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SAFETY EVALUATION OF GEOLOGICAL DISPOSAL CONCEPTS FOR MEDIUM LEVEL AND ALPHA WASTES IN ROCK SALT

Objective

THE OVERALL OBJECTIVES OF THE GSF CONTRIBUTION TO THE PACOMA PROJECT ARE TO DEVELOP AND DEMONSTRATE PROCEDURES FOR THE RADIOLOGICAL SAFETY ASSESSMENT OF A DEEP REPOSITORY FOR ALPHA-BEARING AND MEDIUM-LEVEL RADIOACTIVE WASTE IN SALT ROCKS.

THE RESEARCH COVERS THE DISPOSAL IN A REPOSITORY MINED IN A SALT DOME. THE REFERENCE REPOSITORY DESIGN WILL BE TAKEN AS A BASIS FOR THE CALCULATIONS. DESIGN VARIANTS AND ALTERNATIVE DISPOSAL CONCEPTS ARE INVESTIGATED. THE RESULTS ARE GIVEN IN TERMS OF RELEASE RATES TO GEOSPHERE AND IN TERMS OF DOSES TO THE INDIVIDUALS AND POPULATIONS.
The overall objective of the Pacoma project was the assessment of the consequences associated with deep disposal of radioactive waste in 3 types of geological formation. The project objective was to develop and demonstrate procedures for radiological safety of repositories in salt domes. The influence of the appropriate choice of the repository design parameters on the whole system has been investigated.

The research covered deterministic calculations for 3 scenarios: the normal evolution scenario with subrosion of the salt dome, the combined brine intrusion scenario with brine intrusion from brine pockets and via an anhydrite vein, and the human intrusion scenario of solution mining of a storage cavern.

For the combined brine intrusion scenario alternative waste inventories, different disposal concepts, variants of the layout of dams and sealings were investigated, and results obtained from variations of parameter values. Additionally, for this scenario, comprehensive probabilistic calculations have been carried out with the help of a Monte Carlo simulation. Results have been obtained in the form of an uncertainty analysis of the maximum dose and global sensitivity studies of system parameters.

The main result of the assessment was that, in the reference case where the reference repository design and the reference disposal concept are applied, deterministic calculations with best estimate values as well as probabilistic calculations do not manifest unacceptable risk. Investigation of alternative concepts and design variants indicate a high potential for system optimisation.
1. DISPOSAL SITE.
2. REPOSITORY DESIGN.
3. SCENARIOS.
4. MODELS
5. CALCULATIONS.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

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