By means of critical heterogeneous atom core reactor from the pressure kettle type

摘要

1,069,016. Controlling reactors. SIEMENSSCHUCKERTWERKE A.G. Aug. 6, 1965 [Aug. 8, 1964], No. 33893/65. Heading G6C. A heterogeneous nuclear reactor is cooled and moderated by light or heavy water at supercritical thermal conditions to provide automatic control. The water enters the core in two streams, one of which is at a low temperature and is primarily a moderator and the second of which cools the fuel directly. Adjustment of the water temperature by control of the flow, produces large changes in density, at the critical temperature condition. Changes in density are accompanied by changes in the neutron spectrum and hence in the core reactivity. An increase in reactor activity raises the moderator temperature and hence its volume. An increased rate of flow results which is restricted by throttle nozzles. This further raises both the moderator temperature and specific volume and decreases the moderation and reactivity. Each moderator inlet is provided with a nozzle and a radial and axial flux-flattening effect is produced. Further control is provided by the addition of a liquid neutron absorber during start-up and shutdown. In nuclear power plant, the liquid absorber is injected into an auxiliary coolant circuit by-passing the turbines.