Management of Commercially Generated Radioactive Waste - U.S. ...

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4.8 ACCIDENT IMPACTS FOR PREDISPOSAL OPERATIONS
The environmental impacts of accidents that occur during operation of predisposal sys-
tems for both the once-through cycle and for the reprocessing cycle are described in this
section. Potential accidents for the predisposal functions of treatment and/or packaging,
transport, and storage are discussed here for both cycles.
The environmental impacts of accidents described in this section are representative of
impacts from all postulated predisposal accidents. Using a methodology of accident identi-
fication and classification that included an umbrella source term, we selected the largest
source term in classified release categories for environmental impact analysis. Results of
this analysis are summarized here. Umbrella source terms are a conservative representation
of releases that result from other accidents in their release category. A description of
the methodology used to develop and select umbrella source terms for impact analysis is
given in Section 3.2.7. Unless specified otherwise, the maximum-exposed individual in the
following discussion is considered to be a member of the general public, not a radiation
worker. Accident impacts are generally greater to the public than to the workers.
4.8.1 Accident Impacts for the Once-Through Cycle
This section describes the impacts of postulated accidents for handling spent fuel
until it is placed in the disposal facility. Operational and long-term accident impacts
from spent fuel disposal are discussed in Sections 5.5 and 5.6.
While extended storage of packaged spent fuel is not included in the example case, it
may be desired if the operation of the disposal facility is delayed longer than is now
expected. Therefore, analysis of accident impacts of packaged spent fuel storage are
included as a contingency.
4.8.1.1 Radiological Impacts from Spent Fuel Transportation Accidents
Safety during transport of radioactive material depends primarily on shipping contain-
ers. Shipping containers must meet standards established by the Department of Transpor-
tation and the Nuclear Regulatory Commission. Containers holding significant amounts of
radioactive material must prevent loss or dispersal of radioactive contents, retain shield-
ing efficiency, ensure nuclear criticality safety, and provide adequate heat dissipation
under normal conditions of transport and under specified (hypothetical) accident damage test
conditions (49 CFR 173.398). Improbable accidents that exceed the severity of hypothetical
tests, accidents caused by equipment failures and accidents that are less severe than the
test conditions were considered in this analysis to demonstrate the range of potential
occurrences in a transportation environment. Impacts of these accidents are summarized
below.
Recent regulations for the shipment of spent fuel require that all shipments of spent
fuel be escorted in transit; while severe accidents involving this material are still pos-
sible, the chances of occurrence will be reduced with this required increased surveillance.
Chances of a period of no action by emergency response personnel following an accident,