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

More documents

Recommendations

Info

Thorium as an Energy Source - Opportunities for Norway Temperature Reactors (HTR). The Atom Versuchs Reaktor (AVR, 50 MWth) was in operation for more than 21 years. In the Thorium High Temperature Reactor (THTR, 750 MWth), 675 000 graphite spheres containing coated fuel particles (~10 g ThO2 / sphere) were used for three years after extensive approval procedures for the thorium fuel. Much of the work was dedicated to the question of high conversion and breeding with thorium cycles. The THOREX (thorium extraction) process for the reprocessing of spent thorium fuel based on the PUREX (plutonium uranium extraction) process was also developed in Jülich. This development ended in the 1970s because breeders seemed superfluous and the US had virtually prohibited all use of highly enriched uranium. Ever since, all developments for modular High Temperature Reactors (HTRs) assume a low enrichment of the fuel (LEU; about 8wt% U-235). Jülich has persistently studied the possibilities of the thorium cycle for e.g. the use in PWRs and in transmutation facilities. Jülich’s know-how covers the production of thorium fuel, the operation of critical reactors and the reprocessing of thorium. The following is based on the report summarizing the German experience [48]. 5.3.2.1 AVR (Atom Versuchs Reaktor) The Atom Versuchs Reaktor (AVR) was the world’s first high temperature gas cooled “pebble bed reactor”, where the spherical fuel elements (“pebbles”) were used for more than 21 years of operation. Thorium containing coated particle fuel was tested extensively with very good success. Different forms of spherical fuel elements and different types of coated particles were tested. Thorium containing fuel elements fulfilled all requirements. The reactor used continuous loading and unloading of fuel elements, and therefore excess reactivity for the compensation of fuel burn-up was not necessary. This is very important for considerations on very severe reactivity accidents. The fuel elements were recycled several times before they reached their final burnup. The AVR experiments demonstrated that the pebble bed reactor concept works and that such a reactor can be operated relatively easily. Many useful and new safety experiments have been carried out, especially the experiments to demonstrate the concept of self-acting decay heat removal, important for all new modular High Temperature Reactors (HTRs) worldwide. About 200 kg of thorium were inserted in the AVR, and the operation showed that there can be attractive features in the use of thorium in nuclear technology in the future [49], [50], [51], [52], [53]. 5.3.2.2 THTR (Thorium High Temperature Reactor) The High Temperature Reactor (HTR) can be operated with different fuel cycles. The fuel consists of the nuclides U-233, U-235, Pu-239, Pu-241 as fissile materials and Th-232, U-234, U-238 as fertile materials. In the pebble bed reactor, these materials can be used in mixed or separated form. Dependent on today’s economic conditions and regarding the situation and perspectives of fuel supply for the next decades, the open cycles (without reprocessing) will have advantages for a time schedule of some decades. With rising costs of uranium the closed cycles (with reprocessing) will become interesting in the far future. Cycles with different enrichments and different breeding materials have been developed and proved in mass tests in the AVR and the THTR. The following cycles are fully developed: 1. Cycles with 93wt% enriched uranium and thorium (high enriched uranium (HEU) cycles). 44
Nuclear Reactors for Thorium 2. Cycles with 20wt% enriched uranium and thorium (medium enriched uranium (MEU) cycles). 3. Cycles with 8wt% enriched uranium and U-238 as fertile material (low enriched uranium (LEU) cycles). Because of the International Nuclear Fuel Cycle Evaluation (INFCE) regulations, cycles with more than 20wt% enrichment are not allowed today because of non-proliferation requirements. Today, for all new HTR projects, LEU cycles are foreseen with around 8wt% enrichment and a burnup of 80 000 to 100 000 MWd/tHM. Based on an HEU/Th concept similar to the THTR fuel elements (moderation ratio: NC/NHM = 325, heavy metal loading: 11.2 g/ball, burnup: 100 000 MWd/tHM, enrichment: ~10wt%) one gets characteristic data of the equilibrium core as given in Table 5.3 below. Table 5.3: Characteristic Data of the Equilibrium Core. Parameter Value Dimension Average Enrichment (at start) 7.16 wt% Burnup 100 000 MWd/tHM Conversion Rate 0.59 - Fissile Material Inventory 917 kg/GWe U3O8-demand (0.25 tail) 462 kg/Gwde Loading U-235 1.81 kg/Gwde Discharging U-233, U-235 and Pa-233 0.51 kg/Gwde Discharging Np-239, Pu-239 and Pu-241 0.002 kg/Gwde Pu(fiss)/Pu(tot) in Discharged Material 19 % In-situ use of Pu-239 and Pu-241 98 % Fast Fluence 5.1 10 21 n/cm 2 These data show that production of plutonium is almost entirely avoided and that the power of the balls and the fast neutron dose stay within allowed limits. The MEU cycle with medium enrichment (< 20wt%) would still be proliferation resistant (see Figure 5.6 for the balance of fissile material during the passage through the reactor). The pebble bed HTR allows major cycle flexibility. During normal operation of the AVR, fuel elements corresponding to 10 different options have been tested in a continuous change without any major changes of plant parameters [48]. The Thorium High Temperature Reactor (THTR) used spherical fuel elements loaded with U-235 (93wt% enriched) as fissile material and Th-232 as fertile material, both in the form of oxides. 45
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 and 48: 4.3.2 HTGR Fuel Performance The Fro
Page 49 and 50: 5.1 Properties of the Fertile Mater
Page 51 and 52: Nuclear Reactors for Thorium Table
Page 53: 5.3.1 Light Water Reactor (LWR) Nuc
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
Page 137 and 138:
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
Page 143 and 144:
216 Po α 0.145 s 6.906 (805) 212 P
Page 145 and 146:
18. ACRONYMS AND ABBREVIATIONS Acro
Page 147 and 148:
Po polonium Po-208 polonium-208 Po-
Page 149 and 150:
19. REFERENCES References Chapter 2
Page 151 and 152:
References [35] J.D. SEASE et al.,
Page 153 and 154:
References [68] E. Merle-Lucotte, D
Page 155 and 156:
References [97] "On-going activites
Page 157 and 158:
References [122] L. CINOTTI, “Inh
Page 159 and 160:
References [149] M. Crick, UNSCEAR,
show all

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

Create successful ePaper yourself

Delete template?

Save as template?