Application of Improved Technologies for Ensuring High Quality in Safety, Maintenance and Operation Activities of Units 56 of Kozloduy - A Successful Project

摘要

The Units 5 and 6 of Kozloduy Nuclear Power Plant (KNPP) became operative in 1987 and 1991, respectively. These units, consisting of a VVER-1000/320 type reactor, have design characteristics, basically elaborated in accordance with Russian rules and standards in force at the time of the design. In order to reach a full compliance with the international safety standards that evolved over the last two decades KNPP decided to introduce the Kozloduy Units 5&6 Modernization Program to upgrade the plant, with the main objective to bring the installation to a safety level compatible with current international practices. Developed on the basis of the recommendations of the chief designer of the nuclear facility, international missions and accumulated operational experience, the Program comprises 212 individual modifications aimed at enhancing safety, reliability and operational conditions of the 1000 MW units. The implementation of these modifications, including replacement of existing or installation of new equipment, as well as conduction of analyses and studies, has been achieved by an international team of specialists who have put great effort, knowledge and experience in the successful implementation of such a large-scale project, strictly observing the budget and time restrictions. This Report presents part of the implemented Measures and the resulting positive effect, thus establishing and evidencing the conditions required for unit operation extension above the designed life-time. The brief illustration of the main characteristics of the Modernization Program of Units 5&6 of Kozloduy clearly shows how well the use of advanced technologies may fit into the structure of the existing plant. The adoption of high quality products and techniques, associated with a well structured design, with clearly-defined objectives, ensures an added value to the innovation. The replacement of the existing equipment with qualified new products, the installation of powerful computational machines and intelligent instrumentation, the increase of use of preventive and predictive tools, and the consequent upgrading in the plant staff culture and operating philosophy, will allow at Kozloduy NPP a more reliable and long-lasting safe operation of the plant, complemented by a better performance for the maintenance activities, in compliance with the highest nuclear safety requirements. The Modernization of Kozloduy can show that with a systematic design approach and with the use of the adequate resources available nowadays in the nuclear industry, the safety and the operational parameters of the plant can be raised to the levels requested by the international opinion, and that the estimated residual lifetime of the installation can be extended beyond the design limits. Taking in consideration the intricacies encountered upon the implementation of such a complex modernization program that required multiple interventions in the original design of the units, the Report draws special attention to the value of the experience gained upon the management and implementation of such large-scale and complex designs in the nuclear field.