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UNM, SNL Research Long Term Behavior of Salt Repositories for Nuclear Waste

Research will examine how salt reseals excavated areas

By

John Stormont

A new, three-year, $800,000 grant from the U.S. Department of Energy will be used by research groups in the UNM School of Engineering Civil Engineering Department and Sandia National Laboratories to improve scientific understanding of the behavior of consolidating granular salt. 

Principal Investigators John Stormont, chair of the UNM Department of Civil Engineering and SNL researcher Stephen Bauer want to understand how granular salt consolidates or becomes dense in response to stress and temperature.  Granular salt is currently under consideration as a sealing material for the shafts and tunnels in salt formations in waste repositories such as the Waste Isolation Pilot Project in southern New Mexico.  It’s known that granular salt will slowly consolidate over time to a condition comparable with intact salt, and will eventually erase tunnels and shafts as the salt closes around the radioactive material.  The researchers want to know whether it is possible to confidently predict how the salt will behave under various stress, temperature and moisture conditions.

Stormont says an intact salt bed is nearly impermeable to moisture, and he expects they will be able to use their research results to estimate how quickly the salt will consolidate around the waste to bring the repository to the condition of an intact salt bed.  The researchers will construct mathematical models that will allow them to make predictions about how the salt will behave under varying conditions.

“Granular salt consolidation is a complex response,” Stormont said.  “We will use measurements and observations to develop models to describe granular salt as it consolidates under conditions expected in repository environments, focusing on the time required for complete consolidation.  The development of models that explicitly couple the mechanical response with the thermal and hydrologic responses will be a major advance in the fundamental understanding of granular salt consolidation.”

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