DEVELOPMENT AND EVALUATION OF AN X-RAY-ANALYTICAL TECHNIQUE FOR CORES FROM EXPLORATION HOLES DRILLED ON A WASTE-DISPOSAL SITE.

Objective

THE EXPLORATION OF SITES FOR THE DISPOSAL OF RADIOACTIVE WASTE IN VARIOUS TYPES OF DEEP GEOLOGICAL FORMATIONS, AND OF POSSIBLE LOCATIONS FOR UNDERGROUND LABORATORIES, IS MAINLY BASED ON THE USE OF CORED BOREHOLE. IT IS DESIRABLE TO STUDY THE RESULTING CORES IN A NON-DESTRUCTIVE MANNER.
X-RAY PHOTOGRAPHY IS WIDELY USED IN MECHANICAL AND METALLURGICAL INDUSTRY.
IN GEOLOGY, ONLY A FEW STATIONARY X-RAY MACHINES ARE USED FOR LIMITED APPLICATIONS.
THE AIM OF THE RESEARCH IS THUS, FOR DIFFERENT ENVIRONMENTS :
- TO ADAPT RADIOSCOPIC TECHNIQUES TO THE STUDY OF GEOLOGICAL MATERIALS THAT ARE AVAILABLE AS DRILL CORE;
- TO CREATE A MOBILE UNIT THAT CAN BE TRANSPORTED TO THE SITES WHERE CORES ARE AVAILABLE AND MUST BE STUDIED, SUCH AS A DRILL SITE, AN UNDERGROUND LABORATORY OR A VESSEL ENGAGED IN SEDIMENT STUDIES;
- TO ALLOW NON-DESTRUCTIVE TESTING AND STUDY OF THE CORES THAT ARE TAKEN WITHIN A SLEEVE AND REQUIRE IMMEDIATE CONFINEMENT AFTER BEING PULLED FROM THE HOLE, SUCH AS IS THE CASE FOR CLAYEY AND SALT-BEARING MATERIALS THAT ARE DESTINED FOR MECHANICAL AND GEOCHEMICAL TESTS;
- TO HAVE ACCESS, BEFORE ANY DESTRUCTIVE OPERATIONS, TO THE INTERNAL STRUCTURE OF CORES, AS A FURTHER AID TO MECHANICAL TESTS, AND TO GEOLOGICAL AND GEOCHEMICAL STUDY;
- TO ADAPT AND DEVELOP IMAGE-PROCESSING SOFTWARE FOR THE GEOLOGICAL STUDY OF RADIOSCOPIE IMAGES.
An X-ray radioscopy mobile unit, adapted to the study of geological cores, has been developed and constructed. The main components of the XCORE device fall into 3 groups. Firstly, the X-ray part, which includes the high voltage generator, the X-ray transmitter tube, the receiver or brightness amplifying tube and all the acquisition, visualization and recording system for the video images, and the X-ray control rack. Secondly, the mechanical part, composed of the core handling system and the mechanism that controls the core's motions. Thirdly, the microcomputer and its peripherals, complete with digitizing and image processing card.

The equipment is mounted in a container transportable by lorry and weighs about 9T.

An important part of the work has been devoted to the development and adaptation of the digitized image processing software. Noise has been reduced, and contrast enhanced. The main functions of the software are described. This technique has been applied to a wide range of geological materials including clay, salt, granite, and shale. In each case, data have been collected that could not been obtained by other methods: decompression cracks and erosion figures of the core sides in clay; small inclusions; lithological variations; grain joints. This nondestructive analysis is a great help for the sampling, and it contributes displays of some specific phenomena, such as a prefential positioning of minerals in the rock matrix.
THE EQUIPMENT THAT IS THE SUBJECT OF RESEARCH DIFFERES FROM EXISTING X-RAY APPARATUS IN THE FOLLOWING POINTS:
- AN IMAGE-ANALYSER WILL BE FITTED IN ORDER TO BE ABLE TO DISPOSE OF VIDEO IMAGES;IMAGE QUALITY COULD BE CONTROLLED AND ADAPTED TO THE GEOLOGICAL MATERIAL BEING STUDIED, THIS BY VARYING THE FEED VOLTAGE OF THE EMITTING TUBE;
- A DIAPHRAGM WILL ALLOW ADAPTATION TO THE SIZE AND SHAPE OF THE SAMPLES TO BE ANALYSED;
- THE VIDEO IMAGE WILL ALLOW REAL-TIME OBSERVATION, AS OPPOSED TO CLASSICAL RADIOGRAPHY WHERE STATIC IMAGES ARE OBTAINED AFTER AN EXPOSURE OF LONG DURATION. IT WILL THUS BE POSSIBLE TO GIVE A MOVEMENT TO THE CORE AND TO OBTAIN AN ANALOG-TYPE LOG THAT CAN BE CORRELATED WITH LOGS OBTAINED BY OTHER TECHNIQUES;
- THE VIDEO IMAGES CAN BE DIGITALLY PROCESSED, FOR GRAPHIC RESTITUTION AND THE RECOGNITION OF GEOLOGICAL SUBJECTS.

THE CONTRACT WILL COMPRISE THE FOLLOWING STAGES;
A.DRAWING UP A DETAILED PILOT STUDY OF THE APPARATUS (CONSULTING OF SUPPLIERS OF COMPONENTS, ACCURATE DEFINITION OF THE APPARATUS AND ITS OPERATING ENVIRONMENT).
B.CONSTRUCTION OF THE APPARATUS WITH THE ASSISTANCE OF SPECIALIZED SUPPLIERS.
C.TESTING THE APPARATUS ON VARIOUS CORES OF GEOLOGICAL MATERIALS THAT CAN BE ENVISAGED FOR THE DISPOSAL OF RADIOACTIVE WASTE, SUCH A CLAY (IN A SLEEVE), SALT, GRANIT AND SCHIST/SHALE.
D.ADAPTING AND DEVELOPING IMAGE-PROCESSING SOFTWARE WITH THE FOLLOWING OBJECTIVES :
- GEOLOGICAL EXPLORATION AND IDENTIFICATION (LITHOLOGY, STRUCTURE, TEXTURE) WITHOUT DAMAGE TO THE STRUCTURAL INTEGRITY OF THE SAMPLE;
- TESTING THE SUITABILITY OF THIS TECHNIQUE FOR IDENTIFICATION OF AN HOMOGENEOUS ZONE AND FOR LOCALIZING MECHANICAL AND GEOCHEMICAL TESTS, IN PARTICULAR IN THE CASE OF SAMPLES COVERED BY A SLEEVE;
- IMPROVING THE LEGIBILITY AND USE OF THE IMAGES/USE OF IMAGE-PROCESSING SOFTWARE DEVELOPED FOR REMOTE-SENSING PURPOSES;
- CORRELATING THE X-RAY LOGS WITH OTHER BOREHOLE OR GEOLOGICAL LOGS.
E.PREPARING DOCUMENTS THAT PRESENT THE RESULTS OBTAINED FOR VARIOUS TYPES OF GEOLOGICAL MATERIALS, AND FOR DIFFERENT STRUCTURES AND TEXTURES BEING STUDIED.

Fields of science

Programme(s)

FP1-RADWASTOM 3C - Research and development programme (Euratom) on the management and storage of radioactive waste, 1985-1989

Topic(s)

Data not available

Call for proposal

Data not available

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Bureau de Recherches Géologiques et Minières (BRGM)

EU contribution

No data

Address

39-43 Quai André Citroën
75739 Paris
France

Total cost