Nuclear waste: Bury nuclear waste down a very deep hole, say scientists, Science Daily April 14, 2015 Source: University of Sheffield
The concept — called deep borehole disposal — has been developed primarily in the UK but is likely to see its first field trials in the USA next year. If the trials are successful, the USA hopes to dispose of its ‘hottest’ and most radioactive waste — left over from plutonium production and currently stored at Hanford in Washington State — in a deep borehole………
Deep borehole disposal (DBD) has a number of advantages over the current solution envisaged for all UK nuclear waste, which is in a mined repository at 500m depth:
- DBD is effectively ‘pay-as-you-go’ disposal. A mined repository can cost from hundreds of millions to tens of billions of dollars to construct before any waste can be disposed of; DBD costs a few tens of millions of dollars per borehole.
- There are more geological sites suitable for DBD as the granite layer that is required can be found at appropriate depths under most of the continental crust.
- A borehole could be drilled, filled and sealed in less than five years, compared to the current timescale for a UK mined repository, which is to open in 2040 and take its first waste by 2075 (although a site has not yet been agreed).
- As DBD disposes of nuclear waste at greater depths and with greater safety and because there are more potential sites available, it should be easier to obtain public and political acceptance of the technology.
- DBD has limited environmental impact and does not require a huge site: the holes are a maximum 0.6m in diameter and can be positioned just a few tens of metres apart. Once a borehole is complete, all physical infrastructure on the surface can be removed.
- While seismic activity might damage the containers within the borehole, fracture the surrounding rock and disrupt some of the nearest barriers in the borehole, it would still not destroy the isolation of the waste or make it possible for radioactivity to reach the surface or any ground water.
The demonstration borehole in the USA will be drilled just under half a metre in diameter and trials will be conducted to ensure waste packages can be inserted into the borehole and recovered if required. Initial results are expected in 2016. If these results are positive, disposal of the Hanford waste capsules would then take place in another borehole, just 0.22m in diameter.
Story Source:
The above story is based on materials provided by University of Sheffield. http://www.sciencedaily.com/releases/2015/04/150414100956.htm
