GB1507688A - Passive containment system - Google Patents

Abstract

1507688 Reactor safety NUCLEDYNE ENG CORP 4 Feb 1975 4797/75 Heading G6C In a nuclear reactor plant comprising a reactor, a reactor coolant system including conduit means for circulating high-pressure hightemperature coolant within the coolant system, steam generator means, and a containment structure sealingly enclosing at least the reactor and its coolant system, containment of the plant during accidental loss of coolant is effected by sensing a first preselected pressure differential between the coolant and a first separate body of pressurized cooling liquid, causing the cooling liquid to start to flow into the coolant system and in so doing reducing the pressure of the pressurized cooling liquid, sensing the decreasing pressure thereof until a second preselected pressure differential is attained between the pressurized cooling liquid and the steam within the steam generator means, and causing the steam to be directed to the pressurized cooling liquid when the second pressure differential is attained to thereby provide an additional pumping force to the cooling liquid to continue the flow of the cooling liquid into the coolant system in order to replenish such coolant as has been lost. The pressurized cooling liquid may be chilled. Further steps as follows may be added: permitting such coolant as is lost to vapourize within the containment structure to cause the latter's interior to attain a first relatively high vapour pressure, sensing the attainment of a third preselected pressure differential between that interior and a second separate body of second cooling liquid when the first relatively high vapour pressure is attained, then completing communication between vapour at that pressure and the second cooling liquid to thereby heat and simultaneously pressurize the second cooling liquid, and permitting the latter to flood the interior of the containment structure. The embodiment is a pressurized water reactor with four loops of reactor coolant and includes the following features: (i) stored "deluge" fluid, the reactor vessel refill fluid and the fluid in the annulus between primary and secondary containers have chemicals in solution to serve as neutron poisons (e.g. boron, cadmium, hafnium), oxygen getters (e.g. hydrazine, sodium sulphite), fission product getters (e.g. sodium hydroxide, sodium thiosulphate), and freezing point depressants (e.g. ethylene glycol), (ii) high vacuum in the primary containment and removal of thereform of specified auxiliary systems and massive concrete structures, and (iii) measures to protect against accidental reactor surges.