[en] An experimental apparatus has been constructed to simulate the impact of an aircraft against a nuclear power plant. In order to test the equipment some preliminary tests were carried out with simple inexpensive missiles against a rigid steel plate target. Precalculations for the tests were carried out using initial velocities of 100 m/s, 150 m/s and 200 m/s for the test missile. (orig.)

[en] The strategic goal of POTFIS project and its background philosophy is outlined, and two new examples as parts of this development are described: CFD simulation of fires in turbine halls, and Monte Carlo calculation of large and complicated fire scenarios. For the former guidance is given how to avoid flow oscillations, which although physically based phenomena, are numerical artefacts caused by simplified geometry. For the latter an economic Two Model Monte Carlo method is developed allowing use of CFD at a needed accuracy but fraction of cost of full one model Monte Carlo. (orig.)

[en] he principle and some preliminary results are shown of a new vertical flame spread modelling effort. Quick experimental screenings on relevant phenomena are made, some models are evaluated, and a new set of needed measuring instruments is proposed. Finally a single example of FRNC cable is shown as application of the methods. (orig.)

[en] The PPRISMA project deals with both risk-informed decision making and methods for risk assessment. Approaches have been developed to support maintenance and operability planning, management of fire situations and safety classification. A method for the reliability assessment of computer-based systems has been developed. In addition, the research activities are carried through international co-operation. (orig.)

[en] This research is focused on Nuclear Power Plant (NPP) concrete structures and addresses in general the destructive stresses to which they are subjected. An overall view was also taken into account when selecting constructions and their level of examination during NPP visitations. In addition to examining the NPP containment, some other structures were also included in the study, which were mainly sea structures. This report provides an overview of the main destructive forces on concrete containment structures. (orig.)

[en] In the KOETAR project data and documents of the thermal-hydraulic experiments performed with different facilities at Lappeenranta University of Technology are saved, checked, and archived. Some of the data and documents related to former research programs are still on media that are not compatible anymore with the hardware and software in use today. The work is done following the priority classification of the experiments updated in the SAFIR research program in 2003. The checked data and documents are archived in the STRESA database of Lappeenranta University of Technology and in CD/DVD disks. The archived data and documents can be used in nuclear safety research to validate thermal hydraulic and computational fluid dynamics codes. The data is also suitable material for planning and understanding the future experiments and for educational purposes. It can also be used as a Finnish contribution in international co-operation projects. The data and the documents in the STRESA database can be accessed easily through the Internet. (orig.)

[en] The purpose of the EMERALD project is to achieve a reliable computer code system for all necessary steady-state and transient reactor analyses. Development of models and codes as well as validation of the latter have included neutron cross section studies, nodal, Monte Carlo and deterministic transport methods, criticality safety calculations and the improvement of the dynamics codes to allow coolant flow reversal. Several international meetings have been arranged and the results of the codes have been tested through benchmark calculations and other comparisons. (orig.)

[en] Work is described that has been done to modernise the mechanical modelling of FRAPCON and FRAPTRAN codes. FRAPCON and FRAPTRAN are nuclear fuel performance codes for steady-state and transient analyses, respectively. A new stress and strain analysis approach with a finite element model has been implemented in the codes. The finite element model is capable of handling material nonlinearities such as elastic, thermal, plastic and creep deformations, and geometric nonlinearities like large localised cladding deformations, e.g. ballooning of the cladding under loss-of-coolant accident conditions. (orig.)

[en] Preliminary calculations for planning the tests in the IMPACT project were carried out with ABAQUS code. LSDYNA is used for analyses involving more accurate fluid-structure interaction and capable of simulating the bursting of a tank. Finally, numerical results will be verified against experimental data. (orig.)

[en] The main objective of the work was to map state-of-the-art Requirements Management (ReM) practices, and to study and present a summary of the practices and application possibilities in the selected application areas. The most important application areas were the Finnish nuclear authority (STUK) activities and the modifications and procurement of nuclear power plants. (orig.)