Considering the best international practices and also tendencies in the development of management of ageing in general (including obsolescence), one can conclude that the required condition and functioning of all SSCs relevant to safety should be ensured via

• analyses defining time limits of safe operation (time-limited ageing anal­yses (TLAAs)) and corresponding monitoring of time limiting assump­tions (e. g. fatigue monitoring)

• ageing management programmes (AMPs)

• environmental qualification and programmes for maintaining the qualification

• maintenance and control of effectiveness of maintenance with respect to safety criteria

• scheduled replacements and reconstructions.

This system should be comprehensive in the sense that ageing of any item in the list of safety-related SSCs, should be covered by at least one of the methods. The required safety function and performance of any selected SSC has to be ensured by one of the approaches listed above or a combination of the methods/programmes (e. g. AMP and TLAA). The safety functions are properly ensured if the non-safety classified items, which may affect the safety functions, are also covered by one of the programmes.

The operator should pay specific attention to those structures and com­ponents, the function and performance of which directly limit plant life­time. These are the non-replaceable or not-to-replace SCs to which either an effective ageing management programme should be applied, or the required functions should be demonstrated for the extended operational time by analysis (fatigue, embrittlement, etc.) or by qualification (e. g. in case of cables).

There are different approaches to how the operator defines which method/ programme or combination thereof is applicable for particular SSCs; the optimization of plant efforts may have economical aspects too. The exist­ing plant programmes might be credited as appropriate for ensuring the required plant condition in the long-term, if they are reviewed and found to be adequate. The concept outlined above is illustrated in Table 8.3.