Application of Leak-Before-Break concept in VVER 440-230 results and consequences for TACIS-program 91/1.2

The project TACIS 91/1.2 'Primary Circuit Integrity, Application of Leak-Before-Break (LBB) Concept' was performed within the scope of the TACIS-program (Technical Assistance for the Community of Independent States) of the European Community. The application of the LBB concept was carried out for the primary piping (main coolant lines (MCL) and surgelines (SL)) of the first generation of the Russian VVER NPP's of the type VVER 440/230 of the nuclear power plants Kola 1 and 2 (K1, K2) and Novovoronesh 3 and 4 (NV3, NV4). The work was performed by the Consultant (Siemens, EdF, Framatome) and Russian subcontractors (headed by Vniiaes). The paper describes the comparison of the relevant safety concept, the scope of the LBB-program, the applied LBB-procedures (German and NUREG 1061 procedure), the results obtained and the recommendations (analysis of seismicity, if necessary LBB analysis taking into account additional optimized seismic supports and their installation for NV3 and 4 adaption of inservice inspection (ISI) and leak monitoring systems (LMS)). Proposals have been made for future work to improve the safety of these plants. This project was financed by the European Community's TACIS Programme, which provides grant finance for know-how to foster the development of marked economies and democratic societies in the New Independent States and Mongolia. (C) 1997 Elsevier Science S.A.