During the design of the original HWR stations, potential mechanisms for ageing of the plant were considered, and inspection and maintenance programmes were developed. These programmes were based on the best information available from the nuclear power industry at that time. Since then, the HWR industry have been using the experience gained through the operation of these reactors, and throughout the industry in general, to develop systematic and comprehensive PLiM programmes to assure the on-going safe and economic operation of the reactors.

As stated previously, the objective of a PLiM programme is to effectively integrate ageing management programmes and economic planning to maintain a high level of safety, optimize the operation, maintenance and service life of SSCs, maintain an acceptable level of performance, maximize return on investment over the service life of the NPP; and provide NPP utilities/owners with the optimum pre-conditions for PLiM. The following are typical specific objectives of a systematic PLiM programme for HWRs:

• To perform a comprehensive assessment of the critical SSCs;

• To develop or enhance the plant maintenance, surveillance/monitoring, inspection and testing, and rehabilitation programmes to effectively manage the effects of ageing degradation;

• Strengthening the role of proactive ageing management;

• Implementing a systematic ageing management process;

• For in-service plants, ensure continuing safe, reliable, and cost effective operation during the plant design life in accordance with the following goals:

• Maintain public risk well within the regulatory requirements;

• Maintain high lifetime capacity factors, contributing to providing electricity at a competitive cost;

• Be able to anticipate new and emerging ageing issues and therefore minimize “unexpected” problems; and

• Preserve the option for long term operation of NPP.

For new HWR plants, additional objectives may be to:

• Assure plant owner/operators that HWR can meet and exceed its target design life; and

• Provide an optimized cost effective maintenance programme (using ageing assessment experience to provide this assurance).

The starting point should be the definition of the desired operational life. The programmes and measures for ensuring the required safety and performance levels, also the investments needed, depend on the target time of operation. A reasonable time-target should be selected for the economic investments in order to achieve the profit expected.