European trends in transport and disposal

Above: As new geological waste disposal facilities like Finland’s Onkalo come on stream, more nuclear material transports will be needed

The term “radioactive waste” covers a huge range of materials and activity levels from very lightly contaminated worker PPE through to spent fuel and vitrified high level waste. Consequently, there is an equally wide range of packaging and transport issues and also disposal issues. Taking all these variables together makes for a complex picture, however there are some clear current trends in radioactive waste management across Europe (and indeed beyond).

Waste management hierarchy

There is an increasing drive to manage, rather than just dispose of waste. This starts with designing facilities to minimise waste production. However, from a transport perspective, the main areas of interest are reuse and recycling. Historically, waste has been conditioned into a stable form for disposal (for example by cement grouting) before transport. Recycling opportunities, such as metal smelting facilities in Sweden, means that waste is now routinely shipped in a “raw” state for further treatment. Such raw waste may be a solid which is not fully immobilised within the package, making it difficult to prove there is no movement and hence change in package dose rate in transport or it may be in a less stable chemical form pending treatment. Both of these issues pose transport challenges in order to demonstrate full regulatory compliance.

Timescales

The most active materials will need to be disposed of, sometimes in surface or near-surface facilities, but often in deep geological disposal sites. While some countries, for example Finland, are well advanced towards having facilities to dispose of their high level waste, many, including the UK, are still at an early stage of developing the deep geological disposal facilities needed for the most active wastes. This means that while waste may be being packaged currently, it may not be finally disposed of for decades. This brings challenges for storage and transport packages, particularly in areas such as how to ensure the package meets future transport regulations and has not deteriorated while in storage.

Large volume decommissioning waste

As nuclear reactors around Europe are decommissioned, there will be significant volumes of radioactive waste generated. Analysis of some of this waste has shown that whilst it meets the Low Specific Activity definition for an IP-2 type package, the radiation dose rates may be too high. It therefore does not present a dispersal hazard but would still require shielding. Currently this would require a type B package which is likely to require a greater degree of size reduction of the waste and an associated dose uptake to operators. A new package type is therefore being proposed to meet the type B shielding and accident conditions, but lesser containment requirements commensurate with the risk. This would allow cost- effective transport of larger quantities of this material for disposal. Other approaches are to maximise the size of the type B package to reduce the number of transport operations required, as well as requiring less size reduction of the waste.

Characterisation

In many cases, the exact form and characteristics of the waste, including its radioactive inventory are not well known and difficult to measure. This is particularly true for non-homogeneous waste. Solving this challenge will require innovative approaches to demonstrating the material is safe to transport without limiting the quantity of waste which can be packaged, which would result in additional handling, transport and disposal operations. This may involve novel approaches to characterisation or to the safety assessment of the package shielding, criticality or release performance.

Addressing the long-term legacy

Decommissioning of nuclear power stations and the opening of geological disposal facilities around Europe in the coming decades will increase the amount of radioactive waste that has to be transported. The varied nature of the waste poses new and challenging problems for the transport industry to address. Patram 22 will provide an opportunity for experts to share the latest developments in this vital area of the industry which is required to address the long-term legacy of radioactive waste.