A new conceptual blanket design for a fusion reactor produces fissile material for fission power plants. Fission is suppressed by using beryllium, rather than uranium, to multiply neutrons and also by minimizing the fissile inventory. The molten-salt breeding media (LiF+BeF2+ThF4) is circulated through the blanket and on to the online processing system where 2 "u and tritium are continuously removed. Helium cools the blanket including the steel pipes containing the molten salt. Austenitic steel was chosen because of its ease of fabrication, adequate radiation-damage lifetime, and low corrosion rate by molten salt. We estimate the breeder, having 3000 MW of fusion power, produces 6400 kg of " 3 U per year, which is enough to provide make up for 20 GWe of LWR per year (or 14 LWR plants of 4440 MWt) or twice that many HTGRs or CANDUs. Safety is enhanced because the afterheat is low and the blanket materials do not react with air or water. The fusion breeder based on a pre-MARS tandem minor is estimated to cost $4.9B or 2.35 times an LWR of the same power. The estimated present value cost of the " 3 U produced is $40/g if utility financed or tl6/g i f government f inanced. the tokamak. The particular tandem mirror design is based on a pre-MARS design 5. The plant parameters are given in Table I. The technologies used are listed in Table II.

11. Heat transport system (overhead view) 2' 12. Heat transport system (side view) , 25 13. Steam generator arrangement 1-1. Helium-cooled molten-salt fusion breeder using beryllium as neutron multiplier , 35 2-1. Ring headers for the supply and return helium 38 2-2. Molten-salt breeding blanket (cross section) 39 2-3. Molten-salt breeding blanket showing support hangers and salt tubes 40 2-4. Alternate design for module end 44 2-5. Axially oriented salt pipes 46 2-6. Tokamak module and piping arrangements 49 2-7. Poloidal pod orientation 50 2-8. Oetail of blanket cross section for poloidal pod orientation 51 ?-9. Blanket cross section of poloidal pod orientation 52 2-10. Annusl beryllium cost versus pebble size 59 2-11. Unit cell calculational model for molten salt blanket 62 2-12. Power densities in beryllium/molten-salt blanket 69 ix Temperature profile for steam generator 174 ft fusion-fission electricity-generation system Reference fusion breeder with liquid-metal-cooled blanket 186 x LIST OF TABLES I. Plant parameters for the described fusion-breeder design II. Technologies employed in the fusion-breeder design III. Beryllium requirements for the molten-salt blanket IV. Calculated breeding performance V. Composition and properties of blanket salt. 12 VI. Heat-transport system of blanket VII. Economic analysis 2-1. Nominal pebble/tube parameters 2-2. Beryllium requirements for the molten-salt blanket 2-3. Estimated costs of components for processing beryllium pebbles 2-4. Nuclear performance of the unit cell (MSHE series) 2-5. Comparison of unit cell data for molten-salt/beryllium/ helium cell and reference berylliumfthorium/lithium cell. 64 2-6. Cylindrical-model TART calculations. 2-7. Power density in new Be-MS-Fe blanket at unit first-wall loading {first estimate) 2-8, Estimated helium-loop pumping-power distribution 82 2-9. Composition and properties of the blanket salt, using three concentrations of ThF, 83 2-10. Electrode potentials of container materials in Li 2 BeF 4 (600°C) 86 2-11. Operating conditions of stainless steel thermal-convection loops involving LiF-BeFp-based molten salts 89 3-1. Nomenclature ana symbols for Section 3.0 " 108 3-2. Equations representing tritium permeation aata in metals 113 3-3. Thermal regime for molten-salt reactor tube. ., 122 3-4. Tritium permeation from molten-salt reactor tubes without axial flow 124 3-5. Permeation from the molten-salt loop for three design options 134 xi Pebble volume 470 m Fsbble quantity 0 890 x 10 6 Pebble mass 0.96 g Beryllium mass 860 tonne Average beryllium lifetime 5 yrs. Annu?l pebble throughput 180 x 10 /yr Annual beryllium mass throughput 170 tonne/yr 27-m central cell, 3000 KH fusion power, 0.6-m-thick blanket starting at 1.5-m radius, and a 2 HW/m wall load. 10% of blanket volume is tubes; 60% packing in remainder of blanket. c 1-cm-diameter pebbles. 1.84 g/cm beryllium density. Each neutron multiplication reaction in beryllium yields two neutrons and two alpha particles (helium nuclei). Most of these helium atoms remain trapped in t...

This is in informal reporf intended primarjly for internal or limited c-xirnuJ distribution. The opinions and conclusions stated are those of the author and may or may not be those of ibe Laboratory-Work performed under the auspices of the 115. Department of Energy by Itit Lawrence Mvenaore National Laboratory under Contract W-7405-Eng-46. tmmmi SF ms w.m JS KLCTS

This ti i prtfttM of i paper in rmffd for pvbUctUon in • jour Ait cr protMdmgs Smt* chanp« mij hi made before publication, ihu preprint * made naiUMc «i(h the un drf.1 anding thai it will not be ciled or u-produred *J|J»JIJ| Ihf permission of the author.

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