Protection system for a nuclear reactor

A description is given of a protection system for a nuclear reactor which prevents reactor power excursions when conditions arise causing rapid cooldown of the reactor coolant, as when a steam break occurs in the supply line to a steam generator-turbine steam circuit, or under other conditions requiring rapid insertion of boric acid into the reactor. A pump having its inlet connected to the reactor primary coolant loop discharges into, or takes suction from, a tank containing a 12 percent boric acid or other neutron absorbing solution, and forces the solution into the remaining legs of the reactor primary cooling loop. Valves on both sides of the tank keep the tank isolated from the reactor when not in use