Patent GB-1041221-A (GB)
Title: Improvements in or relating to the control of nuclear power plants
Inventor: TAYLOR ANTHONY JAMES
IPC: G21D5/08
Filed: 1962-02-08
Abstract: 1,041,221. Steam boilers combined with nuclear reactors. BABCOCK & WILCOX Ltd. May 8, 1961 [Feb. 8, 1962], No. 4971/62. Heading F4A. [Also in Division G6] In a nuclear power plant in which a coolant from a reactor core is passed through a boiler, the core reactivity and the flow of working fluid to the boiler are both automatically adjustable, and one of these adjustments is controlled by the temperature or a function of the temperature of the coolant and the other is controlled by the boiler pressure. Embodiments utilizing gas-cooled, pressurized water, and boiling water reactors are described in which core reactivity is controlled by the working fluid pressure and working fluid flow is controlled by the coolant temperature; one embodiment, utilizing a gascooled reactor is described in which the reactivity is controlled by the coolant temperature, and the working fluid flow is controlled by the working fluid pressure. The gas cooled reactor 1 (Fig. 1) has its reactivity varied in response to changes in the working fluid pressure between the boiler 4 and the turbine 6. A pressure sensitive device 10 used in conjunction with a comparator 11 passes appropriate signals to a reactivity control device 9 which actuates the reactor control rods. The working fluid flow is adjusted in response to changes in the gas inlet temperature to the reactor 1. A temperature responsive device 12 compares the gas temperature with a comparator 13 and appropriate signals are sent to a fluid flow control device 8 which actuates a valve 7. Provision is made for adjusting working fluid flow in response to turbine load changes which anticipates the temperature change which will subsequently occur in the coolant gas. A comparator 15 compares the working fluid flow at 14 and 16 and feeds appropriate correction signals to the fluid flow control device 8. A pressurized water reactor (Fig. 2, not shown) is used in an identical layout to that just described, except that, since it is preferable in such a reactor to maintain a constant mean coolant temperature, the temperature responsive device 12 simultaneously compares both the inlet and outlet temperatures with the comparator 13, so that signals to the working fluid flow control device 8 are based on the mean temperature of the coolant in the reactor core. The gas cooled reactor 21 in the plant shown in Fig. 4 has its reactivity controlled by the temperature at which the coolant leaves the reactor, and the operating fluid flows are controlled by the pressure of steam generated in the boilers 23, 27. Each boiler has a coolant pump 22 (30) and a working fluid flow valve 25 (29). The pumps 22, 30 are ganged and supply gas to a common plenum chamber in the reactor. Working fluid vapour from the two boilers passes to a common header 26 and thence to the turbine 31. Signals from a pressure sensor 34 and comparator 35 pass to the working fluid flow control devices 32, 33. Fluctuations in the temperature at which coolant leaves the boilers are compensated by varying the rate at which the pumps 22, 30 operate; thus temperature sensitive devices 36, 38 in conjunction with comparators 37, 39 feed signals to a pump control 40. In order to eliminate temperature differences between the coolant outlets from boilers 23, 27, signals from the temperature sensitive devices 37, 39 are fed to the flow control valves 25, 29. A modification of the plant shown in Fig. 4 (Fig. 5, not shown) uses two working circuits in each boiler; the additional circuits are substantially the same as those already described, except that they generate working fluid vapour at a lower pressure which is fed through a common header to a low pressure section of the turbine.