At Forsmark nuclear power plant the rather old-fashioned software COPTA is used in containment safety analysis. There exists a desire within the organisation to introduce a more modern software with ability to more detailed modeling and increased usability. The goal of this thesis was to evaluate the software APROS in containment safety analysis. APROS models describing one of the containments at Forsmark NPP have been developed. Two simulations of typical containment incidents, one of them a large pipe break, have been made where containment safety parameters such as pressure and temperature are studied. Results are analyzed and verified against results from corresponding COPTA models. The other part of the evaluation includes a listing of detected possibilities and limitations with APROS regarding containment modeling in general. Overall the developed APROS models show a good agreement with results from corresponding COPTA models. Observed differences can in most cases be explained by minor differences in model choices, mostly concerning flow patterns and heat transfer. APROS has many similarities with COPTA regarding the main calculation and modeling methods but APROS can in most cases be seen as the more sophisticated software with more possibilities regarding modeling complexity. The general conclusion is that APROS shows good potential to be used in containment safety analysis.

A new material model, for the FE-program ADINA, has been verified against twoexperiments. One unreinforced concrete beam and one reinforced concrete beam.The model, DF-concrete, has the possibility to estimate true concrete. However theresults indicate that in order to be sure that the estimations are true, there ought tobe data from the true concrete to verify against. Two FE-models have simulated the behavior of a ring-shaped part of the nuclearcontainment vessel. The results from the first, frictionless, model agree with similarsimulations and hand calculations for high pressures in the containment vessel. Thesimulations of the nuclear containment vessel show cracking in the concrete after10-11 bars of over pressurization. For low pressurizations the results differ from thereference simulation. The reason is most likely the lack of friction. The model with friction included cannot give correct results since the simulations failto represent the true friction between tendons and concrete. However the model issimpler and will probably in a functioning state give more accurate results comparedto the frictionless model.