Environmental Engineering Reference
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completing the necessary measures, reached acceptable levels.
The second direction of optimisation of SPM is to ensure the optimum
stock of spare parts and accurate timing of repairs. Repair is the most
common and easiest way to restore the operational efficiency of the
structure to an acceptable level. In most cases, repair is carried to restore
the operational efficiency of structural members and equipment that have
defects of technological nature (cracks, cavities, etc.). In this case, the repair
can be accomplished either by welding or without it when the defect can
be removed by mechanical grinding.
More effective repair procedures can be justified by the optimisation
method in Ref. 138.
As a rule, maintenance is efficient if technological defects are removed.
If the reason for appearance of the defect is poor design, reconstruction
is inevitable.
The reliability characteristics are used to create a maintenance
reserve. This technique is well developed and tested and thus it is not
discussed here.
The third area of optimising SPM is associated with the optimisation
of technical inspection of equipment and pipelines
8.3.2 Optimisation of the frequency and composition of
works on technical inspection
Technical inspection is an integral step in assessing the state of equipment
and pipelines (EP).
The purpose of technical inspection is to determine the actual status of
the EP, confirmation of their compliance with the project, existing rules and
standards, other technical documentation, confirmation of their serviceable
condition, the possibilities and conditions for their further operation on
nuclear power plants.
Technical inspection is carried out according to the results of:
- verification of documentation;
- visual survey of EP in accessible locations inside and outside;
- hydraulic test;
- previous non-destructive testing;
- prior testing of the mechanical properties, microstructure, chemical
composition, geometrical dimensions and operational impacts.
Using the probabilistic methods of structural strength, described above,
to determine the actual values of residual defects, strength, resource,
reliability, safety and durability it is possible to optimise the composition
of operations and frequency of technical inspection. In this case, the results
of technical inspection are used to:
- define the original actual state of EP before operation (if technical
inspection is carried out during commissioning);
- determine the state of EP at the time of technical inspection (if it is
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