The US will drill a borehole more than 16,000 feet (4.8km) into rock in North Dakota to test a new method proposed by UK researchers for storing radioactive waste.
Proponents of the method insist it could solve a problem that has vexed governments for years.
Radioactive material will not be poured into the narrow hole. Instead, scientists will study how such a deep wellbore behaves in order to consider the feasibility of the approach.
Scientists at the University of Sheffield, UK, who have been developing the concept of "deep borehole disposal", say it would be the safest and cheapest way of dealing with the "hottest" – most radioactive – waste.
They claim that all of the UK’s high level nuclear waste from spent fuel reprocessing could be put safely in just six such boreholes on a site no bigger than a football pitch.
Last month the US Department of Energy selected a team to drill a test borehole into a crystalline basement rock formation on a 20-acre patch of state-owned land near Rugby, North Dakota.
The boreholes can survive earthquakes intact and they are cheap to construct, costing tens of millions of dollars as opposed to the tens of billions a mined repository would require
US energy secretary Ernest Moniz said it would be "an important first step" in understanding the potential uses of rock formations in long-term nuclear waste disposal.
The announcement sparked concern among local officials who worried that if the borehole was found to be suitable, the site would be used as a waste dump.
But Sheffield researchers say deep borehole disposal has strong advantages over the mined repository approach, which both the US and UK governments have been pursuing unsuccessfully for years while waste stockpiles have continued to mount.
Anticipating the US test site last year, Sheffield’s Faculty of Engineering said a borehole could be drilled, filled and sealed in less than five years, compared to the current timescale for a UK mined repository, which would not take its first waste until 2075 – although a site has not yet been agreed.
A borehole site would also take up minimal space. The holes in question are just 0.6m in diameter, at most, and can be positioned just a few tens of metres apart.
The boreholes can survive earthquakes intact and they are cheap to construct, costing tens of millions of dollars as opposed to the tens of billions a mined repository would require, the faculty said.
The Sheffield Deep Borehole Disposal Research Group, in collaboration with Sandia National Laboratories of the US, is now developing a programme of research for the North Dakota field test. Issues to be investigated include how to prevent groundwater corrosion of the waste packages and how to seal the borehole to prevent radioactive waste escaping.
In North Dakota the drilling team will consist of research organisation Battelle Memorial Institute, the University of North Dakota Energy & Environmental Research Center, drilling technology giant Schlumberger and Swiss ground engineering firm Solexperts.
Photograph: A permanent solution for storing radioactive waste has eluded governments to date (János Korom/Wikimedia Commons)