By Dan Heyman
New testing is finding unpredictable levels of naturally occurring radioactive materials in the waste from a Marcellus well.
Gas wells in the region produce millions of tons of drill cuttings a year. These normally contain small amounts of uranium and other mildly radioactive isotopes, which can be a problem if the radioactivity becomes concentrated during waste disposal.
But Andrew Nelson, a researcher at the University of Iowa Chemistry Department, says the industry and regulators assume they know how much of each isotope is in the cuttings.
Nelson led what he says is the first attempt at the complex chemical analysis, to tell what and how much is really there.
“No one had actually ever measured uranium 234, polonium 210, lead 210, a lot of these other isotopes,” he states. “Before we can even begin to start asking whether it’s safe or an acceptable risk, we need to first determine what’s in there.”
Nelson says researchers are finding that the isotope levels vary widely depending on the rock formation, and he adds what they found in one well is no reason to panic.
The industry argues the materials’ radiation levels are not that different from typical background radioactivity.
Nelson says the isotopes are tough to accurately test for, and testing requires fairly elaborate and sophisticated chemistry.
If the landfills that dispose of the drill cuttings test for naturally occurring radioactive materials at all, the landfill operators just run it past a gamma meter.
Nelson says that doesn’t produce an accurate picture.
“If you find a dose rate of 10, it doesn’t tell you how much uranium is in there, and it certainly doesn’t tell you whether there is uranium 234 and 238 in the same concentration,” he points out.
Nelson says the levels of the different isotopes are important because they behave differently in a landfill. For example, he says, one isotope of uranium is much more likely to leach than another.
“Although they are the same in their original solid material that comes up, when you start leaching them you start getting significantly more uranium 234 coming off the materials than uranium 238,” he explains.
Nelson maintains there is a pressing need for more research and testing.