THORIUM AS AN ENERGY SOURCE - Opportunities for Norway ...

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Thorium as an Energy Source - Opportunities for Norway 5. NUCLEAR REACTORS FOR THORIUM The thorium isotope, Th-232, is not fissile which means that it cannot undergo fission if bombarded with thermal neutrons. On the other hand, Th-232 is fertile which means that new fissile material uranium-233 (U-233) can be produced by irradiating thorium in a nuclear facility. Like uranium-238 (U-238), the Th-232 isotope can be used in the nuclear fuel cycle as fertile material. Thorium-232 absorbs neutrons in the epithermal region and U-233 is produced via the decay of protactinium (Pa-233): The Thorium-Uranium Fuel Cycle: 232 233 233 233 Th + n → Th (22 min) → Pa (27 days) → U (159 200 years) Analogous to The Uranium-Plutonium Fuel Cycle: 238 239 239 239 U + n → U (23.5 min) → Np (2.4 days) → Pu (24 110 years).Figure 5.1 shows the relevant isotopes in the thorium fuel cycle. 38 Figure 5.1: Relevant Isotopes in the Thorium Cycle.
5.1 Properties of the Fertile Material Thorium-232 Nuclear Reactors for Thorium Thorium-232 (Th-232) has many absorption resonances in the epithermal energy region (see Figure 5.2). These resonances cause the strong negative temperature coefficient of all reactors which contain this material and are designed in an appropriate manner. The absorption of neutrons in Th-232, followed by two successive beta decays, result in breeding of U-233. In the thermal energy region the absorption cross section of Th-232 ((n,γ)-reaction) is about 20 % larger than that of U-238. Above a threshold energy of 1.2 MeV (mega electronvolt) neutron capture will lead to direct fission of thorium however with a very small cross section (see Figure 5.3). Figure 5.2: Absorption Cross Section of Thorium-232 (Th-232) in the Epithermal Neutron Energy Region. Figure 5.3: Fission Cross Sections at High Neutron Energies of the Isotopes Thorium-232 (Th-232), Uranium-238 (U-238), Plutonium-240 (Pu-240) and Plutonium-242 (Pu-242). The formation of a high quantity of Pa-233 (half-life of 27 days) makes a management of Pa-233 necessary to optimize U-233 production in thermal reactors where the neutron balance is tight. This Pa isotope may not only decay to the fissile U-233, but may also be converted to Pa-234 via a (n, γ)-reaction with a high reaction cross section (110 barn). This leads to a significant loss with regard to the recovery of new fissile material. In addition, it causes a delayed reactivity increase after shutdown. 39
Page 1 and 2: 2008 THORIUM AS AN ENERGY SOURCE -
Page 3 and 4: TABLE OF CONTENTS Table of Contents
Page 5 and 6: Table of Contents 14.2 APPENDIX B2:
Page 7 and 8: The Thorium Report Committee was gi
Page 9 and 10: Foreword energy area. The price vol
Page 11 and 12: 1. EXECUTIVE SUMMARY Executive Summ
Page 13 and 14: Radiation Protection of Man and the
Page 15 and 16: Executive Summary nuclear engineeri
Page 17 and 18: Introduction In the context of such
Page 19 and 20: 2.3 The EU Situation Introduction T
Page 21 and 22: Oil, Gas, NGL, Condensate (Million
Page 23 and 24: TWh 160 150 140 130 120 110 100 90
Page 25 and 26: Figure 2.8: Number of Operating Rea
Page 27 and 28: Tonnes 1 200 000 1 000 000 800 000
Page 29 and 30: US $ / kg UF 6 160 140 120 100 80 6
Page 31 and 32: 2.8 Worldwide Activities on Thorium
Page 33 and 34: 1. Alkaline complexes and their peg
Page 35 and 36: Thorium Resources in Norway The tho
Page 37 and 38: Thorium Resources in Norway The pot
Page 39 and 40: Thorium Resources in Norway A serie
Page 41 and 42: 4.1.1 Mining and Extraction The Fro
Page 43 and 44: The Front End of the Thorium Fuel C
Page 45 and 46: The Front End of the Thorium Fuel C
Page 47: 4.3.2 HTGR Fuel Performance The Fro
Page 51 and 52: Nuclear Reactors for Thorium Table
Page 53 and 54: 5.3.1 Light Water Reactor (LWR) Nuc
Page 55 and 56: Nuclear Reactors for Thorium 2. Cyc
Page 57 and 58: 5.3.2.4 Gas Turbine-Modular Helium
Page 59 and 60: Figure 5.7: General Layout of the A
Page 61 and 62: 5.4.2 Generation IV Reactors Nuclea
Page 63 and 64: Nuclear Reactors for Thorium econom
Page 65 and 66: Nuclear Reactors for Thorium • Ad
Page 67 and 68: Nuclear Reactors for Thorium temper
Page 69 and 70: Nuclear Reactors for Thorium Figure
Page 71 and 72: Nuclear Reactors for Thorium the de
Page 73 and 74: Nuclear Reactors for Thorium remova
Page 75 and 76: Nuclear Reactors for Thorium result
Page 77 and 78: The most important drawbacks of the
Page 79 and 80: Nuclear Reactors for Thorium mater
Page 81 and 82: 6. THE BACK END OF THE THORIUM FUEL
Page 83 and 84: The Back End of the Thorium Fuel Cy
Page 97 and 98: 8. REGULATION The use of thorium as
Page 99 and 100:
• Safety, security and emergency
Page 101 and 102:
Regulation • The Agreement betwee
Page 103 and 104:
Non-proliferation Nations with secu
Page 105 and 106:
Economical Aspects conventional rea
Page 107 and 108:
11. Radioecology 12. Decommissionin
Page 109 and 110:
Research, Development, Education an
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Conclusions and Recommendations tho
Page 119 and 120:
13. APPENDIX A: INTRODUCTION TO NUC
Page 121 and 122:
14. APPENDIX B: NUCLEAR REACTOR TEC
Page 123 and 124:
Figure 14.3: Boiling Water Reactor
Page 125 and 126:
Appendix B: Nuclear Reactor Technol
Page 127 and 128:
Table 15.1: The Current Course Pack
Page 129 and 130:
• N12 Reactor Thermal Hydraulics,
Page 131 and 132:
16. APPENDIX D: RADIATION PROTECTIO
Page 133 and 134:
Regulations on Radiation Protection
Page 135 and 136:
”Section 4. (Licence for nuclear
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2. Dues shall be paid for the super
Page 139 and 140:
use the best available technology s
Page 141 and 142:
Summary: Legislation that is or may
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216 Po α 0.145 s 6.906 (805) 212 P
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18. ACRONYMS AND ABBREVIATIONS Acro
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Po polonium Po-208 polonium-208 Po-
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19. REFERENCES References Chapter 2
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References [35] J.D. SEASE et al.,
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References [68] E. Merle-Lucotte, D
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References [97] "On-going activites
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References [122] L. CINOTTI, “Inh
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References [149] M. Crick, UNSCEAR,
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