Maintenance, surveillance, inspection and testing - Tools for ensuring functional and structural integrity

摘要

Systems, structures and components of nuclear power plants that have a bearing on safety must remain in accordance with the assumptions and intent of the design over the whole plant life. Maintenance, surveillance, in-service inspection and testing are the major tools to ensure this. These activities create an integrated system within the program developed and implemented by the plant operator. Maintenance is an organized activity, both administrative and technical, to detect and mitigate damage of functioning components/equipment, or to restore to an acceptable level the performance of designed functions of failed components. In this sense, maintenance is the tool to ensure functional integrity' of active components. Surveillance activity mainly focuses on the integrity of physical barriers, and the availability of safety and protection systems. Non-destructive evaluation as the major area of in-service inspection delivers essential input in terms of existence and size of flaws, usually cracks or crack-like flaws, to assess component's 'structural integrity' on the basis of fracture mechanics principles. In-service inspection deals with passive components. Testing activities are not unrelated elements of monitoring and maintaining technical condition of systems, structures and components but substantial parts of their three basic activities, i.e. maintenance, surveillance and in-service inspection. The paper describes the characteristics of this integrated system of ensuring functional and structural integrity of nuclear power plant systems, structures and components; the role and importance and the relations of its individual elements to each other.