JPS5882195A - Reactor feedwater control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a nuclear reactor water supply control device that controls a nuclear reactor water pump and maintains the water level of the reactor at a constant level.

(b) Prior art In general, for boiling water *atomic, a reactor standard water level is established that is necessary for stable operation of a nuclear reactor, and this reactor standard water level is established in any operating state of a nuclear reactor. The deviation of the reactor water level from the water level must be within the permissible range. In the event that the reactor water level deviates from this allowable range, the reactor must be shut down by reactor scram, and it is extremely difficult to maintain the reactor water level at the standard value in boiling water reactors. It's important. On the other hand, the reactor water level tends to constantly fluctuate due to the change in the flow rate of steam flowing out from the reactor to the turbine depending on the reactor output, so in order to maintain the reactor water level at the standard value, it is necessary to feed water into the reactor. Flow rate must be controlled. A device installed for this purpose is a reactor feedwater control device, which usually controls the rotational speed of the reactor feedwater pump or the opening degree of the flow rate adjustment valve provided at the outlet of the reactor feedwater pump. , controls the flow rate of feed water sent to the reactor.

Figure 1 shows an example of this, so 1 is a nuclear reactor, 2 is a water supply pump for feeding water into the reactor, and 3 is installed at the outlet of the water supply pump 2 to adjust the water supply flow rate. 4 is a water level setting device that provides a water level reference signal, 5 is a water level detector that detects the atomic f water level, and 6 is a water level reference signal L1 from the water level setting device 4 and a water level signal from the water level detector 5. , a water level controller that inputs and calculates the flow rate command signal,
Reference numeral 7 denotes a flow rate detector that detects the flow rate of the pump, and 8 inputs a pump flow rate signal L4 from the flow rate detector 7 and a flow rate command signal R from the water level controller 6 to control the opening degree of the flow rate adjustment valve 3. It is a flow controller.

FIG. 2 is a block diagram showing the operation of the above configuration,
G1(8) is a transfer function representing water level control lI6, G, (
8) is a transfer function representing the flow rate controller 8, G4(8) is a transfer function representing the flow rate regulating valve 3, and G4(8) is a transmission amount representing the nuclear reactor 1. Water level reference signal (8) and water level signal (8) deviation signal (water level deviation signal) L, (8)
is input to the transfer function Gt (8)K of the water level controller, while the flow rate command signal Ls (81) and pump flow rate signal L4 (81
The deviation signal (flow rate deviation signal) L・(81 is input to the transfer function G*(81) of the flow rate controller. The output (opening command signal) of the transfer function Gs(8) of the flow rate controller 8) is,
Glf81 is manually applied to the flow rate adjustment valve transfer function Gmf8).
The output (pump flow rate signal, (8)) is input to the reactor transfer function, (8). Reactor transfer function 04 (
8) is the water level signal LJ81. At this time, the flow rate deviation signal Ls(8) is calculated from the water level reference signal Ls(8).
) The transfer characteristic at t can be expressed by the following equation.

Normally, the water level controller 6 is expressed with a proportional gain, the flow rate regulating valve 3 is 0 type (i.e. Jim G(8) = finite), the reactor l is expressed with integral characteristics, and the flow rate controller 8 includes an integral element. No G, (horizontal = K (2-a) Iim G, (8) = -・(2-b) B -*6 1 im G, (8) z finite ,,,
,,, (2-C) S → 0 G4 (81 = 17↑a8 (Ta: reactor time constant) ・(2-d), and for the step-like change of L, 187, Laplace transform By using the final value theorem, the steady value of L = 0 (3).Therefore, the flow rate command and the pump flow rate signal are expressed, and the flow rate of the water supply pump 2 is controlled by water level control. However, when the water supply pump 2 is stopped, the pump flow rate signal L4 is zero, so the state is the same as o, +81xO, and equation (1) is Ls181 = Gl (8) Lt (8)
...It is rewritten as (4). Therefore, the valve opening command signal Lt at this time is L8) = Gl'% (8) Lt(81...
・ (5)), the final value theorem of Laplace transform, and (2
-b) also shows that the steady value of s Lt diverges to infinity for slap-like changes in . That is, when the water supply pump 2 is stopped, the valve opening command signal L from the flow rate controller 8
! is saturated, and the opening degree of the flow rate regulating valve 3 is always in a fully open state.

In order to simplify the explanation above, the number of water supply pumps 2 is assumed to be one (9); however, in a general atomic coupler plant, multiple water supply pumps are installed, and normal water supply control is performed using several of these pumps (
For example, 2 out of 4 units) are used. The remaining feedwater pumps are for backup purposes and are normally stopped, but in the event of a failure of a constantly running feedwater pump, etc., there is a possibility that the reactor water level may deviate from the permissible range and drop suddenly. It is designed to automatically start up and supply water.

It goes without saying that the time required for automatic startup must be short in order to minimize fluctuations in the reactor water level, but furthermore, automatic startup and flow rate control for the water supply pumps must also begin promptly. - However, as mentioned above, in the conventional reactor feed water control system, the flow rate adjustment valve for the stopped feed water pump is fully open, and the pump flow rate at startup is 100% flow rate. In addition, since the flow rate control @8 itself is saturated, the saturation of the flow rate controller 8 must be eliminated in order to enable flow rate control, but the pump flow rate signal L4
The saturation is not eliminated immediately after the feedback is applied, but is gradually eliminated by the integrator time constant in the flow rate controller 8. Therefore, in the conventional reactor feed water control system, the feed water pump 2 is not automatically started. 100 for the automatically started water pump within a certain period of time determined by the integrator time constant.
1! Or, if a flow rate close to that flow were to flow uncontrolled, it would result in a sudden rise in the reactor water level, with the possibility that the deviation from the reactor standard water level would exceed the allowable range. .

(cl. Purpose of the Invention The purpose of the present invention is to eliminate the saturation of the flow rate controller, and to eliminate fluctuations in the reactor water level at the time of starting the feed water pump, which were caused by the saturation of the flow rate controller). It is said to provide.

(d) Structure of the Invention The present invention will be described below based on an embodiment shown in FIGS. 3 and 4. @Figure 3 is a configuration diagram of a reactor water supply control system showing one embodiment of the present invention.

In the figure, the same reference numerals as in Fig. 1 indicate the same or phased parts;
The difference from the figure is that the output of the flow rate controller 8 is fed back to the flow rate controller 80 via the contact 9.

FIG. 4 is a block diagram showing the operation of the above configuration. In the figure, the same reference numerals as in FIG. 2 indicate the same or equivalent parts as in FIG. 2, and the difference from the block diagram in FIG. This is a point that has been given feedback.

The contact 9 is closed when the water supply pump 2 is stopped. Therefore, when the water supply pump 2 is in operation, the block diagram shown in FIG. 2 is the same as the block diagram shown in FIG. - On the other hand, while the water supply pump 2 is stopped, the flow rate command is r1.

The valve opening command signal is obtained from (8), and the transmission characteristic at (8) t is that the flow rate signal La(8) = o. Therefore, the final value theorem of Laplace transform and (2-b
) From the formula, Ly = Lm - (71 holds true during steady state. Therefore, once the command signal is given, the flow rate 1 ff1J (Ml unit 8 is not saturated, and the flow rate is Control valve 3 is directly controlled by water level control a6.

In the above explanation, it is assumed that the contact 9 is closed when the water supply pump 2 is stopped, but depending on the operating state of the water supply pump 2, the contact is not operated and the pump flow rate signal is output.

may be input to the comparison circuit, and when the pump flow rate ≦ falls below a certain value, the contact 9 may be closed. Furthermore, in order to simplify the explanation, the flow rate of the water supply pump 4 is controlled by the flow rate adjustment valve 2 in the above description, but even if the flow rate is controlled by the rotational speed of the pump, the present invention will not be limited to 1'. )
(9) The same applies.

(el) Detailed Description of the Invention According to the present invention, saturation of the flow rate controller 8 can be prevented even when the leakage pump 2 is stopped, and the opening degree of the flow rate regulating valve 3 can be maintained at all times. It is controlled by a water level control 66. Therefore, the flow rate control is effective immediately after starting the water supply pump, and since the opening and closing of the flow rate adjustment valve 3 is controlled from the beginning according to the state of the plant WjJK, even when the flow rate control is started, it is not possible to set the appropriate @ station. It has become. Therefore, even if the backup water pump is automatically started due to a malfunction of the constantly running water pump, superfeeding of water to the reactor does not occur and the reactor water level can be controlled stably at the allowable shaft internal pressure. It is possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a conventional reactor feed water control device, FIG. 2 is a block diagram showing the operation of a conventional reactor feed water control device, and FIG. 3 is a block diagram showing the configuration of an embodiment of the present invention. Block Diagram FIG. 114 is a block diagram showing the operation of one embodiment of the present invention. 1... Nuclear reactor 2... Water supply pump 3 - Flow rate adjustment valve 4... Water level setting device 5 - Water level detection Is
6...Water level controller 7...Flow rate detection a 8
Flow rate control 49...Contact (7317) Agent Kensuke Chika (and 1 other person) Fig. 1 Fig. 2 12 (s) Fig. 3 Fig. 4 q' 12 (5

Claims (1)

[Claims] a water level controller that inputs a reactor water level reference signal and a reactor base water level confidence and calculates a flow rate command signal for the reactor feed water pump, and inputs the flow rate command signal and the actual flow rate signal of the reactor feed water pump; a flow rate controller including an integral element that controls the flow rate of the reactor feed water pump; and a ride patch loop that feeds an output signal of the integral element to the flow rate command signal when the reactor feed water pump is stopped. A nuclear reactor water supply control system characterized by nine tools and provisions.