POWER September 2021 - 33

NUCLEAR
three-beam GeoChem mode that allows
measurement of various levels of
concentration, for example, in parts per
million (ppm) or in parts per thousand
(ppt), as is needed for the element cesium.
Researchers analyze various items
onsite, including:
2. Pripyat, Ukraine, located within a few
miles of the Chernobyl nuclear power plant,
was founded in 1970 to house workers and
support the facility. It had grown to a population
of about 50,000 residents by the mid1980s,
nearly all of whom were evacuated
within days following the accident on April
26, 1986. An amusement park, which was
scheduled to have its official grand opening
less than a week after the reactor meltdown
occurred, has sat abandoned since that time,
becoming an eerie symbol of the disaster.
Source: Shutterstock
analyzer to determine the elemental
composition and presence of radioactive
elements in the many items, surfaces,
and soils they monitor at the Chernobyl
site (Figure 4). The team typically performs
about 100 analyses a day during a
five-day visit. The tool allows immediate
analysis onsite and therefore reduces
the number of samples that must be
mailed to the lab. Considering all the
planning, logistics, and difficulty in shipping
samples, the handheld analyzers
are indispensable.
Martin and his team visit the Exclusion
Zone twice a year. To measure the
percentage of a given element, the
researchers use a Vanta analyzer with
■ Radioactive pipes.
■ Debris on the ground (Figure 5)-anything
from cesium to uranium and
plutonium.
■ Soil-evaluating heavy metal contamination.
To
analyze the soil, the researchers dig
down about a foot. Most of the radioactive
contamination is retained in the upper
portion of the soil. " Cesium sticks to
the top few centimeters-clays retain the
radiation. It is very sticky, " Martin said.
In-Depth Analysis
Handheld XRF analyzers allow field sampling
on an array of items-from soil,
rocks, steel, piping, and other building
materials to cars and abandoned helicopters,
which can't be easily shipped. More
extensive testing is sometimes completed
on smaller samples shipped back to
Martin's UK laboratory. However, removing
samples from the Exclusion Zone can
be an onerous process, requiring up to
nine months to complete in some cases
including obtaining special permissions
for contaminated samples.
Once permission is granted, items are
shipped to Kiev, Ukraine, and then exported
to the UK. Since radioactive mate5.
The XRF analyzer can be used for many
purposes including scanning debris, soil, and
other materials. Courtesy: Peter Martin/Yannick
Verbelen, University of Bristol
rial is classified as dangerous goods, the
samples must travel on a special plane
via cargo aircraft.
Small Samples Bring Big Learnings
Preparing samples starts by placing soil
samples in disposable petri dishes using
sampling teaspoons. Researchers
then put the samples on a flat surface to
test them with the XRF analyzer. To test
metal samples like piping and staircases,
they hold the XRF analyzer directly
up to the items.
Some of
the
key
learnings have
stemmed from testing items like gas
masks and rain boots often found
loosely buried in the soil. Researchers
now know that those items hold
onto the radioactive material because
elements stick to them, especially cesium.
According to Martin, the biggest
learning has come from the smallest
kind of sample.
" In the Kopachi area, the dosimeter
will indicate especially high areas of radiation, "
said Martin. " You can pick up
grains of sand that are highly radioactive.
We put this black sand on Kapton
tape. The grains will give an entire year's
dose within 10 minutes, " he said.
" The grain is actually small bits of the
reactor that were blown out in the accident
and can still be found in the environment.
Some sand grain pieces are
made of graphite, carbon, and uranium, "
explained Martin.
When a highly radioactive material like
3. A handheld X-ray fluorescence (XRF)
analyzer can be used to identify the material
chemistry and alloys found in samples at the
Chernobyl site. Obtaining lab-quality results
in the field saves time and minimizes dose.
Courtesy: Peter Martin/Yannick Verbelen, University
of Bristol
September 2021 | POWER
this is found, the team immobilizes and
disposes of it at disposal sites made specifically
for radioactive waste. " It's mixed
with a giant drum of concrete, and then
4. Determining the elemental composition
of materials found at the Chernobyl site is
made quick and easy with a handheld XRF
analyzer. Courtesy: Peter Martin/Yannick Verbelen,
University of Bristol
www.powermag.com
they dispose of it, " Martin said. ■
-Michelle Wright is associate manager
of marketing communications for
Olympus' Analytical Instruments
business (www.olympus-ims.com).
33
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POWER September 2021

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