Uncertainty analyses for LB LOCA in VVER-440/213

The paper describes the project recently initiated at the Nuclear Regulatory Authority of the Slovak Republic (UJD SR) to introduce the application of the best estimate methodology with the evaluation of uncertainty (BE+U) in the licensing process. The project is included into the long-term bilateral cooperation between the UJD SR and Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) in the area of nuclear safety of Russian designed WWER-440 reactors under the financial support of the German Ministry of Economy and Labor and presently partially also of Ministry of Environment. Within this cooperation GRS provides UJD SR with the state-of-the-art computer codes and serves as technical advisor. The initial phases of the BE+U project comprise of the methodology transfer and pilot application of the methodology to a selected scenario, which is the LB LOCA. In the following text the current situation in the area of safety analysis in Slovakia is described, the conservative and BE+U methodologies are briefly characterized and compared and the main goals and phases of the project are defined. Finally, recent results of the LB LOCA calculation and future plans are discussed. (authors)