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Monday, 21 September 2015

Location, Location, Location

Nuclear power and nuclear waste are sensitive public issues. Whilst the Finns are already building a geological disposal facility in Onkalo, in the UK we still haven’t decided what to do with our waste. Before the site can be chosen and built, a formal, scientific safety case must be completed, evidencing the likelihood that the containment facility will remain intact on a timescale of at least thousands of years. Learning from the “Yucca Mountain controversy”, where the state of Nevada legally opposed the construction of an American disposal facility on the grounds that they didn’t want to be lumbered with the country’s nuclear waste without consent, the UK government are waiting for volunteer communities to emerge before they can even start studying local geology in detail. Huge climate and geological changes, including at least one ice age, are predicted, which would totally change the landscape, the exact impacts of which could vary widely depending on where nuclear waste goes.

Low-level waste storage pit at the Nevada National Security Site
Nuclear waste is divided into three categories: High, Intermediate and Low Level Waste. High Level Waste is what's left after spent fuel is recycled to extract as many reusable uranium and plutonium fuel isotopes as possible. This waste is usually vitrified: transformed into a glass by fusing with borosilicates at high temperature. Intermediate and Low Level Wastes are non-fuel items (such as containers) that have been or may be been contaminated during normal operation of the nuclear power plant, and comprise the bulk of the waste. Image credit: Nevada Test Site Guide (public domain)

Nuclear waste is building up and is going to need somewhere to go – soon. In the UK, we still haven’t decided where this will be – but we're working on it. Whilst nuclear power does not comprise a vast percentage of the energy industry, the high risk factors associated with nuclear waste mean that even a small amount has be to be processed with caution. At the moment, most of what we have in the UK is sitting at the Sellafield site in Cumbria, waiting. Most of this, the High Level Waste that comes from the very core of the nuclear reactor, is underwater. Water acts as an effective radiation shield and conducts away the excess heat from the waste.

The bulk consensus for long-term nuclear waste storage is geological disposal. Of the 39 countries producing significant radioactive waste, 25, including the UK, have developed a future plan – and ubiquitously opted for geological storage. This requires engineering a no-maintenance, multi-barrier containment facility 200-1000 m beneath the ground, where waste can rest for 100,000 years - the estimated lifetime of some of the radioactive isotopes. The alternative options considered were deep sea disposal or ejection into outer space[2].

Whilst radioactive materials are originally dug up from the earth, the sheer concentration and volume of radioactive waste incurs huge responsibilities for ensuring no leakage nor environmental damage can occur. Before the site can be chosen and built, a formal, scientific safety case must be completed, evidencing the likelihood that the containment facility will remain intact on a timescale of at least thousands of years. Nuclear waste cannot simply be buried.

At the moment, we don't know where to put our nuclear waste - and deciding is not a fast process. We not only need to know about the environmental factors that might impact the security of long term storage, but also the distinct geology of the selected sites, such as exploitable groundwater supply, potential construction engineering challenges, and rock permeability to liquids and gases. Sites with potentially useful resources would be deemed unsuitable, due to the risk of future generations intruding upon the disposal facility whilst mining for materials, as would any sites that would inconvenience current human activities such as sport or industry, or compromise the natural landscape (e.g. national parks). Sites would need a low probability of earthquakes, volcanoes or coastal erosion – of which only the latter is a major concern in the UK. More importantly, a site needs to be suggested – and then the suitability tests can begin.

Although the UK is not ready to start building a geological disposal facility, the Finns are already building one in Onkalo: a 5km long, 400m deep tunnel that starts at the doorstep of the Olkiluoto power stations and zigzags down to enough stores to contain 100 years' worth of nuclear waste. Planned to open in 2020, this is not the first disposal facility. The first pilot deep geological nuclear waste storage repository, WIPP (the Waste Isolation Pilot Plant), is at the site of a power plant in New Mexico in 1999, and the second was going to be Yucca Mountain, on the Nevada-California boundary, 100 miles north west of Las Vegas. But Yucca mountain tells a different story - the problem of locating sites based not only upon the science, but also upon the willingness of local or semi-local communities.

Yucca Mountain was approved for further study in 1985 amongst three other sites, but investigation for nuclear waste containment had already begun in 1978, and so work on the other sites was scrapped early to save money in the so-called "Screw Nevada Bill" of 1987. Although local residents were in favour of the industry and development, outrage at the imposition led to a 70% opposition to the project throughout Nevada, and a series of paralysing lawsuits, headed by Nevadan Senate Majority Leader Harry Reid. Whilst 16% of the electricity supplied to Las Vegas comes from nuclear power, there are no nuclear power plants in Nevada. Residents argued for the right of the state to determine its own environmental future and consent to federal projects before their implementation. Despite the opposition, Yucca Mountain started accepting waste in 2006, with the aim of opening in 2017 with a limiting capacity of 77,000 metric tons. However, after a long standstill, the project was terminated in 2011, leaving the federal government owing hundreds of millions of dollars to utility companies for breach of contract, in addition to its legal fees.

Nuclear power is a sensitive public issue. The American case has underlined the extreme importance of prior consent from residents before launching large scale economic environmental projects. Thus, at the moment, the government are waiting for volunteer communities to emerge before they can even start studying local geology in enough detail. Although geologists have suspicions about certain areas, we really don’t know where the good rocks are - poorly porous ones, likely to stand for 100,000 years until all radioactivity falls below a safe level. And it will take a lot of time and money to find out.

Of course, waste is still building up whilst we’re waiting. The worldwide nuclear industry has so far generated almost 300,000 tonnes of high-level waste. In fact, it is estimated that the industry generates 39.5g of high level nuclear waste per person per year in developed countries, assuming our only energy source was nuclear power (although it must be noted that fossil fuels would generate 10,000,000g per person per year of CO2 waste - most of which is emitted straight into the atmosphere). This could make the carbon neutral energy future a rather slow burner - and we still have a lot of digging to do.

why don't all references have links?

[1] Geological Disposal. An overview of the generic Disposal System Safety Case, December 2010, NDA Report no. NDA/RWMD/010.
[2] GDF White Paper, Implementing Geological Disposal – A framework for the long-term management of higher activity radioactive waste, Department of Energy and Climate Change, URN 14D/235, London, 2014.