Some AMPs are based around addressing a particular degradation mecha­nism, examples of which are shown in Table 8.6.

Structure — or component-oriented AMP

Applying the graded approach, the SCs can be separated into two categories:

1 Highly important from a safety point of view, items with complex fea­tures and ageing mechanisms.

2 Items which have the same type, safety class, identical design features, materials, operating circumstances and dominating ageing mechanism could be grouped into commodity groups and for each commodity group a designated AMP can be implemented, for example pipelines, pipe ele­ments, valves, heat exchangers, etc.

The highly important SCs like the reactor pressure vessel together with internals or components of main circulating loop (SCs of Safety Class 1 and some SCs of Class 2) can have dedicated, individual AMPs, for example:

[17] Reactor pressure vessels

• Steam generators

• Reactor pressure vessel internals

• Pressurizers

• Main circulation pipeline

• Main coolant pumps

• Main gate valves.

[18] the analysis remains valid for the period of LTO;

• the analysis has been projected to the end of the period of LTO via removing the conservatism used in the TLAA analysis by less conserva­tive assumptions and methods for analysis; or

• the effects of ageing on the intended function(s) will be adequately man­aged for the period of LTO.