Nuclear Waste: Greatest environmental challenge facing society
Dr Tim Johnson discusses how we can tackle the nuclear waste epidemic.
A world full of waste
They say you can tell a lot about a society by what it throws away. Like me, I’m sure you can recall the excitement of archaeologists on numerous TV documentaries, sifting through the remains of a rubbish dump or ‘midden’ on the edge of some long-forgotten settlement in a muddy field somewhere. It seems these deposits of unwanted and discarded items rarely disappoint and often open an incredible window onto the daily lives of people long since lost in the mists of time.
Sometimes I wonder what archaeologists yet to come will make of what we throw away. Will they be filled with the same excitement? Will it reveal anything more than we just threw away a lot of stuff? One thing is for certain, they won’t have to look very hard to find enough rubbish to fill a lifetime of TV documentaries. But amongst all the regular detritus of modern life, surely they would conclude that one of the true pinnacles of waste from the last 100 years (and one of the most revealing) is that arising from the nuclear industry. For what waste it is.
A new generation of nuclear waste
Of all the waste ever created by mankind, this small subset of rubbish is by some distance the most hazardous, surpassing anything previous generations could ever have imagined. It required the most technologically advanced equipment to create it and it presents the greatest waste treatment challenge ever faced by mankind. Amongst these various wastes, the legacy of discarded nuclear materials from the early days of atomic energy development is especially chaotic and difficult.
And yet, we need to be careful in how we regard this waste. Nuclear power was pioneered by people who had lived through two world wars and were living in the shadow of a third and very final one at the height of the Cold War. If it is true that they didn’t seem to think much about how those in the future would deal with the waste they were creating, perhaps one should not judge too harshly the actions of those who believed ‘the future’ might be very short indeed. Plus, it cannot be denied the enormous amount of electrical power generated by these plants over the last 50 years has helped to restrict the rise in greenhouse gas generation, given nearly all the realistic alternatives at the time were fossil fuel-based. Furthermore, the new generation of nuclear power plants that owe their existence to these pioneers continue to make a critical contribution to the fight against global warming.
Sharing our knowledge
The reason this is all in my mind right now is I have just attended the World Nuclear Decommissioning & Waste Management Congress in London. This very interesting conference featured senior players from the nuclear industry from across the EU and beyond, who spelt out just how much has been achieved so far in the decommissioning and dismantling of nuclear power plants (NPPs) but also just how far there is to go.
At present there are 129 NPPs in operation across the EU with an average age 29 years. Of these it is estimated around 50 will be shut down by 2025. When coupled with the closure of the associated nuclear facilities that were built to support these NPPs during their operating life, this is a truly epic task. Thankfully, around 80% of all waste generated from the clean-up of these facilities is very ordinary non-hazardous waste and a majority of the metals waste can even be recycled. A further 15% or so is termed Low Level Waste (LLW), which is actually very simple to dispose of safely, and a further 1% is High Level Waste (HLW). Ironically, because HLW is so dangerous (and present in relatively small quantities) good treatment methods already exist for it. It is the remaining 4% of Intermediate Level Waste (ILW) that presents the biggest challenges to the industry at present.
Too abundant to be suitable for the treatment methods used for HLW without incurring huge expense and too hazardous to use the treatment methods applied to LLW, ILW falls into an awkward netherworld between the two. This is also where much of the most difficult (in a practical sense, as well as from a hazardous point of view) legacy wastes fall and consequently, the world will need to find solutions for the treatment of unprecedented amounts of a many disparate types of ILW over the coming decades.
A hunger for new treatment solutions
For many years the most common method for treating ILW has been to mix it with cement and store it in drums. However, whilst this is a very simple method it has clear drawbacks too. Firstly, it does nothing to actually treat the waste but merely encases it. Secondly, it leads to significant increases in volume compared with the original waste, which is a major consideration when everything needed for long term storage of nuclear waste is so costly. Thirdly, and most importantly, it is not a long term treatment option, as the radioactive material produces gases as it decays and this leads to expansion of the waste and ultimately to the splitting of the storage drums. As a result, it is clear from discussions with people across the nuclear industry all around the Globe over many years that there is a hunger for new treatment processes that can convert these difficult ILW materials into a final form that is truly stable over the genuinely long term. I am very happy to say, Tetronics’ DC plasma arc vitrification technology is one of these processes.
Tetronics worked with the UK nuclear industry for many years, using its existing technology to treat different batches of non-radioactive ‘surrogate wastes’, which are safe versions created to behave as similarly as possible to their original radioactive ILW equivalent. Good success was achieved with each of these wastes, in terms of both volume reduction and stability of the final vitrified material but the equipment used remained firmly outside the standards required for the nuclear industry. Tetronics, in collaboration with Costain, were awarded a substantial grant from the UK government via Innovate UK to upgrade our existing technology to nuclear standards. Over the course of two years, a new full-scale pilot plant was designed and built in Tetronics’ state of the art research and development facilities in Swindon and then tested with three key types of surrogate ILW: two sludges looking back to the early days of atomic energy development and one solid waste looking forward to the type of ILW likely to arise from the decommissioning of NPPs.
Plasma makes the future look brighter
The resounding success of this project has resulted in considerable interest and excitement from many stakeholders in the UK nuclear sector over its potential to offer a desperately-needed new option for the treatment of ILW. As with all things in the nuclear industry, things move slowly and cautiously, but the time is coming very soon now where the size of the ILW challenge will be so great that new solutions will be imperative. Here at Tetronics, we are all eager to make our contribution to one of the greatest environmental challenges facing society today and with our plasma vitrification technology, we believe that is exactly what we will be able to do.
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