WP 5.2:Benchmark

Workpackage number

WP 5.2

Start date or starting event:

Month 18

Activity type

Benchmark – RTD

Participant id

1

2

5

4

6

7

8

9

10

12

Person-months per participant:

3

1

4

6

18

11

14

28.4

18

7

Objectives

This workpackage will allow to better understand and quantify the thermal impact of heat emitting radioactive waste on the host-rock and the Damaged Zone, and to realise predictive modelling of a repository scale experiment (the PRACLAY experiment). The aim of the workpackage is to assess the performance of coupled THM analysis, using different codes, of proposed laboratory tests and in situ tests (available and prospective), with a main focus on the development and evolution of the DZ. The modelling work together with the results of the lab and the in-situ tests should give clear indication on the evolution of the DZ with time: What are the risks of fracturation? What are the favourable and the unfavourable effects of the thermal load on sealing? What are the THMC governing processes and parameters at repository time and spatial scale?

Description of work

The modelling work performed within this workpackage will focus on the following topics:

• Investigation of the thermal impact on EDZ
• Investigation of possible additional damage due to thermal load
• Transition between brittle and visco-plastic behaviour due to thermal loading
• Difference between continuum modelling and discrete element modelling

Different codes will be evaluated by participation in Benchmark exercises for modelling of THM processes in clays. The benchmark should allow to assess the influence of the constitutive laws on the long term and large scale predictions, and to see if different modelling teams using different codes and/or constitutive laws could obtain similar predictions.

The workpackage is divided in three tasks:

Task1: Benchmark 1:  laboratory experiments modelling

The benchmark 1 consists in modelling the simulation tests performed in laboratory (sub-workpackage 3.3). The following table summarises the participation of the partners in the benchmark exercises:

Partner                                        1    2   4   5   6   7   8   9   10   12

WP3.3 simulation test on BC      x              x  x   x    x   x    x              

WP3.3 simulation test on OC           x    x            x    x   x    x     x    

WP3.3 simulation test on COC         x    x       x   x    x   x    x     x              

BC: Boom Clay – OC: Opalinus Clay – COC: Callovo-Oxfordian Argilitte

Task 2: Benchmark 2: small scale in-situ  experiments modelling

The benchmark 2 consists in modelling the small scale in situ tests performed in sub-workpackage 4.2.

The following table summarises the participation of the partners in the benchmark exercises:

Partner                                         1    2   4   5   6   7   8   9   10   12

Mt. Terri experiment                         x                   x  x                x

Atlas experiment                          x             x             x           x 

Task 3: Blind prediction of the PRACLAY experiment

This task consists mainly in, using different codes, blind prediction of the large scale heater test PRACALY experiment. The predictive modelling results of the PRACLAY experiment will be assessed with comparison to measured data. Models can be improved by back-calculations in a second phase.

The following table summarises the aspects on which the partners will focuses:

Partner                                         1   2   4   5   6   7   8   9   10   12

THM                                            x             x   x    x   x        x     x

Localisation                                                                x   x

Sealing                                                                                         x

C                                                                       x

Deliverables

D13 Report on the results of the benchmark exercises and conclusions on relevant issues for a safety case

Milestones and expected result

The conclusions on relevant issues for a safety case constitute a milestone for WP6

Prior approval by the GB of the enduser review reports to proceed with the next modelling work - Months 8,26,44

Conclusions on relevant issues for a safety case ....................................................................................Month 48