JPH0363597A - Nuclear reactor pressure regulating device - Google Patents

Abstract

PURPOSE:To suppress neutron flux variation by detecting the variation rate of the reactor core flow rate of a nuclear reactor, and comparing the variation rate with a permissible variation rate and regulating the pressure of the nuclear reactor. CONSTITUTION:The reactor water flow rate signal S1 of the nuclear reactor detected by a reactor core flow rate detector consisting of a differential manometer is inputted to the nuclear reactor pressure regulating device. The nuclear reactor pressure regulating device performs specific arithmetic for the reactor core flow rate signal S1 to obtain a nuclear reactor pressure regulating signal S2. Namely, a detecting circuit 161 detects the variation rate of the signal S1, a decision circuit 162 compares the detected value with the permissible variation rate of the reactor core flow rate, and an incomplete differentiating circuit 163 performs incomplete differential arithmetic for the output signal of the circuit 162 according to the result to obtain the signal S2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for controlling neutron flux when the core flow rate increases rapidly due to the occurrence of a recirculation control system or a disturbance other than the recirculation control system in a nuclear power plant. The present invention relates to a nuclear reactor pressure regulating device suitable for suppressing fluctuations.

[Conventional technology]

Conventional examples of neutron flux control in nuclear power plants are:
It is described in detail in Atomic Kangyo Vol. 14, No. 12 from the viewpoint of power control of a nuclear reactor using a recirculation control system.

FIG. 5 shows this conventional example. In the figure, steam generated in a nuclear reactor 1 is supplied to a turbine 3 via a turbine control valve 2, and the steam is supplied to a turbine 3 and a generator 4.
After rotating, it is condensed into water in the condenser 5. This water is supplied again by the condensate pump 6! It is returned to the child furnace. The turbine bypass valve 8 is used to bypass the surplus steam of the reactor 1 when the turbine control valve 2 is closed to the condenser 5 when the rotational speed of the turbine 3 increases abnormally. Further, the core flow rate of the nuclear reactor 1 is changed by the recirculation pump 7 to control the reactor output.

The deviation between the turbine rotational speed signal N and the set rotational speed Ns is proportionally calculated by the speed controller 11, and then added to the load setting signal RI to form the load request signal s3, which is input to the low value selection circuit 12. On the other hand, the deviation between the turbine input pressure signal P1 detected by the pressure detector 9, the set pressure Ps, and the output of the set pressure adjustment circuit (hereinafter referred to as PSAJ) is phase compensated/gain calculated in the pressure controller 10, and the total steam flow rate is This becomes a request signal S4 and is input to the low value selection circuit 12. Normally, the total steam flow rate request signal S4 has a lower value than the load request signal S3 by the bias amount in the load setting signal La, so the low value selection circuit 12 selects the total steam flow rate request signal S4 and This becomes the opening request signal Scv. Further, the deviation between the total steam flow rate request signal S4 and the turbine control valve opening request signal Scv becomes the turbine bypass valve opening request signal Sep. Here, Bp is a chattering prevention bias of the turbine bypass valve 8.

Furthermore, the total steam flow rate request signal S4 and the load request signal S3,
And the deviation from the bias BL is the load following error signal S5
This is input to the PSAJ 13 and the recirculation control system 14. The recirculation control system ↓4 outputs a recirculation pump rotation speed request signal SPLR to the recirculation pump 7.

Output control of a nuclear power plant follows the steps below.

That is, the load setting signal Ld is changed and the load following error signal S5 is changed. The recirculation control system 14 controls the number of rotations of the recirculation pump 7 based on this load following error signal S5, and controls the reactor output by changing the core flow rate on the reactor. As the reactor power changes, the reactor pressure changes,
As a result, the turbine control valve opening request signal Scv changes by the pressure controller 10, the amount of steam flowing into the turbine 3 changes, and ultimately the required output of the generator 4 changes. Here, the PSAJ 13 proactively controls the opening degree of the turbine control valve 2 by initially changing the set pressure Ps, since the response time of the reactor output change due to the core flow rate change by the recirculation control system 14 is long. and generator 4
Used to improve initial response.

[Problem to be solved by the invention]

The above-mentioned conventional technology is an extremely effective control method for controlling reactor output by controlling the core flow rate.

At this time, changes in the core flow rate caused by the recirculation control system have great sensitivity to changes in the reactor's neutron flux. Therefore, the gain of the recirculation control system is set so that a change in the core flow rate is obtained such that the change in neutron flux is within an allowable range.

The purpose of the present invention is to provide a recirculation control system or a reactor pressure adjustment system that can suppress neutron flux fluctuations when the rate of change in the core flow rate is such that the neutron flux changes more than necessary due to the occurrence of disturbances, etc. The goal is to provide equipment.

[Means to solve the problem]

In order to achieve the above object, the core flow rate change rate detection means, the core flow rate change rate detected by the change rate detection means and the permissible change rate, and the comparison determination means, based on the determination result by the comparison determination means. A reactor pressure adjustment device is provided, which comprises a reactor pressure adjustment means. In particular, the reactor pressure control means is performed by manipulating the pressure set point of the reactor pressure or by manipulating the turbine control valve opening request signal.

C Effect] The core flow rate change rate detecting means detects the change rate of the core flow rate. The means of comparison and judgment is that the fluctuation of neutron flux is an allowable fluctuation! i
! The allowable rate of change in the core flow rate within the range and the detected rate of change in the core flow rate are compared and determined.

When the rate of change in the detected core flow rate is outside the allowable rate of change, the means for adjusting the reactor pressure controls the reactor pressure to change the void fraction distribution within the reactor, thereby reducing the amount of neutrons. Suppress the fluctuation of the bundle so that it is within the permissible fluctuation range.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a control system diagram of the reactor pressure regulating device of the present invention.

In Fig. 1, the difference from the prior art Fig. 5 is as follows.
It is as follows. That is, the core flow rate signal S1 of the nuclear reactor 1 detected by the core flow rate detector 15 consisting of a differential pressure gauge becomes an input to the reactor noeka adjustment device 16. The reactor pressure adjustment device 16 performs a predetermined calculation on this core flow rate signal S1, and sets the pressure set point Ps as the reactor pressure adjustment signal S2.
Add to.

An embodiment of the reactor pressure regulator 16 is shown in FIG. That is, in the change rate detection circuit 161, the core flow rate signal SL
A comparison judgment circuit 16 detects the rate of change in the core flow rate.
Output to 2. The rate of change comparison/determination circuit 162 compares the permissible rate of change in the core flow rate at which the fluctuation of neutron flux falls within the permissible fluctuation range with the detected rate of change in the core flow rate, and determines whether the reactor 1
Determine whether the change in core flow rate is within the allowable range for neutron flux fluctuations. In the incomplete differentiation circuit 163, an incomplete differentiation operation is applied to the output signal from the rate of change comparison and determination circuit 162 to obtain a reactor pressure adjustment signal S2.

This reactor pressure adjustment signal S2 is, as shown in FIG.
It is added to the pressure set point Ps and used as an input to the pressure controller 10. Total steam flow rate request signal S4 which is the output of the pressure controller 10
is selected by the low value selection circuit 12 and becomes the turbine adjustment valve opening request signal Scv. By changing the opening degree of the turbine control valve 2, the reactor pressure changes. the result,
The void fraction distribution of the nuclear reactor 1 changes, and it becomes possible to keep the fluctuations in neutron flux within the permissible fluctuation range.

FIG. 3 shows the main conditions and quantities of a nuclear power plant equipped with the reactor pressure regulating device of the present invention. The core flow rate signal S1 has small fluctuations as shown in FIG. Fluctuations in the neutron flux exhibit a response close to a differential relationship with this small fluctuation in the core flow signal S1. Here, if there is a sudden change in the core flow rate due to a disturbance other than the recirculation control system 14 at point A, the neutron flux will show a response as shown by the broken line in the absence of the reactor pressure regulating device of the present invention. Become. On the other hand, when the reactor pressure adjustment device is installed, the rate of change comparison and determination circuit 162 determines that the rate of change in the core flow rate is equal to or greater than the allowable rate of change.

The opening degree of the turbine control valve 2 is increased by the reactor pressure adjustment signal S2 obtained by applying an incomplete differential calculation to the pulse signal based on the determination result. As a result, the increase in neutron flux is suppressed, as shown by the solid line, due to the increase in void fraction due to the decrease in reactor pressure.

FIG. 4 is a control system diagram of another embodiment of the reactor pressure regulating device of the present invention. The difference between FIG. 4 and FIG. 1 is that the reactor pressure adjustment signal S, which is the output of the reactor pressure adjustment system [16], is
2 to the total steam flow rate request signal S4, and the low value selection circuit 1
2, the turbine control valve opening request signal Scv is set. By doing this, it is possible to eliminate the signal transmission delay caused by the reactor pressure adjustment signal S2 passing through the pressure controller 10, so that the reactor pressure can be adjusted more easily when the rate of change in the core flow rate increases rapidly. It can be implemented quickly.

〔Effect of the invention〕

According to the present invention, when there is a change in the core flow rate recirculation control system or due to a disturbance that causes a sudden fluctuation in the neutron flux, the reactor pressure is temporarily adjusted based on the rate of change in the reactor flow rate. I try to do that.

This has made it possible to more reliably keep neutron flux fluctuations within the permissible fluctuation range6.

[Brief explanation of drawings]

FIG. 1 is a control system diagram of an embodiment in which the reactor pressure regulating device of the present invention is applied to a nuclear power plant, FIG. 2 is a block diagram of the reactor pressure regulating device, and FIG. 3 is the same as that shown in FIG. 4 is a control block diagram of another embodiment in which the reactor pressure regulator of the present invention is applied to a nuclear power plant, and FIG. 5 is a conventional control system diagram. . DESCRIPTION OF SYMBOLS 1... Nuclear reactor, 2... Turbine control valve, 3... Turbine, 7... Recirculation pump, 10... Pressure controller, 11... Speed controller, 12... Low Value selection circuit, 1
3...Preset pressure adjustment circuit (PSAJ), 14...
Recirculation control system, 15...core flow rate detector, 16...
Reactor pressure adjustment system Figure 2 Reactor fi' change 4□ Figure 3 β'i rnM 5PL scale 8P

Claims (1)

[Scope of Claims] 1. In a nuclear power plant, a means for detecting a rate of change in the core flow rate of a nuclear reactor, a means for comparing and determining a rate of change in the core flow rate detected by the detecting means and an allowable rate of change, and the comparison 1. A nuclear reactor pressure regulating device comprising: means for regulating reactor pressure based on a determination result by the determining means. 2. The reactor pressure regulating device according to claim 1, wherein the reactor pressure regulating means operates a pressure set point of a reactor pressure control system. 3. The reactor pressure regulating device according to claim 1, wherein the reactor pressure regulating means operates a turbine adjustment valve opening request signal.