Quality assurance during design, construction and operation of nuclear power plants

R. GASCA, Asociacion Nuclear Asco — Vandellos II, Spain

Abstract: In order to provide enough confidence that the nuclear station will produce electricity in a safe and reliable way, the implementation of quality assurance principles is necessary. This chapter identifies the main elements for establishing and implementing a quality assurance system for the stages of design, construction commissioning and operation in a nuclear power plant project.

Key words: quality, quality assurance, design, construction, commissioning, operation, management.

21.1 Introduction

The objective of this chapter is to identify the main elements for establish­ing and implementing a quality assurance system for the stages of design, construction, commissioning and operation in a nuclear power plant project. The content is applicable to all individuals and organizations involved in the project and the main objective of the system is to ensure and maximize safety and reliability.

In the general industrial activity, not only in nuclear, the precedent of the quality assurance process was quality control. It was based on the applica­tion of inspection and testing techniques, to verify the quality of a product against a set of acceptance criteria previously specified. The quality assur­ance process is based on the implementation of a set of contour conditions, affecting people, organizations and installations, to avoid or minimize devia­tions and to provide a reasonable assurance of getting a steady-state quality level. The quality assurance process does not eliminate quality control because critical parameters must be specifically controlled in some cases.

To better understand the role of quality assurance in nuclear safety it is convenient to introduce the concept of ‘defence in depth’ and its relationships.

The International Nuclear Safety Group (INSAG) of the International Atomic Energy Agency (IAEA) has established (INSAG, 1996) that defence in depth consists in a hierarchical deployment of different levels of equipment and procedures in order to maintain the effectiveness of physical barriers placed between radiological material and workers, the public or the environment, in normal operation, in anticipated operational occur­rences and, for some barriers, in accidents at the plant. For the effective implementation of defence in depth the IAEA establishes that three basic prerequisites must be considered: conservatism, quality assurance and safety culture. Each level of defence can be effective only if the quality of design, materials, structures, components and systems, operation and main­tenance can be relied upon. Quality assurance programmes can ensure the development of a safe design. They can also ensure that the intent of the design is achieved in the plant as built and that the plant is being operated as intended and maintained as designed.

In this chapter, the most widely applied approach for quality assurance in nuclear projects has been considered. However, the fact that nowadays a new approach called ‘management system’ has been established should be pointed out. This system could be defined as a set of interrelated or interacting elements that establishes policies and objectives and which enables those objectives to be achieved in a safe, efficient and effective manner.

In the area of nuclear installations this new approach has been recently introduced in the IAEA Safety Fundamentals (IAEA, 2006a) and devel­oped in a requirements document (IAEA, 2006b). These documents define the requirements for establishing, implementing, assessing and continually improving a management system that integrates safety, health, environmen­tal, security, quality and economic elements to ensure that safety is properly taken into account in all the activities of an organization. The system con­siders the implications of all actions not within separate management systems but with regard to safety as a whole.

The management system established by the IAEA includes some addi­tional elements such as safety culture, satisfaction of interested parties and an approach to process implementation.

The IAEA has developed additional safety guides, IAEA (2006c) and IAEA (2009), to facilitate the implementation of the above-mentioned approach. Finally it should be pointed out that, for the moment, this new approach established by the IAEA is not widely applied around the world.

Coming back to the main intent of this chapter, basic criteria that are applicable to all stages of a nuclear power plant project will be identified in the following paragraphs and, afterwards, more specific elements related to the management and performance for each stage will be described.

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