Experience with licensing of K2/R4 and results of the IAEA/SNRCU seminar on safe commissioning of nuclear power plants

According to the National Energy Program, in 2004, commissioning is planned in Ukraine for two new units at Khmelnitsky (referred to as K2) and Rivne (referred to as R4) NPPs. The design of these units is based on the unified reactor WWER-1000/V-320. Nine NPPs of this type have been already in operation at the Nuclear Power Stations of Ukraine since the 1980s. During completion of K2/R4, their design has been sufficiently modified as a result of implementation of the Modernization Program. The main advantages of K2 (connected to the grid since 8 August 2004) in comparison with the unified design are the following (Expert Conclusions): - New modification of nuclear fuel (TVS-A), which has no drawbacks peculiar to the previous design and which passed trial service at Zaporozh NPP Unit 3; - Modern instrumentation and control system (I and C); - Measures of the Modernization Program (implementation of the up to date radiation monitoring system at the unit and the 30 km surveillance zone, installation of the improved modern heat-mechanical and electrical equipment, fire safety improvement, water chemistry improvement, etc.); - Comprehensive safety analysis report (SAR). The same modifications (except TVS-A implementation) are also completed at R4, the commissioning of which is planned for October of this year. Commissioning is one of the most important stages in an NPP lifetime. This stage covers the following: - Final assessment of NPP safety, taking into account design modification during construction stage; - Final inspection of quality of construction, assembling, fabrication of equipment, etc.; - Inspection of staffing and training of operating personnel, operating documentation, etc.; - Complex testing of functional ability of components, systems and plant as a whole; - Final decision regarding fuel loading (point of no return). After that decision, the object of construction is fundamentally changed into a nuclear installation. The faults during this stage are very difficult or impossible to be fixed. The approaches used by the SNRCU and its scientific and technical support organization SSTC NRS on both: regulatory review of safety case and regulatory control of measures on safety upgrading of K2(R4), as well as experience obtained in K2/R4 licensing are described in this paper