United Kingdom nuclear spent fuel reprocessing facility in the UK test against a flask in its most vulnerable position. Video footage is available on various hosting services. showing minor superficial damage. 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 , and transports usually no more than of
spent nuclear fuel. 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. 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 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 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 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.
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.
Safety 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 ; 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. 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. A report in 2001 identified potential risks, and actions to be taken to ensure safety.
United States 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: • A free fall onto an unyielding surface • A puncture test allowing the container to free-fall onto a steel rod • A 30-minute, all-engulfing fire at • An 8-hour immersion under of water • Further, an undamaged package must be subjected to a 1-hour immersion under of water. In addition, between 1975 and 1977
Sandia National Laboratories conducted full-scale crash tests on spent nuclear fuel shipping casks. Although the casks were damaged, none would have leaked. 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: • Follow only approved routes; • Provide armed escorts for heavily populated areas; • Use immobilization devices; • Provide monitoring and redundant communications; • Coordinate with law enforcement agencies before shipments; and • Notify in advance the NRC and States through which the shipments will pass. 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. The fire burned for 3 days, with temperatures as high as . Since the casks are designed for a 30-minute fire at 800 °C, 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.
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: • "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: ==International maritime transport==