Among the challenges facing our society today is the safe management and permanent disposal of the country’s radioactive waste. It is not a new challenge – after all, the world’s first commercial nuclear power station was opened at Calder Hall in Cumbria in 1956.
In the early days, not much attention was paid to the fate of the waste produced by the new technologies. As the beneficiaries of nuclear technologies, we do have a moral obligation to deal with the waste and not leave it to people many generations in the future.
Radioactive waste arises from a variety of sources. Over 90% of it is low-level waste (LLW), arising from the everyday operation of nuclear facilities such as protective clothing, water and air filters, redundant equipment, etc. Activity will decay to background levels in anything from a few days to a hundred years or more. So, this can be stored relatively simply in surface disposal facilities like the one near Drigg in Cumbria.
The remainder, ‘higher activity’ waste (HAW) covers the range of: intermediate level waste (ILW) and high level waste (HLW). Much of the intermediate waste inventory comes from decommissioning of nuclear facilities and includes contaminated components of buildings and machinery. Some wastes are in the form of liquids and sludges which are turned into solids to make them easier to manage and treat. A very small proportion of waste generates heat by virtue of its radioactivity – this is referred to as high level waste as the heat component has to be taken into consideration when designing storage and disposal strategies.
We often think of radioactive waste as spent fuel and some other highly radioactive substances. However, these are not actually classified as waste, but referred to as nuclear materials, as it is possible that new uses may be found for them. Certainly, there is a great deal of interest in the engineering and scientific community in making use of the large amounts of energy still contained in them. However, they could, in the future, be reclassified as waste and for this reason RWM includes them in its long term disposal plans as a contingency measure.
The total volume of radioactive waste accumulated over more than 60 years is about the same as the toxic waste produced every year. And unlike toxic waste, we know that the level of radioactivity will decrease at a specified rate over time. The science is incontrovertible. While that process is taking place we have to ensure that the waste does not harm the environment, including humans.
UK Government policy is that higher activity waste should be disposed of permanently in a geological disposal facility (GDF) deep underground. This approach is globally accepted as best practice and is being followed by nuclear countries around the world. Through the International Atomic Energy Agency (IAEA) and other bodies, we share knowledge with similar organisations around the world in developing these facilities.
A GDF is a highly-engineered subterranean facility that uses both engineering and geology to ensure that the waste is isolated from the surface environment and contained until it is no longer dangerous.
A GDF is a long term project, taking decades to build and many more decades to place the waste safely underground. In the meantime, waste is stored securely at a number of sites around the country, most of it near the power station where it originated.
Because higher activity waste is destined for a GDF –and RWM is designated by Government as the developer of that facility – we work with waste producers to ensure that it is stored in robust packaging that is compatible with final disposal. These highly-engineered packages can remain in these interim stores for up to one hundred years before emplacement in the GDF.
Safe management and permanent disposal of radioactive waste are the two parts of RWM’s mission – in reality they are two aspects of the same process, summed up by our vision to provide “a safer future by managing radioactive waste effectively, to protect people and the environment”.
Ann McCall FIMechE is Waste Management Director at Radioactive Waste Management Ltd.
The views of the writer do not necessarily represent the views of the Institution.