Entwicklung des Werkstoffs X10CrNiMoTiB 15 15 als Strukturmaterial für Brennelemente

In Germany, the project of a sodium-cooled fast reactor (SNR 300) was stopped in 1993 after 30 years of intensive research and development. Up to that date efficient fuel elements were developed which reached burn-ups of about 200 GWd/t. An essential prerequisite for that was the selection of suitable structural materials for fuel elements and wrappers. The behaviour of these materials under the extreme conditions of high accumulated neutron dose, which resulted in some completely new irradiation phenomena, i.e. swelling, irradiation induced creep and embrittlement, turned out to be a life-time-limiting factor. Fundamental scientific and technological work to develop, characterise and test appropriate materials for these components was carried out by a cooperation between the company Interatom/Siemens-KWU and Forschungszentrum Karlsruhe, temporarily supported by contracts with international partners. From the beginning, in contrast to some other international fast reactor projects, the work concentrated on the group of stabilised, heat resistant austenitic steels for fuel element claddings, mainly on the material X10CrNiMoTiB 15 15 (W.-Nr. 1.4970). In numerous irradiation experiments neutron doses up to 3x10 2 3 n/cm 2 could be reached. Due to the abrupt stop of the German fast reactor programme it was not more possible to prove if the endeavoured goal of 4x10 2 3 n/cm 2 for a commercial reactor unit could be reached with an improved modification of the Ti-stabilized steel (W. -Nr. 1.4970 mod.) The following report will give a comprehensive assessment of all the results gained during the development of this material. It contains a description of the separate steps for the development, a rather extensive documentation of the examined properties and the most substantial items necessary for a technological application of the material. It also includes a summary of the irradiation experiments and performance tests. With regard to knowledge preservation, the report also wants to give a survey of all the research work for this type of structural material, which might thus be used for general application in reactor technology and also for future studies for advanced reactor systems.