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

4.92
Severe accidents resulting from extreme impacts and a prolonged loss of cooling to a
design load of fuel assemblies could release significant amounts of radioactive material.
Such an accident was estimated to occur once every 50,000 years. Seventy-year accumulated
doses to the maximum-exposed individual of 130 rem and 140 man-rem to local populations
excluding the maximum-exposed individual would result from such an accident involving
6-month cooled fuel. However, with fuel that has been cooled for several years before ship-
ment (as planned for the once-through fuel cycle), an accident of this severity is not
plausible. In a separate study of fuel transportation accidents (DOE/EIS-0015), it is
reported that a maximum-exposed individual would receive a 50-yr accumulated dose of only
about 0.4 rem from such an accident involving 4-yr cooled fuel (0.6 rem for a 70-yr dose).
4.8.1.2 Radiological Impacts from Unpackaged Spent Fuel Storage Accidents
The example concept for interim spent fuel storage is a 3000-MTHM capacity away-from-
reactor storage facility (AFR). Eighteen accidents were postulated for the receipt and
storage of unpackaged spent fuel at an AFR: eight minor, seven moderate and three severe.
Accident details are described in DOE/ET-0028, Section 5.7. Eight accidents were determined
to have potential for release of radioactive material. Four of the eighteen accidents relate
to the operation of off-gas systems at the AFR. These accidents are not discussed here
because releases from this system would be smaller than accidental releases from the dissol-
ver off-gas system in the fuel reprocessing plant (Section 4.8.2.1) that were designated as
the umbrella source terms. (Those releases result in an estimated 70-yr accumulated dose to
the maximum-exposed individual of 2 x 10 -3 rem.)
Releases resulting from minor accidents were added to expected annual operational
releases for this facility based on their estimated frequencies.
Moderate accidents include fuel-handling mistakes, dropped transport casks and uncon-
trolled venting of rail casks. Releases from these accidents are smaller than those from a
packaging facility accident, which is designated as the umbrella source term discussed in
Section 4.8.1.3. (Those releases result in less than 3 x 10 -5 rem accumulated dose to the
maximum-exposed individual during the 70 years after the accident.)
A strike by a design-basis tornado, a criticality event in storage, and a loss of cool-
ing were considered severe accidents at an AFR. The postulated criticality is estimated to
occur only once every 100,000 years and results in an estimated 70-yr dose to the maximum-
exposed individual of 5 x 10-2 rem.
4.8.1.3 Radiological Impacts Due. to Accidents at a Fuel Packaging Facility
A fuel packaging facility (FPF) will be required to prepare fuel for disposal in the
once-through cycle. The fuel packaging facility may be colocated with either the AFR, a
packaged fuel storage facility or a spent fuel disposal facility. Radiological impacts
that result from accidents at the packaging facility are not dependent on its location.