Regional Basic Professional Training Course in Korea

Some typical uses of level 2 PSA are:
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9. Probabilistic Safety Analysis
To gain insights into the progression of severe accidents and containment
performance;
To identify plant specific vulnerabilities of the containment to severe accidents;
To identify major containment failure modes and to estimate the corresponding
releases of radionuclides;
To provide a basis for the evaluation of off-site emergency planning strategies;
To provide a basis for the development of plant specific accident management
strategies;
To provide a basis for the prioritisation of research activities.
9.1.5.2. Steps of a PSA level 2
Interface to level 1 PSA and sequence grouping
Information about the many different accidents that lead to core damage is passed
fromthe accident frequency analysis to the accident progression by means of Plant
Damage States (PDS). One PDS is defined by the values taken by several indicators that
will give all the information needed to determine the progression of accident.
Accident progression
The accident progression is described by an Accident Progression Event Tree (APET),
that begins with the core uncovery and ends with the core corium interaction.
The APET is composed of questions that must address all of the relevant issues important
to the progression of severe accidents, containment response failure and source terms.
The tree generally is divided into time frames, delineated by the major events in the