KERNREAKTORSCHUTZSYSTEM IM FALLE EINES EINGEFALLENEN REAKTIVITAETSVERMINDERNDEN ELEMENTES

The protection against the consequences of the accidental fall of a control rod cluster is ensured by four lines, each comprising two neutron flux detectors (D1A, D1B), two primary processing circuits (R1A, S1A and R1B, S1B) associated with these two detectors, to provide each with a primary fall signal in the case of a rapid decrease in the flux measured by the corresponding detector, and a gate (P1) of the OR type to supply a drop signal at the output of the line in the presence of at least one such primary signal. The detectors (D1A, D4B, D3A, D1B, D2A, D3B, D4A and D2B) are distributed angularly around the vertical axis (A) of the core (2). A secondary processing circuit (6) orders an emergency shutdown of the reactor when it receives drop signals at the output of at least two lines. ……