[en] In the present paper the Leak Before Break (LBB) methodology is described on the way, as it was evaluated in Slovenian Nuclear Safety Administration in the process of the nuclear power plant (NPP) Krsko modernization process. In the recent decade, reviewed regulatory position regarding elimination the dynamic effects of the postulated primary coolant pipe ruptures in some countries was issued. The basis for such new approach are research achievements on different areas of science like metallurgy, fracture mechanics, dynamic analysis and testing of materials. By this new regulatory position the utility has the possibility to adopt LBB concept, but has to fulfill at least general prerequisites, described in standard review plan, where the basic principles and objectives of the evaluation process are described. World wide practice shows that more intensive and detailed evaluation is necessary as it is described in the standard review plan. The concerns and requests raising during evaluation of the consequences of the adopted LBB concept have generally some common points comparing regulatory experience of different countries which have already accepted this methodology or are currently under the process of evaluation. But nevertheless every nuclear power plant is unique, comparing specific material properties, dynamic analysis assumptions, safety analyses performed etc. One of the most important areas in the LBB evaluation process is reliable primary piping material evaluation. Several generic material studies were performed and the applicability of these studies for the justification of LBB has to be carefully performed. Elimination of the double ended guillotine break from the safety analysis has very strong impact to the safety analysis results and finally to the structures, systems and components too. Nuclear safety administration has made a lot of effort to make its position on this methodology clear. The expertise of the authorized institutions is in such process necessary. It helps to justify and assess different areas of the standard review plan which has to be fulfilled and needs more detailed analysis. In the addition to the standard scope of items to be reviewed during the LBB evaluation, some questions arise which has not been previously discussed neither evaluated on the plant specific basis. These questions and the way of their evaluation and justification is described in the paper. (author)