Regional Basic Professional Training Course in Korea

Regional Basic Professional Training Course (BPTC) on Nuclear Safety
accident progression:
In vessel processes during the early phase of damage progression before vessel
breach;
Ex-vessel processes at an soon after vessel breach;
Long term processes following vessel breach.
The answers to the questions corresponding to the physical evaluation of the system are
given by deterministic accident progression analysis performed by appropriate computer
codes [9.7-8].
For some phenomena, like direct containment heating, production of hydrogen, and steam
explosions, the answers are expressed by probability distributions generally produced by
expert judgment.
The APET will provide the conditional probability that a containment failure mode can
be realized, given a PDS. The APET produce a large number of end states, which are
generally grouped in release categories or BINS. One BIN is defined by the values taken
by several indicators that will give all the information needed to determine the release of
fission product in the atmosphere.
Source term
The different steps of evaluation are the following:
Grouping of fission products in accordance with their common chemical and
physical characteristics.
Release of fission products from fuel during the in-vessel phase.
Retention of fission products within the reactor coolant system.
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