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Partitioning and transmutation

Objective

Specific Objectives

- Within the research on aqueous partitioning techniques for the separation of long-lived actinides and fission products, to generate high active raffinates from dissolved spent fuel, and to produce from the raffinates high active concentrates, which will be used for separation of minor actinides in the DIAMEX process;

- To demonstrate the electro-refining of actinides using U, Pu, Am, Cm, ZrRE alloys, and to perform tests of salt-metal extraction for the separation of minor actinides;

- To prepare the transfer of the pyrochemistry caisson for shielding in the hot cells facility;

- To finalise the commissioning and start the hot operation of the MA Lab for the manufacture of fuel pellets and pins for transmutation experiments;

- To manufacture in the MA Lab Pu and Am containing fuels (zirconia-based, homogeneous and composite compounds) to be used for characterisation and for transmutation experiments;

- To perform the new irradiation experiment SMART in HFR Petten (collaboration with IE), for the testing of high Pu-containing fuels (including inert matrices) in fast reactor systems;

- To determine the material properties of zirconia-based targets and fuels;

- To conclude the analysis of EFTTRA-T4 (spinel inert matrix);

- To fabricate by the infiltration method Pu-containing pyrochlore pellets, and to measure their properties;

- To assess advanced nuclear fuel cycle concepts with regard to waste generation (radio-toxicity), and material accountancy (non-proliferation);

- To assess thermodynamic data (Pu, Am, Cm oxides) and include them in the new ITU data base.
Planned Deliverables

- Produce 7 litres of raffinates, and high active concentrates according to the aqueous reprocessing process;

- Installation and testing of new centrifuges;

- Installation of new equipment for salt-metal extraction;

- Start of the operation of the MA Lab (7 boxes);

- Fabrication of 3 batches of Pu- and then 3 batches of Am-containing zirconia pellets for characterisation;

- Final assessment of the in pile and out of pile performance of MgAl2O4 (spinel structure) as inert matrix (IM) for americium incineration;

- Fabrication of one Pu-based zirconia pin for the SMART experiment in HFR;

- To complete the property determinations of these zirconia-based materials
(with Pu): thermal diffusivity, melting point, specific heat; to complete a set of material properties on pyrochlores;

- To perform a series of new Helium damage experiments in zirconia inert matrices; to publish final results of the study of alpha damage and helium release from ion-implanted, cubic-stabilised ZrO2, and to evaluate the helium diffusion coefficients;

- To issue the EFTTRA-T4 final internal report;

- To report on studies on non-proliferation aspects of pyroprocessing, and photo-transmutation of actinides;

- Introduction in the data base of new Am and Cm thermodynamic data: publication in Journals;

- Total publications: 15, from which 7 in recognised Journals

Specific deliverables to DGs:

- Alert function for new technologies;

- Policy formulation regarding waste management;

- Policy formulation regarding safeguards and non-proliferation issues.

As a result of the research:

The work performed will help demonstrate, on a small scale experimental basis, the feasibility of the partitioning and transmutation scenario. It includes work of partitioning by two different methods, the fabrication of samples to be irradiated in specific transmutation experiments, and the as-fabricated and post-irradiation materials behaviour.

Summary of 2000 Deliverables: 31/12/2000

Highlight 2000: Demonstration of pyrochemical reprocessing of nuclear fuels by electrorefining.

In a co-operation between ITU and CRIEPI (Japan) non-aqueous (molten salt) reprocessing of irradiated spent nuclear fuels is being studied. This process is considered a major part of a partitioning and transmutation strategy for nuclear waste management. Its goal is to demonstrate the feasibility of recovering actinides from irradiated fuel and HLW (High Level Waste), e.g. waste from the PUREX process. In the ITU laboratories, a hot cell facility for up to 1 kg of melt has been constructed and its performance successfully tested. The installation operates under highly pure Air atmosphere (<10ppm O2 and <10ppm H2O). First demonstrations of the electro-refining process in 2000 have generated deposits of up to 10g of metallic U.

The Ion Chromatography High Resolution Inductively coupled plasma mass spectrometer was successfully installed behind the ITU hot cells and tested for measuring impurities in hot samples (genuine spent fuel).

In the frame of the work on inert matrices, zirconia beads infiltrated with Pu were produced for the first time in 2000. Production of alpha-doped material, both for in-house experiments and for external customers continues to gain interest. The characterisation of existing samples of inert matrix materials doped with Am and the measurement of their properties have continued, as well as the study of radiation damage with fission products.

The construction of the Minor Actinide Laboratory continued, with the complete installation of the water walls, and the delivery of the major equipment. A workshop team was dedicated to the construction of the first series of glove boxes. These efforts will be pursued in the upcoming years, since a significant workload is planned from 2002 onwards for this laboratory.

Output Indicators and Impact

Publications, patents, prototype electrochemical equipment, Minor Actinide Laboratory, design and process flow schemes, capsules, targets and fuel pins for irradiation experiments, new analytical methods, material properties data base, workshops, active participation in international working groups and symposia.
Summary of the project

The objective of the research in partitioning and transmutation is to test and evaluate processes which permit an efficient separation of radiotoxic elements from spent fuel with a minimum of losses, to optimise fuel fabrication technology for actinide containing fuel and to develop analytical techniques for these new applications.

Performed in close collaboration with European partners, the research work will focus on the following major topics:

- Testing and evaluation of advanced aqueous and dry reprocessing techniques;

- Installation of a new facility for pyrochemical reprocessing;

- Testing and application of existing or new fabrication techniques for fuels and targets;

- Performance of fuels and targets irradiation experiments;

- Completion, commissioning and operation of the minor actinide fuel fabrication laboratory (MA Lab).

- Basic studies on inert matrices and material behaviour experiments;

- Testing and evaluation of analytical techniques for quantitative measurements of minor actinide fuel solutions and compounds;

- Radiotoxicity and non-proliferation studies related to new fuel cycle concepts for minor actinides transmutation;

- Establishment of a thermodynamic database on Am and Cm compounds for fuels and of lanthanide-actinide compounds for molten salt systems.

Rationale

The safe disposal of highly active wastes dominates the nuclear debate in several countries. The major issue is the potential risk due to the long-term radio-toxicity of the transuranium elements contained in the wastes.

To further reduce the potential long-term hazard of such wastes, partitioning and transmutation research is performed in the framework of a European collaboration. The objective is to efficiently separate the long-lived nuclides from the waste, to develop the technologies to allow their incorporation in well designed fuels or targets, and to transmute them in dedicated reactors by neutron capture or fission into nuclides with much shorter half-lives.

This research also addresses the management of the increasing stockpiles of separated plutonium from both civil and military origin. In this context, new fuel cycle concepts and new fuels are being considered in order to optimise the disposition rate of plutonium and/or to minimise the additional production of minor actinides during reactor irradiation.

Coordinator

Institute for Transuranium Elements
Address

Karlsruhe
Germany