Regional Basic Professional Training Course in Korea

failure of which might put in jeopardy systems mentioned above.
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12. Surveillance Programmes
Components subjected to in‐service inspection are examined by visual, surface and
volumetric methods as a general rule. In addition, the pressure‐retaining components are
checked by a leak test to ascertain possible leakage.
Consistent with their importance to safety, some components may be exempted from the
surface and volumetric examinations, either because of their size, the size of their
connections, or the number of barriers between the component and the fuel or the outside
atmosphere. In such cases, however, these components are not exempt from examinations
for evidence of integrity as part of the system hydraulic tests.
The number, frequency and extent of in‐service inspections of similar systems and
components may be reduced by a sampling programme that will vary according to the
design, the number of similar components or systems involved, operational requirements,
or the existence of identical units in a multiple unit plant. The sampling rate is consistent
with the importance to safety of the component and the rate of degradation.
12.3.3. Inspection schedule
The in‐service inspection programme of a particular nuclear power plant is completed
during an interval, the length of which is chosen with a conservative assumption to ensure
that deterioration, if any, of the most exposed component is detected before it can lead to
failure. The examination schedule provides for repetition of the inspection programme
during the operating life of the nuclear power plant. The examination programme may
involve evenly distributed inspection intervals or alternatively, the inspection intervals
may be varied during the operating life of the plant to improve the correlation between