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In Situ Investigation of the Long Term Sealing System as a Component of a Dam Construction

Objective

Dam constructions represent an essential component of the multi-barrier safety concept for a repository for radioactive waste in salt formations. Within the scope of the dam project the long-term seal, which is responsible for the long-term safety of a dam construction is subjected to an in situ test. Main objectives of the scientific investigation programme are:

- to provide proof of the tightness of the long-term seal as a dam construction component by means of experimental investigations to obtain essential data concerning the effectiveness and
- to prognosticate its functioning (tightness) over long time periods (up to approximately 500 years) via model calculations.
The long-term evolution of permeability and porosity will be considered, investigating the chemical stability and the petrophysical behaviour.
The state of the art on calculations and codes for multiple-phase flow will be analyzed, adequate mathematical models and computer codes developed and verified. [N.B. In December 1992 the BMFT (D) decided to have the project reviewed; in-situ experiments were suspended].
Dam constructions represent an essential component of the multibarrier safety concept for a respository for radioactive waste in salt formations. Within the scope of the dam project, the long term seal, which is responsible for the long term safety of a dam construction, is subjected to an in situ test. Main objectives of the scientific investigation programme are to provide proof of the tightness of the long term seal as a dam construction component by means of experimental investigations to obtain essential data concerning the effectiveness, and to prognosticate its functioning (tightness) over long time periods (up to approximately 500 years) via model calculations.

In order to collect geochemical data, the physicochemical and petrophysical characteristics of the component of the long term seal were investigated. The solubility of materials in fresh water and brine have been measured and laboratory dynamic experiments with laboratory percolation test through different assemblages of briquettes have been performed. The design of the pilot test has been finished and the preparation of the testfield is going on. In the field of geochemical and petrophysical modelling, an overview of the development of recent geochemical model on application on thermodynamic codes are performed. Considering modelling of petrophysical characteristics of briquettes assemblages, a review on dissolution of solid and porous materials by fluids was achieved. A literature study for analyzing state of the art calculations and codes for multiple phase flow has been done. It has been proven that a large number of codes deal with topics strongly related to the hydromechanical behaviour of salts.
Work programme:

DBE and GSF

I/1 Conception, numerical preliminary investigations and detailed planning of the long-term seal test in the Asse Mine
I/2 Preliminary and parallel laboratory and in situ (borehole) tests
I/3 Instrumentation of the long-term seal construction
I/4 Performance of the large scale test long-term seal with gas and brine
I/5 Evaluation of the test results
I/6 Hydraulic modelling

ANDRA

II/1 Physicochemical and petrophysical characterization
II/2 Evaluation of the solubility of materials
II/3 Dissolution kinetics
II/4 Laboratory batch experiments
II/5 Laboratory open system experiment
II/6 Pilot study in mine gallery (Amélie Mine)
II/7 Geochemical modelling
II/8 Petrophysical modelling
II/9 Interpretation and final modelling of the coupled system

ENRESA

III/1 Analysis of the state-of-the-art on calculations & codes for multiple-phase flow
III/2 Conceiving laboratory experiments for measuring the permeability of the long-term seal against brine
III/3 Development of adequate mathematical models and computer codes for the numerical simulation of multiple-phase flow
III/4 Code verification
III/5 Interpretation of the in-situ test measurements using the developed codes

Coordinator

DEUTSCHE GESELLSCHAFT ZUM BAU UND BETRIEB VON ENDLAGERN FUER ABFALLSTOFFE MBH
Address
Woltorfer Strasse 74
31224 Peine
Germany

Participants (3)

EMPRESA NACIONAL DE RESIDUOS RADIOACTIVOS S.A.
Spain
Address
7,Emilio Vargas 7
28043 Madrid
GSF - FORSCHUNGSZENTRUM FUER UMWELT UND GESUNDHEIT GMBH
Germany
Address
Ingolstaedter Landstrasse 1
85764 Neuherberg
NATIONAL RADIOACTIVE WASTE MANAGEMENT AGENCY OF FRANCE
France
Address
Rue Jean Monnet 1-7
92298 Chatenay Malabry