Transition from Thermal to Fast Reactors
5.2 Parametric Study concerning FRs
5.2.3 Reprocessing options
In the previous paragraphs, it has been indicated that reprocessing options give an effect on the composition of the fresh fuel loaded in FRs. In order to clarify this point, the ESFR case has been considered and two different reprocessing options (related to the reprocessing start-up date) have been adopted.
The FRs start-up date is maintained fixed to 2080, but the reprocessing plant start-up date has been fixed to: 1) two years before the FRs start-up, or 2) once the LWRs spent fuel has been produced (i.e. the first SF from LWRs is discharged in 2025 and therefore, taking into account 5 years of cooling before reprocessing, the first material reprocessed would be in 2030).
Assuming the same energy demand as described in Figure 5.2, where ESFR plants are introduced for maximizing the energy share, one of the parameters affected by the reprocessing option is the Pu balance in Pu stock as indicated in Figure 5.37.
0 20 40 60 80 100
2040 2060 2080 2100 2120 2140 2160 2180 2200
Pu balance in Pu stock (tons)
years
Parametric study: reprocessing option Start−up in 2030
Start−up in 2078
Figure 5.37: Impact of the reprocessing option on the Pu stock balance
From Figure 5.37 is clear that the Pu needed for the FRs start-up when reprocessing plant starts working close to 2080 is lower than in the case of early reprocessing start-up: the Pu that remains in Pu stock is slightly higher as indicated by Figure 5.38 (zoom of Figure 5.37 for the period 2090-2110).
In addition, the quantity of Pu in stock (represented by the peaks in 2080) is much lower in the case with
reprocessing start-up close to FRs introduction. The Pu remains in stock for less time (additional favorable aspect: good also from proliferation resistance point of view) because once reprocessed it is used for the fabrication of new FR fuel. The annual mass treated by the fabrication capacity (both FRs and LWRs) is independent from the reprocessing options adopted16(see Figure 5.39). Only the composition of the fuel fabricated is changed on the basis of the Pu vector in Pu stock.
0
Pu balance in Pu stock (tons)
years
Parametric study: reprocessing option
Start−up in 2030 Start−up in 2078
Figure 5.38: Impact of the reprocessing option on the Pu stock balance: zoom for the period 2090-2110
The behavior indicated in Figure 5.38 is related to the composition in stock (affected by Am241 and Np237 build-up) and to the way in which fresh fuel is calculated.
As indicated in Figure 5.40 and Figure 5.41, the build-up of Am241 and Np237 when is drastically reduced shifting the reprocessing start-up date close to FRs introduction date.
The differences in term of Pu241 and Am241 are respectively presented in Figure 5.42 and Figure 5.44.
These behaviors substantially impact the Pu and MAs content in the fresh batches.
In fact, according to the COSI6 procedure for core reloading, the presence of Am241 and Np237 in the Pu stock is reflected in MAs loading in fresh batches and in an increased Pu content for maintaining the same criticality level (evaluated in COSI6 on the basis of the "Pu239 equivalent" as previously described).
The Pu and MAs content in the fresh fuel for the two cases is compared in Figure 5.43 and Figure 5.45.
The adoption of closed reprocessing start-up date reduced the MAs content of the first batches from 2%
(mainly Am) to 0.2-0.3%.
More details about the MAs and Pu content versus scenario are indicated in Table 5.15.
The adoption of a reprocessing start-up date close to the FRs introduction date gives better results in terms of Pu and MAs content loaded in core as indicated in Figure 5.43 and Figure 5.44. However it implies that reprocessing plants works at its maximal capacity during the first years in order to produce enough material for the fast reactor start-up.
16For the study, the fabrication plant has been modeled with "unlimited" capacity to follow the needs of the reactors. The fabrication start-up date (both for LWR and FR fuel) has been considered fixed.
0 50 100 150 200 250
2020 2040 2060 2080 2100 2120 2140 2160 2180 2200
Annual Fabrication Capacity (tons)
Years
Parametric study: reprocessing option EPR fuel (start−up reprocessing in 2030)
EPR fuel (start−up reprocessing in 2078) ESFR fuel (start−up reprocessing in 2030) ESFR fuel (start−up reprocessing in 2078)
Figure 5.39: Annual fabrication capacity assuming different options for reprocessing start-up: LWR and FR fuels
0 1 2 3 4 5 6
2040 2060 2080 2100 2120 2140 2160 2180 2200
Pu balance in Pu stock (tons)
years
Parametric study: reprocessing start−up in 2030 Pu241
Am241 Np237
Figure 5.40: Composition in Pu stock: reprocessing start-up in 2030
0 0.5 1 1.5 2 2.5 3 3.5 4
2080 2100 2120 2140 2160 2180 2200
Pu balance in Pu stock (tons)
years
Parametric study: reprocessing start−up in 2078
Pu241 Am241 Np237
Figure 5.41: Composition in Pu stock: reprocessing start-up in 2078
0 0.5 1 1.5 2 2.5 3 3.5 4
2040 2060 2080 2100 2120 2140 2160 2180 2200
Pu balance in Pu stock (tons)
years
Parametric study: Pu241 in Pu stock
Start−up in 2030 Start−up in 2078
Figure 5.42: Pu241 content in Pu stock: comparison between reprocessing start-up dates
14.5 15 15.5 16 16.5 17
2080 2100 2120 2140 2160 2180 2200
Pu content in fresh fuel (%)
years
Parametric study: reprocessing start−up Start−up in 2030 Start−up in 2078
Figure 5.43: Pu content in fresh fuel assuming different reprocessing start-up options
0 1 2 3 4 5 6
2040 2060 2080 2100 2120 2140 2160 2180 2200
Am balance in Pu stock (tons)
years
Parametric study: Am241 in Pu stock
Start−up in 2030 Start−up in 2078
Figure 5.44: Am241 content in Pu stock: comparison between reprocessing start-up dates
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2
2080 2100 2120 2140 2160 2180 2200
MA content in fresh fuel (%)
years
Parametric study: reprocessing start−up
Start−up in 2030 Start−up in 2078
Figure 5.45: MAs content in fresh fuel assuming different reprocessing start-up options
Start-up 2030 Start-up 2078
year Pu content MAs content Pu content MAs content fresh fuel
2080 16.96% 2.01% 15.90% 0.01%
2090 15.69% 1.15% 15.37% 0.26%
2120 15.24% 0.07% 15.29% 0.04%
2150 15.21% 0.04% 15.22% 0.03%
2190 15.24% 0.07% 15.24% 0.08%
spent fuel
2086 17.30% 1.44% 16.28% 0.43%
2096 16.56% 1.14% 16.04% 0.54%
2126 15.84% 0.39% 15.88% 0.36%
2156 15.86% 0.33% 15.84% 0.32%
2196 15.88% 0.32% 15.88% 0.32%
2206 15.90% 0.32% 15.89% 0.32%
Table 5.15: Pu and MAs content in fresh and spent fuel versus reprocessing option
Different situation appears when reprocessing operation starts once the SF is generated in LWRs. The reprocessing annual capacity follows the LWR SF inventory annually discharged behavior.
In order to compare the two approaches the contribution of the LWR and FR reprocessing has been taken into account separately. The comparison between the reprocessing annual capacity based on different reprocessing options is shown in Figure 5.46 where the behaviors above described are visible. Concerning FRs reprocessing annual capacity, the two approaches lead to results which are in very good agreement (in both cases SF coming from FRs is reprocessed once it has been created). The comparison is summarized in Figure 5.47.
0 100 200 300 400 500 600 700 800 900
2040 2060 2080 2100 2120 2140 2160 2180 2200
HM treated (tons)
Years
Annual Reprocessing capacity: SF from LWRs Start−up in 2030 Start−up in 2078
Figure 5.46: Annual reprocessing capacity assuming different options for reprocessing start-up: LWR fuel reprocessing plant
The differences are mainly related to the annual reprocessing capacity during the first years of FRs introduction. In fact the cumulative LWR SF reprocessing capacity for the two options is fully comparable, as expected and indicated in Figure 5.48.
0 20 40 60 80 100 120
2040 2060 2080 2100 2120 2140 2160 2180 2200
HM treated (tons)
Years
Annual Reprocessing capacity: SF from FRs Start−up in 2030 Start−up in 2078
Figure 5.47: Annual reprocessing capacity assuming different options for reprocessing start-up: FR fuel reprocessing plant
0 2000 4000 6000 8000 10000
2040 2060 2080 2100 2120 2140 2160 2180 2200
Cumulative HM reprocessed (tons)
years
Parametric study: reprocessing options
Start−up in 2030 Start−up in 2078
Figure 5.48: Cumulative reprocessing capacity for LWRs assuming different reprocessing options