Irradiated nuclear fuel contains hundreds of man-made radioactive
poisons for which the natural background level is zero. They fall
into three broad categories:
(1) fission products — radioactive isotopes of xenon, krypton,
iodine, cesium, tellurium, ruthenium, and many others — which
are the broken pieces of atoms that have been split or “fissioned”;
(2) activation products — radioactive isotopes of argon, cobalt,
iron, and many others — which are created when non-radioactive
materials in the reactor absorb one or two neutrons and are
transformed into radioactive elements; and
(3) transuranic elements — plutonium, neptunium, americium, curium,
and others — which are created when uranium atoms absorb one or
more neutrons and then transform themselves into new elements.
See http://ccnr.org/hlw_chart.html and http://ccnr.org/hlw_graph.html
In addition to these man-made radioactive materials, there are also
huge amounts of radioactive materials created which do exist in small
amounts in nature — such as tritium (radioactive hydrogen) and
carbon-14 (radioactive carbon). These radioactive atoms are easily
incorporated into organic molecules of all kinds, including DNA.
This is the stuff that the nuclear industry wants to bury in geologic
formations in order to protect the biosphere for millions of years.
But when a reactor melts down, that radioactive junk is trapped in
the molten blobs that form. It’s an enormous toxic mess. Ad hoc
measures must be taken to package and move and guard these
unwieldy radioactive blobs and contain them so that they do not
leak their radioactive poisons into the environment.
At Chernobyl, where the core of the reactor melted right into the
earth, moving it has proven to be impossible. Constructing a
containment above the site of the core melt is also impossible
because of the intense radiation levels. An enormous structure
is being built AWAY from the reactor core melt, which will then — when
finished — be “slid” over the reactor site, enclosing the remnants of
the reactor building and all.
Already over $650 million (US) has been spent to build
this new structure, which will take the place of the crumbling
sarcophagus that was hastily erected over the molten core
following the accident 25 years ago. Authorities are now
seeking hundreds of million more in order to complete
the task — and this is by no means a permanent solution!
Meanwhile, the remnants of the half-melted TMI core (from
32 years ago) are also presenting storage difficulties….
William Freebairn, Washington (Platts), 15 April 2011
The US Department of Energy facility storing melted fuel from the Three
Mile Island nuclear plant has not done enough to address crumbling
concrete modules encasing the radioactive material, the US Nuclear
Regulatory Commission said in a letter made public Friday.
The DOE facility at the Idaho National Laboratory holds the damaged fuel
from unit 2 of the Three Mile Island Plant, which, in 1979, suffered a partial
meltdown of the core, leading to the US’ worst nuclear accident.
The so-called spent fuel rubble is now contained in concrete storage
modules located at an independent storage installation owned by DOE.
The concrete modules are “showing significant cracking and degradation,”
even though they were built in 1999 to last for 50 years, NRC said in the
letter, which is dated April 7.
DOE has analyzed the structural integrity of the modules, which have
walls two feet thick, and determined that the problem is getting
progressively worse, NRC said.
Since the NRC inspection, DOE has identified funding to pay for repairs
and will begin the work this construction season, meaning from the spring
to the fall, spokeswoman Katinka Podmaniczky said in an email Friday.
“These cracks have no impact on the storage modules’ ability to safely
store spent nuclear fuel,” she said.
At the time of the inspection, it was not clear whether DOE had approved
or scheduled measures to stabilize the degradation, NRC said in the
letter. It asked DOE to provide the regulator with information about
corrective measures, a schedule for their implementation and a plan
for monitoring the effectiveness of actions taken.
The degradation of the modules was likely due to “water intrusion and
the annual thawing and freezing cycle,” NRC said in an inspection report
attached to the letter. Chunks of concrete have fallen from areas of the
modules and there are signs they are no longer water-tight, NRC said.
Cracking was first recognized in 2000 but considered to be “cosmetic,”
NRC said. In 2008, DOE recognized that continued cracking called into
question the ability of the modules to protect the fuel canisters inside
from natural phenomena and shield people from the radiation of the
A recent study determined that protective caps should be installed,
damaged concrete replaced and a sealant applied, but those actions
have not yet been taken, the NRC inspection report said.
NRC licensed DOE’s Idaho Operations office in 1999 to store the
damaged fuel in dry shielded stainless steel canisters, which are
loaded inside the reinforced concrete modules.
The 30 dry shielded canisters at the site contain melted fuel from the
Three Mile Island-2 reactor core. That unit, located in Pennsylvania,
experienced the melting of about half the fuel in the core during an
accident. The adjacent Three Mile Island-1 continues to operate.
The NRC inspectors concluded that the storage facility continues to
meet standards, but the degradation of the modules is “a concern
that will be tracked in the future,” agency spokesman David McIntyre
said in an email.
NRC also cited DOE in the inspection report for a “deviation from a[n]
NRC commitment” because it deleted certain material from an
NRC ordered the energy agency to respond within 30 days. The
deviation was minor, Podmaniczky said.
William Freebairn, firstname.lastname@example.org
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