Managing the land, and sea13 October 2016
Bob Burton, former UKAEA manager of Fuel Cycle and Wastes, and Colin Haslam, professor of finance and accounting at Queen Mary College, offer a new perspective on the challenges the UK faces with regard to nuclear waste disposal and the potential innovative response to them.
In the 1980s, the UK started to search for somewhere to dispose of its radioactive waste, which comes mainly from its nuclear power stations and reprocessing plants. After nearly four decades there is still considerable uncertainty about an integrated strategy for the decommissioning of UK nuclear waste, i.e. dismantling buildings, the management and disposal of all waste, and remediation of land.
These delays have inflated decommissioning costs: in 2016, the UK’s Nuclear Decommissioning Authority (NDA) estimated these to be £117 billion compared to roughly £55 billion in 2005 – a doubling of costs over ten years. The preference to date has been to build large underground geological disposal facility (GDF), the cost of which would be enormous.
We, the authors, have published several NEI articles on the disposal of radioactive waste. In the first of these in 2009, ways of disposing intermediate level waste (ILW) were reviewed. The second and third, in 2012 and 2014, discussed disposal of solid high-level waste (HLW). In the most recent article, in 2016, the dilution of liquid HLW in brine was suggested to give a liquid denser than seawater, which could be poured down deep boreholes to seep into rock and percolate downwards. The present note adds on the requirements for disposing of vitrified waste. New hazard rules, put forward by Professor Wade Addison of Oxford, are then applied to the above.
Act on vitrified waste now
According to calculations in a UKAEA study in 1980 the rate of erosion of vitrified waste, if uncanned and placed at the end of the Sellafield pipeline, would result in activity discharges well below those permitted by UK Government limits at that time.
In a surface emplacement with drainage (SED) at Sellafield, described as ‘Low Fell’ in 2009, the water in the drainage section would flow down boreholes to a saline zone below. If water did contact waste inside a unit in any way, it would then drain safely into saline groundwater below sea level. This is in accord with the government rules for toxic wastes (which of course have a half-life of infinity), where any drainage must be into non-potable groundwater. Searching for deep sites is therefore unnecessary and could be wound up, freeing vast sums of taxpayers’ money for more sensible non-nuclear uses.
An activity sequence could then be to drill boreholes from the Sellafield site, testing for salt concentrations at intervals until saline regions are reached; next waste blocks could be placed in a surface building, whose base is above the high tide level. If necessary, intermediate lower-activity blocks could be stacked with the HLW blocks to reduce early local heat loads. The boreholes would pass down from under the building base to a connection for groundwater to flow from under the waste to the saline zone (see Fig. 1).
After a century or so with some supervision, to decay out Sr90 and Cs137, the holes would be filled with granular material for long-term drainage. In the meantime, research may indicate useful absorbers to add to the mix that would pick up traces of very long-lived activity.
Further, during this time, new cancer treatments will surely be developed, so removing a further part of the hazard.
After a comprehensive review of radiation hazards, Professor Wade Allison, emeritus professor of physics and Fellow of Keble College at Oxford University, has recently published ‘Radiation and Reason’, on the management of nuclear material. It is a first attempt to define a threshold of exposure, stating the limit as Ahars (‘as high as relatively safe’), a different ethos to the ‘as low as reasonably practicable/achievable’ (Alarp/ Alara) approach. Ahars results in a far higher level for radiation limits than currently used, a consequence of which is that the overall effect of small doses to individuals of a large population can be taken as zero.
There are several countries with nuclear power but with no routes for treatment and disposal of resulting waste. They could be invited to join in UK operations at any point between transfer of spent fuel to disposal of HLW (the fate of recovered fissile material must be agreed).
A considerable area around Sellafield could well be suitable for the disposal of liquid waste by drainage into saline zones. On the site itself, there would be ample room for safe emplacement of solid wastes in SEDs. Further, temporary boreholes could be drilled along the coast: liquid HLW would be tankered from Sellafield, poured down the holes and the surface restored. A fraction of the income could be directed towards paying for new jobs generated and non-nuclear local projects.
What’s to be done?
The financial liabilities facing future UK governments from nuclear waste decommissioning continue to inflate and threaten to become an unacceptable burden on taxpayers. To reduce these:
- Existing borehole data should be examined to suggest locations for boreholes from Sellafield to connect to good drainage zones.
- Sites for SEDs should then be established.
- Tests to set up points for brine disposal of liquid HLW.
- Possible liquid disposal sites along the coast at or near Sellafield should also be examined.
- Overseas bodies should be approached for possible disposal at the sites identified.
- The effect of Ahars limits on the handling of all kinds of nuclear waste, especially that from reactors, should be assessed.
It is now time for the UK to face up to the political and economic reality of an out-of-control nuclear decommissioning strategy. It is difficult to see how it can go ahead with new reactor schemes without having agreed on a sensible place and method to dispose of the resulting waste.
How nice, in the long-term, would it be to have a Low Fell at Sellafield with cows and sheep grazing peacefully and radwaste decaying safely below.
The views expressed in this article are those of the authors and not necessarily those of NEI.