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Core characteristics above: The following conditions are assumed for neutronic assessment in the two modes defined • the proportions of minor actinides, 237 Np, 241 Am, 243 Am and 244 Cm in the material recovered from the LWR spent fuel, are 54, 23, 17 and 6 wt%, respectively; • a quantitative Pu recovery and 98% of minor actinides to be recovered in reprocessing. • the core is composed of inner and outer regions with a combined thermal output of 1 600 MWt; • the refuelling interval is 15 months with 3 batches, and the refuelling time is 60 days; • the average discharge burn-up is ~90 GWd/tHM. The performance parameters [83] of the FBR core at equilibrium recycle in the two modes described above are summarised in Table II.10 with the non-recycle core included for comparison. Here, the feed plutonium comes only from LWR and is used once-through. In the self-recycle core, the minor actinides and rare earths amount to 0.6 and 0.3 wt%, respectively, at equilibrium recycle. In the minor actinide-enriched mode, the following significant characteristics appear: • the burn-up reactivity swing becomes smaller with the increase in minor actinide enrichment; • the minor actinide composition shifts to higher masses with recycling; • the fast fission contribution causes an increase in void reactivity; • the minor actinide-enriched core has a smaller Doppler constant due to the reduced uranium content; • at full-power, the power coefficients which relate to fuel, cladding, structural components and coolant, and to the Doppler effect are reduced. Taking the decreased β eff of minor actinide-enriched core into account, it is quite difficult to use metal fuel with minor actinides of higher than a few percent. Transmutation performance In the self-recycle core, the minor actinides amount to 0.6 wt% at equilibrium. In an FR with 2 wt% minor actinide-enriched fuel, the transmutation rate is 31% at each refuelling the reactor can consume the minor actinides and plutonium recovered from 2.5 LWRs per year. Effect of lanthanide nuclides In nuclear reactors, lanthanide nuclides (i.e. rare earth isotopes) are created by fission of actinides. But transmutation rates in fast reactors are not changed substantially by their presence [86,87]. Rare earth fission products have capture cross-sections that cause them to act as a poison. With low distribution factors there will be large burn-up reactivity loss. The weight ratio of the total rare earth fission products to minor actinides in pyrochemical process is ~1. The reduction of reactivity due to rare earth fission product must be compensated by increased plutonium concentration [86]. Therefore, the increase of rare earth fission products content causes the decrease of Doppler coefficient and β eff [87]. But the transmutation rate is not changed markedly by the content of rare earth fission products. 162
Table II.10 Core performance at the equilibrium cycle of metal -fuelled fast rea ctor Non-recycle Self-recycle 2%MAs enriched 5% MAs enriched MAs/RE concentration 1) (wt%) 0.0/0.0 0.6/0.3 2.0/0.9 5.0/2.0 Pu concentration (wt%, IC/OC) 2) 13.5/21.2 14.0/22.8 14.2/23.3 13.8/23.0 Burn-up reactivity (%∆k/k) 2.76 1.24 1.09 0.33 Internal conversion ratio 0.85 0.89 0.89 0.9 ß eff (×10 -3 ) 3.65 3.47 3.39 3.24 Void reactivity (%∆k/k) 1.78 2.03 2.19 2.5 Doppler constant (×10 -3 Tdk/dT) -4.62 -4.18 -3.70 -2.94 Power coefficient (¢/%-power) -0.191 -0.163 -0.118 -0.036 1) concentration: wt% of (heavy metals +RE) 2) IC: Inner core, OC: Outer core 2.3.4 Transmutation of minor actinides and fission products in dedicated systems Dedicated transmutation systems are being studied at JAERI [88-90] and CEA [91] based on a strategy named the double strata fuel cycle concept (or multi component concept). The double strata concept is to consider a P&T fuel cycle (second stratum) separated completely from the conventional fuel cycle for commercial power reactors (first stratum) as illustrated schematically in Figure II.15. The first stratum is devoted to the electricity production and consists of standard power reactors (LWR-UO 2 , LWR-MOX and FR), fuel fabrication plants and reprocessing plants. The U fuel irradiated in LWRs is reprocessed and the recovered Pu is recycled in LWR-MOX and in fast reactors. HLW from the reprocessing goes to the second stratum. In the second stratum, MAs (Np, Am, Cm) and long-lived fission products are partitioned from HLW to be fabricated into fuels and targets. They are irradiated in dedicated systems for transmutation, and then reprocessed for multiple recycling. There are several advantages in using dedicated transmutation systems compared with recycling MAs into commercial power reactors. Because of much lower mass flow in the P&T cycle, it could be on a correspondingly smaller scale than the main cycle. Its separation from the main powerproducing cycle, and the small number of units required, would allow the extensive innovation in fuel fabrication, core design and reprocessing technology needed to optimise this part of the overall system [91-93]. It would also avoid burdening the main cycle with the problems associated with higher radioactivity and decay heat, and reduced safety margins in reactor physics parameters [94]. The P&T cycle could be made very compact by co-locating the entire facilities. This would minimise the transportation of nuclides that are troublesome with respect to waste management, and confine them effectively in the P&T fuel cycle. 163
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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
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On peut voir sur la Figure I.4 les
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Figure I.4 Flux de matières dans u
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À court terme, les produits de fis
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Par conséquent, au cas où l’on
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De nombreux laboratoires dans le mo
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usé devrait représenter environ 3
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le nucléide le plus gênant est le
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transuraniens. Pour obtenir un taux
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On peut considérer des opérations
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devrait en principe ouvrir de nouve
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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 130 and 131: Figure II.11 Flow sheet of pyro-rep
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 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
Page 180 and 181: Mass balance The MA mass balance, f
Page 182 and 183: 4. IMPACT OF P&T ON RISK ASSESSMENT
Page 184 and 185: For deterministic effects, in the c
Page 186 and 187: • accounting for a number of safe
Page 188 and 189: Table II.17 Effective dose coeffici
Page 190 and 191: MOX fuel and recycling of recovered
Page 192 and 193: Figure II.22 Potential radioactivit
Page 194 and 195: Moreover, plutonium recycling and m
Page 196 and 197: Curium is assumed to be stored for
Page 198 and 199: Figure II.25 shows the radiotoxicit
Page 200 and 201: decrease is obtained in the radioto
Page 202 and 203: 4.4 Risk and hazard assessment over
Page 204 and 205: 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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