by Elizabeth Hunt
When Ukraine
closes its Chernobyl nuclear power plant later this year, it may seem as if
the country is at last bringing an end to the story of the world’s worst
civil nuclear accident. But although most of the world only read about the 1986
disaster, others were far more directly affected. Tens of thousands of men,
women, and children were exposed to radiation as a result of the accident, and
for them, Chernobyl’s story continues. No one knows how it will end, but
a researcher at IU South Bend has helped the story unfold, providing new information
about how radiation exposure has affected those living in Chernobyl’s shadow.
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| Jerry Hinnefeld, associate professor of physics at IU South Bend, works in the Radioactive Nuclear Beam Facility at the University of Notre Dame. Like many other physicists, Hinnefeld collaborates regularly in his work. Photo Steven Heim. |
As a member
of a multidisciplinary team based at the University of Cincinnati, Jerry Hinnefeld,
associate professor
of physics at IU South Bend, has
studied people who lived 120 miles or less from Chernobyl at the time of the
accident. Hinnefeld’s study involved eighty adults and children who came
to the United States in the years after the accident.
“It’s
a small study, especially compared to the International Chernobyl Project, which
involved thousands of people,” Hinnefeld says. “But we have better
data for a smaller set of people. In fact, we have very precise data for twenty
of the people we studied.”
The data reveal
the rate at which ingested cesium 137, a radioactive isotope produced in fission
reactors, leaves the body.
“We know
that it has a half-life of thirty years and that on average, it clears the body
in 100 days,” Hinnefeld says. “But there’s quite a bit of variability
in that clearance time, and that’s what makes this study useful. It gives
us precise, individual measurements ofthe clearance time for cesium 137 on a
small group of people.”
To make the
measurements, Hinnefeld and his colleagues used a “whole-body counter,”
an eight-foot square steel room equipped with high-efficiency radiation detectors.
“The counter is made of steel from a pre-World War II battleship,”
Hinnefeld explains. “That means that the steel was made before the first
nuclear explosion. The goal is to have very low background radiation so you
get an accurate count for the person in the room.” Many of the study’s
participants returned once or twice to undergo additional measurements of the
cesium 137 in their bodies.
Whole-body
counters are fairly uncommon. Although portable counters exist, the process
of measuring radiation exposure using a low-background counting room is still
quite cumbersome. So, as a part of its project, Hinnefeld’s team also explored
the development of two additional methods for quantifying radiation exposure.
“These
are much simpler tests,” says Hinnefeld. “They’re basically blood
tests. One requires only an epithelial scrape, so it’s much easier to do.
And we did find that, in general, the simpler tests correlated pretty well with
the measurements we took using precise instrumen- tation.”
Hinnefeld, whose basic research focuses on heavy ion interactions, says he enjoyed
taking part in an applied physics study.
“I really
love experiments in basic physics, but I enjoyed working as part of a team with
doctors, statisticians, and biologists,” he says.
Working with
the whole-body counter also appealed to Hinnefeld. “The one we used has
been around since the 1960s,” he says, “and I was really interested
in the records of the technicians who have made counts over the years.
“What
you see is that in the 1960s and 1970s, everyone had cesium in their bodies,”
Hinnefeld says. “Atmospheric nuclear testing ended in the early 1960s,
so you can see how that continued to affect people for years.”
It will take
many more years to learn what will happen to the population living near Chernobyl
at the time of the accident, Hinnefeld says, and how radiation exposure will
continue to affect them.
“Nobody doubts the fact that radiation has mutagenic effects,” Hinnefeld says. “And we know that even exposure at a relatively low level continues to show up in biological assays. But whether or not the people who took part in this study face long-term health consequences, we can’t say.”
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