Breeding Capability of Moltex's Stable Salt Reactor. Naoyuki Takaki, Takumi Iida Department of Nuclear Safety Engineering

Transcription

1 Breeding Capability of Moltex's Stable Salt Reactor Naoyuki Takaki, Takumi Iida Department of Nuclear Safety Engineering

2 Contents Recent movement in Japan Why breeder? Moltex s Stable Salt Reactor Pin cell analysis Full core analysis Conclusions 2

3 New strategic energy plan On July 3rd 2018, the Japanese Cabinet approved the 5th Strategic Energy Plan that will guide the national energy policy going forward to 2030 or beyond. Referring to renewable energy as a core power source, it also continues to position nuclear power as an important base-load power source and maintains the current figures of share (20-22%) in FY2030 for Japan s energy mix. 3

4 Renewable Nuclear Geothermal Biomass Wind Solar Hydro LNG Coal Oil Energy mix targeted in

5 5

6 It refers to molten salt reactor for the first time in Chapter 3 Promotion of technology development 溶融塩炉 (Yoyu En Ro) Molten Salt Reactor 6

7 New strategic energy plan Technical challenges to be pursued LWR technology improvement Innovation is necessary to improve safety, reliability and efficiency of nuclear energy To promote this with strategic flexibility, the Cabinet shows visions and keeps watching on SMR and MSR developments progressing in US and EU. This movement was driven by some representatives of the Liberal- Democratic Party stirred up by some enthusiastic thorium evangelists. This seems to affect decisions by Ministries (finance, industry, education) for building budget for MSR studies. 7

8 International forum on MSR was held at members hall of the Liberal-Democratic Party on June Presentaters invited from ThorCon, Elysium Industry and SINAP >200 participants from nuclear Industry 8

9 Activities in Atomic Energy Society of Japan 2010/6-2016/9 2013/6-2018/3 2018/8- Working Group on Utilization of Thorium fuel in LWRs and FBRs (Shinsuke Yamanaka, Osaka University) Specialists committee on Spreading out of molten salt technology to nuclear energy (Michio Yamawaki, University of Tokyo) Specialists committee on Thorium nuclear energy system (Naoyuki Takaki, Tokyo City University) Members: > 40 (Manufacturers, Utilities, Universities, Institues) Purposes: 1. Following up on world trend 2. Comparison between Uranium and Thorium system from scientific and engineering view points 3. Proposal for how Japanese strategy for thorium R&D including MSR ought to be 9

10 Contents Recent movement in Japan Why breeder? Moltex s Stable Salt Reactor Pin cell analysis Full core analysis Conclusions 10

11 Resource utilization factor [%] Resource utilization factor [%] Why breeder? CR>1 Averaged burnup : 7% Recovery loss 1 [%] JSFR CR<1 U-235 enrichment: 5% Burnup: 5% Burner Converter Breeder 3[%] 5[%] maximizing 0,5 0,6 0,7 0,8 resource 0,9 1 1,1 1,2 utilization 1,3 and minimizing wastes, Conversion ratio / Breeding ratio Averaged burnup [%] Monju Breeding with closed cycle is essential for regardless of U or Th, solid or liquid. Recovery loss [%]

12 Stable Molten Salt Reactor (SSR) 12

13 Core specifications of SSR TRU composition (LWR SF, 45-49GWd/t 4years cooling) Nuclides Pu-238 Pu-239 Pu-240 Pu-241 Pu-242 Np-237 Am-241 Am-243 Cm-244 (wt%)

14 Methods Pin cell calculation for parametric survey Full core calculation for core performance evaluation Then Continuous energy Monte-Carlo code Burnup calculation code Nuclear data library MVP-2.0 MVP-burn JENDL

15 k-inf Burnup performance 1,05 1,04 1,03 1,02 1,01 1 0,99 0,98 Reference core (SSR) 0,97Pu enrichment: 30wt% 0,96 0, Burnup [GWd/t]

16 k-inf Burnup performance 1,05 1,04 1,03 Modifications: 1.Chlorine composition : Natural Enriched Cl-37 (to reduce absorption) 1,02 1,01 1 0,99 Cl-37 enriched core Pu enrichment: 27wt% Z 18 0,98 Reference core (SSR) 0,97Pu enrichment: 30wt% 17 0,96 0, Burnup [GWd/t] 16 16

17 k-inf Burnup performance 1,05 1,04 1,03 1,02 1,01 1 0,99 Cl-37 enriched core Pu enrichment: 27wt% Cl-37 enriched + Na cooled core Pu enrichment: 15wt% Modifications: 1.Chlorine composition : Natural Enriched Cl-37 (to reduce absorption) Z 18 2.Coolant material : Fluoride salt Sodium (to mitigate spectrum softening) 0,98 Reference core (SSR) 0,97Pu enrichment: 30wt% 17 0,96 0, Burnup [GWd/t] 16 17

18 s [a.u.] Neutron flux [neutron/cc/sec] Neutron Spectrum and scattering contributers 1,E+16 1,E+15 1,E+14 1,E+13 1,E+12 Cl-37 enriched + Na cooled core Pu enrichment: 15wt% Cl-37 enriched core Pu enrichment: 27wt% Reference core (SSR) Pu enrichment: 30wt% 1,E+11 1,E+10 1,E+01 1,E+02 1,E+03 1,E+04 1,E+05 1,E+06 1,E+07 エネルギー [ev] 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0,0 1,E+01 1,E+02 1,E+03 1,E+04 1,E+05 1,E+06 1,E+07 エネルギー [ev] 冷却塩全体 F-19 Na-23 K-39 K-40 K-41 Zr-90 Zr-91 Zr-92 Zr-94 Zr-96 18

19 Neutron flux [neutron/cc/sec] Neutron Spectrum and η (neutron reproduction factor) 1,E+16 1,E+15 1,E+14 1,E+13 1,E+12 Cl-37 enriched + Na cooled core Pu enrichment: 15wt% Cl-37 enriched core Pu enrichment: 27wt% Reference core (SSR) Pu enrichment: 30wt% 1,E+11 1,E+10 1,E+01 1,E+02 1,E+03 1,E+04 1,E+05 1,E+06 1,E+07 エネルギー [ev] (JENDL-4.0) 19

20 Burnup [GWd/t] Conversion Ratio Pu breeding gain [kg/gwt/y] MA production [kg/gwt/y] Performances 160 1, Burnup [GWd/t] Conversion ratio* 1,1 1 0, Pu breeding [kg/gwt/y] MA production [kg/gwt/y] , ,7 0,6 0, Reference core (SMSR) Cl-37 enriched core Cl-37 enriched + Na cooled core 0,4-100 Reference core (SMSR) Cl-37 enriched core Cl-37 enriched + Na cooled core

21 Full core analysis Thermal output Equivalent core diameter Core height Thickness of axial blanket (upper / lower) 3530MWth 535cm 154.5cm 45cm / 45cm No. of fuel assemblies 574 No. of fuel pins/assembly 61 No. of radial blanket assemblies Assembly pitch Equivalent core diameter Thickness of wrapper duct 288 (with 3 layers) 21.3cm 535cm 0.5cm Fuel assemblies (574) Radial blankets assemblies (288) Control rods assemblies (57) SUS shielding (60cm) 21

22 Breeding ratio (at BOC) Achievable burnup (GWd/t) Breeding & burnup performance UCl 3 /NaCl ratio in blanket region was parameterized (40% 100%) Pu: 30%, UCl 3 /NaCl: 40% BR: 0.84, BU: 26GWd/t Increase in UCl 3 /NaCl ratio Not effective to improve BR Pu enrichment [wt%] UCl 3 /NaCl ratio 100 / 0 70 / / 60 Reduction in Pu enrichment Effective to improve BR But degrading BU 22

23 Why SSR cannot breed? Fluoride salt causes spectrum dip in critical energy range for breeding Cl-35 (76%) in Chloride salt works as parasitic absorber (and produces Cl-36 as long-lived activation products > 4kg/GWt/year) Static salt reactor has smaller fuel volume ratio Any fuel salt contains less fuel material than solid fuel (per volume) Smaller actinide inventory in core means * less fertile smaller fissile production less fissile needs higher enrichment less fertile* large leakage effect needs higher enrichment less fertile* 23

24 Conclusions Separated salt (fuel/coolant) type reactor has advantages to limit circulation area of highly activated materials However, it shows difficulty in breeding due to less HM inventory with large neutron leakage effect If thorium is used for this fast spectrum reactor, worse result estimated Combination of molten salt fuel + liquid metal coolant required for further consideration 24