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Accidents at Nuclear Waste Decommissioning Sites
The most likely method for decommissioning nuclear wastes is to store
them at Yucca Mountain. Thus the biggest
possibility for an accident that would release dangerous amounts of nuclear
waste into the environment is likely to happen at a repository such as
Yucca Mountain. This section uses the Yucca Mountain Project as a model
and summarizes an accident scenario study performed by the Department
of Energy (DOE) in their Environmental
Impact Statement for the Yucca Mountain Project.
For this study, the DOE examined all of the accidents that could possibly
occur on the system. These possible accidents ranged from human initiated
acts such as fires, explosions, or aircraft crashes, to natural phenomenon
such as seismic activity, or extreme weather, to such internal accidents
such as human error, or system failure. They then put together a series
of sequences that could lead to any accidents that would result in the
leakage of radioactive materials. They calculated the probabilities of
all of the events in the sequence and from that, obtained probabilities
for each of the events.
The DOE next analyzed the magnitude of radiation the each of four classifications
of individuals would be exposed to. The first classification is the involved
worker, who is a factory worker who is directly involved in activities
at the location where the accident occurs. The second classification is
the maximally exposed noninvolved worker. This worker is assumed to not
be involved with the accident, but works at the plant. He must be at least
100 feet downwind of the site of the accident when it occurs. The third
classification is the maximally exposed offsite individual. This person
is assumed to be between 8 to 11 kilometers from the site of the accident
(the calculated maximum offsite point of radiation exposure). The analysis
of this type of person is different from the other three because this
individual is only assumed to be exposed to a single dose of radiation
because this person is not supposed to be on the government land. The
final classification of people is the offsite people. This group of people
is characterized by people who are within 80 kilometers of the site.
Overall, the DOE studied ten possible scenarios for two possible conditions:
50th percentile meteorological conditions and 95th percentile meteorological
conditions. Fiftieth percentile meteorological conditions are those that
have conditions more severe than then 50% of the time, 95th percentile
meteorological conditions are only surpassed 5% of the time. The shown
graphs represent the results found by the DOE.8
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Radiological consequences of accidents at the Yucca
Mountain site for 50th percentile meteorological conditions. Source
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Radiological consequences of accidents at the Yucca Mountain site
for 95th percentile meteorological conditions. Source
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