The German Approach to the Disposal of Radioactive Wastes Ernst Warnecke Physikalisch-Technische Bundesanstalt Bundesallee 100 D-3300 Braunschweig Finnish-German Seminar on Nuclear Waste Management Otaniemi, Espoo, Finland September 23-25, 1986 THE GERMAN APPROACH TO THE DISPOSAL OF RADIOACTIVE WASTES Ernst Warnecke Physikalisch-Technische Bundesanstalt Bundesallee 100 D-3300 Braunschweig, Federal Republic of Germany Abstract In the Federal Republic of Germany the PTB is responsible for the construction and operation of the repositories in which radioactive wastes will be disposed of. Two repository ries are planned: - Gorleben (salt dome; for all types of radioactive wastes) - Konrad (abandoned iron ore mine; for radioactive wastes with negligible thermal influence upon the host rock). The safe operation of the repositories has to be demon- strated to the licensing authorities. These are the respon- sible Ministers of the Federal States (Lander) and the mining authorities. According to the "safety criteria for the disposal of radioactive wastes in a mine", the safety of a repository has to be demonstrated by a site specific safety assessment for the normal operation of a repository, for incidents in the operational phase, and the post-opera- tional phase. These assessments result in waste acceptance requirements. The compliance of the waste packages to be disposed of with the waste acceptance requirements is checked with a waste package quality control either by random tests on waste packages or a qualification and in- spection of waste conditioning processes. Preliminary waste acceptance requirements have been set up for the planned Konrad repository. In the Kernforschungsan- lage Julich (KFA) a group for the quality control of radio- active waste has been established on behalf of the PTB. The application documents for Konrad have been completely sub- mitted to the licensing authority. The operation of the Konrad repository is anticipated for the year 1990. Prelimi- nary safety assessments have only been performed for the Gorleben site on the basis of model assumptions. These are planned to be updated in 1986 /87 on the basis of the results of the site investigation from surface and on new data of the wastes to be disposed of. Presently, the sinking of the two shafts is under way. This will be followed by an underground investigation of the salt dome, which will last until about 1992. The beginning of ope- ration of this repository is planned for about the year 2000. According to the recent inquiries it will be possible by this approach to dispose of all arising radioactive wastes of the Federal Republic of Germany. 1. INTRODUCTION In the Federal Republic of Germany the Physikalisch-Techni- sche Bundesanstalt (PTB) is responsible for the construction and operation of the repositories in which radioactive wastes will be disposed of /1/. The PTB may make use of the services of third parties in order to construct or operate these facilities. For this task the Deutsche Gesellschaft zum Bau und Betrieb von Endlagern fur Abfallstoffe mbH, DBE (German Company for the Construction and Operation of Repo- sitories for Waste Material), was founded in 1979. It is directly supervised by federal authorities. The organization of the disposal of radioactive wastes is illustrated in Fig. 1. Two repositories are planned (Fig. 2): - Gorleben (salt dome; for all types of radioactive wastes) - Konrad (abandoned iron ore mine; for radioactive wastes with negligible thermal influence upon the host rock'. Additionally, it is planned to inject tritium-containing water from the reprocessing of spent fuel into deep geologi- cal formations, especially porous sediments. A pre-examina- tion of possible sites in Bavaria is under way. From 1967 to 1978, the former Asse salt mine was used as a pilot repository within the scope of a licence limited in time. It now serves as the R+D facility whose work aims at determining above all the thermal and thermomechanical effects of the heat generating wastes. This information is required for the construction of the Gorleben repository. The costs for work carried out in connection with the re- positories are being paid by the waste producers according to the "Endlagervorausleistungs-Verordnung" (Advance Payment Ordinance), /2/. The total costs which will have accumulated until the repositories will be put into operation have been estimated to be about 109 DM for Konrad and about 2,6-109 DM for Gorleben. The state of the planning and practical work carried out in connection with the repositories and the organisational measures taken indicate that it is possible to dispose of all radioactive wastes arising from the operation of nuclear power plants and other facilities where radionuclides are used. 2. THE PLANNED REPOSITORIES 2.1 Gorleben The Gorleben site is under investigation to check the suitability of the salt dome for the disposal of all types of radioactive wastes, especially heat-generating wastes. A comprehensive site investigation programme has been elabo- rated in cooperation with the Bundesanstalt fur Geowissen- schaften und Rohstoffe, BGR Federal Institute of Geosci- ences and Natural Resources) The investigations from above ground are almost terminated and the results were published in May 1983 in a summarizing interim report /4/. These investigations were carried out in an area of roughly 300 km2 and included: - 129 hydrogeological exploratory drillings, - 275 observation drillings, which have been expanded for use as ground water measuring locations, - 1 well for pumping tests, - 11 core drillings, - more than 40 drillings sunk down to 80 m into the salt, - 4 salt dome exploratory drillings of about 2000 m into the flanks of the salt dome, and - an intensive seismic measuring programme. Fig. 3 shows the exploration area and the locations of the hydrogeological investigations, the 4 salt dome exploratory drillings and 2 shaft pre-borings. The resulting site-specific data include special information about - the hydrogeological situation in the overlying and sur- rounding strata of the salt dome, - the sorption data of radionuclides in Gorleben samples (sediment and waters) /5/, - the geological situation in the caprock area, - the existence and sequence of the various strata within the salt dome, and - the locations for the shafts. Figures 4 and 5 are sectional views of the overlying strata and the salt dome as examples of the results of the site investigation. It was concluded from these results that the salt dome's suitability for waste disposal was confirmed and that those data which can only be obtained by an underground explora- tion are still lacking. For this purpose, two shafts must be sunk. The salt dome is to be explored by drillings from galleries of the exploratory mine into the surrounding rock '6/. An area of about 19 km2 is to be investigated. in July 983, the Federal Government approved of the speedy commencement of the underground exploration. The two shafts are being sunk by the Arbeitsgemeinschaft Schachte Gorleben, ASG (Gorleben shafts pool) making use of the "freezing technique". The work has been in progress since 1984. The preparation of the "freezing boreholes" began in May 1984 (Fig. 6'. After the construction of a frost jacket the work on the sinking of the first shaft began in March 1986 (Fig. 7) and has now reached a depth of about 50 m. Work on the second shaft will be started in October 1986. The cumulative inventory of 3/y-emitters and of -emitters in the repository after 50 years of operation has been estimated on the basis of previous planning work to be in the order of magnitude of 102 Bq and 1019 Bq, respec- tively /A, 7/. The annual data for the amounts of waste, the required host rock volume and activities are compiled in Table 1, /7/. The heat-producing wastes are to be disposed of in boreholes (300 - 600 m deep). The other wastes will be emplaced in mined rooms (Fig. 8). These planning data are currently being revised and will be updated in 1986/87 due to new developments in the data basis for radioactive wastes and the results of the site investi- gation. 2.2 Konrad The Konrad mine is the most recent of all former iron ore pits in the Peine-Salzgitter area und has two shafts (Fig. 9) It is located in the south of the large iron ore sediment (Fig. 10) which was deposited about 150 million years ago 'during the Upper Jurassic (Malm). Ore Mining in 800 - 1300 m depth started in 1965 and was stopped in autumn 1976 for economic reasons. As the Konrad mine is very dry it was investigated from 1976 - 1982 by the Gesellschaft fur Strahlen- und Umweltforschung mbH, GSF (Company for Radia- tion and Environment Research) for its potential suitability for the disposal of radioactive wastes. On the basis of the positive results of the GSF /8/ the PTB applied for the initiation of a plan-approval procedure on August 31, 1982 and sub itted the completed documents on June 30, 1986 to the licensing authority. In the meantime the PTB carried out supplementary work necessary to demonstrate the suitability of the mine in the course of the licensing procedure. This work included - an underground exploration of the disposal areas, - seismic measurements, - one deep drilling, - the development of a concept for the design and operation of the repository and a drafting of the facilities, - the measurement of sorption data for radionuclides on Konrad samples (sediment-and waters) /5/, - the performance of safety assessments (for the normal operation of the mine, for incidents and for the post- operational phase), and - the derivation of preliminary waste acceptance require- ments. As examples of the results of this supplementary work, a revised sectional view of the Konrad strata (Fig. 11), a diagram of the planned storage operations (Fig. 12), and a diagram of the anticipated waste emplacement areas 'Fig.