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Test Disposal of High-Level Radioactive Waste in the Asse Salt Mine

Objective

In order to improve the final concept for the disposal of high-level radioactive waste (HAW) in boreholes drilled into salt formation plans were developed a couple of years ago for a full scale testing of the complete technical system of an underground repository. To satisfy the test objectives, thirty highly radioactive radiation sources were planned to be emplaced in six boreholes located in two test galleries at the 800-m-level in the Asse salt mine, for a testing period of 5 years. Because of licensing uncertainties the German Federal Government decided on December 3rd 1992 to stop all activities for the preparation of the test disposal immediately.
As a consequence of the early termination of the project the working programme 1992-1994 was revised. The new programme for 1993 and 1994 agreed to by the project partners includes a controlled shut-down of the heater tests in 1993 and a continuation of the laboratory activities until the end of 1994.
The heater tests consisted in emplacing two reference non-radioactive electrical heaters in-situ. The original programme comprised the estimation and observation of the thermal, mechanical and radiation-induced interaction between the rock salt and the electrical heaters and the radiation sources, respectively. Also a radioactive source handling system was developed and installed in the mine.
For a number of years research and development activities have been carried out in the Asse salt mine for the final disposal of high level radioactive waste (HAW) in salt formations. The heat producing waste has been simulated so far by means of electrical heaters and also cobalt-60 sources. In order to improve the final concept for HAW disposal in boreholes drilled into salt formations, the complete technical system of an underground repository is to be tested in a full scale test facility. For handling of the radioactive canisters and their emplacement into the boreholes, a system consisting of 6 transport and storage casks, 2 above ground and underground shuttle transport casks, an above ground transfer station, an underground transport vehicle, a disposal machine, and of a borehole slider will be tested. The scientific investigation programme is based on the estimation and in situ observation of the thermal, radiation induced, and mechanical interaction between the radioactive canisters and the rock salt.

Due to licensing uncertainties, the German Federaal Government decided to stop all activities for the preparation of the test disposal facility in 1992.
In preparation of the radioactive tests however, two nonradioactive electrical heater tests were started in 1988 and were continuously surveyed until August 1993 in resoect of the thermomechanical and geochemical response of the rock mass.
Work programme:

In-situ activities

1.1 Controlled shut-down of the heater experiments and continuation of in-situ measurements
1.2 Thermomechanical analysis
1.3 Post test sampling

Laboratory activities

2.1 Irradiations on salt samples at Saclay
2.2 Irradiations at the HFR in Petten and modelling of radiation damage
2.3 Development of a measuring system for high doses
2.4 Gamma field and gamma spectra calculations
2.5 Post test analyses of salt and fluid phase samples
2.6 Post test analyses of corrosion specimens

Desk studies

3.1 Description of the mineralogical and geochemical properties of the underground test field
3.2 Evaluation of the experiences gained from the cold training with the handling system.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

GSF - FORSCHUNGSZENTRUM FUER UMWELT UND GESUNDHEIT GMBH
Address
Ingolstaedter Landstrasse 1
85764 Neuherberg
Germany

Participants (3)

Commissariat à l'Energie Atomique (CEA)
France
Address
Route Du Panorama Robert Schuman
92266 Fontenay-aux-roses
EMPRESA NACIONAL DE RESIDUOS RADIOACTIVOS S.A.
Spain
Address
7,Emilio Vargas 7
28043 Madrid
ENERGY RESEARCH CENTRE OF THE NETHERLANDS
Netherlands
Address
Westerduinweg 3
Petten