Nuclear power plant accident management aid system

The system of the present invention collectively recognizes a state of a nuclear reactor, on a real time, after occurrence of a scram accident and informs this state to an operator by a method capable of recognizing the state at a glance. Namely, a measuring means measures the state for each reactor portions after occurrence of the scram accident. A calculation means calculates a risk index showing a degree of danger of the reactor state based on predetermined measured information among individual information obtained by the measuring means. A display means displays the risk index calculated by the calculation means. In the system thus constituted, since the risk index is calculated/displayed by using only the predetermined measured information obtained by the measuring means, the operator can recognize the degree of danger of the reactor state collectively on real time at a glance. As a result, the operator can easily perform a countermeasure at an early stage, thereby enabling to effectively prevent the scram accident from developing to severe accidents. (I.S.)