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Regional Basic Professional Training Course in Korea

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guidel<strong>in</strong>es for this categorization.<br />

* PC: Plant Condition<br />

❙ 477 ❙<br />

8-A. Determ<strong>in</strong>istic Accident Analysis (Non‐LOCA)<br />

Table 8.1 Event Classification Accord<strong>in</strong>g to Its Frequency<br />

For each category, a number of envelop<strong>in</strong>g scenarios are identified <strong>in</strong> such a way that<br />

their analysis covers all events to be considered <strong>in</strong> that category. Each envelop<strong>in</strong>g<br />

scenario is then analyzed by us<strong>in</strong>g some conservative assumptions <strong>in</strong> the <strong>in</strong>itial<br />

conditions of the plant, reactor power, pressure, <strong>in</strong>strument uncerta<strong>in</strong>ties, etc., and<br />

unfavorable hypotheses concern<strong>in</strong>g the accident progression such as s<strong>in</strong>gle failure<br />

criterion and stuck of the most reactive control rod.<br />

There are also other categorizations, based on: (1) pr<strong>in</strong>cipal effect on potential<br />

degradation of fundamental safety functions, (2) pr<strong>in</strong>cipal cause of the <strong>in</strong>itiat<strong>in</strong>g event,<br />

(3) relation of the event to the orig<strong>in</strong>al NPP design (for the exist<strong>in</strong>g plants). The first<br />

categorization is widely used <strong>in</strong> licens<strong>in</strong>g of a nuclear power plant, where each group of<br />

the PIEs trends toward similar core and RCS behaviors, pay<strong>in</strong>g the analyst’s attention to<br />

the same safety aspects. In this categorization, all <strong>in</strong>itiat<strong>in</strong>g events except BDBAs and<br />

SAs may be grouped as follows:

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