Neutronic Feasibility of a Breed & Burn Molten Salt Reactor

Transcription

1 Neutronic Feasibility of a Breed & Burn Molten Salt Reactor A. KASAM, E. S HWAGERAUS Serpent User Group Meeting Milan September, 206

2 Objectives. Demonstrate possibility of breed & burn operation in a system with separate molten salt fuel and coolant 2. Compare performance with benchmark system: TWR 3. Thermal-hydraulic analysis in OpenFOAM 2

3 System Description BBMSR : Breed & burn molten salt reactor Separate fuel & coolant salts (based on Moltex SSR) Fast breeding of fissile Pu from natural U Partially burned regions contribute neutrons to fresh fuel Image: I. Scott, T. Abram, and O. Negri, Stable Salt Reactor Design Concept, in Proceedings of the Thorium Energy Conference, (Mumbai, India),

4 Overview of Analysis Homogeneous 2-D unit cell in SERPENT Benchmark vs. initial BBMSR configuration Increase HM loading Absorption balanceà low-capture version Reduce scattering 4

5 Benchmark: Traveling Wave Reactor 35 vol% U2Zr metal fuel 50 vol% sodium coolant 5 vol% T9 cladding.4.2 Pin cell burnup in Serpent: k-inf Burnup (MWd/kg) Image: T. Ellis, et. al, Traveling-Wave Reactors: A Truly Sustainable and Full-Scale Resource for Global Energy Needs, International Congress on Advances in Nuclear Power Plants,

6 Starting BBMSR configuration 64 vol% fuel: 40 mole % UCl 3 (natural U) 60 mole % NaCl 2 vol% KF-ZrF 4 -NaF coolant 5 vol% molybdenum cladding k-inf Pin cell burnup in Serpent: TWR Starting BBMSR mm Diameter & Pitch Burnup (MWd/kg) 6

7 Increase relative HM loading Increase tube diameter Increase UCl 3 concentration D = 0mm D = 50mm D = 75mm D = 00mm D = 50mm % UCl 3 60% UCl 3 80% UCl 3 00% UCl k-inf k-inf Burnup (MWd/kg) Burnup (MWd/kg) 7

8 Neutron Absorption Balance Natural Enriched TWR BBMSR BBMSR Fission: Σ f 2.77E-03.8E-03.4E-03 Pu % 77.52% 77.74% U % 0.42% 0.00% Pu % 5.23% 5.35% Pu24.79% 5.86% 5.99% Capture: Σ c 3.9E E E-03 U % 39.8% 46.62% Pu %.2% 2.64% Pu % 3.96% 4.63% Nat-Mo % ( 94 Mo) 0.7% Nat-Zr 0.4% 2.58% ( 90 Zr) 0.00% Cl35-2.5% ( 37 Cl) 0.54% Natural materials: 40% capture in 238 U 7.5% capture in natural Mo, Zr, Cl Relatively low capture in fission products Enriched BBMSR: 47% capture in 238 U 0.7% capture in 94 Mo, 90 Zr, 37 Cl 8

9 Low-capture BBMSR 0.9 k still < Nat. Materials BBMSR Low-Capture BBMSR Many holes remain in spectrum # Nat. Materials BBMSR Low-capture BBMSR k-inf Volume Normalized Flux Burnup (MWd/kg) Energy (MeV) 9

10 Chloride coolant: MgCl 2 -NaCl-KCl Cl coolant hardens spectrum BBMSR k >! Potential for LEU version # F-cooled BBMSR Cl-cooled BBMSR.5 TWR BBMSR with natural U BBMSR with 20% eriched U BBMSR with Th Volume Normalized Flux 2.5 k-inf Energy (MeV) Burnup (MWd/kg) 0

11 Neutronics Summary Neutronically feasible BBMSR identified using Serpent burnup calculations and detectors 50 mm tube 00% UCl 3 Enriched Mo & Cl Chloride coolant May not need all! TBD Ongoing: Trade-off study with low-enriched U in fuel salt à may allow operation with natural Cl, smaller diameter, etc.

12 Thermal-hydraulic modelling Natural convection of heat-generating fluid a tricky problem! Momentum (Boussinesq approximation) Energy 2

13 TH result in OpenFOAM * To be coupled to Serpent model diameter, power density? 3

14 Thanks! To you, for listening! To the Cambridge Trust and Winston Churchill Foundation of the United States, for funding Questions? 4

15 Backup

16 NaCl-UCl 3 Melting point Image: R. E. Thoma, Phase diagrams of nuclear reactor materials, tech. rep., Oak Ridge National Laboratory,

17 Homogeneous vs Heterogeneous 7

18 BBMSR versus BBSFR TWR - example 35 vol% U2Zr fuel 5 vol% T9 cladding 50 vol% Na coolant % UCl 3 BBMSR High-density BBMSR BBSFR 0.8 High density BBMSR 238 U and 235 U nuclide densities from BBSFR Conclusion: fuel density is not the only weakness! k-eff Burnup (MWd/kg) 8

19 Fuel: 00% ThCl % UCl 3 00% ThCl k-inf Burnup (MWd/kg) 9