INVESTIGATION OF AN INERTIAL CONFINEMENT FUSION-FISSION HYBRID REACTOR

1. INVESTIGATION OF AN INERTIAL CONFINEMENT FUSION-FISSION HYBRID REACTOR Kiranjit Mejer PTNR Research Project 2009 Frazer-Nash Consultancy University of Birmingham INVESTIGATION OF AN INERTIAL CONFINEMENT FUSION-FISSION HYBRID REACTOR

2. The Basic Concept Fusion neutron source D + T → α + n + 17.6 MeV (n energy 14.1 MeV) Sub critical fission blanket Neutron multiplier blanket Reflector Benefits of a Hybrid Waste transmutation – reducing inventory of HLW Production of energy Development of fusion technology Inherent safety The Fusion-Fission Hybrid Reactor

3. Laser Inertial confinement Fusion-Fission Energy Engine • Inertial confinement fusion source • Surrounded by Beryllium blanket • Spherical blanket of sub-critical fission fuel • Graphite blanket • Pb-Li first wall coolant • FLiBe (2LiF+BeF2) coolant • Power conversion system Image from ”Thermal and Mechanical Design Aspects of the LIFE Engine” R P Abbot et al, 2009

4. Pure 9Be – 1.85 gcm-3 Peak at 17 cm blanket thickness Factor ~ 2.06 Pebble packing fraction 60 % - 1.11 gcm-3 Factor ~ 1.81 at 16 cm Supported by “A Sustainable Nuclear Fuel Cycle Based on Laser Inertial Fusion Energy” Moses et al, 2009 Multiplication Factor of Be Blanket

5. Fuel Blanket Investigation • Below - Energy gain from fission blanket of natural Uranium 19.1 gcm-3 surrounding a Beryllium blanket • Above - Energy gain from fission blanket of pure 238U

6. Neutron energy entering the fission blanket ~ 0.05 at 14 MeV Large proportion at thermal energies Maxwell-Boltzmann distribution peaks at 0.025 eV Spectrum of neutrons returning from reflector shows same form Energy Spectrum of Neutrons

7. coated particles embedded in graphite matrix SiC High - density Pyc radius 1 cm Buffer layer (C) 30% TRISO 70% Carbon Outer radius 0.5 mm Kernel radius 0.3 mm Other Fuel Options • Fuel composition based on graphite pebbles containing TRISO particles Image adapted from http://blogs.princeton.edu/chm333/f2006/nuclear/trisoball.jpg

8. Fission blanket energy gain and criticality

9. Coolant Effects • First wall coolant Pb83Li17 • Primary coolant FLiBe (2LiF + BeF2) 6Li + n → 4He + T + Q 7Li + n → 4He + T + n’ – Q • Tritium Breeding Ratio (TBR) – ratio of T produced to consumed • For self sufficiency TBR > 1.05 • Requires 6Li enrichment of 50% or more

10. Improvements to the Model Geometry – structural materials etc Fuel blanket compositions Temperatures Number of neutron histories Other fuel fabrication options Time dependent nature of the reactor - evolution of fuel with breeding from fertile isotopes - flattening power output with 6Li content Project Extensions

11. Summary • Demand for clean, abundant energy and concerns over HLW management have led to renewed interest in the hybrid concept • MCNP modelling has demonstrated the viability of a number of fuel options particularly SNF • Enrichment of 6Li content in coolants can provide tritium self sufficiency for the reactor • Timescale for LIFE machine large

12. www.fnc.co.uk

13. Isotropic, monoenergetic neutron point source Pb-Li first wall coolant Beryllium multiplier blanket Fission Blanket Graphite reflector Stochastic approach - uses random number generation and reaction cross section data to determine the ‘history’ of a particle Many histories followed to give a representation of a real world situation MCNP Model