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Terrorism and Nuclear Reactors:
Nuclear Fuel
- Before it is used in the reactor, nuclear
fuel consists of low-enriched uranium and is made up of 4-5% of
the radioactive isotope uranium-235 and 95-96% of the stable isotope
uranium-238.
- Fresh nuclear fuel is relatively harmless.
Although concentrated exposure can lead to lung and kidney problems,
fresh fuel is much less dangerous than other substances such as
asbestos.
- After about three years in a reactor, nuclear
fuel loses its capability to efficiently self-sustain a reaction.
At this point, the “spent” nuclear fuel consists of
about 94% uranium-238, 0.5% uranium-235, and 1% plutonium, a highly
radioactive isotope.
- Used nuclear fuel is highly radioactive and
must be very well shielded. Spent fuel removed from the reactor
will administer a lethal dose of radiation to a person in fifteen
to twenty seconds at a distance of a few feet.
- Some fission products take many years to decay.
Cesium-137, for example, has a half-life of 30 years, meaning
that half of the radioactivity will decay every thirty years.
- Spent fuel is stored near nuclear reactors
in spent fuel pools, where at least 20 feet of coolant water separates
spent fuel and the surface. The coolant contains neutron-absorbing
boron and acts as a radiation shield.
- There are about 1.6 million pounds of spent
fuel in the Salem spent fuel storage facility.
- The “cladding” around fuel rods
contains zirconium. New fuel assemblies can start a zirconium
fire if they are not constantly surrounded by coolant. In the
event of an enormous explosion in the spent fuel facility followed
by a complete loss of coolant, this zirconium fire can eject harmful
radiation into the air and may create a radiological emergency
of a greater magnitude than nuclear meltdown.
- During the first three days after a
worst-case zirconium fire, 38,600 thousand square miles would
experience an increase in cancer fatalities above one percent.
Residents living within the closest 9,650 thousand square miles
will experience an increase in cancer risk above 10 percent, and
this risk will increase according to proximity to the radiation
source.
Prepared by the Princeton University
Woodrow Wilson School undergraduate task force on Nuclear Reactor
Terrorism, May 2002. Prepared for the Coalition for Peace Action as
part of the Princeton University Community Based Learning Initiative.
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