MODERNIZATION OF THE 900 MW NUCLEAR POWER PLANTS AT EDF: WHICH STRATEGIES AND SOLUTIONS?

摘要

EDF operates a homogeneous fleet of 58 Nuclear Power Plants (NPP), of which 34 are of the 900 MW type. EDF is now preparing the fourth ten-yearly outage of these 900 MW NPPs, of which the first will take place in 2019, and like most utility providers, EDF is considering extending their lifetime up to 60 years. For this reason, EDF are studying the necessity and potential profitability of potential modernization scenarios of all or parts of the Instrumentation and Control (I&C) systems. These plants continue to be operated with the original I&C Systems which are based on the technology of the 1970s, i.e. electromechanical relays and analog technology. This paper describes the various phases of the project that begun at the beginning of 2011 in order to define the best strategy for each I&C system: 1. Diagnostic of each I&C system, through an "Observation Phase": 1.1 Survey of the obsolescence of I&C components. 1.2 Analysis of I&C ageing mechanisms. 1.3 Analysis of functional margins in existing systems. 1.4 Evaluation of the knowledge and competencies of site workers and of the potential effect of a change in technology used on the NPPs. 2. Identification of external influences impacting the current I&C systems, such as functional improvements or additional safety requirements. 3. The evaluation of the possible technical solutions, which could be one of the following: 3.1 Maintenance of the existing I&C materials. 3.2 Re-design of old modules with new technologies such as AS1C/FPGA. 3.3 Replacement of I&C systems with more modern technologies such as PLCs. 3.4 Total refurbishment with significant impact on the cabling and on interfaces with other systems and with the plant control room.