The FuTure oF nuclear Fuel cycle - MIT Energy Initiative

is that it will be many decades before the U.S. adopts a closed fuel cycle, and thus the possibility
exists that a geological repository for disposal of wastes will be sited before implementation
of any closed fuel cycle. This creates the option of collocation and integration of reprocessing
and fuel fabrication, with the repository facilities, which could result in potentially major
reductions in closed fuel cycle costs and risks. It enables technical options for termination of
safeguards on wastes containing fissile materials. Collocation and integration of back-end fuel
cycle facilities may also aid the siting of future repositories. A reprocessing-fabrication facility
would provide many more direct and indirect jobs than would a geological repository. It is not
known if the benefits of collocating and integrating backend facilities are sufficiently large to
drive fuel cycle choices.
In the 1950s it was thought that the cost of the closed fuel cycle would be low. This was partly
based on the experience of reprocessing defense SNF at the Hanford site with onsite disposal
of wastes. However, the improper disposal of those wastes resulted in high-cost remedial action
programs. By the 1960s it was understood that geological disposal should be used for the
ultimate disposal of many wastes. In the 1960s and early 1970s, the U.S. government encouraged
private construction of reprocessing and fuel fabrication facilities. Because no geological
repository existed, there was no option for collocation of reprocessing, fabrication, and repository
facilities. Reprocessing, fabrication, and repository facilities would be separately located.
Separate siting of closed fuel cycle reprocessing and fabrication facilities necessitates storage
and transport of wastes to the geological repository. In turn, these requirements favor
reprocessing and fabrication processes being chosen to minimize waste volumes. However,
by the 1980s it was recognized that the costs of geological repositories for the disposal of
low-heat wastes (clad and hardware, transuranics, low-level, failed equipment, etc.) would
be inexpensive but that the costs of disposal of high-heat wastes (spent nuclear fuel and
high-level waste) would be significant. Most of the wastes from reprocessing and fuel fabrication
plants are low-heat wastes. If the reprocessing and fabrication plants were collocated
and integrated with the repository [1], the restrictions on waste volumes for low-heat
wastes would be dramatically relaxed with several impacts.
p Cost. Relaxation of waste volume constraints enables the use of lower cost processes in
reprocessing (such as the chemical decladding of SNF that was done at Hanford) and
fabrication plants. The recognition that collocation of backend facilities could result in
significant cost savings resulted in German plans [2] in the 1970s to collocate and integrate
all fuel cycle facilities at Gorleben—their proposed repository site. Because of the
German decision to use a once-through fuel cycle, that option was never implemented.
p Risk. Facility collocation eliminates some shipping and storage requirements (except
storage of HLW before disposal). Facility integration has the potential to significantly
reduce the process complexity by reducing the requirements to minimize waste volumes
with resultant reductions in potential accident risks.
p Repository performance. The relaxation of waste volume constraints allows lower waste
loadings in final waste forms. This, in turn, (1) enables the use of waste forms with potentially
superior performance but that for technical reasons have low waste loadings, (2)
reduces radiation damage to the waste form over time and (3) allows isotopic dilution of
solubility-limited radionuclides to boost performance.
204 MIT STudy on The FuTure oF nuclear Fuel cycle