The FuTure oF nuclear Fuel cycle - MIT Energy Initiative

Figure 6.10 total amount of tru in the System (base case)
16,000
MThM
12,000
8,000
oTc
MoX
Fr cr=0.75
Fr cr=1.00
Fr cr=1.23
4,000
0
2010
2020 2030 2040 2050 2060 2070 2080 2090 2100 2110
Time (year)
p In the breeder scheme: TRU producers (LWR) are replaced by TRU producers (Fast
Breeders), which adds to the overall growth in TRU inventories, and end up with a higher
total inventory than the once-through cycle.
As seen in Fig 6.10, starting from a total TRU inventory of 840 tHM (600 tHM in interim
storage, 125 tHM in cooling storage, and 115 tHM in LWR cores), the inventory reaches
11,785 tHM in the OTC scenario in the year 2100. However, adoption of the MOX scheme
reduces the inventory by a small amount, while the fast burner reactors yield further reduction.
The breeder on the other hand ends up increasing the TRU inventory in the entire
system slightly above the OTC case.
As can be seen in Figure 6.11 for the self-sufficient fast reactor case at the intermediate
growth rate of 2.5%, once the TRU legacy is depleted, the TRU becomes mainly located
in the cooling storage (at-reactor pools) and in the reactor cores themselves. To the extent
the reactor cores may be considered more secure than interim storage, there is some advantage
from a proliferation point of view. Additionally, little TRU is sent to the repository
compared to the Once-Through option. However, if at some point in the future the nuclear
energy system starts being abandoned in favor of an alternative energy source, the TRU
inventory in the entire system will have to be dealt with. Some of it will be used as fuel in
the reactors operating at that time. However, a disposal option will be needed at some point
in the future, or pure burners will have to be deployed for many decades to reduce the TRU
inventory.
impaCt on repoSitory needS
Although the recycling options dramatically reduce the total mass of wastes (95% w of the
spent UO 2 fuel is recovered and recycled), they do not eliminate the necessity of a deep
repository, as fission products and unrecoverable TRU amounts (losses) still have to be disposed
of. Figure 6.12 shows the total mass of HLW destined to a repository in the various
schemes for the base growth case. In the recycling schemes, the assumption of 1% unrecoverable
heavy metals is made. Recall that the repository is assumed to open in 2028 and
HLW is sent to disposal 25 years after it is generated.
chapter 6: analysis of Fuel cycle options 87