HYDRAULIC SYSTEM FOR DRIVING CONTROL ROD

PURPOSE:To prevent the erroneous function of a control rod driving mechanism during periodic inspection by providing a remote control valve for closing a cooling water stop valve when the pressure difference between a nuclear reactor and the inlet of a cooling water line, line measured by a differential manometer, exceeds a set value. CONSTITUTION:A cooling water stop valve 25 disposed in a cooling water line 4 is a remote control valve and when the pressure difference between a nuclear reactor 14 and the inlet of the cooling water line 4 exceeds a set value, a pressure difference signal 31 is delivered from a differential manometer 18 disposed in an instrumentation line 40. The cooling water stop valve 25 is closed automatically by the pressure difference signal 31. Consequently, even if an operator conducts the remote control of a hydraulic pressure control unit 7 while missing the closing operation of a return line stop valve 20, the differential manometer 18 detects the increase of cooling water supply pressure and interrupt the circuit between a control rod driving water pump 3 and the hydraulic control unit 7 thus preventing erroneous function of the control rod driving mechanism 8. The pump 3 is protected by providing a minimum flow line 16.