7.4 Overview

To ensure that nuclear power plants are safe and reliable, the system components and structural systems must be built to the quality required. Life cycle management is generally defined as a combination of ageing management and financial planning. Ageing management is thus part of life cycle management, and covers everything that the operators need to do to ensure that their nuclear power plants remain safe as they get older. The fundamental principles here are laid down by KTA 1403 [106] which gives rules for ageing management at nuclear power plants.

The main role of ageing management in structural installations is to map what may happen to building materials as they age and prevent their having harmful effects specifically and effectively. These ageing mechanisms are also known as physical ageing: so ageing management deals primarily with physical ageing, with measures to ensure permanence and in particular the structural safety of building structures in use.

The term life cycle management is used instead of ageing management if the focus is on financial aspects as well as structural safety. Life cycle management thus goes beyond ageing management: as well as physical ageing, it also includes conceptual ageing and technological ageing (see Figure 9.1).

Conceptual ageing covers changes to design standards due to introducing new rules such as standards and guidelines with altered requirements or changes to safety philosophy. These changes must be assessed to see how far they are relevant to the structural safety of buildings designed to the ‘old’ rules.

Technological ageing covers changing findings in terms of possible harmful operating mechanisms and material characteristics. It also covers innovations in verification methods (changes to calculation standards) and testing and calculation methods. It is relatively unimportant in structural engineering compared with plant engineering, as the characteristics of the principal materials, concrete, reinforced concrete and building steel, have remained fundamentally unchanged for the past 40 years.

Like life cycle management, ageing management involves maintaining buildings as knowledge-based preventive maintenance. This preventive maintenance covers the different measures involved in terms of maintenance, inspection, repairs and strength­ening as shown in Figure 9.2.