Environmental Engineering Reference
In-Depth Information
may in turn jeopardize the safety functions. The review of plant condition
is based on the information related to the health of components from the
following sources:
Results of operational information, records of the operational events.
Failure data, root-cause analysis, failure statistics.
Outage and maintenance records.
The inspection programme for safety Class 1 SCs is the most rigorous. It
includes the following:
Data of the non-destructive testing of the SCs.
Evaluation of the results of the in-service inspections.
Evaluation of the results/fi ndings of the maintenances.
Evaluation of the results of the ageing management programmes.
Evaluation of failure data and other lifetime information.
Evaluation of operational information.
Non-destructive testing is a regular activity at nuclear power plants.
However, in the context of the plant review for the justifi cation of LTO,
some additional tests might be necessary. Individual programmes can be
useful and developed for the Class 1 SCs, the reactor, main isolation valves
(if such exist), main pipelines of the primary loops, steam generators and
pressurizer.
In the case of SSCs in safety Classes 2 and 3, the most practical review
method is visual on-site inspection. Application of the graded approach
is useful, so that, in the case of higher importance or safety relevance, the
inspection has to be performed for each particular item, whereas the review
can be limited to the inspection of a representative sample of the commod-
ity. The selection of the representative sample has to be made taking into
account its type, the material, dominating degradation mechanism, environ-
mental stressors, etc.
There are minor aspects to be checked during the inspections, for
example:
symptoms of leakages
condition of the insulation
paint condition
condition of unpainted surfaces
condition of welding
condition of components at junction points of different materials
condition of bolted joints.
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