JPS60169796A - Controller for operation of nuclear reactor - 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] [Technical Field of the Invention] The present invention relates to an operation control device for a boiling water nuclear reactor, and in particular to a system for controlling the operation of a boiling water nuclear reactor. The present invention relates to a nuclear reactor operation control device equipped with a reactor safety control device that monitors and controls these.

[Technical background of the invention and its problems]

In boiling water reactors, the inherent stability of the reactor may be compromised even if the expected operating conditions occur, for example, after loss of on-site power, the coolant forced circulation pump loses its function and enters a natural ring state. It is designed so that it will not be damaged. The inherent stability of the reactor and the hydraulics in the channels are such that oscillations in the coolant flow impede heat transfer to the moderator and thereby cause oscillations in the reactor outlet. The stability of the reactor and the stability due to the reactivity feedback effect of the entire reactor will be considered.

Normally, these stability evaluation methods are performed using a mid-range ratio. FIG. 1 is a diagram showing the relationship between reactor parameters such as pressure and flow rate and reactor output, and the mid-range ratio will be explained using this diagram. Now, a certain reactor parameter is A.

When the reactor output is maintained at PO, if a minute step input change of ΔA occurs in the reactor parameters at time to, the reactor output oscillates as shown in FIG. The reduction ratio is the ratio of the first overshoot deviation x 1 of the reactor output to the second overshoot deviation X with respect to the final reactor output setting value P1 at this time.
/X1.

2 In addition, from the perspective of reactor design, the reduction [1] ratio (hereinafter referred to as the "limit standard") that should be maintained under all expected operating conditions during reactor operation and the good stability during actual operation are important. A mid-range ratio (hereinafter referred to as "operational design standard") is defined as a design margin that is expected to ensure the above characteristics, and a value larger than this is not desirable. Specifically, the limit criteria for the hydraulic stability of the channel are 1.
0, the operational design criterion is 0.5, the core stability limit criterion is 1.0, and the operational design criterion is 0.25.

As for these stability, the lower the cooling removal flow rate and the higher the reactor output, the larger the range-to-range ratio becomes, and the stability becomes worse. In addition, the lower the coolant flow rate and the higher the reactor power, the larger the steam void volume fraction, and the larger the ratio of the coolant two-phase pressure loss to the coolant liquid single-phase pressure loss, which affects the hydraulic stability of the channel. make it worse Furthermore, when the void volume fraction is large, the void reactivity coefficient becomes large and the core stability deteriorates.

In conventional technology, operation was controlled to prevent operation under the unstable conditions described above based on the operating conditions.Figure 2 shows the correlation between reactor output and coolant flow rate. 2 is a diagram showing the operating range of a nuclear reactor according to the prior art. In FIG. The pump constant speed curve is the cavitation prevention interlock curve C, the forced coolant circulation pump minimum speed curve d, the 105% reactor power control rod pattern flow control curve e, and the reactor rating point a to the left. This is the range (portion indicated by cedar) surrounded by a straight line connecting the intersection f with the control rod pattern flow rate control curve e when the control rod is moved in parallel and the reactor rated point a.

Figure 3 shows the region in Figure 2 where the unstable condition (range-to-range ratio exceeds 1.0) is established, and indicates the hydraulic instability condition curve q of the channel or the instability of the core. The region to the left of the conditional curve (indicated by diagonal lines) is the region where the unstable condition holds.

In the conventional technology, in order to prevent operation under such unstable conditions, an operator constantly monitors the operation and restricts operation based on operating conditions. Therefore, there is a problem that the burden on the operators is heavy and the range in which the reactor can be operated is narrow.

[Purpose of the invention]

The present invention has been made in consideration of these points,
Rather than restricting operating conditions as in conventional technology, the reactor is monitored using equipment configuration and equipment automation technology, and when the reactor approaches an unstable region, it is possible to prevent the reactor from approaching the unstable region any further. By automatically preventing such occurrences, reactor operational performance is improved by reducing the burden on operators and easing operational constraints, and safety performance is improved by preventing unstable conditions from occurring with higher reliability. The purpose is to provide a nuclear reactor operation control device that can improve the performance of nuclear reactors.

[Summary of the invention]

The present invention provides reactor power instrumentation, a control rod drive device that drives control rods based on a control rod drive device control signal from a control rod drive device controller, and a control rod drive device that drives a control rod using a control rod drive device control signal from a control rod drive device controller, and In a reactor safety control system for a nuclear reactor, which includes a coolant forced circulation pump that forcedly circulates a portion of the coolant, and a coolant flow rate measuring device that measures the flow rate of the coolant forced circulation pump,
A stability monitoring device, a stability setting device, and a stability control device are installed in the circuit that connects the coolant circulation flow rate measurement device and the control rod drive side meter, and the stability monitoring device measures the coolant circulation flow rate. The stability allowable output signal is calculated by calculating the stability allowable output signal based on the coolant circulation flow rate signal emitted from the measuring device, and the reactor power output emitted from the reactor power instrumentation and the signal 1 novel of this stability allowable output signal are calculated. The signal level of the signal is compared with the stability setting device, and when the signal level of the reactor output signal exceeds the signal level of the stability allowable output signal, a stability maintenance signal is generated, and this stability maintenance signal is used as the stability setting device. The control device converts the reactor output signal into a predetermined stability control signal according to the signal level, and performs any of the following actions: preventing control rod withdrawal, selective control rod insertion, or emergency insertion of all control rods. It is characterized by being equipped with a reactor stability control device that stably controls the reactor.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 4 and 5.

In FIG. 4, reference numeral 401 is a pressure vessel of a boiling water reactor, and inside this pressure vessel 401, an IC core 403, control rods 404, and a reactor power instrumentation device that emits a reactor output signal are supported by a core support plate 402. 405 etc. are arranged,
The coolant is guided into the pressure vessel 4.01 through the water supply pipe 406, evaporated within the pressure vessel 401, and then guided out of the pressure vessel 401 through the main steam pipe 407. Also,
A part of the coolant introduced into the pressure vessel 401 is led out from the suction pipe 409 by the coolant forced circulation pump 408, passes through the discharge pipe 410, and flows back into the pressure vessel 401.

A coolant circulation flow rate measuring device 413 is connected to the coolant forced circulation pump 408, which measures the flow rate of this pump and generates a coolant circulation flow rate signal 414. Further, the coolant circulation flow rate measurement device 413 is a coolant circulation flow rate measurement device 413.
It is connected to a stability monitoring device 415 that calculates the stability allowable output of the reactor based on the coolant circulation flow rate signal 414 emitted from the reactor. This calculation of the stability allowable output is performed using the characteristic curve of the reactor's stability allowable output Y=f (w), which is expressed as a function of the coolant circulation flow rate W, as shown in Figure 5. . For example, the flow rate of the coolant forced circulation pump 408 is W. If so, this coolant circulation flow rate W. Regarding the stability allowable output Y that falls below the alarm display and control rod withdrawal prevention curve Z1, the alarm display and control rod withdrawal prevention output Y1
, selected control rod insertion output Y2 is determined from the selected control rod insertion output curve Z2, and all control rod emergency insertion output Y3 is determined from the all control rod emergency insertion output curve Z3. These three characteristic curves are set in advance, and the stability allowable output Y for any given coolant circulation flow (iw) always maintains the relationship Yl < Y2 < Y3. Stability monitoring The stability allowable output Y calculated by the device 415 is converted into a stability allowable power signal 416 and input to the stability setting device 412 connected to the stability monitoring device 415.

Here, each stability allowable output Y1 ・Y・Y
Let the stability permissible output signal corresponding to yl.3 y2.y3.

The stability setting device 412 is also connected to the reactor output instrumentation 405, and the stability setting device 412 determines the signal level of the reactor output signal 411 issued from the reactor power instrumentation 405 and the stability. The signal level of the stability allowable output signal 416 emitted from the monitoring device 415 is compared, and the signal level of the reactor output signal 411 is the stability allowable output signal 4.
When the signal level of 16 is exceeded, the stability maintenance signal 41
It is designed to emit a number 7.

The stability setting device 412 is connected to a stability control device 418 that issues stability control signals 420A, 420B, and 420C according to the signal level of the reactor output signal 411 based on the stability maintenance signal 417.

The stability control device 418 is connected to an alarm display device 421, and includes a control rod withdrawal prevention signal generation device 422 that generates a control rod withdrawal prevention signal 425, and a selective control rod insertion signal generation device 423 that generates a selective control rod insertion signal 426. ,
It is connected to a full control rod emergency insertion signal generator 424 that generates a full control rod emergency insertion signal 427 . These devices 4
22.423.424 is the control rod drive control signal 42
9 is connected to a control rod drive controller 428 , and a control rod drive control signal 429 is input to a control rod drive 430 to control the control rods 404 .

Next, the operation of this embodiment having such a configuration will be explained.

The stability allowable output signal 416 emitted from the stability monitoring device 415 and the reactor output signal 411 are sent to the stability setting device 41.
2, the signal level of the reactor output signal 411 is the three signals y1 and y2 of the stability allowable output signal 416.
・If it is smaller than any signal level of y3,
It is determined that the reactor output is in a stable operating range, and the stability setting device 412 does not generate the stability maintenance signal 417.

Reactor output signal 411 is y of stability allowable output signal 416
When the level is between l and y2 or at the same level as yl, the stability setting device 412 issues a stability maintenance signal @417 to the stability control device 418, and the stability control device @418
Based on this signal 417, it issues one alarm display signal 41 and a stability control signal 420A. As a result, an alarm is displayed to the operator from the alarm display device @421 that has received the alarm display signal 419, and a control rod withdrawal prevention signal 425 is sent from the control rod withdrawal prevention signal generator 422 that has received the stability control signal 420A. is the control rod drive controller 428
issued against. The control rod drive controller 428 is
A control rod drive device control signal 429 is issued to all of the plurality of control rod drive devices 430 existing in the nuclear reactor to prevent the control rods 404 from being pulled out any further. This prevents the reactor from approaching a more unstable operating region due to withdrawal of the control rods 404, and maintains the stability of the reactor.

Next, the reactor output signal 411 is the stability allowable output signal 41
When the level is between y2 and y3 of 6 or at the same level as y2, the stability setting device 412 issues a stability maintenance signal 417 to the stability control device 418, and the stability control device 418 receives this signal 417. Based on the stability control signal 4
Emit 20B. Stability control signal 420B is input to select control rod insertion signal generator 423 and select control rod insertion signal 426 is issued to control rod drive controller 428. As a result, the control rod drive device controller 428 controls the control rod 404 for all of the plurality of control rod drive devices 430.
A control rod drive device control signal 429 is issued to prevent further withdrawal of the control rods 404 and to command some of the control rod drive devices 430 to insert the control rods 404 . As a result, the control rods 404 are selectively inserted, and the operating state of the reactor is shifted to a more stable operating range.

Reactor output signal 411 is y of stability allowable output signal 416
3, the stability setting device 412 also issues a stability maintenance signal 417 to the stability control device 418, and the stability control device 418 maintains the stability based on this signal 417. A sex control signal 420C is issued. The stability control signal 8420C is input to the all control rod emergency insertion signal generator 424, and the all control rod emergency insertion signal 42
7 is issued to the control rod drive controller 428.

As a result, the control rod drive device controller 428 controls all control rod drive devices 430 in the reactor.
Control rod drive control signal 429 commanding emergency insertion of 04
The reactor is safely shut down by a so-called scram.

In addition, the stability setting device 412 and the coolant circulation flow rate measuring device 41
3. The functions of the stability monitoring device 415 can also be realized using functions such as a computer.

〔Effect of the invention〕

As described above, according to the present invention, the signal of the stability allowable output, which is a function of the flow rate of the coolant forced circulation pump, is compared with the reactor output signal, and the optimum nuclear reactor control method is determined according to the signal level. The reactor can be maintained in a stable operating state or shut down safely.

FIG. 6 is a diagram showing the effect of the present invention in terms of the relationship between the midrange ratio of the hydraulic stability of the channel and the reactor output. In the figure, the shaded area is the area where the range ratio exceeds 1.0, and the third
This corresponds to the hydraulically unstable region of the channel shown in the figure. In addition, each broken line indicates each level of the stability control signal, the dotted line is the signal level L1 corresponding to the alarm display and control rod withdrawal prevention output curve in Figure 5, and the dashed line is the selected control rod insertion in Figure 5. The signal level L2 corresponds to the output curve, and the two-dot chain line is the signal level L3 corresponding to the all control rod emergency insertion output curve in FIG. In this way, according to the present invention, on the output line where the mid-range ratio becomes large (safety becomes strict),
Optimal output control can be performed according to the hydraulic stability ratio of the channel in each operating state.

Figure 7 is a diagram showing the relationship between the mid-range ratio of core stability and the reactor output; similar to Figure 6, the shaded area indicates the mid-range ratio of 1.0.
, which corresponds to the unstable region of the reactor core shown in FIG. In addition, each broken line indicates each level of the stability control signal, the dotted line is the signal level L1 corresponding to the alarm display and control rod withdrawal prevention output curve in Figure 5, and the dashed line is the selected control rod insertion output in Figure 5. The signal level L2 corresponding to the curve is the signal level L2, and the two-dot chain line is the signal level L3 corresponding to the all control rod emergency insertion output curve in FIG. As is clear from FIG. 7, according to the present invention, it is possible to perform optimal power control according to the core stability ratio in each operating state.

FIG. 8 is a diagram showing the overall effect of the present invention in relation to the correlation between reactor output and coolant flow rate.

In FIG. 8, the shaded area indicates a nuclear reactor operating range expanded compared to the conventional technology by employing the reactor stability control device according to the present invention. That is, according to the present invention, by constantly monitoring the stability of the reactor, when the reactor approaches an unstable operating region, an alarm is displayed, control rod withdrawal is prevented, selected control rods are inserted, or all control rods are emergency activated. With the insertion, stable control of the reactor is achieved, and the operating range of the reactor can be expanded to the extent that it is no longer necessary to shut down the reactor compared to before.

As described above, according to the present invention, the burden on the operator is reduced, and by providing optimal stability maintenance means,
The number of scrams in the reactor can be reduced, and the economic efficiency of reactor operation can be improved.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between reactor parameters such as pressure and flow rate and reactor output, and Figure 2 is a diagram showing the operating range of a nuclear reactor in the conventional technology as shown by the correlation between reactor output and coolant flow rate. , FIG. 3 is a diagram showing the region where the unstable condition is satisfied in FIG. 2 as a correlation between reactor output and coolant flow rate, FIG. 4 is a block diagram showing a nuclear reactor operation control device according to the present invention, Figure 5 is a diagram showing the characteristic curve of reactor stability allowable power;
Figure 6 shows the effects of the present invention on reactor output and CH1? Figure 7 shows the effect of the present invention in terms of reactor output and core stability range ratio, and Figure 8 shows the overall effect of the present invention. FIG. 2 is a diagram showing the correlation between reactor output and coolant flow rate. 4,05... Reactor power instrumentation, 408... Coolant forced circulation pump, 411... Reactor output signal, 412...
...Stability setting device, 413... Coolant circulation flow rate measuring device, 414... Coolant circulation flow rate signal, 415... Stability monitoring device, 416... Stability allowable output signal, 41
7... Stability maintenance signal, 418... Stability control device, 420A, 420B, 420G... Stability control signal, 428... Control rod drive device controller, 430... Control rod drive device . Applicant's agent Kiyoro Inomata 1 Illustration 0 Time 62 Kuni 53 Prisoner 64 Illustration 5 Illustration

Claims (1)

[Scope of Claims] 1. Reactor power instrumentation that measures the reactor output and issues a reactor output signal, and reactor power instrumentation that measures the flow rate of the coolant forced circulation pump and cools the coolant.
] A coolant circulation flow rate measuring device that emits a material flow rate signal, and a control rod insertion signal is input to a control shaft drive device control head based on the reactor output signal and the coolant circulation flow rate signal to control the safety of the reactor. In the operation control device for a boiling water reactor, the reactor safety control device calculates a stability allowable output based on the coolant circulation flow rate signal, and calculates a stability allowable output signal. a stability monitoring device that emits; compares the signal level of the reactor output signal and the stability allowable output signal, and maintains stability when the signal level of the reactor output signal exceeds the signal level of the stability allowable output signal; a stability setting device that generates a signal; a stability control device that generates a stability control signal according to the signal level of the reactor output signal based on the stability maintenance signal; and a control rod insertion signal that generates a control rod insertion signal based on the stability control signal; 1. A nuclear reactor operation control device comprising a first control rod insertion signal generator. 2. The control rod insertion signal emitted by the control rod insertion signal generator is characterized in that it is a control rod withdrawal prevention signal, a selective control rod insertion signal, or an emergency all control rod insertion signal. A nuclear reactor operation control device according to claim 1.