Survey report 2012 - Research programme on regulatory safety research

The Federal Nuclear Safety Inspectorate (ENSI) is the Swiss regulatory authority for nuclear installations. It has to continuously check the safety of nuclear plants and the intermediate storage pools for spent fuel assemblies and nuclear waste, as well as to act in the research on deep underground repository. In order to stay at the top of knowledge in the field of nuclear safety, ENSI pursues projects in different domains of the regulatory safety research, especially: 1) Fuels and Materials, which are used in the reactor core and the structure materials of the diverse barriers against a loss of radioactive products. By the fuel and fuel cladding the requirements and limitations are imposed during the normal operation of the reactor. On the other hand, materials of the primary loop and the containment have to fulfill their duty during all the life of the power plant. 2) Data bases on damages and internal events: The goal of this project is to internationally exchange experience on incidents in nuclear power plants and on damages that could give rise to incidents. 3) External events: Besides damages within the nuclear power plant, the safety analyses consider also external events which can disturb the normal plant operation, especially earthquakes and flooding. 4) Human factors: The goal of research in this field is to reduce the non-safety of human handling. With probabilistic safety analyses the risk of incidents can be quantitatively evaluated. The reliability of operator's behaviour under different stress situations is analyzed with the so called Human Reliability Analysis. 5) System behaviour and incident unfolding: Beginning from normal operation, the reactor behaviour after some disturbance is simulated with computer codes till core meltdown. Correlated with experiments and probabilistic safety analyses, such evaluations give information about the plant risks. 6) Radiation protection: The work here concerns the check and calibration of measuring systems for ionizing radiations. The dose intensity in the vicinity of nuclear plants is measured by means of helicopter flights. The international cooperation contributes to the harmonization of the norms. 7) Decommissioning and storage: It is foreseen to store the radioactive wastes in deep underground repositories. The research on Opalinus clay at the rock laboratory Mont Terri plays a central role in the knowledge of underground installations. The design of a geological storage and its supervision are evaluated. Special attention is devoted to the gas production in the underground repository. Some projects are concerned with long term effects such as erosion through glaciers after a tectonic elevation of the landscape. Both projects 'Fuels and Materials' and 'Human factors' are treated specially at the Halden reactor