pPvS^o-'/^ ^3 tOmiSSARIAT A L'ENERGIE ATOMIQUE

CENTRE D'ETUDES NUCLEAIRES DE SACLAY CEA-CONF -- 8187 Service de Documentation F9I191 GIF SUR YVETTE CEDEX P2

REPROCESSING OF FAST BREEDER REACTOR FUELS IN FRANCE

Louis PATARIN CE.A. IRDI/DERDCA/DGR

Communication presentee à : INTERNATIONAL MEETING ON SOLVENT EXTRACTION AND ION EXCHANGE IN THE Horw.il IUK) 3-6 Sep 1985 Reprocessing of Fast Breeder Reactor Fuels in France Louis Patarin, Coordonnateur Pour Le Retraitement Des Combustibles Nucléaires a l'Institut de Recherche Technologique et de Développement Industriel (C.E.A.)

INTRODUCTION The reprocessing of breeder reactor fuels is a direct technical descendant of the reprocessing of thermal reactor fuels which was developped first. The process used is in both cases the PUREX process, which consists in dissolution by ni' trie acid followed by selective extraction using TBP. In France, the application of this technique to breeder reactor fuels greatly benefited from the scientific and industrial ex­ perience initially acquired with metallic fuels of the MAGNOX type and then with oxide fuels of the LWR type.

Another feature of French advances in this sector is the constant monitoring of the programs for, on the one hand, fast breeder reactors and, on the other, their fuel cycles, includ­ ing reprocessing. Figure 1 summarises French developments in reprocessing breeder reactor fuels with reference to the paral­ lel development of the reprocessing of thermal reactor fuels and fast breeder reactor.

FRENCH ACHIEVEMENTS The experimental reactor RAP SODIE was associated with the ATI reprocessing pilot facility on the La Hague site, which en­ tered service in 1969, two years after the reactor, and with a small capacity (1 kg/day). Until 1979, when it was definitively shut down, this shop processed one tonne of heavy metals from mixed oxides irradiated to a burn-up of up to 120,000 MWd/t and sometimes only slightly cooled (1$ months for some fuels)* It thus closed the cycle several times and at the end of St 66 67 «9 74 76 M 88 91 9S > I. t 1 I | » l * ' ' • l ' | ' ' * ' ' ' » ' ' | • | • ' | ' ' '

Wl UP2 HAO UPS UP2 800

RAPSOOIE PHENIX SUPERPHENIX © ATI T TOR HAR 600 © SAP

© THERMAL REACTOR FUEL REPROCESSING. © FAST BREEDER REACTOR. © FAST BREEDER REACTOR FUEL REPROCESSING. UP | MARCOULE PLANT (HAGNOX). UP2 LA HAGUE PLANT (MAGNOX). HAO LA HAGUE OXIDE HEAD END. UP 3 LA HAGUE OXIDE PLANT (800 t/y) I»* UNIT. UP2 800 LA HACUE OXIDE PLANT (800 t/y) 2<* UNIT. ATI LA HAGUE FBR REPROCESSING PILOT PLANT. SAP NARCOULE FBR REPROCESSING PILOT PLANT. TOR SAP EXTENSION. HAR 600 MARCOULE FBR REPROCESSING PLANT (SO t/y) RAPSODIE EXPERIMENTAL BREEDER. PHENIX DEMO BREEDER (250 MWe). FIGURE 1 SUPSRPHEMIX INDUSTRIAL BREEDER (1200 MU«).

•> .A-rtfE/i*******'' ' Ch.5] Reprocessing of fast reactor fuels in France 67

initial Pu/U • Pu Teera t

ATI LA RAGOE RAPSODIE 25 - 30 X 69 - 79 0.91 PILOT PLANT PHENIX 18 X 78 - 79 0.18

SAP MA1COULE RAPSODIE 30 X 75 0.05 PILOT PLANT KNK 1 ENRICHED U 75 - 76 1.65

PHENIX ENRICHED U 77 - 78 2.30

PHENIX l 18 X 79 and 83 0.380

PHENIX 2 25 X 79 - 83 6.36

HAO-UP2 LA HAGUE PHENIX 1 18 X 79 - 84 9.91

TOTAL 21.74 t

FIGURE 2

its life, allowed experimentation with PHENIX fuel repro­ cessing.

PHENIX, however, required a new pilot facility, the SAP at Mar coule, in aesociation with HAO oxide head end of the UP2 plant at La Hague, which uees dilution in the MACNOX fuels. After processing various fuels, in particular frosi RAPSODIE, KMU and the first enriched uranium core of PHENIX, the SAP facility reserved its processing activities for the PHENIX fuel which was the richest in (25%), and from 1979 to 1983, proecaaed a total quantity of 6.3 tonnes. For its part, the HAO oxide head end processed almost 10 tonnes of PHENIX fuel (18Z of plutonium), the last processing period taking place at the end of 1984.

Figure 2 shows the production figures with the varioua French resources. 68 Fuel processing [Ch.5 PROJECTS TOR - The Marcoule pilot facility ia undergoing renovation and extension to become the future TOR plant. The capacity will thus be extended to 5 tonnes of heavy metal per year. The re­ search potential will also be increased, thanka to specific cells and équipaient which will stake up the TOR "advanced tech­ nology units"• The new pilot shop comprises three sections. Installed in a new building, the largest section, T0R.1, comprises twenty or so cells containing the process head end equipment. This build­ ing houses the receipt and storage facilities for the ir­ radiated fuela, the mechanical processing, chemical dissolution and aolution clarification units, as well a» the waate storage and packaging facilities. The main head operations may be per­ formed either using conventional equipment, or with the "ad­ vanced technology unite" which can operate in parallel with the main line. T0R.1 is equipped with a high degree of remote con­ trol and maintenance equipment. The other sections, TOR.2 and T0R.3, are located in the premiaes of the old pilot shop. TOR.2 comprises storage facili­ ties for finished products in the form of purified nitrate (U and Pu) and T0R.3 comprises a new pulsed column extraction first cycle with the possibility of partition, as well as a new evaporator for fission products solution. The TOR will enter service at the beginning of 1986. MAR.600 - Between 1979 and 1982, the CEA Group studied a project for a large plant capable of reprocessing the fuels from 6 1500 MWe fast breeder reactors (PURR project), since a plant of this capacity corresponded to the industrial develop­ ment programme envisaged at that time. This project showed that the technical bases existed for a plant of this size and gave a clear indication as to the economic aspects. After the construction of SUPERPHENIX (1200 MWe), present fast neutron reactor strategy foresees a fairly long inter­ mediate stage on a fully European scale which will precede true industrialisation on a large scale. This intermediate stage could comprise two 1500 MWe reactors to enter service before the year 2000. Thia is why the new project for a French plant only had a capacity of 50 tonnes/year, which would cover the needs of SUPERPHENIX and the two subsequent large reactors. The European scale was broadened in 1984 with the entry of the United Kingdom and a plan is afoot for this project to become Franco-British. The following description only refers to the French study planned for the Marcoule site (project MAR.600) and entrusted to SGN by COGEMA. Ch.5) Reprocessing of fast reactor fuels in France 69 The characteristics of KAJt.600 are as follows:

- optimum use of the existing infrastructures and general services of the Marcoule centre,

- a single equipment line,

- fuels cooled for three years with a maximum burn-up of 125,000 MVd/t,

» study schedule compatible with a decision for construc­ tion in 1986,

- UP3 technology (new La Hague plant) when applicable, or specific technology of the R and D programme described in paragraph 3*

EXPERIENCE ACQUIRED AND R AND D Although the reprocessing technology for fast breeder re­ actor fuels is to a large extent common to that of PWR reactor fuels, additional experience is needed for industrial implemen­ tation. The specific characteristics of fast breeder fuels which need in particular to be taken into account are:

- the assembly structure which comprises small-diameter fuel pins in stainless steel cladding in a thick case, thus making bulk shearing impossible,

- the mixed oxide composition with a high concentration of plu­ tonium (10 to 20Z), which complicates the criticality prob­ lems and makes dissolution more difficult, v

- the level of fission products, which considerably increases the thermal power at all stages at which they appear.

The results obtained in the various French plants (para­ graph 1) on significant quantities, are already providing ex­ tremely valuable lessons for the future. In particular, the pilot facility allowed considerable experience to be gained, the major points of which are as follows:

- trapping of iodine released upon dissolution can be extremely efficient,

- ruthenium is the major contaminant of cladding debris (solid waste), 70 Fuel processing [Ch.5 - the hydraulic behaviour of pulsed extraction coluans is satisfactory under diverse conditions,

- decontamination, measured for each extraction cycle, is ex­ cellent since the levels of uranium and plutonium meet the standard values as early as the end of the second cycle,

- mixer-settler electrolysis partition or partition with hydr­ oxy lamine nitrate plus a valence 4 uranium filler is perfect­ ly satisfactory,

- finally, the plutonium balance is well controlled since the total divergence over five cycles is 0.48Z.

The pilot shop has also allowed innovative experiments, such as the processing of the solvent by hydrasine carbonate or trapping of iodine on solid absorbants, to be performed.

In addition to thia collection of operating results, the laboratories of the CEA are running studies and tests which are today based around the MAR.600 project* This extremely import­ ant research programme (80 million francs in 1985) can be sum­ marised by looking at the main techniques envisaged for use in the plant.

Mechanical Processing

The first phase consisting of th* dismantling of the fuels will use H.P. electrical cutting to remove the upper end- piece. In the second phase, the case will be opened by TIC cracking by embrittlement with a special metal electrode. This latter method has already been successively tried with four ir­ radiated PHENIX fuels.

The fuel pins will then be extracted from the bundle one after the other and will pass through a machine which will re­ move the spacing wire using a "rotating arc". The mechanical processing will be completed by chopping the fuel pins into 30 mm sections in a rotating shearing machine, the blade of which may be remotely replaced.

The case will also be broken down into shorter pieces for waste disposal by means of cracking by embrittlement. Ch.5] Reprocessing of fast reactor fuels in France 71

Dissolution presents both chemical and équipaient problems. In hot cells, the CEA defined optimum conditions for oxide etching by using nitric acid and finalised a high-performance dissolution process to supplement the main dissolution process if necessary.

The cladding sections will be dissolved in a continuous helicoidal circulation apparatus. This apparatus has already been tested in a non-active environment and will first of all be operationally tested in a TOR "advanced technology unit".

The solution may be clarified in a centrifuge of the type developed for UP3 in La Hague.

The extraction cycles will use "salt-free processes". Thus separation using hydroxylamine nitrate and processing of the solvent with hydrazine carbonate will be developped. The nep- tumium content will be oriented towards the plutonium flow for recycling in the reactor. The second plutonium cycle will be a concentrating cycle and a reflux will provide the necessary flexibility. The second uranium cycle will also be a reflux cycle. This flowsheet will be proven in the TOR facility. As far as the equipment is concerned, CEA proposée pulsed columns with disk-crown packing. Finally, in order to reduce alpha emitters release, there will be "alpha traps" which will allow reextraction of plutonium traces from the solvent prior to its processing.

Production of Pu02

MAR.600 will use new techniques for oxalic precipitation and oxalate calcination: rotating bowl precipitator, flat fil­ ter, double-screw calcinator.

The rectification of plutonium outside standardized values may be done using a new extremely efficient dissolution pro­ cess.

Processing of Fission Products

The CEA will sdapt its vitrification process to the fis­ sion products solutions produced in MAR.600. It will slso at­ tempt to improve its technology by creating a high temperature fusion furnace operating with direct electric induction. 72 Fuel processing [Ch.5

Wactc Process** All plant waste will be proceaaed and packaged: for ex­ ample, the iodine will be trapped on solid silver supporta and clad waate will be melted by direct induction.

Rsajste Control and Maintenance

The general architecture of the plant will be compact and with no duplication of lines* The nain workshops wi}l be equip­ ped with siodern reaote control resources which are more reli­ able and «ore aobile than conventional mechanical aaster-slave cquipaent. In particular, an electronically controlled servo- manipulator designed by CEA and already widely operational will be uaed (MA 23 M manufactured by La Calhene).

Instrumentation

MAR.600 will be equipped with in-line analysis devices and will for exaaple use fibre optics spectrophotometry.

CONCLUSION Thanks to the wealth of experience already acquired in its laboratoriea and plants, France can be confident of technical success in its future installations, in particular in the field of faat breeder reactor fuel reprocessing. A constant R and D effort is resulting in constant progress towards a level of economic success which is the future challenge for this type of industrial activity. European cooperation, sought after and actively undertaken by those countries interested in the fast breeder reactors, will confirm this hope before ths year ^2000 if it ia baaed around concrete projects.