ANL/FPP/TM-128 THE IMPACT OF ALTERNATE FUSION FUELS OK FUSION REACTOR TECHNOLOGY An Initial Assessment Study FUSION POWER PROGRAM Aiftnit MctioMl Latentary 97M Suva Uss AVMW U. S. Bflpirtwun if Ewf|y ArfMM, !tf TW8 SOCgf^lT IS TABLE OF CONTENTS Pa ABSTRACT vi 1.0 Introduction ...... 1 1.1 Study Objectives 2 1.2 Study Methodology > 2 1.3 Brief Review of Advanced Fuel Cycles 3 2.0 Plasma Engineering 9 2.1 Introduction. 9 2.2 Tokamak Concepts Studies. ........ 9 2.2.1 Background and Motivation. 9 2.2.2 The Tokamak Global Code 10 2.2.3 Field and Current Limitations. 11 2.2.4 Cat-D Tokamaks 13 2.3 FRM Concept Studies 15 2.4 Cyclotron Radiation Considerations 21 2.4r.l Introduction 21 2.4.2 Effects of Nonunifortn Plasma Fro files 22 2.4.3 Effects of Holes in the Wall 32 2.5 Review of the p-6Li Fusion Chain Reaction 34 2.5.1 Introduction 34 2.5.2 The p-5Li Fusion Chain Reaction 35 2.5.3 Energy Balance 36 2.5.4 Neutron and Radioactive Ash Yields 39 2.6 Summary of Typical Power Splits and Sensitivity Studies 42 2.6.1 Typical Power Splits 42 3.0 Engineering/Technology Considerations. .. ..... 49 3,1 Materials, First-Wall and Blanket Considerations. .... 49 3.1.1 First-Wall Surface Effects 50 3.1.2 Structural Materials 52 3.1.3 Candidate Coolants » . 52 3.1.4 General First-Wall/Blanket Design Considerations . 53 Table of Contents (cont'd.) Page 3.2 Nuclear Analysis 54 3.2.1 Scope of Analysis 56 3.2.2 Radiation Damage to the First Wall 61 3.2.3 Blanket and Shield Performance 64 3.2.4 Radiation Damage to Superconducting Magnets .... 71 3.2.5 Neutron Energy Spectra in Alternate Fuel Systems. 74 3.2.6 Reactor Activation and Environmental Impact .... 74 3.2.7 Biological Shielding 84 3.2.8 Major Penetration Shielding . 87 3.3 Tritium and Fuel Processing Considerations 92 3.3.1 Fuel Cycle Considerations 92 3.3.2 Vacuum Pumping 96 3.3.3 Fuel Processing and Tritium Safety. 96 3.3.4 Fuel Supply 98 3.3.5 Costs . 99 3.3.6 Conclusions 100 3.4 Magnet Design Considerations for Alternate Fuel Tokamak Reactor 100 3.4.1 Geometrical Limits on Plasma Current and Toroidal Field 100 3.4.2 Irradiation Effects on Nb3Sn Superconductors. 102 3.5 Safety 102 4.0 Summary and Conclusions 110 List of Figures Number Page 1-1 Reaction parameters and cross sections for various fusion reactions. The reaction parameter is average over a Maxwellian ion distribution. The curves shown for p-6Li, p-9Be, and p-1:lB contain large uncertainties. Five strong D-6Li reactions occur with different <ov>, but all lie near or below p-eLi 4 2-1 Ignited fully-catalyzed deuterium tokamaks which are consistent with field and current limitations and Alcator scaling for 6=0.10 14 2—2 Ignited fully-catalyzed deuterium tokamaks which are consistent with field and current limitations and Alcator scaling for g = 0.06 15 2-3 The FRM confinement scheme displaying both closed and open field line regions 17 2—4 Magnetic field model for a field-reversed mirror. The closed field region essentially has a toroidal shape and is embedded in an external open-type mirror field ... 17 2-5 Containment of fusion products in the FRM as a function of plasma radius (a) and vacuum magnetic field (B ) 19 2—6 Labeling of first few azimuthal angles for polar angle 6. 25 2-7 Power loss spectra for plasma with nonuniform profiles ... 29 2-8 Power loss spectra for plasma with uniform profiles .... 30 2-9 Power loss (arbitary units) as a function of hole fraction. Same plasma as in Fig. 3, with R = .95 34 2-10 Chain reaction for p-6Li 35 2-11 Normalized fusion and Bremsstrahlung power vs. temp- erature 39 3-1 Importance of the source neutron energies on dose in epoxy - insulator 55 3-2 Importance of the source neutron energies on biological hazard potential 57 3-3 Effect of Bremsstrahlung radiation on nuclear heating structural material: 316 stainless steel . 63 3-4 Effect of alternate fuel systems on shielding require- ment structural material: 316 stainless steel .. 66 3-5 Effect of alternate fuel systems on shielding require- ment structural material: V-15Cr-5Ti 67 3-6 Effect of alternate fuel systems on shielding require- ment structural material: T14381 68 List of Figures (cont'd.) Number Page 3-7 A comparison of alternate fuel systems on neutron spectrum in blanket structural material: 316 stainless steel ..... .... 75 3-8 A comparison of alternate fuel systems on fraction spectrum in blanket structural material: 316 stainless steel 76 3-9 A comparison of alternate fuel systems on biological hazard potential structural material: 316 stain- less steel 80 3-10 A comparison of advanced fuel systems on biological hazard potential structural material: V-15Cr-5Ti 81 3-11 A comparison of alternate fuel systems on biological hazard potential structural material: T14381 82 3-12 Isotopic contribution to BHP-alr in Cat-D system structural material: 316 stainless steel 83 3-13 A comparison of alternate fuel systems on 63Ni isotope contribution to BHP-air, structural material: 316 stainless steel ..... 85 3-14 Effect of alternate fuel systems on biological shield requirement on normal concrete, structural material: 316 stainless steel 86 3-15 A comparison of alternate fuel system on biological dose at reactor shutdown, structural material: 316 stainless steel 88 3-16 A comparison of alternate fuel systems on penetration shield requirement, structural material: 316 stain- less steel 90 3-17 Effect of alternate fuel systems on biological shielding during reactor operation 91 3-18 Fuel cycle scenario for Cat-D 93 3-19 Tritium facility scenario for Cat-D .... 94 3-20 Fuel processing cycle for D-3He 95 3-21 Maximum plasma current and toroidal fields for alternate fuel tokamak reactors 101 3-22 Relative effect of Ti4381 structural material on different alternate fuel systems 104 3-23 Relative effect of V-15Cr-%ti structural material on different alternate fuel systems. 3-24 Relative effect of 316 stainless steel sti -tural material on different alternate fuel systems ..... 105 List of Tables Number Page 1-1 Fuel Characteristics 5 1-2 Fuel/Confinement Alternatives 7 2-1 Reference Tokamak Reactor Designs 12 2-2 Reference FRM Reactor Designs 20 2-3 Neutron and Radioactive Ash Yields as a Function of Temperature for p-6Li 41 2-4 Power Splits for Tokamaks 44 2-5 Power Splits for FRM 44 2-6 Power Splits for Cat-D Tokamak 46 3-1 Comparison of Power Splits and Allowable Wall Loadings for Alternate Fuel Cycles „ 49 3-2 Thermal Stress Factors for Candidate Structural Alloys . 53 3-3 Characteristics of the Alternate Fuel Systems Studied. 58 3-4 Structural Material Composition ... 59 3-5 System Dimensions and Material Compositions ....... 60 3-6 Nuclear Radiation Response Rates at the First Wall .... 62 3-7 Shielding Performance of Alternate Fuel Systems for a Total Integral Wall Load of 30 MW-yr/m2 69 3-8 System Energy Multiplication of Advanced Fuel Systems per Source Neutron ......... ... 70 3-9 Maximum Response Rates in Superconducting Magnets .... 72 3-10 A Comparison of Short-Term Radiological Impacts of Alternate Fuel Systems 78 3-11 Fuel Processing Requirements for Alternate Fusion Fuel Cycles 97 3-12 Tritium Inventories (g) 98 3-13 Estimated Tritium and Vacuum Costs ($M) for Various 2500 MWth Reactors 99 ABSTRACT The initial results of a study carried out to assess some of the technology implications of non-D-T fusion fuel cycles are presented. The primary emphasis in this report is on D-D, catalyzed-D and D-3He fuel cycles. Tokamaks and field-reversed mirrors have been selected as sample confinement concepts. A new technique of employing neutronic computer codes to study the transport of cyclotron radiation for cases of non-uniform density and temperature profiles is described. The technology areas con- sidered include first wall design considerations, shielding require- ments, fuel cycle requirements and some safety and environmental considerations. Conclusions resulting from the study are also presented. 1.0 Introduction This report describes the initial results of a program to examine the fusion reactor technology impacts of non-deuterium/tritium fusion fuel cycles. A variety of elements other than deuterium and tritium can undergo fusion; examples include D-D, D-3He, 3He-3He, p-6Li, p-7Li, D-6Li, and p-11B. These fuels have, in varying degree, the generic features of reduced neutron pro- duction, increased fusion energy carried by charged particles, and the elimi- nation of a need for tritium breeding. On the other hand, the combination of lower cross sections, higher plasma temperature, lack of availability of some fuels (3He), and increased radiation losses make efficient confinement (i.e., high energy multiplication) more difficult. A key consideration then is whether or not the advantages are indeed sufficient to justify the develop- ment of alternate fuel power plants. A quantitative evaluation of the tech- nology involved must be undertaken. Deuterium-based fuels have the advantage of operating at relatively low temperatures but involve more neutron and tritium production via "side" D-D reactions. Lower temperature deuterium based fuels, being easier to burn, are compatible with a wide range of confinement concepts; for example, tokamaks could burn catalyzed deuterium and D-3He. (Catalyzed deuterium refers to burning deuterium such that the reaction products of tritium and 3He are also burned at a rate equal to its birth rate.