Oak Ridge Associated Universities 2006 Annual Report

ORISE’s Independent Evaluation of Groundwater Samples from Nuclear
Power Plants Helps NRC Build Public Trust
When leaking water pipes present a potential hazard,
everyone knows a plumber is the right person to fix
the problem. But what happens when pipes suspected
of inadvertently contaminating nearby groundwater
with radioactive tritium are discovered at a number of
aging nuclear power plants?
That was the issue facing the U.S. Nuclear Regulatory
Commission (NRC) in 2006 when nearly a dozen
nuclear power plants found heightened levels of
tritium in on-site groundwater supplies. Tritium, a
radioactive isotope of the element hydrogen, naturally
occurs in the environment in very low concentrations
and is a by-product of electricity-producing nuclear
reactors and weapons plants. To determine whether
dangerous levels of tritium could potentially endanger
drinking water supplies, the NRC called upon ORISE’s
Radiochemistry Laboratory to exclusively carry out a
series of independent radioanalytical evaluations.
Since October 2005, ORISE has analyzed more than
700 groundwater samples from 13 nuclear facilities
scattered mainly throughout the Midwest.
Tritium is most commonly used in biomedical
research as a radioactive tracer and is also produced
commercially in luminescent devices, such as exit signs
in buildings, aircraft dials, gauges, and wristwatches.
People come in contact with small amounts of tritium
on a daily basis as it is present in the atmosphere and
in the food chain. Because this exposure is typically
negligible and falls below the U.S. Environmental
Protection Agency’s (EPA) guidelines for safe exposure,
it is common for low levels of tritium to make their
way to drinking water supplies via atmospheric and
groundwater movement.
The EPA considers tritium readings of 20,000
picocuries (a unit of radiation) or less per liter safe
for human consumption. During evaluation, however,
ORISE chemists reported readings as much as 10 times
greater than EPA’s limit—enough to gain the attention
of the NRC, public interest groups, politicians, local
residents, and national media.
In 2006, ORISE independently analyzed more than
700 groundwater samples from 13 nuclear power plants
suspected of inadvertently releasing tritium.
“Our lab analyses indicated tritium readings as high
as 200,000 picocuries,” said Dale Condra, ORISE’s
Radiochemistry Laboratory manager. “Though these
readings were only found in groundwater, it is not
surprising that this discovery generated concern that
tritium levels found in samples taken from outside
the plants could potentially endanger local drinking
water supplies.”
Despite tritium’s being considered one of the least
dangerous radionuclides because it emits very weak
radiation, exposure to extreme levels can result in
increased health risks, including cancer. In order to
maintain public safety and confidence, the NRC and
plant officials are using ORISE’s findings to address
ways to prevent future unintentional releases.
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