Chris Schneidmiller
WC Monitor
1/8/2016
Initial preparations have begun on a Department of Energy project to drill a 16,000-foot borehole in North Dakota to test the use of such formations for storage of high-level radioactive waste, lead contractor Battelle Memorial Institute said Friday.
In total, the project on 20 acres of land near the city of Rugby is expected to last five years and cost $35 million. The intent is to gather data that will help determine whether deep boreholes in crystalline rock formations “are appropriate for the disposal of smaller DOE-managed radioactive waste forms, which will fit in a borehole without further repackaging,” a DOE spokesperson said by email Thursday, without further specifying waste types that could eventually be placed in boreholes.
The drilling techniques to be used will be similar to those in oil and gas and deep geothermal well drilling, Rod Osborne, energy business line manager for Battelle’s infrastructure and environment business unit, said in a Friday interview. The drilling will ultimately result in a hole that is about 8 ½ inches in diameter at the bottom.
“The project started Tuesday … so we’re off and running,” Osborne said. The project team has conducted initial calls with DOE and will spend several months studying the well design and the drilling methods. Construction will start later in 2016 and last for upward of a year, followed by more than a year of testing the hole.
The research team will study the hydrogeological, geochemical, and geomechanical characteristics of the rock deep into the Earth, the DOE spokesperson said. Large amounts of information will be collected during the drilling and further testing will be conducted afterward, DOE said. The test will not involve use of any actual radioactive material.
A multitude of tests will be conducted in each segment of the borehole, Osborne said, including removing rock samples and sending instruments down into the Earth to determine rock characteristics, collecting fluids to see what is found at various depths, and conducting injection flow tests to see how liquids move in the rock.
“The whole idea is by the time the project is done we have a very thorough understanding of the rock types, the rock materials, the chemical materials, the mechanical materials, the stresses that exist in those formations, what natural fractures exist around the wellbore,” he said. “We’ll be doing, as I mentioned, various fluid samplings, so we’ll know a great deal about the fluids that are there, the water and the concentration of minerals in that water.”
Scientific proof will be necessary to prepare a safety case demonstrating that wastes can be placed in deep boreholes without the material contaminating the surrounding environment – for example, by tainting groundwater that flows through the area. This demands determining the hydrological, geochemical, and geomechanical characteristics of the surrounding subsurface zone to produce “defensible predictive numerical models,” DOE said.
The test ultimately is meant to increase the department’s future options for disposal of radioactive wastes, the spokesperson said. The department noted that there are numerous U.S. regions featuring sizable, geologically stable rock formations akin to those found near Rugby.
The project would also offer data that would help DOE develop viable schedules and expenses for such projects. “The number of boreholes required would be dependent on the waste forms selected for disposal,” according to the spokesperson. “For example, all the [cesium and strontium] capsules currently stored at Hanford would fit in a single deep borehole.”
Specific regulations would have to be established for use of deep boreholes for radioactive waste storage, the official noted.
It has been more than four decades since scientists proposed use of miles-deep holes in granite to permanently store waste that was the byproduct of nuclear weapons production. The Obama administration’s Blue Ribbon Commission on America’s Nuclear Future, which was established after the suspension of the Yucca Mountain geologic repository project, suggesting studying deep boreholes “particularly as a disposal alternative for certain forms of waste that have essentially no potential for re-use.”
The administration’s current waste storage plan calls for using separate repositories for defense and commercial waste. The Department of Energy in late December began taking public comment on siting of locations for storage of high-level radioactive waste and spent nuclear fuel.
The deep borehole research team consists of Battelle, which specializes in geologic characterization; the University of North Dakota Energy & Environmental Research Center, which Osborne said knows best the site and can interpret the data; oil and gas services giant Schlumberger, which will oversee the drilling; and Switzerland-based Solexperts, which has expertise in geologic testing.
