Watching the waste line

The UK’s nuclear industry has teamed up with a number of universities to form a national network to investigate new storage and testing technologies for the safer disposal of radioactive waste.

Researchers plan to investigate the development of alternative storage materials, improved testing facilities and technologies for the remote monitoring of underground repositories.

They also hope to improve the public’s perception of the industry’s efforts to clean up nuclear waste.

There is now a pressing need for new waste handling technologies following the discovery that much of the UK’s legacy waste is not held in adequate storage containers.

At Harwell in Oxfordshire, the UK Atomic Energy Authority has embarked on a multi-million pound 20-year programme to retrieve intermediate level waste fromthousands of steel cans which have corroded and collapsed since they were deposited in the 1950s.

On the same site there are 2,000 sea drums that must also be repackaged.Meanwhile it was decided earlier last year that the Thorp waste reprocessing plant atSellafield should close by 2010. The Nuclear Installations Inspectorate (NII) has ordered that a number of storage tanks must be emptied as soon as possible, while it has also been revealed that part of the waste processing equipment no longer works properly.

The network has almost 300 members, including Imperial College, Sheffield, Cambridge and Leeds universities, plus BNFL, Nirex, the NII, AEA Technology and a range of other companies involved in the industry.

The research, to be funded over the next three years by the EPSRC, will be vital if the option of nuclear power is to be kept open, according to Prof Bill Lee, director of Sheffield University’s Immobilisation Science laboratory.

‘If there is going to be the potential for nuclear power in the future, people have to be confident that we can deal with the waste,’ he said.

Novel glass, ceramic and cement materials will be investigated for their suitability for the long-term storage of the industry’s legacy waste, or waste that is difficult to deal with using existing facilities. These are likely to include materials such as geopolymers, hydrothermal cements, and phosphate-based glasses.

Researchers will also investigate improved accelerated testing facilities, which use techniques such as raised heat and pressure to speed up the ageing process and assess the likely durability of storage systems over thousands of years.

‘We are looking at accelerated testing to tell us the durability of something over 100,000 years, which includes several ice ages. These are the things we have to do because these materials are going to be sitting around for a long time,’ said Lee.

Inevitably, underground water will eventually find its way into repositories, so researchers will be using the testing techniques to study the effect of this water – which will already have travelled through layers such as granite – on the material.

‘Glass is encased in metal, so we will be looking at the effect of the metal corrosion and water mixture [on the glass],’ said Lee.

Also to be debated will be how best to deal with the radioactive waste from new reactors, including the pebble-bed modular reactor and AP1000, and the next generation reactors – the so-called Generation IV – likely to be installed by around 2030.

Finally, remote-monitoring systems capable of sensing changes in the radioactive waste underground and sending information back to the surface without using wires, which could cause contamination, will also be considered.

‘How are we going to monitor repositories? We have to assume the loss of any sort of civil structure over that period, and decide over what timescale it is actually worth monitoring, given that radiation levels will reduce over time,’ said Lee.