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Nuclear find may stall K-25 demolition
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Magnu-@aol.com
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Sep 10, 2009 08:49 PDT
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_http://www.knoxnews.com/news/2009/sep/09/nuke-find-may-stall-k-25-demolitio
n/_
(http://www.knoxnews.com/news/2009/sep/09/nuke-find-may-stall-k-25-demolition/)
Nuclear find may stall K-25 demolition
Widespread presence of element could slow project, raise cost
* By _Frank Munger_ (http://www.knoxnews.com/staff/frank-munger/)
* Posted September 9, 2009 at midnight
Bechtel Jacobs Co.
The demolition of the west wing of the K-25 plant in Oak Ridge is about
one-third complete. Officials say demolition of the east wing may be delayed
as the presence of radioactive technetium is more widespread than
previously thought.
OAK RIDGE - One of the most challenging demolition projects in history may
get even more difficult.
It appears the presence of technetium-99, a devilish radioactive element,
may be more widespread than previously thought in processing equipment at
the K-25 uranium-enrichment plant. If so, that could complicate plans for
taking down the east wing of the massive, U-shaped building and potentially
delay the project's schedule and jack up the cost.
The Department of Energy and environmental regulators have been studying
the issue since March, but there's still uncertainty, according to Steve
McCracken, DOE's environmental manager in Oak Ridge.
DOE and its cleanup contractor, Bechtel Jacobs Co., along with the state of
Tennessee and the U.S. Environmental Protection Agency, are working on a
"characterization plan" to better understand where the technetium is and
where it isn't, McCracken said.
The radioactive technetium, along with other products of nuclear fission,
was introduced into the Oak Ridge equipment decades ago when reprocessed
uranium - that had previously been in a nuclear reactor - was used as feed
material to enrich uranium for nuclear fuel.
The remnants of Tc-99 are problematic because regulations allow only tiny
amounts in DOE's Oak Ridge nuclear landfill, where most of the massive
amount of contaminated rubble from K-25's demolition is destined for disposal.
John Owsley, who oversees DOE's activities for the Tennessee Department of
Environment and Conservation, said technetium is a concern because its
radioactivity is long lived and the element is especially mobile in the
environment due to its solubility in water. It also can be difficult to detect,
he said.
The standard in place at the Oak Ridge landfill is protective of the
environment and human health, Owsley said, but he emphasized that regulators
want to make sure no waste is disposed there that exceeds the criteria.
Materials too hot for the Oak Ridge landfill have to be shipped off site to
Nevada Test Site or another location for disposal, and that's a lot more
costly and time-consuming.
Oak Ridge officials previously believed that the presence of technetium was
confined to a relatively small section in the massive plant's southeast
corner, and they planned to treat it separately. If other areas also have the
high-hazard contamination, they need to be identified before demolition
work begins on the east wing, McCracken said.
The original plan for taking down K-25 was to first dismantle and remove
the contaminated processing equipment and dispose of it before demolishing
the building's metal-and-concrete structure.
That approach was dramatically altered, however, after a worker was
seriously injured in early 2006 when he felt through a weakened floor in the old,
deteriorated building. The revised technique is to inject equipment with a
stabilizing foam, allowing workers to collapse everything in place. The
piles of debris are then hauled to the landfill.
About a third of the west wing of the mile-long, U-shaped building - the
largest building in the world at the time of its construction - has already
been demolished, but McCracken said technetium-99 isn't an issue there.
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