|
The U.S. Department of
Energy has decided that most of the plutonium from dismantled
nuclear weapons will be made into an experimental fuel (called
MOX) for use in commercial atomic reactors. Southeastern
utilities are lining up to get involved in this dangerous,
large-scale plutonium business (although other utilities also may
join the program). Use of reactors does not get rid of the
plutonium and further complicates existing nuclear safety and
radioactive waste problems.
SECURITY THREATS
The MOX project will
include numerous shipments of plutonium by truck and/or rail.
Transportation of plutonium, even when guarded, opens
possibilities for the theft or diversion of plutonium. Plutonium
fuel will be stored at the reactor sites before it is loaded for
use into the reactor. This puts plutonium safeguarding
responsibilities into the hands of commercial utilities, which
sometimes have had inadequate security records. Only 13 pounds of
plutonium were used to destroy Nagasaki.
DANGEROUS REACTORS MADE EVEN
MORE DANGEROUS
Plutonium from nuclear
weapons has never been used in fuel for nuclear reactors on more
than a research scale. Using weapons-grade plutonium at nuclear
reactors would be an experiment that could have devastating
results.
In the U.S., most
commercial light water reactors are not designed to use
plutonium-based fuel. Differences in the characteristics of
plutonium fission as compared to the normally-used uranium are
likely to create problems. The neutrons from plutonium fission
have a higher average energy than
neutrons from uranium fission. This will increase the rate of radiation damage to key reactor parts,
which could affect reactor control and maintenance. In addition,
the rate of fission of weapons-grade plutonium tends to increase
with temperature. When fuel temperature increases, so does the
rate of fission, which further increases the temperature, and so
on. This property of plutonium makes the reaction harder to
control.
MOX plutonium fuel also
produces more heat and radioactivity than uranium fuel. Uranium
fuel that has been used in a reactor core for three years is
about a million times more radioactive than unirradiated uranium
fuel. This is from the atoms called "fission products"
that are actually fragments of the uranium-235 atoms that have
been split in the reactor core. These include hundreds of
radionuclides like cesium, strontium, iodine, xenon and a host of
others. The plutonium atom is even bigger and heavier: when it
splits there is a higher yield of these highly radioactive
elements. There is also more energy released in the form of heat.
IN CASE OF AN ACCIDENT
An early 1999 study by the
respected Nuclear Control Institute revealed that a severe
accident at a civilian reactor powered with plutonium (or MOX)
fuel could cause twice as many fatal cancers as an identical
accident at a reactor that uses uranium fuel.
Similarly, according to an
International MOX Assessment report, the consequences to human
health and the environment would increase in case of a severe
accident at a nuclear power plant that uses plutonium fuel,
because more plutonium and other dangerous radioactive materials
would be released into the environment if containment is lost at
a reactor. Studies indicate that the
doses from a major reactor accident such as Chernobyl could be as much as 2 1/2 times higher to those in the
reactor community than would be expected from a uranium core
accident.
ATOMIC WASTE
Using plutonium in a
nuclear reactor will not get rid of the plutonium. From 40
–70% of the plutonium from the MOX fuel remains in the
waste. Meanwhile, the reactor also produces new plutonium from
the uranium oxide in the fuel. The Westinghouse Corporation
estimates that putting plutonium in a reactor as MOX fuel may
only reduce the amount of plutonium by as little as one percent,
compared to the initial content. At best, less than a third of
the plutonium inventory is "used up," the rest remains
in the radioactive waste.
Indeed, the real point of
the MOX program is not to get rid of plutonium—an impossible
goal—it is to mix the plutonium with high-level nuclear
waste. The idea is that terrorists and rogue nations will be
unlikely to approach this lethal waste to attempt to steal the
plutonium. On the other hand, no nation yet has a workable,
scientifically-defensible solution for its radioactive waste
problem. Use of MOX will exacerbate this problem..
All reactor waste contains
some plutonium. Thus, plutonium levels in "low-level"
waste also could be expected to increase by use of MOX-powered
reactors.
The radioactive waste
produced by the plutonium fuel program would further aggravate
existing radioactive waste problems. Current forms of irradiated
fuel storage, in liquid pools or in dry containers, are
vulnerable to heat load and possible criticality. MOX fuel, which
is thermally hotter and is likely to have a higher concentration
of plutonium that could still fission, may challenge these
storage options. Thermal load and criticality are also key issues
for any geologic repository concept. There is currently no way to
safely store this kind of waste for the length of time that it
will remain a threat. Plutonium-239 remains hazardous for 240,000
years.
AN EXPERIMENT
Although MOX fuel has been
used occasionally in Europe, it is not made with such a high
percentage of plutonium-239 as is contemplated for the United
States. This form of plutonium is the material of choice for
nuclear weapons precisely because it is easiest to explode.
Obviously, this is not the goal in reactor operation. Compounding
the concern about the use of a weapons material is the disclosure
that the plutonium is not pure. In order to make the nuclear
weapons, other ingredients were added to the plutonium. One of
these is Gallium, which has not been put in a reactor core
before, and which interacts with zirconium, one of the metals
composing the fuel rod’s "cladding."
Compromise of fuel
cladding can cause a host of problems including greatly increased
releases of radioactivity to air and water. People living near
the Pilgrim nuclear power reactor in Massachusetts had a 400%
greater chance of suffering leukemia than those who lived upwind
during the years when that reactor was using fuel with faulty
cladding. The stakes of current reactor operation are very high
without compounding them with MOX fuel use.
Prepared by Carrie
Benzschawel, Nuclear Energy Information Service, Evanston, IL
For more information,
contact: Nuclear
Information and Resource Service,
1424 16th St. NW,
#404,
Washington, DC 20036.
202.328.0002; fax: 202.462.2183;
nirsnet@nirs.org
www.nirs.org
|
