Basis and methods for in situ measurements on liberation and generation of volatile components concerning the disposal of high- level radioactive waste in rock salt.

Rock salt formations which are considered for disposal of radioactive wastes contain besides the main mineral halite the minor minerals polyhalite, anhydrite and kieserite as well as traces of clay, bitumen and carbonates. The water in the rock salt derives from the hydrated minerals, may be adsorbed at the crystal boundaries together with gases such as CO2, H2S and hydrocarbons, or form inclusions. By elevated temperature and radiation these volatile components will be liberated and further be generated. Methods have been developed for the determination of the volatile components which are liberated already at natural mine temperatures, generated and liberated at elevated temperatures, and which are generated by gamma -radiation (radiolysis)

Natural, thermal and radiolytical gas leberation in rock salt as a result of disposed high-level radioactive waste.

Rock salt contains crystal water of the hydrated minerals, water in the form of brine inclusions or adsorbed to the crystal boundaries, as well as primary gases. Further gases are produced or liberated due to the disposed high-level, heat producing wastes resulting from the thermal and radiolytic decomposition of the main and secondary constituents. All volatile components which are present in a final repository have an influence on the disposal horizon, promote the spreading of possibly liberated radionuclides, increase corrosion of the containment and may lead to a pressure increase in a disposal borehole. Therefore a qualitative and quantitative determination of the components which could be liberated from the rock salt as a result of the disposal of high-level wastes is of significance for a final repository

The geochemistry of brines and minerals from the Asse Salt Mine, Germany.

The chemistry and stable isotopes (18O, D) of highly concentrated chloride brines and minerals from the Asse salt mine in the north of the Federal Republic of Germany were studied. Chemical data indicate the occurrence of three types of brines: (a) Mg-Cl type, of carnallitite origin with Li < 30 mg/kg; (b) Na-Cl type brines, of rock salt origin, with Li > 100 mg/kg; and (c) almost pure MgCl2-type brines with Li > 100 mg/kg. The first group may be subdivided into brines with Li < 4.0 mg/kg and brines with Li between 18 and 30 mg/kg. Lithium is shown to be an efficient complementary tool in tracing the origin of the brines. The complex evolution of carnallitite-type brines is discussed in detail. Isotopic data of brines that were sampled directly from seepages (presumably unaltered) indicate that these brines are not a mixture with relatively fresh ground water from the overburden sediments. The stable isotope composition (18O and D) of hydration water in carnallite, kieserite and polyhalite sampled from the Asse mine were also studied. It is shown that water extracted from the so-called primary carnallite is isotopically different from water extracted from secondary carnallite. The isotopic fractionation factors for 18O and D between carnallite hydration water and mother solution were studied in the laboratory. Assuming that crystallization water of the so-called primary carnallite samples is not altered, the isotopic composition of the mother solution is evaluated

Gas release and migration in the boom clay of mol within the project 'Corrosion of Active Glass in the Underground conditions' (CORALUS)

Within the scope of national and international radioactive waste disposal concepts, the intention is to dispose of radioactive waste in deep geological formations, in order to isolate them from the biosphere and avoid the release of radionuclides above an acceptable limit. Besides salt and granite, clay formations are investigated. For investigating the suitability of clay formations in terms of their physical and chemical behaviour, the Belgian research centre SCK-CEN is performing an in situ test called CORALUS (CORrosion of Active gLass in Underground Storage conditions) in the Boom clay of the Underground Research Facility HADES in Mol/VAL 97/. The overall objective of the CORALUS project is to study the performance of both active and inactive HLW glass specimens in direct contact with different types of backfill materials under conditions as representative as possible for those expected to prevail in a disposal site in the Boom clay formation (#alpha#- and #gamma#-irradiation, temperature, pressure, backfill material, formation water,...). The experimental set-up represents a scenario in which the vitrified waste comes into direct contact with the interacting backfill material and/or the Boom clay, because of the occurrence of fissures in the waste canisters and the metallic overpack. (orig.)SIGLEAvailable from TIB Hannover: RN 6050(171)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Bestimmung von leicht fluechtigen Bestandteilen in triassischen Sedimentgesteinen der Asse

Copy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Preliminary investigations for the characterization and selection of a test field for a two-phase flow in the AespoeHard Rock Laboratory

The investigations of the AespoeHRL are being carried out as a precaution, in addition to the research in Germany for final disposal in a salt formation; the purpose is to complete the knowledge on other potential host rock formations. The work is concentrated on investigations related to groundwater flow, radionuclide transport and geochemistry, on two-phase flow investigations, as well as the development and testing of instrumentation and methods for underground rock characterization. (orig./GL)SIGLEAvailable from TIB Hannover: RN 6050(145) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman