material) at 100 miles per hour (160 km/h); the flask sustaining minimal superficial damage without compromising its integrity, while both the flatbed wagon carrying it and the locomotive were more-or-less destroyed. [6] Additionally, flasks were heated to temperatures of over 800 °C (1,470 °F) to prove safety in a fire.[ citation needed ] However, critics [ who? ] consider the testing flawed for various reasons. The heat test is claimed to be considerably below that of theoretical worst-case fires in a tunnel,[ citation needed ] and the worst case impact today would have a closing speed of around 170 miles per hour (270 km/h).[ citation needed ] Nevertheless, there have been several accidents involving flasks, including derailments, collisions, and even a flask being dropped during transfer from train to road, with no leakage having occurred.[ citation needed ]

Problems have been found where flasks "sweat", when small amounts of radioactive material absorbed into paint migrate to the surface, causing contamination risks. Studies [7] [8] identified that 10–15% of flasks in the United Kingdom were suffering from this problem, but none exceeded the international recommended safety limits. Similar flasks in mainland Europe were found to marginally exceed the contamination limits during testing, and additional monitoring procedures were put into place. In order to reduce the risk, current UK flask wagons are fitted with a lockable cover to ensure any surface contamination remains within the container, and all containers are tested before shipment, with those exceeding the safety level being cleaned until they are within the limit.[ citation needed ] A report in 2001 identified potential risks, and actions to be taken to ensure safety. [9]

United States

A typical small SNF shipping cask being mounted on a truck Shipping Cask 02.jpg
A typical small SNF shipping cask being mounted on a truck
A nuclear waste Container from Nevada National Security Site is transported on public roads Nuclear waste container 2010 nevada.jpg
A nuclear waste Container from Nevada National Security Site is transported on public roads

In the United States, the acceptability of the design of each cask is judged against Title 10, Part 71, of the Code of Federal Regulations (other nations' shipping casks, possibly excluding Russia's, are designed and tested to similar standards (International Atomic Energy Agency "Regulations for the Safe Transport of Radioactive Material" No. TS-R-1)). The designs must demonstrate (possibly by computer modelling) protection against radiological release to the environment under all four of the following hypothetical accident conditions, designed to encompass 99% of all accidents:

In addition, between 1975 and 1977 Sandia National Laboratories conducted full-scale crash tests on spent nuclear fuel shipping casks. [10] [11] Although the casks were damaged, none would have leaked. [12]

Although the U.S. Department of Transportation (DOT) has the primary responsibility for regulating the safe transport of radioactive materials in the United States, the Nuclear Regulatory Commission (NRC) requires that licensees and carriers involved in spent fuel shipments:

Since 1965, approximately 3,000 shipments of spent nuclear fuel have been transported safely over the U.S.'s highways, waterways, and railroads.

Baltimore train tunnel fire

On July 18, 2001, a freight train carrying hazardous (non-nuclear) materials derailed and caught fire while passing through the Howard Street railroad tunnel in downtown Baltimore, Maryland, United States. [13] The fire burned for 3 days, with temperatures as high as 1000 °C (1800 °F). [14] Since the casks are designed for a 30-minute fire at 800 °C (1475 °F), several reports have been made regarding the inability of the casks to survive a fire similar to the Baltimore one. However, nuclear waste would never be transported together with hazardous (flammable or explosive) materials on the same train or track. [15]

State of Nevada

The State of Nevada, USA, released a report entitled, "Implications of the Baltimore Rail Tunnel Fire for Full-Scale Testing of Shipping Casks" on February 25, 2003. In the report, they said a hypothetical spent nuclear fuel accident based on the Baltimore fire: [14]

  • "Concluded steel-lead-steel cask would have failed after 6.3 hours; monolithic steel cask would have failed after 11-12.5 hours."
  • "Contaminated Area: 32 square miles (82 km2)"
  • "Latent cancer fatalities: 4,000-28,000 over 50 years (200-1,400 during first year)"
  • "Cleanup cost: $13.7 Billion (2001 Dollars)"

National Academy of Sciences

The National Academy of Sciences, at the request of the State of Nevada, produced a report on July 25, 2003. The report concluded that the following should be done: [16]

  • "Need to 3-D model (bolts, seals, etc) more than HI-STAR cask for extreme fire environments."
  • "For safety and risk analysis, casks should be physically tested to destruction."
  • "NRC should release all thermal calculations; Holtec is withholding allegedly proprietary information."

NRC

The U.S. Nuclear Regulatory Commission released a report in November 2006. It concluded: [13]

The results of this evaluation also strongly indicate that neither spent nuclear fuel (SNF) particles nor fission products would be released from a spent fuel transportation package carrying intact spent fuel involved in a severe tunnel fire such as the Baltimore tunnel fire. None of the three package designs analyzed for the Baltimore tunnel fire scenario (TN-68, HI-STAR 100, and NAC LWT) experienced internal temperatures that would result in rupture of the fuel cladding. Therefore, radioactive material (i.e., SNF particles or fission products) would be retained within the fuel rods.
There would be no release from the HI-STAR 100, because the inner welded canister remains leak tight. While a release is unlikely, the potential releases calculated for the TN-68 rail package and the NAC LWT truck package indicate that any release of CRUD from either package would be very small - less than an A2 quantity.

Canada

By comparison there has been limited spent nuclear fuel transport in Canada. Transportation casks have been designed for truck and rail transport and Canada's regulatory body, the Canadian Nuclear Safety Commission, granted approval for casks, which may be used for barge shipments as well. The commission's regulations prohibit the disclosure of location, routing and timing of shipments of nuclear materials, such as spent fuel. [17] [ specify ]

International maritime transport

Nuclear flasks containing spent nuclear fuel are sometimes transported by sea for the purposes of reprocessing or relocation to a storage facility. Vessels receiving these cargoes are variously classified INF-1, INF-2 or INF-3 by the International Maritime Organisation. The code was introduced as a voluntary system in 1993 and became mandatory in 2001. The "INF" acronym stands for "Irradiated Nuclear Fuel" though the classification also covers "plutonium and high-level waste" cargoes. In order to receive these classifications, vessels must meet a range of structural and safety standards. [18] Vessels used for the transportation of spent nuclear fuel are typically purpose built and are commonly referred to as Nuclear Fuel Carriers. The global fleet includes vessels under flags of the United Kingdom, Japan, Russian Federation, China and Sweden.

See also

Related Research Articles

<span class="mw-page-title-main">Radioactive waste</span> Unusable radioactive materials

Radioactive waste is a type of hazardous waste that contains radioactive material. Radioactive waste is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, nuclear decommissioning, rare-earth mining, and nuclear weapons reprocessing. The storage and disposal of radioactive waste is regulated by government agencies in order to protect human health and the environment.

<span class="mw-page-title-main">Yucca Mountain nuclear waste repository</span> Unused deep geological repository facility in Nevada, US

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 radioactive waste in the United States. The site is on federal land adjacent to the Nevada Test Site in Nye County, Nevada, about 80 mi (130 km) northwest of the Las Vegas Valley.

<span class="mw-page-title-main">Nuclear fuel cycle</span> Process of manufacturing and consuming nuclear fuel

The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. It consists of steps in the front end, which are the preparation of the fuel, steps in the service period in which the fuel is used during reactor operation, and steps in the back end, which are necessary to safely manage, contain, and either reprocess or dispose of spent nuclear fuel. If spent fuel is not reprocessed, the fuel cycle is referred to as an open fuel cycle ; if the spent fuel is reprocessed, it is referred to as a closed fuel cycle.

<span class="mw-page-title-main">Sellafield</span> Nuclear site in Cumbria, England

Sellafield, formerly known as Windscale, is a large multi-function nuclear site close to Seascale on the coast of Cumbria, England. As of August 2022, primary activities are nuclear waste processing and storage and nuclear decommissioning. Former activities included nuclear power generation from 1956 to 2003, and nuclear fuel reprocessing from 1952 to 2022.

<span class="mw-page-title-main">Dry cask storage</span> Radioactive waste storage method

Dry cask storage is a method of storing high-level radioactive waste, such as spent nuclear fuel that has already been cooled in a spent fuel pool for at least one year and often as much as ten years. Casks are typically steel cylinders that are either welded or bolted closed. The fuel rods inside are surrounded by inert gas. Ideally, the steel cylinder provides leak-tight containment of the spent fuel. Each cylinder is surrounded by additional steel, concrete, or other material to provide radiation shielding to workers and members of the public.

<span class="mw-page-title-main">Dounreay</span> Location of two former nuclear research establishments in northern Scotland

Dounreay is a small settlement and the site of two large nuclear establishments on the north coast of Caithness in the Highland area of Scotland. It is on the A836 road nine miles west of Thurso.

<span class="mw-page-title-main">Integral fast reactor</span> Nuclear reactor design

The integral fast reactor (IFR), originally the advancedliquid-metal reactor (ALMR), is a design for a nuclear reactor using fast neutrons and no neutron moderator. IFRs can breed more fuel and are distinguished by a nuclear fuel cycle that uses reprocessing via electrorefining at the reactor site.

<span class="mw-page-title-main">Dangerous goods</span> Solids, liquids, or gases harmful to people, other organisms, property or the environment

Dangerous goods (DG), are substances that are a risk to health, safety, property or the environment during transport. Certain dangerous goods that pose risks even when not being transported are known as hazardous materials. An example for dangerous goods is hazardous waste which is waste that has substantial or potential threats to public health or the environment.

<span class="mw-page-title-main">PUREX</span> Spent fuel reprocessing process for plutonium and uranium recovery

PUREX is a chemical method used to purify fuel for nuclear reactors or nuclear weapons. PUREX is the de facto standard aqueous nuclear reprocessing method for the recovery of uranium and plutonium from used nuclear fuel. It is based on liquid–liquid extraction ion-exchange.

<span class="mw-page-title-main">La Hague site</span> Nuclear fuel reprocessing plant at La Hague, France

The La Hague site is a nuclear fuel reprocessing plant at La Hague on the Cotentin Peninsula in northern France, with the Manche storage centre bordering on it. Operated by Orano, formerly AREVA, and prior to that COGEMA, La Hague has nearly half of the world's light water reactor spent nuclear fuel reprocessing capacity. It has been in operation since 1976, and has a capacity of about 1,700 tonnes per year. It extracts plutonium which is then recycled into MOX fuel at the Marcoule site.

<span class="mw-page-title-main">Spent fuel pool</span> Storage pools for spent nuclear fuel

Spent fuel pools (SFP) are storage pools for spent fuel from nuclear reactors. They are typically 40 or more feet (12 m) deep, with the bottom 14 feet equipped with storage racks designed to hold fuel assemblies removed from reactors. A reactor's local pool is specially designed for the reactor in which the fuel was used and is situated at the reactor site. Such pools are used for short-term cooling of the fuel rods. This allows short-lived isotopes to decay and thus reduces the ionizing radiation and decay heat emanating from the rods. The water cools the fuel and provides radiological protection from its radiation.

<span class="mw-page-title-main">High-level waste</span> Highly radioactive waste material

High-level waste (HLW) is a type of nuclear waste created by the reprocessing of spent nuclear fuel. It exists in two main forms:

DUCRETE is a high density concrete alternative investigated for use in construction of casks for storage of radioactive waste. It is a composite material containing depleted uranium dioxide aggregate instead of conventional gravel, with a Portland cement binder.

<span class="mw-page-title-main">Deep geological repository</span> Long term storage for radioactive and hazardous waste

A deep geological repository is a way of storing hazardous or radioactive waste within a stable geologic environment, typically 200–1,000 m below the surface of the earth. It entails a combination of waste form, waste package, engineered seals and geology that is suited to provide a high level of long-term isolation and containment without future maintenance. This is intended to prevent radioactive dangers. A number of mercury, cyanide and arsenic waste repositories are operating worldwide including Canada and Germany. Radioactive waste storage sites are under construction with the Onkalo in Finland being the most advanced.

<span class="mw-page-title-main">Spent nuclear fuel</span> Nuclear fuel thats been irradiated in a nuclear reactor

Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor. It is no longer useful in sustaining a nuclear reaction in an ordinary thermal reactor and, depending on its point along the nuclear fuel cycle, it will have different isotopic constituents than when it started.

<span class="mw-page-title-main">Gorleben</span> Municipality in Lower Saxony, Germany

Gorleben is a small municipality (Gemeinde) in the Gartow region of the Lüchow-Dannenberg district in the far north-east of Lower Saxony, Germany, a region also known as the Wendland.

The Rokkasho Nuclear Fuel Reprocessing Facility is a nuclear reprocessing plant with an annual capacity of 800 tons of uranium or 8 tons of plutonium. It is owned by Japan Nuclear Fuel Limited (JNFL) and is part of the Rokkasho complex located in the village of Rokkasho in northeast Aomori Prefecture, on the Pacific coast of the northernmost part of Japan's main island of Honshu.

<span class="mw-page-title-main">High-level radioactive waste management</span> Management and disposal of highly radioactive materials

High-level radioactive waste management addresses the handling of radioactive materials generated from nuclear power production and nuclear weapons manufacture. Radioactive waste contains both short-lived and long-lived radionuclides, as well as non-radioactive nuclides. In 2002, the United States stored approximately 47,000 tonnes of high-level radioactive waste.

<span class="mw-page-title-main">Nuclear power in Bangladesh</span>

Bangladesh first conceived building a nuclear power plant in 1961. The Bangladesh Atomic Energy Commission was established in 1973. The country currently operates a TRIGA research reactor at the Atomic Energy Research Establishment in Savar.

The Czech Radioactive Waste Repository Authority was established on 1 June 1997 as a state organisation established by the Ministry of Industry and Trade. In 2001, SÚRAO assumed the status of a government agency. The Authority is headed by its managing director, Dr. Jiří Slovák. The governing body of SÚRAO consists of its Board which is made up of representatives from the government, radioactive waste producers and the general public. The managing director and members of the Board of SÚRAO are directly appointed by the Minister of Industry and Trade.

References

  1. "Package Types used for Transporting Radioactive Materials" (PDF). World Nuclear Transport Institute . Retrieved 2019-07-12.
  2. Nuclear Waste Trains Investigative Committee: Scrutiny of the transportation of nuclear waste by train through London (2001), para 3.17 (p.11)
  3. When British Railways deliberately crashed a train
  4. "Flask Specifications" (PDF). Greenpeace. Retrieved 22 February 2014.
  5. "Question on Rail transport of radioactive materials - Hinkley Point". www.onr.org.uk. Retrieved 2017-05-11.
  6. 1 2 "Train test crash 1984 - nuclear flask test". September 8, 2008 via YouTube.
  7. Competent Authorities 1998 'Surface Contamination of Nuclear Spent Fuel Transports: Common report of the Competent Authorities of France, Germany, Switzerland and the UK' October 1998
  8. Transport Minister: Parliamentary Answer 10 June 1998 (see Hansard)
  9. Nuclear Waste Trains Investigative Committee: Scrutiny of the transportation of nuclear waste by train through London, October 2001
  10. "Sandia's Full-Scale Crash Tests, 1975-1977". Sandia. Archived from the original on 2011-03-23. Retrieved 2019-07-11.
  11. "Nuclear Waste Transportation - Crash Tests". www.nuclearfaq.ca.
  12. "Sandia National Laboratories - News Releases". www.sandia.gov.
  13. 1 2 Spent Fuel Transportation Package Response to the Baltimore Tunnel Fire Scenario (NUREG/CR-6886), November 2006, U.S. Nuclear Regulatory Commission, Retrieved 2007-6-8
  14. 1 2 Implications of the Baltimore Rail Tunnel Fire for Full-Scale Testing of Shipping Casks, February 25, 2003, State of Nevada, Retrieved 2007-6-8
  15. 49 CFR 174.81
  16. Baltimore Tunnel Fire, July 25, 2003, State of Nevada, Retrieved 2007-6-8
  17. Canadian Nuclear Safety Commission
  18. "The INF Code and purpose-built vessels" (PDF). World Nuclear Transport Institute. Retrieved 2020-12-20.

PD-icon.svg This article incorporates public domain material from Spent Fuel Transportation Package Response to the Baltimore Tunnel Fire Scenario (NUREG/CR-6886). United States Government.