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.
The transport of nuclear materials has an impressive record of safety and reliability spanning several decades. The procedures employed are designed to ensure the protection of the public, property and the environment.
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 (Hex) | |
| Enrichment | Fuel fabrication | Enriched Hex | |
| 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
Nuclear fuel cycle materials come in a variety of chemical and physical forms and the potential hazard they present differ widely. The underlying philosophy of the IAEA Transport Safety Regulations is that safety is vested principally in the package – the more hazardous the material, the tougher the package.
The Regulations specify five different primary packages; Excepted, Industrial, Type A, Type B, and Type C, and set the criteria for their design according to both the activity and physical form of the radioactive material they may contain. The Regulations also specify corresponding test procedures to demonstrate compliance with the required performance standards.
In France alone there are around 750 shipments each year of Type B packages, out of a total 15 million shipments classified as 'dangerous materials'.
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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 packages with integral shielding are used.
The IAEA Transport Safety Regulations require transport organisations to implement Radiation Programme Programmes to control radiation doses to workers and the public. Dose assessment is a key feature and the three categories into which workers are classified determine the degree of dose monitoring which is required.
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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. Regulatory performance tests include fire, impact, immersion, pressure, heat and cold.
There has never been an 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 INF3 Class ships for the bulk transport of radioactive material are designed to withstand a side-on collision with a large oil tanker. If the ship did sink, the casks would remain sound for many years and would be relatively easy to recover since instrumentation including location beacons would activate and monitor the casks.
View the safety features of the INF class ship (pdf format)
Sources:
BNFL, COGEMA, JNFL, SKB, ANSTO and WNA publications and papers.
