Britain leads race to make nuclear waste safe

British scientists are designing a revolutionary cement that could withstand the impact of intense radiation for thousands of years. The project could prove vital in dealing with the challenges of Britain’s proposed expansion of its nuclear industry.

Radioactive waste

The government has announced plans to build several nuclear power stations over the next decade to provide power previously generated by coal, oil and gas stations. These are now likely to be phased out as part of the UK’s climate change commitments. However, a move towards more nuclear power will lead to the generation of extra nuclear waste.

It is estimated that about 300,000 cubic metres of highly radioactive intermediate waste – including old fuel rods and irradiated reactor components – will have accumulated in the UK by 2030 as a result of this expansion. At present, these swelling stocks are stored above ground, near reactors. However, their growing risk to the environment has forced the government to pledge to dispose of the material underground in a major depository.

However, before its location is agreed, planners will have to ensure that the waste will remain safe for at least 100,000 years, the time needed to allow their radioactivity to decay to a safe level. A key part of that effort will include the design of cement that can withstand intense radiation levels so that it can be used to cover nuclear waste once it has been placed in pits deep underground.

“To work out how materials – in this case cement – are going to behave for tens of thousands of years is quite mind-boggling, but that is exactly what we are now doing,” said the project’s leader, Claire Corkhill of Sheffield University. She is due to present details of the project at the annual meeting of the American Association for the Advancement of Science in Washington on Sunday.

The key to her team’s project is the UK’s Diamond Light Source, near Oxford. The facility accelerates electrons almost to the speed of light, so that they give off a light 10 billion times brighter than the sun. These bright beams are then directed off into laboratories, where they are used to study the properties of many different types of material: ice, viruses, cancer drugs – and cement.

“Many of the technological problems that affect society today are ones that take place at a very slow rate: melting ice in the Arctic or the decay of batteries,” said Professor Trevor Rayment, head of physical sciences at Diamond. “By using our machine to measure very accurately changes taking place in the materials we are studying, we can discover how those changes might affect them in hundreds or thousands of years.”

In the case of the cement being studied, Corkhill and her team have examined how it reacts with water over the long term. “That interaction between water and cement granules can go on for decades,” added Corkhill. “We are using Diamond to predict what cement will be like thousands of years in the future. No one has ever done that before.”

From this work, the group has designed a new form of cement which could then be used to cover nuclear waste inside underground stores. “That cement will be able to capture all of the radioactive elements that might be released from the waste over time,” added Corkhill. “Cements that are currently in use do not do this. Our cement will therefore make nuclear waste disposal even safer.”

Source: The Guardian

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