Chemical leak forces evacuation of 6,000 people

SALT LAKE CITY -- A railcar leaking acid forced the closure of major highways and the evacuation of more than 6,000 people.

By late Sunday, about 5,000 of the 13,000 gallons of industrial waste had leaked into the ground, but South Salt Lake fire officials were hoping to pump out the rest within a few hours and end the evacuation.

There were no injuries, but the area downwind of the leak was evacuated because of fumes from the spill, Fire Chief Steve Foote said. Evacuation centers were set up at church meeting houses, but most of those evacuated were staying with friends or relatives.

The waste, eventually found to be hydrochloric, hydrofluoric, nitric and sulfuric acids, was discovered leaking about 6 a.m. and the tanker wall was becoming soft, Foote said Sunday night.

Officials brought in 6,500-gallon portable tank. They first planned to lift a hazmat technician in a cherry picker to the top of the tanker so he could attach a hose to the rail tanker and pump the acids into the portable tanks.

However, they changed their plans after a specialist from Las Vegas arrived and the latest idea was to pierce the side of the tank with remotely operated equipment and pump it into the portable tanks. "Once we have one tank that's filled and holding, we could lift the evacuation order," Foote said. The cherry-picker plan was being kept in mind as a backup.

The fire officials and Gov. Jon Huntsman expressed displeasure at the difficulty in determining exactly what was in the tanker. "It's tough to know how to respond if you don't know the contents of the bulk container," Huntsman said.

The leak was discovered while crews were loading chemicals into the parked railcar at a Union Pacific rail yard. Officials said the tanker car was owned by Kennecott Utah Copper and was sublet to Phillips Environmental, which could not tell them immediately what all was in the waste.

"We're going to be looking into that," Foote said. "When we ask a direct question, we expect a direct answer."

Eventually, tests determined what acids were in the waste, and Phillips Environmental provided verbal confirmation. Documents finally were delivered late Sunday.

The spilled acid has not yet been neutralized. Foote said authorities wanted to concentrate on the tanker first.

Officers closed 600 West from 2100 South to 2700 South. Northbound I-15 from 4500 South to 2100 South, the westbound I-80 off ramp to southbound I-15, and the southbound collector on I-15 up to westbound I-80 also were closed.

The area south and east of the rail yard was evacuated. A little less than one square mile recommended for evacuation, with less than half of that a mandatory evacuation area.

The acids were not full strength but still are highly toxic and can cause severe burns if they come in direct contact with the skin or eyes, and the fumes can cause respiratory problems.

Transport of Raadioactive Materials

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Transport of Raadioactive Materials

Nuclear Issues Briefing Paper # 51

October 2003

About twenty million packages of all sizes containing radioactive materials are routinely transported worldwide annually on public roads, railways and ships.
These use robust and secure containers. At sea, they are generally carried in purpose-built ships.
Since 1971 there have been more than 20 000 shipments of spent fuel and high-level wastes (over 50 000 tonnes) over more than 30 million kilometres.
There has never been any accident in which a container with highly radioactive material has been breached, or has leaked.

About 20 million transports of radioactive material (which may be either a single package or a number of packages sent from one location to another at the same time) take place around the world each year. Radioactive material is not unique to the nuclear fuel cycle and most transports of such material are not fuel cycle related. Radioactive materials are used extensively in medicine, agriculture, research, manufacturing, non-destructive testing and minerals' exploration.

The regulatory control of shipments of radioactive material is independent of its intended application and the same safety procedures are employed, whatever the intended end-use.

Nuclear fuel cycle facilities are located in various parts of the world and materials of many kinds need to be transported between them. Many of these are similar to materials used in other industrial activities. However, the nuclear industry's fuel and waste materials are radioactive, and it is these 'nuclear materials' about which there is most public concern.

Nuclear materials have been transported since before the advent of nuclear power over forty years ago. The procedures employed are designed to ensure the protection of the public and the environment. For the generation of a given quantity of electricity, the amount of nuclear fuel required is very much smaller than the amount of all other fuel. Therefore, the conventional risks and environmental impacts associated with fuel transport are greatly reduced with nuclear power.

Materials being transported

Transport is an integral part of the nuclear fuel cycle. There are some 430 nuclear power reactors in operation in 32 countries but uranium mining is viable in only a few areas. Furthermore, in the course of over forty years of operation by the nuclear industry, a number of specialised facilities have been developed in various locations around the world to provide fuel cycle services. It is clear that there is a need to transport nuclear fuel cycle materials to and from these facilities. Indeed, most of the material used in nuclear fuel is transported several times during its 'life'. Transports are frequently international, and are often over large distances. Nuclear materials are generally transported by specialised transport companies.

The term 'transport' is used in this document only to refer to the movement of material between facilities, i.e. through areas outside such facilities. Most transports of nuclear fuel material occur between different stages of the cycle, but occasionally a material may be transported between similar facilities. When the stages are directly linked (such as mining and milling), it is sometimes advantageous to construct facilities for the different stages on the same site and no transport is then required.

With very few exceptions, nuclear fuel cycle materials are transported in solid form. The following table shows the principal nuclear material transport activities:

From:	To:	Material:	Notes:
Mining	Milling	Ore	Rare: usually on the same site
Milling	Conversion	Yellowcake
Conversion	Enrichment	Uranium hexafluoride (UF₆)
Enrichment	Fuel fabrication	Enriched UF₆
Fuel fabrication	Power generation	Fresh (unused) fuel
Power generation	Spent fuel storage	Spent fuel	After on-site storage
Spent fuel storage	Disposal*	Spent fuel
Spent fuel storage	Reprocessing	Spent fuel
Reprocessing	Conversion	Uranium oxide	Called reprocessed uranium
Reprocessing	Fuel fabrication	Plutonium oxide
Reprocessing	Disposal*	Fission products	Vitrified (incorporated into glass)
All facilities	Storage/disposal	Waste materials	Sometimes on the same site

* Not yet taking place

Although some waste disposal facilities are located adjacent to the facilities that they serve, utilising one disposal site to manage the wastes from several facilities usually reduces environmental impacts. When this is the case, transport of the wastes from the facilities to the disposal site will be required.

Packaging

The principal assurance of safety in the transport of nuclear materials is the design of the packaging, which must allow for foreseeable accidents. The consignor bears primary responsibility for this. Many different nuclear materials are transported and the degree of potential hazard from these materials varies considerably. Different packaging standards have been developed to recognise that increased potential hazard calls for increased protection.

'Type A' packages are designed to withstand minor accidents and are used for medium-activity materials such as medical or industrial radioisotopes. Ordinary industrial containers are used for low-activity material such as U₃O₈.

Packages for high-level waste (HLW) and spent fuel are robust and very secure containers are known as 'Type B' packages. They also maintain shielding from gamma and neutron radiation, even under extreme conditions. There are over 150 kinds of Type B packages, and the larger ones cost some US$1.6 million each.

Type B transport cask click to enlarge

In France alone, there are some 750 shipments each year of Type B packages, among 15 million shipments classified as 'dangerous materials', 300 000 of these being radioactive materials of some kind.

Smaller amounts of high-activity materials (including plutonium) transported by aircraft will be in 'Type C' packages, which give greater protection in all respects than Type B packages in accident scenarios.

Radiation protection

Since nuclear materials are radioactive, it is important to ensure that radiation exposure of both those involved in the transport of such materials and the general public along transport routes is limited. Packaging for nuclear materials includes, where appropriate, shielding to reduce potential radiation exposures. In the case of some materials, such as fresh uranium fuel assemblies, the radiation levels are negligible and no shielding is required. Other materials, such as spent fuel and high-level waste, are highly radioactive and purpose-designed containers with integral shielding are used. To limit the risk in handling of highly radioactive materials, dual-purpose containers (casks), which are appropriate for both storage and transport of spent nuclear fuel, are often used.

As with other hazardous materials being transported, packages of nuclear materials are labelled in accordance with the requirements of national and international regulations. These labels not only indicate that the material is radioactive, by including a radiation symbol, but also give an indication of the radiation field in the vicinity of the package.

Personnel directly involved in the transport of nuclear materials are trained to take appropriate precautions and to respond in case of an emergency.

Environmental protection

Packages used for the transport of nuclear materials are designed to retain their integrity during the various conditions that may be encountered while they are being transported and to ensure that an accident will not have any major consequences. Conditions which packages are tested to withstand include: fire, impact, wetting, pressure, heat and cold. Packages of radioactive material are checked prior to shipping and, when it is found to be necessary, cleaned to remove contamination.

Although not required by transport regulations, the nuclear industry chooses to undertake some shipments of nuclear material using dedicated, purpose-built transport vehicles or vessels.

Regulation of transport

Since 1961 the International Atomic Energy Agency (IAEA) has published advisory regulations for the safe transport of radioactive material. These regulations have come to be recognised throughout the world as the uniform basis for both national and international transport safety requirements in this area. Requirements based on the IAEA regulations have been adopted in about 60 countries, as well as by the International Civil Aviation Organisation (ICAO), the International Maritime Organisation (IMO), and regional transport organisations.

click to enlarge

The IAEA has regularly issued revisions to the transport regulations in order to keep them up to date. The main publication on which other IAEA transport regulations are based is Safety Series No. ST-l, Regulations for the Safe Transport of Radioactive Material.

The objective of the regulations is to protect people and the environment from the effects of radiation during the transport of radioactive material.

Protection is achieved by:

containment of radioactive contents;
control of external radiation levels;
prevention of criticality; and
prevention of damage caused by heat.

The fundamental principle applied to the transport of radioactive material is that the protection comes from the design of the package, regardless of how the material is transported.

Transport of uranium fuel assemblies

Uranium fuel assemblies are manufactured at fuel fabrication plants. The fuel assemblies are made up of ceramic pellets formed from pressed uranium oxide that has been sintered at a high temperature (over 1400^oC). The pellets are aligned within long, hollow, metal rods, which in turn are arranged in the fuel assemblies, ready for introduction into the reactor. Different types of reactors require different types of fuel assembly, so when the fuel assemblies are transported from the fuel fabrication facility (where they are manufactured) to the nuclear power reactor, the contents of the shipment will vary with the type of reactor receiving it.

In Western Europe, Asia and the US, the most common means of transporting uranium fuel assemblies is by truck. A typical truckload supplying a light water reactor contains 6 tonnes of fuel. In the countries of the former Soviet Union, rail transport is most often used. Intercontinental transports are mostly by sea, though occasionally transport is by air.

The annual operation of a 1000 MWe light water reactor requires an average fuel load of 27 tonnes of uranium dioxide, containing 24 tonnes of enriched uranium. The assemblies containing this are normally supplied in one consignment occupying 4 to 5 trucks.

The fuel assemblies are transported in packages specially constructed to protect the precision-made fuel assemblies from damage during transport. Uranium fuel assemblies have a low radioactivity level and radiation shielding is not necessary.

Fuel assemblies contain fissile material and in some circumstances fissile material can spontaneously become critical, i.e. start a self-sustaining, nuclear chain reaction, releasing energy. Criticality is prevented by the design of the package, the arrangement of the fuel assemblies within the package, limitations on the amount of material contained within the package, and on the number of packages carried in one shipment.

Transport of LLW and ILW

Low-level and intermediate-level wastes (LLW and ILW) are generated throughout the nuclear fuel cycle. The transport of these wastes is commonplace and they are safely transported to waste treatment facilities and storage sites.

Low-level radioactive wastes are a variety of materials that emit low levels of radiation, slightly above normal background levels. They often consist of solid materials, such as clothing, tools, or contaminated soil. Low-level waste is transported from its origin to waste treatment sites, or to an intermediate or final storage facility.

A variety of radionuclides give low-level waste its radioactive character. However, the radiation levels from these materials are very low and the packaging used for the transport of low-level waste does not require special shielding.

Low-level wastes are moved by road, rail, and internationally, by sea. However, most low-level waste is only transported within the country where it is produced.

Low-level wastes are transported in drums, often after being compacted in order to reduce the total volume of waste. The drums commonly used contain up to 200 litres of material. Typically, 36 standard, 200 litre drums go into a 6-metre transport container.

The composition of intermediate-level wastes is broad, but they require shielding. Much ILW comes from nuclear power plants and reprocessing facilities.

Intermediate-level wastes are taken from their source to an interim storage site, a final storage site (as in Sweden), or a waste treatment facility. They are transported by road, rail and sea.

The radioactivity level of intermediate-level waste is higher than low-level waste. The classification of radioactive wastes is decided for disposal purposes, not on transport grounds. The transport aspects of intermediate-level waste take into account any specific properties of the material, and provide shielding.

Classification of radioactive wastes

There are several systems of nomenclature in use, but the following is generally accepted:

Exempt waste - excluded from regulatory control because radiological hazards are negligible.
Low-level waste (LLW) - contains enough radioactive material to require action for the protection of people, but not so much that it requires shielding in handling or storage.
Intermediate-level waste (ILW) - requires shielding. If it has more than 4000 Bq/g of long-lived (over 30 year half-life) alpha emitters it is categorised as "long-lived" and requires more sophisticated handling and disposal.
High-level waste (HLW) - sufficiently radioactive to require both shielding and cooling, generates >2 kW/m³of heat and has a high level of long-lived alpha-emitting isotopes.

Transport of spent fuel

When spent fuel is unloaded from a nuclear power reactor, it contains: 96% uranium, 1% plutonium and 3% of fission products (from the nuclear reaction) and transuranics).

Spent fuel looks the same as fresh fuel but when the fuel assembly is removed from a reactor it will be emitting high levels of both radiation and heat. It is stored in water pools adjacent to the reactor to allow the initial heat and radiation levels to decrease. Typically, spent fuel is stored for at least five months before it can be transported, although it may be stored there long-term.

From the reactor site, spent fuel is transported by road, rail or sea to either an interim storage site or a reprocessing plant where it will be reprocessed.

Spent fuel assemblies are shipped in Type B casks. These casks are shielded with steel, or a combination of steel and lead, and can weigh up to 110 tonnes each when empty. A typical transport cask holds up to 6 tonnes of spent fuel.

Since 1971 there have been some 7000 shipments of spent fuel (over 35 000 tonnes) over more than 30 million kilometres with no property damage or personal injury, no breach of containment, and very low dose rate to the personnel involved (e.g. 0.33 mSv/yr per operator at La Hague).

In the USA alone, one percent of the 300 million packages of hazardous material shipped each year contain radioactive materials. Of this, about 250,000 contain radioactive wastes from US nuclear power plants, and 25 to 100 packages contain spent fuel. Most of these are in robust 125-tonne Type B casks carried by rail, each containing 20 tonnes of spent fuel.

Transport of plutonium

Plutonium is separated during the reprocessing of spent fuel. It is normally then made into mixed oxide (MOX) fuel.

Plutonium is transported, following reprocessing, as an oxide as this is its most stable form. Plutonium oxide is a solid, and normally transported as a powder in sealed packages. It is insoluble in water and only harmful to humans if it enters the lungs.

Plutonium oxide is transported in several different types of packages and each can contain several kilograms of material. Criticality is prevented by the design of the package, limitations on the amount of material contained within the package, and on the number of packages carried on a transport vessel.

Plutonium is subjected to physical protection controls and special physical protection measures apply to plutonium transports.

A typical transport consists of one truck carrying one protected shipping container. The container holds a number of packages with a total weight varying from 80 to 200 kg of plutonium oxide.

A sea shipment may consist of several containers, each of them holding between 80 to 200 kg of plutonium in sealed packages.

Transport of vitrified waste

The highly radioactive wastes (especially fission products) created in the nuclear reactor are segregated and recovered during the reprocessing operation. These wastes are incorporated in a glass matrix by a process known as 'vitrification', which stabilises the radioactive material.

The molten glass is then poured into a stainless steel canister where it cools and solidifies. A lid is welded into place to seal the canister. The canisters are then placed inside a Type B cask, similar to those used for the transport of spent fuel.

The quantity per shipment depends upon the capacity of the transport cask. Typically a vitrified waste transport cask contains up to 28 canisters of glass. The main characteristics of the canister are as follows:
- height (with lid) = 1.34 m
- outside diameter = 0.43 m
- weight (empty) = 90kg

So far, France is the only country that has carried out transports of vitrified waste. Since 1995, there have been five transports (two to Germany by rail, six to Japan by sea). This figure should increase in the years to come.

In the UK, storage is on the same site as reprocessing and vitrification.

Sea shipments of wastes

Some 300 sea voyages have been made carrying spent nuclear fuel or separated high-level waste over a distance of more than 8 million kilometres. The major company involved has transported over 4000 casks, each of about 100 tonnes, carrying 8000 tonnes of spent fuel or waste. A quarter of these have been through the Panama Canal.

In Sweden alone, more than 80 large transport casks are shipped annually from nuclear power stations (all on the coast) to a central interim waste storage facility called CLAB. Each 80 tonne cask has steel walls 30 cm thick and holds 17 BWR or 7 PWR fuel assemblies. The spent fuel is shipped to CLAB after it has been stored for about a year at the reactor, during which time heat and radioactivity diminish considerably. A purpose-built 2000 tonne ship is used for moving the spent fuel.

Shipments of spent fuel from Japan to Europe for reprocessing use 94-tonne Type B casks, each holding a number of fuel assemblies (e.g. 12 PWR assemblies, total 6 tonnes, with each cask 6.1 metres long, 2.5 metres diameter, and with 25 cm thick forged steel walls). More than 160 of these shipments have taken place since 1969, involving more than 4000 casks, and moving several thousand tonnes of highly radioactive spent fuel.

Return shipments from Europe to Japan since 1995 are of vitrified high-level wastes in stainless steel canisters. Up to 28 canisters (total 14 tonnes) are packed in each 98-tonne steel transport cask. Each is 6.6 metres long and 2.4 metres diameter, with a 25 cm thick wall.

Apart from Sweden's dedicated small ship, there are five purpose-built 5100 tonne ships, with elaborate safety provisions, which carry the casks. These have double hulls with impact-resistant structures between the hulls, together with duplication and separation of all essential systems to provide high reliability and also survivability in the event of an accident. Twin engines operate independently. Each ship can carry up to 17 spent fuel flasks or 14 waste transport flasks. The ships are owned by Pacific Nuclear Transport Ltd, a subsidiary of British Nuclear Fuels plc (BNFL).

Within Europe, spent fuel in casks has often been carried on normal ferries, e.g. across the English Channel.

Accident scenarios

There has never been any accident in which a Type B transport cask containing radioactive materials has been breached or has leaked.

For the radioactive material in a large Type B package in sea transit to become exposed, the ship's hold (inside double hulls) would need to rupture, the 25 cm thick steel cask would need to rupture, and the stainless steel flask or the fuel rods would need to be broken open. Either borosilicate glass (for reprocessed wastes) or ceramic fuel material would then be exposed, but in either case these materials are very insoluble.

The transport ships are designed to withstand a side-on collision with a large oil tanker. If the ship did sink, the casks will remain sound for many years and would be relatively easy to recover since instrumentation including location beacons would activate and monitor the casks.

Sources:
BNFL, Cogema, JNFL, SKB and ANSTO publications and papers.

For further information

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phone (03) 9629 7744
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