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Figure II.11 Flow sheet of pyro-reprocessing of spent fuel (ANL/CRIEPI) 1.2.2.2 Pyrochemical separation of transuranic elements from high-level liquid waste The process investigated at CRIEPI to recover transuranic elements from high-level PUREX wastes consists of denitration to oxides, chlorination, reductive extraction and electrorefining in a LiCl- KCl/Cd or LiCl-KCl/Bi system. After denitration and leaching with water to remove the soluble alkalimetal nitrates, the undissolved oxides (mainly of actinides, rare earths and transition metals) and platinum-group metals are converted into chlorides in a bed of LiCl-KCl at above 700°C. The mixed chlorides are reductively extracted or electrorefined in contact with liquid cadmium or bismuth [43,47]. Thermodynamic data for actinides and rare earth elements in this system are needed to establish the separation process. The flowsheet illustrated in Figure II.12 is based on the results of small-scale tests. Electrorefining may be used merely for a rough separation of uranium before counter-current reductive extraction, but can afford a more complete separation between transuranic and rare-earth elements. A small-scale experiment showed that over 99% of each actinide could be recovered from a simulated waste. The treatment of highly-active salt waste is also shown in the figure. The LiCl-KCl mixture can be recycled after purification, while the salts of fission products are electrolytically decomposed and converted to oxides for vitrification in borosilicate glass [48]. The waste produced throughout the process is expected to be minimal, since most of the materials (such as the eutectic salt, cadmium and bismuth metal, and chlorine) will be recycled. As an alternative treatment, waste might be solidified directly into an artificial rock such as zeolite or sodalite with high integrity and leach resistance [49]. Further technological assessment requires a pilot-scale demonstration with the full range of actinides. 136
Figure II.12 Flow sheet of pyrochemical partitioning of TRUs from HLW (CRIEPI) 1.2.3 Condensed actinide-burner cycle: double-strata concept The Japan Atomic <strong>Energy</strong> Research Institute (JAERI) has proposed a P&T scheme based on a double-strata concept in which MAs from the familiar fuel cycle pass to an “actinide burner cycle” for total fission [50]. Here, concentrations of actinides are kept high in nitride fuels to be reprocessed pyrochemically. Nitrides have excellent properties, allowing (a) low fuel temperatures that reduce release of fission gas, and (b) a thinner cladding with consequently harder neutron spectrum than with oxide. Moreover, actinide mononitrides, unlike the metals, are expected to be mutually soluble. The outline of the burner cycle is shown in Figure II.13: • actinide salts from the first stratum are converted to mononitride microspheres by sol-gel techniques. A very high yield is expected. • irradiated nitride fuel is reprocessed by a molten-salt electrorefining technique [51], basically the same as for metal fuels. The highly-enriched 15 N, necessary to minimise production of 14 C, is easily recovered and recycled. • recovered metallic actinides are converted to nitride by direct reaction between liquid cadmium alloys and nitrogen [52]. In a recently devised alternative to this last step, called LINEX (Lithium Nitrate Extraction of Actinides), actinide nitrides are produced in a single step by addition of Li 3 N to the molten salt [53]. It is obtained by direct reaction of Li metal with the 15 N evolved on dissolution of fuel in molten salt. Thus recycling of 15 N is also facilitated. 137
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TABLE OF CONTENTS EXECUTIVE SUMMARY
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TABLE DES MATIÈRES NOTE DE SYNTHÈ
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PART II. TECHNICAL ANALYSIS AND SYS
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4. IMPACT OF P&T ON RISK ASSESSMENT
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Figure II.31 Evolution of the expec
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Part II: Technical analysis and sys
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There are several scenarios which c
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eactor concepts are still in the co
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intermediate storage management, th
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1. INTRODUCTION 1.1 Involvement of
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and natural decay play an important
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Figure I.2 A schematic diagram of b
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Instead of recycling, one could ado
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to address there is the separation
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improvement of the biological shiel
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Figure I.3 A schematic diagram of t
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Figure1.5 A notional materials flow
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A few specific regulatory and safet
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• irradiation of FR-fuel in Fast
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dispersion in the geosphere or bios
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In the meantime the burn-up of spen
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Any reprocessing campaign of spent
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4. CRITICAL EVALUATION • P&T may
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5. GENERAL CONCLUSIONS • Fundamen
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NOTE DE SYNTHÈSE ET PORTÉE DU RAP
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Présentation générale Cette part
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courts. L’application de cette te
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éalisable, à condition d’augmen
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PREMIÈRE PARTIE : PRÉSENTATION G
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La troisième réunion internationa
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1.5 Objectifs du rapport Dans l’e
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Figure I.1 Schéma de principe du c
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• l ’241 Am est le précurseur
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plutonium et environ 2 m 3 de déch
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2.3 Technologie de fabrication des
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cadre de la coopération EFTTRA ont
Page 80 and 81: On peut voir sur la Figure I.4 les
Page 82 and 83: Figure I.4 Flux de matières dans u
Page 84 and 85: À court terme, les produits de fis
Page 86 and 87: Par conséquent, au cas où l’on
Page 88 and 89: De nombreux laboratoires dans le mo
Page 90 and 91: usé devrait représenter environ 3
Page 92 and 93: le nucléide le plus gênant est le
Page 94 and 95: transuraniens. Pour obtenir un taux
Page 96 and 97: On peut considérer des opérations
Page 98 and 99: devrait en principe ouvrir de nouve
Page 101: 5. CONCLUSIONS GÉNÉRALES • La m
Page 105: PART II: TECHNICAL ANALYSIS AND SYS
Page 108 and 109: 1.1.1.1 Minor actinides Americium a
Page 110 and 111: thus preventing its dispersion in t
Page 112 and 113: By contrast, information about the
Page 114 and 115: DIDPA [5] (see Figure II.3) process
Page 116 and 117: The generation of secondary effluen
Page 118 and 119: Figure II.5 TRPO process TRPO solve
Page 120 and 121: According to Jarvinen et al. in LAN
Page 122 and 123: curium. • Separation of americium
Page 124 and 125: 1.1.4.4 Separation of technetium an
Page 126 and 127: The second option is production of
Page 128 and 129: Figure II.9 Fuel cycle actinide bur
Page 132 and 133: The metathetical reaction between L
Page 134 and 135: This is confirmed by the radiotoxic
Page 136 and 137: For the same burn-up as in the pure
Page 138 and 139: planned for a burn-up range of 1.5
Page 140 and 141: On the basis of the study, it is no
Page 142 and 143: In a given reactor system, the diff
Page 144 and 145: - deterioration of the effectivenes
Page 146 and 147: Table II.5 Mass balances for homoge
Page 148 and 149: manufacture is 2 years. 12×24 targ
Page 150 and 151: Figure II.14 MA-loading methods in
Page 152 and 153: Table II.7 Mass balances for homoge
Page 154 and 155: Table II.8 Mass balances for hetero
Page 156 and 157: Core characteristics above: The fol
Page 158 and 159: Figure II.15 Concept of double stra
Page 160 and 161: Figure II.16 Concept of accelerator
Page 162 and 163: In Reference [99], the sodium coole
Page 164 and 165: In Germany, some small activities r
Page 166 and 167: OECD/NEA programmes The OECD/NEA Nu
Page 168 and 169: As a part of MA nuclear data evalua
Page 170 and 171: Table II.13 Pu and minor actinide b
Page 172 and 173: 2.4.1.3 Transmutation in light wate
Page 174 and 175: 3. DESCRIPTION OF CURRENT TRENDS IN
Page 176 and 177: The SPIN programme studied various
Page 178 and 179: • the RP1-2 scenario is compared
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Mass balance The MA mass balance, f
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4. IMPACT OF P&T ON RISK ASSESSMENT
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For deterministic effects, in the c
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• accounting for a number of safe
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Table II.17 Effective dose coeffici
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MOX fuel and recycling of recovered
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Figure II.22 Potential radioactivit
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Moreover, plutonium recycling and m
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Curium is assumed to be stored for
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Figure II.25 shows the radiotoxicit
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decrease is obtained in the radioto
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4.4 Risk and hazard assessment over
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4.4.2 Radiological impact of waste
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0.191 man-Sv/TWhe and the RFC with
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• conventional reprocessing does
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The maximum inventory of reactor co
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pursued. Since 137 Cs and 90 Sr are
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Figure II.26 Surface facilities. Ge
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Doses are controlled by 36 Cl up to
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Figure II.30 Overview of the canist
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surface. The reference repository i
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Figure II.34 Cavern-convection scen
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Figure II.36 Normal evolution scena
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considerable energy release as a re
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• taking into account the potenti
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• on the subject of transmutation
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[12] Arnaud-Neu, F., et al., “Cal
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Fuel”, Proc. Int. Conf. on Future
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[64] Arai, T., Suzuki, Y., Handa, M
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[88] Murata, H., and Mukaiyama, T.,
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[117] Gudowski, W., “Accelerator-
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[146] D’angelo, A., Marimbeau, P.
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[172] OECD/NEA and IAEA, Uranium: R
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[202] Schmidt, E., Zamorani, E., Ha
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