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Transmutation of All German Transuranium under Nuclear Phase Out Conditions - Is This Feasible from Neutronic Point of View?

Merk B, Litskevich D - PLoS ONE (2015)

Bottom Line: A basic insight for the optimization of the time duration of the deep burn phase is given.Further on, a detailed balance of different isotopic inventories is given to allow a deeper understanding of the processes during transmutation in the molten salt fast reactor.The effect of modeling and simulation is investigated based on three different modeling strategies and two different code versions.

View Article: PubMed Central - PubMed

Affiliation: Institute of Resource Ecology, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany.

ABSTRACT
The German government has decided for the nuclear phase out, but a decision on a strategy for the management of the highly radioactive waste is not defined yet. Partitioning and Transmutation (P&T) could be considered as a technological option for the management of highly radioactive waste, therefore a wide study has been conducted. In the study group objectives for P&T and the boundary conditions of the phase out have been discussed. The fulfillment of the given objectives is analyzed from neutronics point of view using simulations of a molten salt reactor with fast neutron spectrum. It is shown that the efficient transmutation of all existing transuranium isotopes would be possible from neutronic point of view in a time frame of about 60 years. For this task three reactors of a mostly new technology would have to be developed and a twofold life cycle consisting of a transmuter operation and a deep burn phase would be required. A basic insight for the optimization of the time duration of the deep burn phase is given. Further on, a detailed balance of different isotopic inventories is given to allow a deeper understanding of the processes during transmutation in the molten salt fast reactor. The effect of modeling and simulation is investigated based on three different modeling strategies and two different code versions.

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Related in: MedlinePlus

Cycle averaged k deviation (left) and burnup dependent keff values in each cycle (right)over the whole operation time.
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pone.0145652.g005: Cycle averaged k deviation (left) and burnup dependent keff values in each cycle (right)over the whole operation time.

Mentions: The multiplication factor in the calculation of the cycles is controlled during transmuter operation as well as in the deep burn phase. This task is performed via the feeding of fissile material which has to be adopted during the life of the reactor several times to keep the cycle averaged multiplication factor always in a band of ± 0.005 around criticality. This process of continuous insertion of fissile material to compensate the burnup of fissile material will take place in the real reactor, too. However, the process will be performed in a more continuous way than in the simulation. This kind of process is typical for all kinds of reactors with the possibility of continuous feeding, like molten fuel reactors or pebble bed high temperature reactors. The curve for the deviation of the averaged multiplication factor swings in the given band of ± 0.005 around criticality during the whole observation period of more than 80 years (see Fig 5, left). The Δk curve stabilizes in the transmuter operation after around20 years. This is a consequence of the increasing amount of TRUs in the core (see Fig 6) during the transmuter phase. The increasing amount of even plutonium isotopes (seelater dicussion) plays the major role. These isotopes act as fertile material for the breeding of new fissile material. The mostly fertile isotopes accumulate to an asymptotic amount in the first 10 to 20 years of operation. This process leads to the significantly increased TRU content in the core, compared to the starting value and causes the observed stabilization. The effect can be observed in the averaged Δk curve (Fig 5, left) as well as in the burnup dependent keff values in each cycle (Fig 5, right).


Transmutation of All German Transuranium under Nuclear Phase Out Conditions - Is This Feasible from Neutronic Point of View?

Merk B, Litskevich D - PLoS ONE (2015)

Cycle averaged k deviation (left) and burnup dependent keff values in each cycle (right)over the whole operation time.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4696651&req=5

pone.0145652.g005: Cycle averaged k deviation (left) and burnup dependent keff values in each cycle (right)over the whole operation time.
Mentions: The multiplication factor in the calculation of the cycles is controlled during transmuter operation as well as in the deep burn phase. This task is performed via the feeding of fissile material which has to be adopted during the life of the reactor several times to keep the cycle averaged multiplication factor always in a band of ± 0.005 around criticality. This process of continuous insertion of fissile material to compensate the burnup of fissile material will take place in the real reactor, too. However, the process will be performed in a more continuous way than in the simulation. This kind of process is typical for all kinds of reactors with the possibility of continuous feeding, like molten fuel reactors or pebble bed high temperature reactors. The curve for the deviation of the averaged multiplication factor swings in the given band of ± 0.005 around criticality during the whole observation period of more than 80 years (see Fig 5, left). The Δk curve stabilizes in the transmuter operation after around20 years. This is a consequence of the increasing amount of TRUs in the core (see Fig 6) during the transmuter phase. The increasing amount of even plutonium isotopes (seelater dicussion) plays the major role. These isotopes act as fertile material for the breeding of new fissile material. The mostly fertile isotopes accumulate to an asymptotic amount in the first 10 to 20 years of operation. This process leads to the significantly increased TRU content in the core, compared to the starting value and causes the observed stabilization. The effect can be observed in the averaged Δk curve (Fig 5, left) as well as in the burnup dependent keff values in each cycle (Fig 5, right).

Bottom Line: A basic insight for the optimization of the time duration of the deep burn phase is given.Further on, a detailed balance of different isotopic inventories is given to allow a deeper understanding of the processes during transmutation in the molten salt fast reactor.The effect of modeling and simulation is investigated based on three different modeling strategies and two different code versions.

View Article: PubMed Central - PubMed

Affiliation: Institute of Resource Ecology, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany.

ABSTRACT
The German government has decided for the nuclear phase out, but a decision on a strategy for the management of the highly radioactive waste is not defined yet. Partitioning and Transmutation (P&T) could be considered as a technological option for the management of highly radioactive waste, therefore a wide study has been conducted. In the study group objectives for P&T and the boundary conditions of the phase out have been discussed. The fulfillment of the given objectives is analyzed from neutronics point of view using simulations of a molten salt reactor with fast neutron spectrum. It is shown that the efficient transmutation of all existing transuranium isotopes would be possible from neutronic point of view in a time frame of about 60 years. For this task three reactors of a mostly new technology would have to be developed and a twofold life cycle consisting of a transmuter operation and a deep burn phase would be required. A basic insight for the optimization of the time duration of the deep burn phase is given. Further on, a detailed balance of different isotopic inventories is given to allow a deeper understanding of the processes during transmutation in the molten salt fast reactor. The effect of modeling and simulation is investigated based on three different modeling strategies and two different code versions.

Show MeSH
Related in: MedlinePlus