System and safety studies of accelerator driven transmutation ... - SKB

Finally, to build one or several Fast Reactors (FR) which are reportedly
very effective as transuranium burners.
The last option, Fast Reactors as transuranium burners, has been deliberately left
unexplored in this report.
Several scenarios have been modeled with a help of the FCA code:
Phase-out scenario;
BWR MOX burners;
PWR MOX burners;
ADS MOX burners;
BWR + ADS MOX burners.
A very general conclusion has been made about BWR MOX reactors being more
efficient in burning plutonium in the form of MOX fuel. In this respect BWR reactors
supersede PWR ones by approximately 10%. In addition, BWR reactors produce
about 10% less americium inventory. However, neither BWRs alone nor PWRs alone
are capable of incinerating 99% of TRU.
It was found that ADS reactor park can theoretically in the ideal case burn 99% of
transuranium isotopes. The duration of this scenario heavily depends on the time
needed for cooling the spent fuel. If we assume 10 years of cooling the nuclear waste
from ADS, the scenario duration becomes at least 200 years under most optimistic
technical assumptions. On the other hand, the use of advanced pyro-processing with a
cooling time of only 2 years dramatically decreases the incineration time down to 50
years only. Moreover, ADS reactors have turned out to be a necessary component to
decrease the americium inventory because neither BWR nor PWR alone can provide
prevalence of americium destruction over its production during the operation time.
Nevertheless, the economic advisability of these scenarios calls for further
investigation.
In addition, a combination of MOX1->MOX2->ADS has been found more
efficient (approximately by 10%) in reducing the transuranium inventory.
Economic analysis of various scenarios has been performed under a number of
simplifying assumptions. It has been found that the MOX scenario is more than twice
as expensive as ordinary UOX fuel cycle. On the other hand, ADS burners reduce this
factor down to about 1.5, in other words electricity produced after year 2025 at a
hypothetical combination of BWR MOX reactors together with ADS MOX reactors
appears to be approximately 50% more expensive in comparison with the nowadays
situation. However, the cost for permanent disposal and monitoring of the spent fuel
in the phase-out scenario has not been taken into account.
This study has been separately published by SKB in 2006 [21]
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