less than the ADS, resulting in longer transmutation era and larger remaining TRU.
Figure 19.12 shows amounts of TRU excluding vitrified MA. An amount of the
ADS scenario is reduced to 125 t after the first generation of the transmutation era
from 2050 to 2110. In the FBR scenario, equal decrement is achieved after the
second generation. Very high MA content up to 15 % in the FR fuel is also
problematic. The decrement of the FR+ADS scenario is as same as that of the FR
scenario until the second generation, but after that the decrement becomes faster
because of ADS introduction.
Although transmutation performance of the FR is inferior to the ADS, cost
including profit of electricity generation by transmuter would be much smaller
than the ADS because the number of ADSs is doubled, accelerator cost is added,
and thermal efficiency of the ADS is worse. Considering high MA content in the FR
scenario, the FR+ADS scenario can be a modest solution, although the ADS
scenario is preferable if rapid transmutation is required regardless of the cost.
19.5 Conclusion
With consideration of the phase-out option from NP utilization in Japan, an ADS
for Pu transmutation was designed and scenario analysis introducing it was
performed. The ADS was designed based on the existing design of the ADS for
MA transmutation considering two options of Pu supply: pure Pu and a mixture of
the same amount of Pu and U from the reprocessing plant for the LWR. After
designing a one-batch core with large criticality drop, a six-batch core with a short
operation day was analyzed. The criticality drop of the six-batch core was small
enough in the equilibrium state. Several maintenance cases were assumed, and
0
50
100
150
200
250
300
350
400
2000
2050
2100
2150
2200
2250
2300
Available TRU (t)
A.D.
FR
ADS
FR+ADS
1st
4th
2nd
3rd
Fig. 19.12 Trans-uranium (TRU) amount available for transmutation in transmutation scenarios
excluding minor actinides (MA) vitrified in waste
19 Transmutation Scenarios after Closing Nuclear Power Plants
229