Workplan

The overall structure of the work plan is given by the division into five work packages:

WP1: Management, coordination, and dissemination

WP2: Preparation and characterisation of samples and experimental systems

WP3: Spent fuel dissolution experiments

WP4: Model material dissolution experiments

WP5: Chemical modelling

The project started on 1^st of June 2017 and will last for 48 months. Consult the project time schedule.

Beneficiaries: SKB, AMPHOS21

WP Leaders: Lena Z. Evins (SKB)

The objective of the WP is to ensure the fulfilment of the contractual obligations, submission of deliverables and progress of the work. This work package will ensure that the input of the End User Group, consisting of Waste Management Organisations, is duly considered, and organize the planned training and mobility activities. Additionally the aim is to efficiently disseminate the results to identified potential users and stake-holders, of which some are represented in the End User Group and Associate Group.

Specifically, the following goals are foreseen:

• General management and coordination
• Communication, dissemination and training

Beneficiaries: USFD, VTT, KIT, CIEMAT, JUELICH, UCAM, CTM, SCK•CEN, CEA, NNL, JRC

WP Leader and Deputy: Ian Farnan (UCAM) and David Hambley (NNL)

WP2 gathers all preparatory work and information on the experimental systems before dissolution experiments are initiated. It aims at providing the “initial state” of the experimental systems.

The following objectives are defined within WP2:

• Synthesis of model materials. Two different preparation works could be differentiate:
  • Alpha glove box work
  • U/Th laboratory work
• Preparation and information of the spent fuel samples
• Description of the aqueous phase and experimental set-up

Summary of samples to be prepared and characterized within WP2 by task.

Beneficiaries: CTM, KIT-INE, JRC, Studsvik

WP Leader and Deputy: Volker Metz (KIT-INE) and Olivia Roth (Studsvik)

The main goal of WP3 is to study and determine both the matrix dissolution and the instant release fraction (IRF) of various fuel types under different relevant disposal conditions.

A total of 12 leaching experiments will be conducted with cladded segments and fragments (without cladding). The experiments will be performed under reducing, anoxic and oxic conditions.

Summary of the experiments to be performed within the WP3 are presented in the table.

Beneficiaries: USFD, VTT, CIEMAT, JUELICH, UCAM, SCK•CEN, CEA

WP Leader and Deputy: Dirk Bosbach (JUELICH) and Ian Farnan (UCAM)

The main objective of WP4 is to understand matrix corrosion of modern LWR fuels under deep geological repository relevant conditions. This WP is closely related with the other technical WPs:

These objectives will be achieved by:

• Determination of element release and corrosion rates,
• Characterisation of the microstructural evolution upon corrosion by advanced micro-analytical tools,
• Establishing a link between matrix corrosion behaviour of UO₂-based model systems and spent fuel.

The dissolution studies consider different model systems (prepared in WP2) and a number of relevant disposal conditions (described in WP2 and WP3).

Beneficiaries: A21, NNL, PSI, Armines

WP Leader and Deputy: Lara Duro (A21) and Enzo Curti (PSI)

WP5 focuses on the development and application of thermodynamic and kinetic models as well as reactive transport modeling to provide the basis for understanding the behavior of spent nuclear fuel in the presence of components of the near field.

Initially, the modelling will involve using already existing data for model development. Later in the project, as results become available, new data will be incorporated into the models.

• Solid phase thermodynamics, targeting the effect of dopants in the dry matrix in terms of oxygen potential and the formation of secondary solids during aqueous corrosion inside an iron-based canister.
• Matrix dissolution model, incorporating redox and electron transfer reactions involving matrix, separate phases (e.g. metallic fission products), radiolysis and hydrogen in the system.
• MOX-matrix dissolution model, focusing on
  • the effect of Pu content on the alpha-radiolytic dissolution kinetics of the matrix
  • the interplay with Fe(II) species released from iron-based canister in clayey groundwater under anoxic conditions.