Steam cooled reactor esp. of ship propulsion - in which variable proportion of superheated steam is injected into water

摘要

A steam-cooled nuclear reactor comprises a core contained in a pressure vessel and supplying its heat for superheating steam to drive turbines, esp. for ship propulsion. The ascending, heated steam leaves the core through a number of ducts and is collected in a header above the core; from here, the steam flows through a header and sub-divided into two flows; the principal flow leaves through vessel outlet ducts and passes to the steam turbines, while a secondary flow passes downwards through a series of ducts, each terminating in a nozzle submerged in a tank of water surrounding the core but separated from it by shields, this steam injection evaporates part of the water, producing saturated steam which ascends in the vessel, passes through a screen dryer into the top dome of the vessel and is drawn from there by intakes leading to circulating pumps from which the steam is returned through coaxial inner ducts to a saturated steam header above the core; from this header, each downward saturated steam duct is coaxial and outside the ascending superheated steam duct, so that the descending saturated steam is dried before it enters the core. The high thermal efficiency of a steam cooled reactor circuit is obtained. No damp steam enters the core. Wide variations in turbine load, requiring widely varying supply rates of steam to the turbine, can be accommodated by modifying the amount of steam passed to the turbines and compensating it by the amount injected into the water tank. During shut-down it is possible to maintain the required temp. in the various parts of the sector.