Environmental Engineering Reference
In-Depth Information
strategy for managing nuclear plant safety based on risk analysis for each
individual plant.
Basic principles of the ISI program based on risk information, are as
follows:
• the possibility of determining the consequences, probability and risk
associated with structural failures, so that the ISI programme focuses on
an integrated strategy of defence in depth;
• development of the ISI programme which will reduce the risk of failure
in high-risk areas, taking into account economic considerations (cost) and
radiation doses received by the personnel at the nuclear power plant.
The advantage of this approach is the optimisation of operational
inspection. In this context, the term 'optimisation' means the process of
maintaining defence in depth which envisages:
• improvement or at least maintenance of the overall safety of the
nuclear plants;
• reduction the radiation doses received by personnel involved in
inspection;
• improvement of NPP reliability.
The main elements that make up the planning process of operational
inspection based on risk information, are:
• participation of the operating organisation in the development and
application of methodology based on risk information;
• formation of a group of experts to evaluate the ISI based on risk
information;
• identification of equipment/structures or their elements for which the
programme of operational inspection based on risk information will be used;
• gathering and analyzing information needed to perform risk assessment;
• determination of the level of assessment (i.e. for each equipment or
its component or for the same type of group);
• assess the probability of failure for all the components;
• assess the consequences of failure for all the components;
• ranking of the risks associated with all components;
• selection of components to be controlled according to selected criteria;
• periodic certification of inspection;
• feedback of received information on the results of inspection by ISI
methods and certification of inspection.
The first practical step in the development of the ISI programme,
based on information about the risks is to determine its volume (areas
of application) that will clearly define the scope of the programme, for
example, which systems and structural elements (circular, longitudinal
welds, fasteners, nozzles, etc.) should be included in the programme.
For successful development of this programme, based on risk information,
it is necessary to solve several problems which can be described as follows:
• stability of the programme from a technical point of view - independent
internal and external (e.g. by specialists of a regulatory body), checks
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