International Thorium Energy Conference 2015 (ThEC15) BARC, Mumbai, India, October 12-15, PDF Free Download

International Thorium Energy Conference 2015 (ThEC15) BARC, Mumbai, India, October 12-15, 2015 Feasibility and Deployment Strategy of Water Cooled Thorium Breeder Reactors Naoyuki Takaki Department of Nuclear Safety Engineering 1

Contents Background and Motivations Core design of water cooled thorium breeder Deployment strategy Synergetic system with U-Pu reactors Proliferation resistance of Th cycle Generation cost Concluding remarks 2

Thorium Resource Map 100 170 440 290 5 16 35 World wide 1500 thousand tons 410 http://www.targetmap.com/ 3

Energy Potential of Thorium It is often said that thorium is more abundant in nature than uranium. It is true but the current identified quantity is comparable with that of uranium. Assuming thorium use in breeder type reactors, energy of ~10 6 GWy could be potentially added. equivalent to 1,000 LWRs operation for several 1,000 years To achieve this, enough fissile material needed to ingnite wet (fertile) thorium. 4

Objective / Motivations Develop water-cooled, oxide-fueled thorium breeder reactor Why water/oxide? well-established established plant/fuel technology Why breeder? make full use of resource for world sustainability Why thorium? Diversify fission energy resource Smaller MA production Breeding potential with negative void effect No severe energetics during CDA 5

Breeder type thorium reactors Shippingport PWR (USA) Past studies AHWR (India) RBWR (Hitachi, UCB) Our study PHBR (PWR with tight pitch fuel & D 2 O) (TCU) Moderator Light water Heavy water Light water Heavy water Breeding Ratio 1.0 0.65 1.025 >1.05 Total Burnup 15 GWd/t 24 GWd/t 45 GWd/t 70GWd/t Core Heterogeneous Design Pressure tube Axial hetero Homogeneous Movable fuel with blanket No blanket Pin gap - - Very tight 1mm > 2.5 mm Void Coeff. Negative Negative Negative Negative Shutdown Margin Enough Enough Not enough Enough 6

Design window of H2O cooled thorium breeder 60 Limit line for negative VRC Geometrical gap limit (>1mm) for triangular 50 40 Limit line for breeding 30 20 Shippingport, LWBR 10 0 0 0.5 1 1.5 Moderator to Fuel Volume Ratio (MFR) [-] 2 8

Design window of D2O cooled thorium breeder 60 50 40 30 Limit of negative void reactivity Limit of breeding 20 10 00 MFR 1.0 Feasiblewindow area of of breeding Design breeding and negative void reactivity And negative void reactivity 5 10 15 20 Moderator to Fuel Ratio [-] 25 30 9

Reactor / fuel type comparison 10 Reactor type Coolant Fuel type BLBR (BWR with tight pitch) PHBR (PWR with tight pitch) H 2 O D 2 O U-Pu oxide Th-Pu oxide Th-U233 oxide BLBR : Boiling Light water Breeder Reactor PHBR : Pressurized Heavy water Breeder Reactor

Fissile Inventory Ratio with Burnup for PHBR 1.4 U-Pu_11.5w% U-Pu_12.5w% 1.3 1.2 1.1 MFR 0.8 1.0 1.0 0.4 0.6 0.2 U-Pu_13.5w% Th-Pu_15w% Th-Pu_15.6w% Th-Pu_17w% 11 0.9 0.8 0.7 MFR=1.0 0.8 0.6 0.4 0.2 0.6 0 50 100 150 200 250 0.00001 0.50001 1.00001 1.50001 2.00001 2.50001 Achievable Burnup [GWd/t]

Fissile Inventory Ratio with Burnup for PHBR 12 1.4 U-Pu_11.5w% U-Pu_12.5w% 1.3 U-Pu_13.5w% Th-Pu_15w% Th-Pu_15.6w% 1.2 Th-Pu_17w% 1.1 0.8 0.6 0.6 0.4 0.2 Th-U233_6.6w% Th-U233_7.2w% Th-U233_7.7w% 1.0 1.0 1.0 0.2 0.9 1.0 0.8 0.7 0.2 0.6 0.00001 0 0.50001 1.00001 100 1.50001 150 2.00001 200 2.50001 250 Achievable burnup [GWd/t]

Detailed enrichment survey (PHBR, ThTh-233U fuel) 1.2 7.4w% 7.6w% 7.7w% MFR=0.4 1.1 7.2w% MFR=0.5 MFR=0.6 6.6w% MFR=0.8 1 MFR=1.0 Achievable burnup [MWD/t] 0.9 0 0 20 20,000 40 40,000 60 60,000 80 80,000 100 1,00,000 120 1,20,000 140 1,40,000 13

Reactor / fuel type comparison 14 Reactor type Coolant Fuel type BLBR (BWR with tight pitch) PHBR (PWR with tight pitch) H 2 O D 2 O U-Pu oxide Th-Pu oxide Th-U233 oxide BLBR : Boiling Light water Breeder Reactor PHBR : Pressurized Heavy water Breeder Reactor

Fissile Inventory Ratio & Burnup for BLBR 15 1.2 1.1 1.0 0.2 0.9 0.8 0.7 0.6 0.5 MFR=1.0 0.2 MFR=1.0 Th- 233 U MFR=1.0 Th-Pu U-Pu_10.4w% U-Pu_11.5w% U-Pu_12.5w% Th-Pu_13.7w% Th-Pu_15w% Th-Pu_15.6w% Th-U233_5.5w% Th-U233_6.7w% Th-U233_7.7w% 0.4 0 0 50,000 50 100 150 1,00,000 1,50,000 2,00,000 200 250 300 2,50,000 3,00,000 Achievable burnup [GWd/t]

Doppler coefficients 16 1.0E-05 0.0E+00-7.0E-20 Reference BWR -1.0E-05-2.0E-05 U-Pu -3.0E-05 Th-Pu -4.0E-05-5.0E-05 Th-U233-6.0E-05-7.0E-05 0.2 0.4 0.6 0.8 1 MFR BLBR -1.0E-05-2.0E-05-3.0E-05-4.0E-05 05-5.0E-05-6.0E-05-7.0E-05 Th-U233 Reference BWR U-Pu Th-Pu 0.2 0.4 0.6 0.8 1 MFR PHBR Reference BWR Kashiwazaki-Kariwa Unit2, TEPCO

Void coefficients 17 1.0E-03 1.0E-03 5.0E-04 0.0E+00 U-Pu 5.0E-04 0.0E+00 U-Pu -5.0E-04-1.0E-03 Th-Pu Reference BWR -5.0E-04-1.0E-03 Th-Pu Reference BWR -1.5E-03-1.5E-03 Th-U233-2.0E-03-2.5E-03 Th-U233-2.0E-03-2.5E-03-3.0E-03 0.2 0.4 0.6 0.8 1 MFR BLBR Reference BWR Unit2, TEPCO -3.0E-03 Kashiwazaki-Kariwa 0.2 0.4 0.6 0.8 1 MFR PHBR

Core specifications of PHBR U-Th fuel (282) D2O reflector (96) B4C control rod (19) 18

Fuel specifications of PHBR U-Th fuel (282) D2O reflector (96) B4C control rod (19) 19

Control rods U-Th fuel (282) D2O reflector (96) B4C control rod (19) 20

Cladding material integrity Evaluated fast neutron fluence : 2.87 1022 n/cm2 because of long cycle length (1,300 3 days) with hard spectrum Limitation for Zircaloy-4 : 1.5 1022 n/cm2 U-Pu FBR Th-Pu D2O PWR Th-U233 D2O PWR UOX LWR Other cladding material that can withstand higher fluence with small σa has to be employed. SiC 21

Impacts of SiC clad. on keff and CR SiC Zircaloy SiC Zircaloy 22

Impacts on core performances Zircaloy-4 SiC Burnup reactivity loss %dk/kk -1.81-1.38 Control rod worth %dk/kk 13.58 13.67 Av. discharged bunup GWd/ton 74.47 74.60 Fissile Inventory Ratio 1.039 1.056 By changing cladding material to SiC, neutronic performances were improved. 23

Void reactivity coefficient (cm) 370 250 170 0 Zone wised local void coefficients at EOEC Zircaloy case (%dk/kk /%void) SiC case (%dk/kk /%void) Coefficients are negative all over the core. 24

Neutron fluence and spectrum 1.6E+01 Zircaloy SiC 1.4E+01 1.2E+01 Fast fluence 1.0E+01 Limitation Zircaloy-4 2.87 1022 < 1.5 1022 SiC 2.88 1022 < 8.0 1022 8.0E+00 6.0E+00 4.0E+00 2.0E+00 0.0E+00 1.E-04 1.E-02 1.E+00 1.E+02 Neutron Energy [ev] 1.E+04 1.E+06 25

Deployment scenario Current phase Natural uranium UOX Fuel Fabrication LWR Reprocessing Disposal Thorium Pu (Th,Pu)O 2 Fuel Fabrication Th/Pu (Th,Pu)O 2 Fueled PHBR? Reprocessing Disposal Transition phase U-233 Th/U-233 Breeder phase Thorium (Th,U-233)O 2 Fuel Fabrication (Th,U-233)O 2 Fueled PHBR Reprocessing Disposal 27

Replacement of UU -LWR by Th Th--HPWR 60 50 40 U-LWR 30 Th-233U PHBR 20 10 Th-Pu PHBR 0 0 20 40 60 80 100 Years 60GWe U-LWRs can be replaced within a century. 28

Reprocessing capacity and SF amount 1800 45,000 1600 40,000 1400 35,000 Stored SF of U-LWR 1200 30,000 1000 25,000 800 Reprocessing capacity for U-LWR 600 400 Pu supply 20,000 from LWR exhausted within15,000 a century. SF generated from U-LWR SF from Th-U3 PHBR 200 10,000 5,000 SF from Th-Pu PHBR 0 0 20 40 Years 60 0 80 Deployable capacity of PHBR depends on Pu stockpile Installed UU -LWR capacity Reprocessing capacity 100 29

Contents Background and Motivations Core design of D 2 O cooled thorium breeder Deployment strategy Synergetic system with U-Pu reactors Proliferation resistance of Th cycle Generation cost Concluding remarks 30

Synergetic system with UU -Pu reactors Sustainable energy system with matured plant technology Diversified fission resources Efficient MA transmutation & easier fuel handling (less heat) Better energy balance than ADS 31

Indice for difficulties in diversion Critical Mass Enrichment technology Implosion technology Heat production U-235 48kg Required Not required None Pu (Weapon grade) 10kg Not required Required Small U-233 (Weapon grade) ( 1ppm U-232) 16kg Not required Not required Small 33

Cost impact Cost reduction factors No need for enrichment (vs. LWR) Proven PWR plant technology (vs. FBR) Cheaper resource (vs. UO 2 fuel) Cost increase factors Heavy water coolant (vs. LWR) Tritium production (vs. LWR) Challenging reprocessing technology (vs. UO 2 fuel) High gamma fuel handling (vs. UO 2 fuel) 35

Cost evaluation of PHBR Power output Burnup Cycle length Cycle interval Batch number Capacity factor 3450MWt 1340MWe 61.2GWd/t 1,000days 30days 3 97% Parameters assumed Low Nominal High Unit Construction 130 279 428 10 3 yen/kwe Th Fuel 0.01 7.3 15.9 10 6 yen/ton Fabrication 210 262 314 10 6 yen/tonhm Reprocessing 210 262 314 10 6 yen/tonhm 36

Generation cost 6 5 4 O&M cost Capital cost Fuel cost LWR (5.3 yen/kwe) Evaluated by FEPC in 2004. Plant : 1300MWe PWR 3 2 FBR (2.6 yen/kwe) Evaluated by JAEA in 2010. Plant : 1500MWe MOX-FBR 1 0 Low Nominal High 37

Remarks (1/2) Thorium resource is abundant but available fissile mass determines how many thorium reactors can be deployed. Th reserves Energy derived from thorium. Pressurized heavy water breeder reactor (PHBR) with Th-U233 fuel shows breeding capability with high burnup (>60GWd/t) and negative void effect. Tritium and ThO 2 reprocessing are tough challenges. 39

Reamarks (2/2) All LWRs can be replaced by PHBR by using Pu recovered from the LWR s SF within a century. PHBR works both in transition and sustainable phase. Careful examination should be made for proliferation resistance of Th-cycle. Strong gamma High proliferation resistance. Generation cost of thorium fueled PHBR could be competitive with LWR owing to high BU and CF. Further study required to reduce uncertainty. 40

What I want to share Th shows some preferable characteristics but is not magic fuel. It is basically the same as Uranium. Th reactor produces similar nuclear wastes if the cycle is not closed. Closed cycle just minimizes the waste. Scientists must be humble, objective, mustn t exaggerate. 41