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Recovery of Actinides from Actinide-Aluminium Alloys: Chlorination Route

E. Mendes1, L. Cassayre2, R. Malmbeck1, P. Souček1, R. Jardin1, J.-P. Glatz1

1European Commission, JRC, Institute for Transuranium Elements, Postfach 2340, 76125 Karlsruhe, Germany

2Laboratoire de Génie Chimique (LGC), Université Paul Sabatier, UMR CNRS 5503, 118 route de Narbonne, 31062 Toulouse Cedex 04, France

A method for recovery of actinides (An) from An-Al alloys formed by electrochemical separation of metallic spent nuclear fuel on solid aluminium electrodes in molten chloride salts is described. The proposed route consists of three main steps: Vacuum distillation of salt adhered on the electrodes, chlorination of An-Al alloy by pure chlorine gas and sublimation of formed AlCl3. A thermochemical study of the route was performed to determine important chemical reactions and to find optimum experimental conditions for all process steps. Vacuum distillation of the electrode is efficient for complete removal of remaining salt and most fission products (FP), full chlorination of the An-Al alloys is possible at any working temperature and evaporation of AlCl3 is achieved by heating under argon.. Experiments have been carried out using U-Al alloy in order to define parameters providing full alloy chlorination without formation of volatile UCl5 and UCl6. It was shown that full chlorination of An-Al alloys without An losses should be possible at a temperature approx. 150°C.

INTRODUCTION to obtain the desired output product, e.g. An alloy. A method involving the chlorination of Al- A promising pyrochemical reprocessing option U spent fuel has been proposed by Bohe et al. [5, regarding spent nuclear fuels is the grouped- 6], but up to now is only based on selective separation of all actinides (An's) by thermochemical calculations without validation electrochemical methods in a LiCl-KCl molten by experimental studies involving Uranium. salt. An's are electrochemically grouped- selectively reduced from the mixture of fission Chlorination AlCl3 products (FP) dissolved in the molten salt. In Al-U-Pu-Np-Am Distillation with Cl2(g) + alloy Al-U-Pu-Np-Am An ITU a process based on electrorefining of + LiCl-KCl salt alloy chlorides metallic alloy fuel and the use of solid reactive + FP chlorides aluminium cathodes is under development. In Pure An An alloy recent work, the efficiency of the process and chlorides selectivity over lanthanides has been Chemical Heating under Ar : reduction AlCl3 sublimation demonstrated [1, 2]. It has been shown that the use of solid aluminium cathodes leads to the Fig. 1: Principle of the chlorination route formation of stable An-Al alloys [3], highly (An=actinides, FP=fission products) loaded in An (up to about 70 wt. %) [4]. In this work, a process using the chlorination of Efficient separation of An´s from Al-An is a key An-Al alloys by pure Cl2(g) is investigated. point for the feasibility of the process. The Initially, a detailed thermochemical study of all method to recover An´s proposed and studied in process steps was carried out. Based on this this work is a chlorination route based on a three study, experiments were focussed to optimise step procedure as presented in Fig.1. Initially, the process conditions for a full recovery of uranium salt, which is composed mainly of LiCl-KCl and from U-Al alloys. The reason is that due to the some FP chlorides, adhered on the electrode after high volatility of UCl5 and UCl6, U is the most the electrorefining process is removed by difficult element to convert to chloride form vacuum distillation. The second step is a without any losses. For that purpose, chlorination chlorination of the An-Al alloy in order to fully experiments on a UAl3 alloy were carried out in convert the alloy to chlorides. The last step the temperature range 150-170°C. consists of the sublimation of AlCl3. The final An chlorides can be further chemically processed

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THERMOCHEMICAL STUDY melting point than pure metals, their vapour pressures are most likely lower than the one of The main idea of the chlorination route is to fully each individual metal. Therefore, the vapour chlorinate the alloy and removal of AlCl3 by pressure of alloyed Am will be lower than pure sublimation. Thermochemical calculations using Am. the Factsage software were performed, aiming to determine the most suitable conditions for the Pure LiCl-KCl salt is possible to remove by process. At first, a bibliographic study was vacuum distillation at temperatures around carried out to collect available thermochemical 800°C, which was confirmed experimentally in data (∆fH°, Sm° and Cp(T)) and phase diagrams. the laboratory scale (2g of LiCl-KCl were Most thermochemical data concerning the An’s completely distilled at 900°C and 5.10-5 bar). chlorides are tabulated, apart from AmCln and However, other compounds, especially Ln CmCln gaseous compounds [7-11]. Among An- chlorides, need stronger conditions to be Al alloys, the Gibbs energy of formation of removed. Available thermodynamical data UAl3, UAl4 and PuAl4 are available, together indicate that a temperature of 1000°C is required with phase diagrams for U-Al and Pu-Al systems to fully remove all lanthanide (Ln) chloride [12]. In both systems, the melting point of the compounds, with a vacuum of 10-5 bar, see intermetallic compounds increases with the An horizontal dotted line in Fig 2. However, content, UAl2 and PuAl2 having the highest distillation under these conditions is possibly still melting temperature (1620°C and 1540°C, not sufficient for complete removal of some FP respectively). No phase diagram was found for chlorides (e.g. MoCl2, SrCl2 and BaCl2). Np-Al and Am-Al systems. However, three Np- 1000 °C Al intermetallic compounds are reported in the 0 ZrCl4 Inorganic Crystal Structure Database [13]. No AlCl3 PrCl InCl ternary or quaternary An-Al system was found. -2 3 CeCl3 -4 First step: Distillation of remaining salt SmCl2 GdCl Al 3 SnCl2 vacuum 10 -2 mbar

To ensure a sufficient purity of both end -6 MoCl2 AgCl products (An and Al), it is necessary to clean the / bar (P) log LaCl 3NdCl 3 Np Am cathode from the residual frozen salt adhering at -8 TbCl3 Cm the surface after the electrorefining step. This RhCl2 EuCl3 CdCl2

-10 PdCl2 KCl LiCl salt contains a mixture of LiCl-KCl with YCl SrCl 3 Pu 2 U dissolved FP chlorides. The proposed technique BaCl RuCl3 CsCl is distillation of the salt from the An-Al alloys -12 0.0005 0.001 0.0015 0.002 and recycling of the salt back in the 1/T / K electrorefiner. This requires sufficient difference Fig. 2: Vapour pressure vs. reverse of in vapour pressures between the salt and the temperature for various metals and chlorides. alloy. No thermochemical data exist to fully evaluate the vapour pressure of the salt mixture Second step: Chlorination of An-Al alloy (LiCl-KCl + FP) and of the alloy (Al-U-Pu-Am- Np-Cm). However, as a first estimation, the The main target of the chlorination is to separate vapour pressure, PM, of each individual actinides from aluminium. All metal elements compound (FP chlorides and An metals) can be (U, Pu, Np, Am, Cm, Al) of the alloy have to be calculated from available data according to: fully converted to chlorides and significantly ° more volatile aluminium chloride is ∆rG(T) (1) consecutively evaporated in the following step. log PM = − 2.303RT Each of presented metals forms a chloride where ∆rG° is the Gibbs energy of the compound in equilibrium with pure chlorine gas, equilibrium M(s,liq)=M(g). even at relatively low temperatures (25°C). Therefore, the key point of the process is to Results for the most important An's and FP are control working conditions in order to provide plotted in Fig. 2. It can be seen that, except Am, formation of desired species only. Formation of all An metals exhibit a lower vapour pressure gaseous actinide chlorides (e.g. UCl5 and UCl6) than all chloride compounds. As AnAl3 - AnAl2 has to be suppressed to avoid actinide losses by intermetallic compounds have a much higher volatilization

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The thermochemical study of the chlorination of Al(s) AlCl3(s) An-Al alloys is a complex problem, as many 6 compounds can form, and the reactions are strongly dependent on the applied conditions. As a first approach, two main parameters of the 4 process have been studied: - Temperature of the reaction, moles - Molar ratio Cl2/alloy. 2

3 UCl3(s) For calculations, a constant volume of 1 dm was UCl4(s) UAl4(s) PuCl3(s) Al2Cl6(g) used and the Cl2/alloy molar ratio was fixed by PuAl4(s) the considered amount of actinide alloy. The 0 following calculations have been performed: 0 5 10 15 20 moles Cl (g) 2 Fig. 3: Chlorination of UAl (1.0 mol) and PuAl - Relative stability of An chlorides, 4 4 (0.5 mol) at 150°C - Influence of the amount of - Chlorination of UAl and PuAl at 150°C, 4 4 Cl (g). - Chlorination of UAl in the 100°C-1000°C 2 3 temperature range for a fixed Cl /UAl ratio. 2 3 These calculations show that Pu and U are

chlorinated in preference to Al, leaving non- Chlorination of pure An metals chlorinated Al metal. The behaviour of the alloys The relative stability of An chlorides was is thermodynamically very close to the behaviour calculated according to the Gibbs energy of the of a mixture of pure compounds. However, this reaction: calculation shows only the equilibrium state 2 2 An(s,l) + Cl2 (g) = AnClx (s,l) (2) towards which the system should tend. The x x considered heterogeneous reaction will be most probably limited by kinetic factors due to a In the 100-1000°C temperature range, all Gibbs surface passivation. Analogous to an oxide layer energy values related to Eq. (2) are strongly formation during some oxidation processes, a negative (between -300 and -600 kJ/mol), solid chloride layer is expected to be formed at indicating that the chloride form is the surface of the alloy, preventing from further thermodynamically promoted. The products of chlorination. This problem can be solved if the chlorination can be sorted according to their electrode is crushed in order to obtain a powder relative stability to the following sequence and increase the surface of reaction. (ascending Gibbs energy): AmCl > AmCl > 2 3 PuCl > CmCl > NpCl > UCl > UCl > NpCl . 3 3 3 3 4 4 Chlorination of UAl in the 100°C-1000°C 3 temperature range for fixed Cl /UAl ratios Provided that the amount of chlorine gas is 2 3 It can be seen from previous calculations that, at sufficient (i.e. at least a stoechiometric amount), 150°C, the chlorination of U yields solid the chlorination of considered metals will lead to UCl4(s), if the Cl2/U ratio is close to the the formation of the following solid chloride stoechiometric amount (i.e. 6.5 mol, compounds at 150°C: PuCl3, AmCl3, UCl4, corresponding to the reaction UAl3 + 6.5 Cl2 = 3 NpCl4 and AlCl3. U forms gaseous species UCl5 AlCl3 + UCl4). This temperature is relatively and UCl6 in presence of an excess of chlorine gas low, and much more favourable reaction kinetics as described later. At higher temperatures (up to could be obtained, if higher temperatures are 1000°C), the order of chlorination remains the used. However, as shown in Fig. 4, an increase same, but liquid and then gaseous compounds of temperature will lead to the formation of will form. gaseous species: UCl (g), UCl (g) and finally 6 5 UCl4(g) will predominantly form with increase Chlorination of UAl4 and PuAl4 at 150°C of temperature from 150°C to 1000°C. As mentioned above, the only data available for The formation of compounds starting from UAl3 An-Al alloys are related to UAl3, UAl4 and alloy and Cl2(g) is plotted versus temperature in PuAl4. These data were used to evaluate the Fig. 4, using three different Cl2/UAl3 initial ratio. behaviour of UAl4 and PuAl4 under pure chlorine It shows that the formation of gaseous uranium atmosphere at 150°C (Fig. 3).

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chloride compounds increases with temperature Third step: Sublimation of AlCl3 and also with the Cl2/UAl3 ratio. a) 0.025 A well managed chlorination step will lead to a Cl2/UAl3Cl2/UAl = 37.5=7.5 mixture of solid chloride compounds composed AlCl (s) AlCl (g) 0.020 AlCl3(s)3 AlCl3(g)3 of AlCl3, UCl4, PuCl3, NpCl4, AmCl3 and CmCl3. The following step is to remove AlCl3 by 0.015 sublimation, keeping all An as solids in the

mole reactor. A temperature increase under chlorine Al2Cl6(g)Al2Cl6(g) 0.010 atmosphere causes volatilization of U together UCl (s) UCl4(s)4 with Al, but the situation is different using inert UCl4(g) 0.005 UCl4(g) Ar atmosphere. As shown in Fig. 5a, the UClUCl5(g)5(g) sublimation of AlCl3 starts at 180°C, while no

0 UCl6(g) 0 100 200 300 400 500 600 700 800 900 1000 other chloride compound volatilize before T(C) UCl (g) 6 450°C. At this point, NpCl4 melts, and quickly volatilizes due to its high vapour pressure. The 0.004 b) same behaviour was calculated for UCl4, but at a Cl /UAl =51 Cl2/UAl32 =3 51 higher temperature (~ 550°C). As detailed in Fig.

0.003 AlCl (s) AlCl (g) 5b, a temperature range of more than 200°C AlCl3(s)3 AlCl33(g) allows to remove AlCl3 and thus to perform an effective separation of AlCl3 from the An 0.002 mole chlorides. Al Cl (g) Al Cl2 (g)6 2 6 a) 2.5

0.001 UCl (s) UCl (g) UCl (s) 4 6 4 UCl (g) UCl6(g ) 5 UCl (g) UCl5(g) 4 AlCl3(s) AlCl3(g) UCl4(g) 2.0

0 0 100 200 300 400 500 600 700 800 900 1000 T(C) 1.5 c) 1.2E-04

ClCl2/UAl32/UAl3 =1500= 1500 moles Al2Cl6(g) AlClAlCl (g)3(g) 1.0 AlCl3(s)AlCl3(s) 3 UCl4(liq) UCl4(s) UCl4(g) 8.0E-05

PuCl3(s) PuCl3(liq) 0.5 NpCl4(s) NpCl4(g) AmCl3(s) mole AmCl3(liq) Al2Cl6(g) Al2Cl6(g) NpCl4(liq)

4.0E-05 UCl (g) 0.0 UCl66(g) UCl4(s) 0 200 400 600 800 1000 UCl5(g) UCl4(s) UCl5(g) T (°C) UCl (g) UCl4(g)4

0.0E+00 UCl4(g) b) 100 0 100 200 300 400 500 600 700 800 900 1000 gas phase T(C) 90 Al Np U Fig. 4: Chlorination of UAl3 alloys - Calculation 80 of the evolution of the amount of chloride 70 compounds with temperature and Cl2/UAl3 molar 3 60 suitable temperature ratio. Initial conditions: 1 dm reactor containing range 50 2000 - 300 - 10 mg of solid UAl3 alloy and 4.843 -2 40 10 mol of Cl2(g) (P=1.2 bars at 25°C). 30

These calculations indicate that, in order to 20 % of element in a gaseous form gaseous of element in a % Pu prevent U losses in the gaseous phase, the 10 condensed phase reaction should be carried out with the smallest 0 possible excess of Cl2. However, from the point 0 200 400 600 800 1000 of view of the reaction kinetics, the opposite is T (°C) required, especially because of the reaction type Fig. 5: Sublimation of AlCl3 from the chloride (solid-gas). An experimental study is needed to mixture. a) Evolution of the composition with T. determine the kinetics of the reaction and to b) Evolution of the volatilization with T. Initial conditions: mixture of 1 mole of An chlorides, 2 optimise the Cl2/alloy molar ratio. moles of AlCl3 and Ar (1 atm).

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CHLORINATION EXPERIMENTS, RESULTS AND DISCUSSION Quartz lid Although, from a thermodynamical point of Vacuum connexion view, all steps were proven possible, the Water cooling applicability of the proposed method depends on the reactions kinetics under working conditions Gas outlet suitable for complete An recovery. The experimental study was carried out to determine Quartz tube realistic conditions for the process and to quantify the chlorination efficiency and actinides Thermocouple Gas inlet (Cl or Ar) volatilization under these conditions. 2 The experiments were mainly focused on the chlorination step. UAl alloy was selected as 3 BN crucible input material, since U represents the most difficult element to be completely chlorinated without formation of volatile chlorides.

Accordingly, it is expected that the conditions Fig. 6: Experimental set-up for chlorination – suitable for recovery of U from U-Al alloy Quartz reactor should be appropriate for a process including all An. The input material for chlorination experiments

was selected to be UAl3 alloy. Approx. 3.3g of Experimental U-Al alloy was prepared by melting in an arc furnace (>3000°C) in 1:3 molar ratio. The The chlorination experiments were carried out in composition determined by X-Ray Diffraction a glove box under nitrogen atmosphere, specially (XRD) was 98 wt.% of UAl3, 1 wt.% of UAl2 designed for work with Cl2(g). The box is and 1 wt.% of Al (see Fig. 7). In order to equipped with a chlorine gas line ended by a increase the reacting surface, the alloy was system of gas wash bottles containing KOH crushed into a very fine powder. This was easily solutions (4 and 8 M), where non reacted achieved manually using a mortar, as U-Al chlorine gas is absorbed. A quartz reactor placed alloys are very brittle. in a vertical oven was used for the chlorination (see Fig. 6). Chlorine gas was introduced by a quartz tube guided through the lid of the reactor by a gastight connection. The lid was also equipped by sealed ports for a thermocouple and the gas outlet connected to the chlorine off gas treatment. Boron nitride crucibles were used as containers for the chlorinated material and positioned on the bottom of the reactor.

Fig. 7: X-Ray diffractogram of the U-Al alloy prepared with arc furnace and used as input material.

The molar ratio Cl2/alloy was kept constant for all the chlorination experiments. The volume of Cl2(g) was fixed by the volume of the reactor (1dm3) and the amount of powder to chlorinate was set to be 300 mg. The Cl2/alloy molar ration was then equal to 36 for all the experiments.

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Three experiments were carried out in the TABLE 1 Composition of the input material and temperature range 150 – 170°C. Two the solid chlorination product experiments, at 150 and 160°C, consisted of two Concentration [wt.%] successive chlorinations during approx. 20 hours Specie Input each. The last experiment at 170°C was a single Product 20 hours chlorination. In each chlorination material experiment, the reactor was filled completely UCl3 0.0 18 with chlorine gas and then isolated. After CLUAL150 UCl4 0.0 72.9 chlorination, samples of the chlorinated powder Temp. 150°C UAl3 98.0 2.2 were taken for XRD analysis. In the two first Two UAl2 1.0 0.5 experiments, the rest of the powder was refilled chlorinations AlCl3 0.0 6.4 in crucible for further chlorination. Both the 20h Al 1.0 0.0 initial material and products from the complete mass [mg] 300.5 371.1 chlorination were weighted to calculate a mass UCl3 0.0 19.0 balance. CLUAL160 UCl4 0.0 64.0 Temp. 160°C UAl3 98.0 4.7 Observations Two UAl2 1.0 0.0 chlorinations AlCl3 0.0 12.2 Experimental results are summarised in Tab. 1. 20h Al 1.0 0.0 After the first chlorination, a grey/green powder mass [mg] 300.2 396.4 was obtained for all experiments performed. It UCl3 0.0 84.5 indicates the presence of UCl3 and/or UCl4. An UCl 0.0 0.0 CLUAL170 4 increase of powder mass was also observed. In UCl 0.0 traces Temp. 170°C 5 two samples, i.e. ClUAl-150 and ClUAl-160, a UAl 98.0 0.6 one 3 part of the powder turned into agglomerate that UAl 1.0 0.0 remained stuck at the bottom of the crucible and chlorination 2 AlCl 0.0 14.9 could not be analysed. The formation of this 20h 3 Al 1.0 0.0 agglomerate could be induced by the fine powder structure of the initial UAl material. It shows that mass [mg] 301.04 375.5 the efficiency and the optimal conditions for the chlorination route are strongly dependent of the Composition of the chlorinated product grains size of UAl alloy. After the second chlorination, a pure green XRD analysis of the powder, after the first powder was obtained for all experiments chlorination, indicated a high efficiency of the performed, indicating the presence of UCl chlorination, as less than 2% of the initial alloy 3 remained non-chlorinated. After the second and/or UCl4 as the major phases (see Fig.8). The agglomerate part, when formed, was still chlorination, the same kind of analysis (see Fig. observable but it became brittle which allowed 9) showed the conversion of original product its extraction and analysis. UCl3 to UCl4.

Fig. 8: Pictures of the powder before chlorination and after second chlorination at 150°C.

Fig. 9: X-Ray diffractogram of a sample after second chlorination at 150°C.

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As expected, the analysis of the agglomerate liquid aluminium are investigated at ITU, EC- revealed a lower efficiency of the chlorination, JRC and CEA, France [14]. Final products for as roughly 15% of the UAl3 remained in this part the studied techniques, i.e. electrorefining in even after two chlorinations. This lower molten LiCl-KCl eutectic and reductive efficiency is caused by a limited diffusion of Cl2 extraction to liquid Al in molten LiF-AlF3, are inside the agglomerate, which indicates a actinide-aluminium alloys. As very high drawback in decreasing too much the grain size selectivity and efficiency has been demonstrated of the initial powder. in laboratory scale for both methods, the key During the experiments, a part of the sublimated point for their further application is to identify a AlCl3, and eventually other volatile products, method for recovery of actinides from the was deposited at the cold surface on the top of formed alloys. According to the results described the reactor. This deposit was collected and in this work, a chlorination process seems to be analysed for presence of U compounds. No U advantageous to fulfil this task. was detected in the deposit after the chlorinations carried out at 150 and 160°C. Traces of UCl5 Initially, the theoretical study showed were detected after chlorination at 170°C but thermodynamical possibility of all steps quantification was not possible. However, it proposed for the process. clearly shows that higher temperatures than The conclusions from the study were: 170°C can not be applied due to uranium losses - Vacuum distillation is efficient to remove the by volatilisation. remaining salt including most fission products, except MoCl2, SrCl2 and BaCl2 (proposed It was impossible to make a quantitative conditions: T=1000°C, P=10-5 bar). evaluation of the AlCl3 content by XRD due to its high solubility in the epoxy-resin used for the - Full chlorination of the alloy is possible at any preparation of the sample. Accordingly, the considered temperature (studied temperature concentration of AlCl3 had to be calculated from range: 25 – 1000°C). In this case, as it is a solid- the real mass of the chlorination product gas reaction, the reaction kinetic is the most weighted after the experiment, which was important factor. deduced from the calculated theoretical mass of U chlorides and non-reacted residual alloy. The - Best conditions for the chlorination step are to mass balance and an evaluated composition of chlorinate the finely crushed alloy at 150°C, the chlorination product from the three different using minimum acceptable Cl2 / alloy mass ratio experiments are shown in Tab. 1 (for the two in order to avoid the formation of gaseous U first experiments, final mass was evaluated compounds. taking into account the mass of powder lost after the first chlorination for analysis). For each - Heating of the chlorination products under inert experiment, the final composition indicates that argon atmosphere at 350-400°C allows to chlorination is almost fully efficient as less than evaporate AlCl3 and consequently to recover 5 wt.% of the final product is composed of pure solid An chlorides. metallic U-Al, even at 150°C. The results indicate that a major part of AlCl3 was The experimental study was focused mainly on evaporated already during the chlorination the kinetic aspects of the chlorination step. Three process. According to the calculations, a mass experiments showed that chlorination of UAl3 increase up to 686 – 719 mg was expected after can be efficiently performed in the 150-170°C chlorination of the initial 300 mg of the alloy, if temperature range. Approx. 20 hours of all AlCl3 had remained in the product. The high chlorination yielded products mainly composed percentage of AlCl3 remaining in CLUAL170 is of solid UCl3 and UCl4 even at a temperature of due to the shorter chlorination time, i.e. 20h 150°C, which is in good agreement with the (instead of 40h for the two other experiments). It conclusions of the thermodynamic study. Further also explains why only UCl3 was formed during chlorination led to the conversion of UCl3 into this experiment. UCl4. Traces of volatile UCl5 were identified in the condensate after the chlorination at 170°C. CONCLUSIONS Also in previous experiments it was demonstrated that important amounts of volatile Pyrochemical processes for recovery of actinides UCl5 and UCl6 are formed during chlorinations from spent nuclear fuel using both solid and at temperatures higher than 180°C. As a

ATALANTE 2008 Montpellier (France) May 19-22, 2008 7 O1_11 consequence, for optimum efficiency of the Neptunium, Plutonium, Americium and chlorination, temperatures higher than 170°C Technetium. 2003, Amsterdam: Elsevier. should not be applied. In addition, a single 9. Fuger, J., et al., The Chemical chlorination step running for 20 hrs at 150°C is Thermodynamics of Actinides Elements and enough to sublimate the major part of produced Compounds, Part 8 - The Actinide Halides. AlCl3. 1983, International Atomic Energy Agency. On the other hand, the experiments showed that 10. Konings, R.J.M. The ITU Material: Property too finely crushed input material can decrease Data Base for f-elements and compounds, f- the total efficiency of the reaction, as non-fully MPD, http://www.f-elements.net. 2002. chlorinated agglomerates were formed inside the 11. Konings, R.J.M., L.R. Morss, and J. Fuger, crucible. Thermodynamic properties of Actinides. 3rd The influence of working temperature on the ed. The Chemistry of Actinides and efficiency of the chlorination process was Transactinide Elements, ed. J.J.e.a. Katz. evaluated during the experiments and future 2006, Berlin: Springer. 2113-2224. investigations will be focused on the 12. Chiotti, P., et al., The Chemical optimisation of the molar ratio between Cl2(g) Thermodynamics of Actinide Elements and the alloy. Compounds Part 5: The Actinide Binary Alloys. 1981, Vienna: IAEA. REFERENCES 13. Inorganic Crystal Structure Database. 2007, Fachinformationszentrum Karlsruhe (FIZ), 1. Serp, J., et al. Electroseparation of Actinides Germany, the National Institute of Standards on Solid Aluminium in LiCl-KCl Eutectic. and Technology (NIST), U.S.A. in GLOBAL 2003. 2003. New Orleans. 14. Conocar, O., et al., Promising Pyrochemical 2. Serp, J., et al., Electroseparation of Actinide/Lanthanide Separation Processes Actinides from Lanthanides on Solid Using Aluminium. Nuclear Science and Aluminum Electrode in LiCl-KCl Eutectic Engineering, 2006. 153: p. 253-261. Melts. Journal of the Electrochemical Society, 2005. 152: p. C167. 3. Cassayre, L., et al., On the formation of U- Al alloys in the molten LiCl-KCl eutectic. Journal of Nuclear Materials, 2008(to be published). 4. Soucek, P., et al., Electrorefining of U-Pu- Zr-alloy fuel onto solid aluminium cathodes in molten LiCl-KCl Radiochimica Acta, 2008(to be published). 5. Bohe, A.E., et al. Chlorination Reactions Applied to Reprocessing of Aluminium- Uranium Spent Nuclear Fuels. in 21st International Symposium on the scientific basis for nuclear waste management XXI. 1998. Switzerland. 6. Bevilacqua, A.M., et al. Radioactive Waste Reduction from LEU Al-U Spent Fuel Management by a Dry Chlorination Process. in Global symposium on recycling waste treatment and clean technology. 1999, September 5-9. San Sebastian, Spain. 7. Chase, M.W., NIST-JANAF Thermochemical Table. Journal of Physical and Chemical Reference Data, 1998(Monograph 9). 8. Guillaumont, R., et al., Chemical Thermodynamics Vol 5: Update on the Chemical Thermodynamics of Uranium,

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