WorldWide Drilling Resource

15 WorldWide Drilling Resource ® JULY 2014 Radioactive Waste: Where Should it Go? Adapted from a Press Release by the GSA Geologists are essential to identi- fying safe burial sites and techniques as the U.S. makes new plans for dis- posing of spent nuclear fuel and other high-level radioactive waste deep in the earth. Scientists at the Geological Society of America (GSA) recently met in Denver, Colorado, and described the potential of shale formations as repositories; chal- lenges of deep borehole disposal; and their progress in building a computer model to help improve understanding of the geologic processes important for safe disposal of high-level waste. Over 77,000 tons of commercial nuclear waste are located at more than 70 sites in 35 states in the U.S. Shales and other clay-rich (argillaceous) rocks have never been seriously considered for holding America’s waste of this type. However, France, Switzerland, and Belgium are planning to put waste in tunnels mined out of shale formations while Canada, Japan, and the UK are evaluating the idea. At the GSAmeeting, U.S. Geological Survey hydrology expert C.E. Neuzil reported some shales are so imperme- able there is little risk of radioactivity from buried nuclear waste reaching ground or surface water. “This is usually difficult to demon- strate, but some shales have natural groundwater pressure anomalies that can be analyzed - as if they were per- meability tests - on a very large scale.” said Neuzil. He also explained this capa- bility was shown recently at the Bruce Nuclear Site, a proposed low/interme- diate waste repository 1200 feet under- ground in Ontario, Canada. Neuzil said argillaceous rocks are common and have many attractive quali- ties. He pointed out they are voluminous and tend to be tectonically quiet - mean- ing no earthquakes to crack the walls of a fuel-rod burial chamber. Deep boreholes could also be an option for disposing of nuclear waste. The 2012 presidential Blue Ribbon Commission onAmerica’s Nuclear Future recommended more research, and the U.S. Department of Energy (DOE) is working on a research and develop- ment plan. The Nuclear Waste Technical Review Board (NWTRB) has legal responsibili- ty for evaluating the technical validity of the DOE’s nuclear waste activities, and is on record stating deep boreholes present many challenges and studying Image courtesy of theecologist.org them “should not delay higher priority research on a mined geologic repository.” Review Board senior staff profession- al Bret W. Leslie and Stanford University geophysicist Mary Lou Zoback, an NWTRB member, presented the board’s assessments at the GSA meeting. They included: c Technical feasibility of drilling a borehole of the proposed length (3 miles) and width (around 20 inches), which has never been done. c Exposure risk for workers who would have to repackage waste currently stored in canisters wider than the width of the proposed bore- holes. c Reliability of existing sealing tech- nology. c Requirement of nearly 700 deep boreholes. Whether the waste ends up in tun- nels, boreholes, or both, new analytical tools will aid the planning process. &% ! "" * "(%$ ))) (" $( ' & $ %# # " (" $( $ ( " !" !! ! &% ! % ! (" $( & $ $ $ " ! $ $ ! ! $ ! $ # $ $ $