Regional Basic Professional Training Course in Korea

Regional Basic Professional Training Course (BPTC) on Nuclear Safety
according to their probability of occurrence. The categories typically cover normal
operation, anticipated operational occurrences, design basis accidents and severe
accidents.
Postulated initiating events
In designing the plant, it shall be recognized that challenges to all levels of defence in
depth may occur and design measures shall be provided to ensure that the necessary
safety functions are accomplished and the safety objectives can be met. These challenges
stem from the PIEs, which are selected on the basis of deterministic or probabilistic
techniques or a combination of the two. Independent events, each having a low
probability, are normally not anticipated in the design to occur simultaneously.
Internal events
An analysis of the PIEs shall be made to establish all those internal events that may affect
the safety of the plant. These events may include equipment failures or mal‐operation.
Fires and explosions
Structures, systems and components important to safety shall be designed and located so
as to minimize, consistent with other safety requirements, the probabilities and effects of
fires and explosions caused by external or internal events. The capability for shutdown,
residual heat removal, confinement of radioactive material and monitoring the state of the
plant shall be maintained. These requirements shall be achieved by suitable incorporation
of redundant parts, diverse systems, physical separation and design for fail‐safe operation
such that the following objectives are achieved:
To prevent fires from starting;
To detect and extinguish quickly those fires which do start, thus limiting damage;
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