Development of the multi-unit CANDU life cycle management programme began in the early 1990s with the nuclear power life assurance (NPLA) programme. This programme included a small number of critical structures and components, with replacement cost or time greater than $100M or 6 months. The table below shows the initial NPLA components for the Pickering A station [Ш.1].

The multi-unit CANDU plants were required to respond to the CNSC Generic Action Item on continuing plant safety as components age (see section 2.2). As part of this response, components were classified into short lived and long lived components in order to select the appropriate ageing management programme [III. 1]. Long lived components were subject to ageing assessments; short lived components were considered to be addressed by regular plant maintenance programmes. For short lived components, the relevant plant programmes were reviewed for effectiveness to address ageing, under the auspices of the preventive maintenance optimization programme.

Starting in 1997, the multi-unit CANDU plants developed additional processes to address ageing of other important long lived components that were not included in the NPLA programme. Condition assessments were prepared for components selected on the basis of past incapability, plant concern, or external reports of component ageing. Condition assessments were prepared for about 50 additional components at each of Pickering, Darlington and Bruce. Procedures were also written for system and plant condition assessments.