GB1314498A - Nuclear reactors installtion - Google Patents

Abstract

1314498 Reactor pressure vessels COMMISSARIAT A L'ENERGIE ATOMIQUE 5 April 1972 [9 April 1971 13 May 1971] 15689/72 Heading G6C A nuclear reactor installation comprises a prestressed concrete, axially vertical pressure vessel 1 an upper part of which has therein a main cavity 3 containing the reactor core 4, and a lower part of which, below the core, has vertical cavities 12 connected at their top ends to ;he main cavity and at their bottom ends with the bottom surface of the vessel, the vertical cavities serving to house thermal energy extraction apparatus. In the embodiment shown the cavities 12 have bottom plugs 13 located in a pit 14 beneath the pressure vessel which rests on radial bearing elements 14a. The disposition of the cavities 12 is such as to leave a central concrete block 15 below the main cavity. In another embodiment (Fig. 3, not shown), which utilizes spherical fue elements, the latter are discharged downwards from the core by a device (16) positioned in the central concrete block. In a further embodiment (Figs. 4 and 5, not shown), the reactor, which is a fast neutron reactor, has a thick neutron and heat shield (17) disposed around the core and at the periphery of the main cavity. The shield can be partly cooled by cold gas returning to the core. Fuel charging and discharging is conducted from the bottom of the main cavity by devices (18) disposed in the central concrete block. Some of the vertical cavities are of smaller size than others and receive auxiliary cooling devices. In another embodiment (Fig. 6, not shown) the lower part of the pressure vessel is of reduced diameter defining a shoulder (23) whereby the vessel rests on support structures (24). In general, the reactor coolant gas may be CO 2 or He. The reactor may be thermal (using prismatic or spherical fuel elements), fast or HTR. The thermal energy extraction apparatus may comprise heat exchangers &c. or gas turbines. The arrangement of the vertical cavities enables hot gas to pass downwards through the thermal energy extraction apparatus and cool gas to pass upwards around that apparatus and adjacent the pressure vessel wall before returning to the core. The vessel mounting arrangement is said to afford increased stability in earthquakes; the pit 14 facilitates maintenance of the apparatus in the cavities.