| 摘要 |
<p>1,225,997. Reactors. GENERAL ELECTRIC CO. 13 June, 1968 [26 June, 1967], No. 28263/68. Heading G6C. An emergency cooling system for a boiling water reactor comprises a first auxiliary steam line 23 which includes a valve 24 operated by a pressure-sensitive unit 25 set to open valve 24 at a predetermined pressure above the normal operating pressure in the pressure vessel 10. After-steam from an emergency shut-down, i.e. steam produced for some time after shut-down due to delayed neutrons, heat stored in the nuclear fuel and radio-active decay of fission products, is removed by passing it through the valve 24 and line 23 to a sparger 27 beneath the surface of the water in a pressure suppression vessel 26. The vessel 26 may be provided as a component of a pressure suppression system designed to condense the escaping steam in the event of a major rupture of the pressure vessel 10 or the primary lines within the containment building. A second auxiliary steam line 28 includes a valve 29 operated by a control unit 30 responsive to the liquid level of the coolant in the pressure vessel 10. When the liquid drops below a predetermined level the valve 29 is opened to apply steam to a steam-operated motor or turbine 31, the exhaust from which is condensed in the suppression vessel 26. The turbine 31 drives a pump 32 which supplies make-up water to the pressure vessel 10 from any suitable coolant reservoir, e.g. a storage tank 33 and/or the vessel 26. During a normal shut-down, the after-heat is accommodated by closing a valve 21 to the turbine 15 and opening a by-pass valve 22 to apply the after-steam directly to a condenser 17, the condensate being returned by a feedwater pump 19 to maintain the coolant level in the pressure vessel 10 in the normal manner.</p> |
