JPS61262695A - Nuclear power plant - 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 a boiling water type nuclear power plant in which a bypass path is installed in the main steam flow path, and in particular, the present invention relates to a boiling water type nuclear power plant in which a bypass path is installed in the main steam flow path. This invention relates to a nuclear power plant with an improved adjustment method.

[Technical front of invention]

Generally, a boiling water nuclear power plant is configured as shown in the system diagram in Figure 3, in which a nuclear reactor 1 is connected to a turbine 3 via a main steam passage 2, and the main steam generated in the reactor 1 is Air is supplied to the turbine 3 to drive a generator (not shown). The steam that has done work in the turbine 3 is discharged to a condenser 4, where it is cooled and condensed, and is returned to the reactor 1 as condensate via a condensate system 6 by a water supply pump 5. The coolant inside the nuclear reactor 1 is forcedly circulated by recirculation pumps 8 in a plurality of systems, for example, two recirculation systems 7, and the generated steam (reactor heat output) is controlled by adjusting the core flow rate.

The main steam passage 2 is provided with a bypass passage 10 having a 100% bypass capacity, which branches from the upstream side of the main steam control valve 9 and is connected to the condenser 4. Main steam bypasses the turbine 3 through this bypass passage 10 and is guided directly to the condenser 4. That is, if a generator load cutoff occurs when the reactor output is, for example, 80% or more, the power load unbalance relay that detects the loss of external load is activated, and the main steam control valve 9 is suddenly turned on. 3. Bypass valve 11 is suddenly opened. For this purpose, the main steam is guided into the bypass line 10 and discharged directly to the condenser 4. In addition, with the sudden opening of the bypass valve 11, the two recirculation pumps 8 and the water supply pump 5 are tripped, and the selected control rods are inserted into the core of the reactor 1 by the control rod drive device 12. These three protection i [! As a result of the 7J project, nuclear power plants will shift to isolated operation within the plant.

By the way, when two of the recirculation pumps 8 are tripped,
The coolant in the reactor 1 is not shown in the graph of FIG. 2 and moves to a state of natural circulation m [JJf 13. This causes a mismatch in the main steam flow rate due to the sudden opening of the main steam control valve 9 and the sudden opening of the bypass valve 11, so the pressure inside the reactor 1 increases due to this mismatch, and the neutrons generated as a result of this pressure increase. This is an attempt to suppress the rise of the bundle in a state of natural circulation. Furthermore, the lip of the water supply pump 6 is intended to stop the water supply into the reactor 1 and prevent overfeeding of water.

The insertion of the selected control rod is performed by inserting a selected control rod that has been selected in advance to a preset insertion position,
The purpose is to suppress the increase in output caused by the loss of turbine bleed steam and decrease in feed water temperature during isolated operation within the plant, and to maintain the output within a stable operating range under natural circulation conditions.

(Problems in the background art) However, in such a conventional example, the recirculation pump 8
The three protective operations of 1-rip of the water supply pump 5 and selective control rod insertion are performed almost simultaneously.

Therefore, the reactor output is the output drop line 1 shown in Figure 2.
4 to the output set point 15, and although the integrity of the fuel was sufficiently protected in transient analysis, there were various problems. In other words, a rapid decrease in the void fraction within the reactor 1 causes a significant drop in water level, and simultaneous insertion of selective control rods causes a sudden change in fuel reactivity, which is one of the causes of large disturbances in the reactor 1. They were one. For this reason, there was a problem in that it was difficult to control the reactor output during isolated operation within the station to the set value when the generator load was cut off.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a nuclear power plant that can stably and easily control the reactor output to the set value at the time of power cutoff when the generator load is cut off.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention provides a nuclear power plant having a bypass passage branching from the middle of a main steam flow passage connecting a nuclear reactor to a turbine that drives a generator and connecting to a turbine condenser. A trip detector that outputs a start signal when a trip of the generator circuit breaker and recirculation pump is detected, and a start signal from this trip detector is input to start up and detect the neutron flux in the reactor. A controller that compares the detected value from the neutron flux detector and the set value of the reactor output at the time of generator load interruption and outputs the deviation between the two, and a deviation signal from this suppressor that operates the control rods. The present invention is characterized by a control rod sequencer that converts signals into signals, and a control rod drive device r that receives control rod operation signals from the control rod sequence relay and inserts or withdraws selected control rods.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, the same members as those shown in FIG. 3 are designated by the same reference numerals.

FIG. 1 shows the overall configuration of an embodiment of the present invention, in which neutron flux detection V! is provided in the core of a nuclear reactor 1. A controller 22 is connected to h20 via a neutron flux indicator 21 outside the reactor. The controller 22 includes a setting device 23 that sets the reactor output J when the generator load is cut off, and a trip detector that detects the trip of the generator circuit breaker (not shown) and the trip of all the recirculation pumps 8, for example, two units. 24. This controller 22 compares and calculates the neutron flux feedback signal SF from the neutron flux detector 20 and the set value S1 of the reactor output at the time of generator load cutoff, which is set by the setting device 23, and calculates the deviation between the two. The trip detector 24
It is activated by inputting the activation signal S2 from .

The above set value S1 is set at the output set point 15 in FIG.
The control rod drive unit 27 is connected to a control rod drive unit 27 via a control rod sequencer 26 that is connected to the control rod drive unit 27 . That is, ill ill
The deviation signal S3 from the controller 22 is sent to the control rod sequencer 26.
It is converted into control rod operation signal @S4, and the control rod drive device 2
At step 7, the selection control rod 25 is inserted and withdrawn so that the deviation signal S3 from the tII controller 22 becomes zero.

Next, the operation of this embodiment will be described.

Now, the load of the generator (not shown)! ! When a failure occurs, two units, a generator circuit breaker and recirculation pump 8 (not shown), trip. These trips are detected by the trip detector 24, and a start signal S2 is output to the controller 22. The controller 22 is activated upon receiving the activation signal S2, compares the neutron flux feedback signal SF at the time of generator load cut-off with its set value S1, and generates a deviation signal S which is the deviation between the two.
3 is output to the control rod sequencer 26. The control rod sequencer 26 converts the deviation signal S3 into a control rod operation signal @S4! , If Illll dynamic drive device 27 is activated, and the selection control rod 25 is inserted or withdrawn so that the deviation signal S3 becomes zero. As a result, the reactor output at the time of generator load interruption is controlled to the setting 1ii1!81.

FIG. 2 shows such fluctuations in the furnace heat output in this embodiment, and when two recirculation pumps 8 and one of the feed water pumps 5 (see FIG. 3) trip due to generator load cutoff, As the core flow ff1W decreases, the reactor heat output S slowly decreases to 100% along the control straight line 30, and when it decreases to the output drop point 31, the selection f, II control rod 25 is inserted into the core in stages, and the output Furnace power is reduced to setpoint (setpoint 31) 15. Thereby, the furnace output at the time of generator load cutoff is controlled to the set value S1.

Moreover, in this embodiment, since the degree of descent of the 100% outflow control straight line 30 that drops to the output drop point 31 from the time of generator load cutoff is slower than that of the conventional example 14, the reactor 1 after the recirculation pump trip This alleviates internal disturbances and facilitates adjustment of reactor output under natural circulation conditions.

In addition, even if output fluctuations occur after the reactor output reaches the output set point 15 due to an increase in output due to a drop in feed water temperature or a decrease in output due to accumulation of Zenon, control is performed to eliminate the output fluctuations. Because of the rod operation, the furnace power can always be adjusted to the power set point.

(Effects of the Invention) As explained above, the present invention is applicable to a nuclear power plant having a bypass path that branches off from the middle of the main steam flow that connects the reactor to the turbine that drives the generator and connects to the turbine condenser. , in the generator breaker and power generation plant, a trip detector outputs a start signal upon detecting tripping of the generator breaker and the recirculation pump, and starts by inputting the start signal from the trip detector; A controller that compares and calculates the detected value from the neutron flux detector that detects the neutron flux in the reactor and the set value of the reactor output at the time of generator load interruption and outputs the deviation between the two; It has a control rod sequencer that converts a deviation signal from IT, 11 into a control rod operation signal, and a control rod drive device that receives this control rod operation signal and inserts or withdraws a selected control rod.

Therefore, according to the present invention, when the generator load is cut off, the selected control rod is inserted and withdrawn after the LAyA pump is tripped again, so that it is possible to prevent a sudden drop in the reactor output after the generator load cutoff. , disturbances to the reactor can be reduced. As a result, the reactor output can be stably and easily automatically adjusted in a natural circulation state.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing the overall configuration of an embodiment of the present invention, Fig. 2 is a graph showing fluctuations in furnace heat output in the embodiment shown in Fig. 1 in comparison with that of a conventional example, and Fig. 3 The figure is a system diagram of the main parts of a typical boiling water nuclear power plant. DESCRIPTION OF SYMBOLS 1... Nuclear reactor, 8... Recirculation pump, 20... Neutron flux detector, Sl... Setting value, S2... Starting signal, S3... Deviation signal, S4... Control Bar operation signal. Representative Patent Attorney Nori Chika Kensuke (1 idiot) Haya 2 Diagram

Claims (1)

[Claims] Detects trips of generator circuit breakers and recirculation pumps in nuclear power plants that have a bypass path that branches off from the middle of the main steam flow path that connects the reactor to the turbine that drives the generator and connects to the turbine condenser. A trip detector that outputs a start signal when the trip detector outputs a start signal, and a neutron flux detector that starts by inputting the start signal from this trip detector and detects the neutron flux inside the reactor and the generator load. A controller that compares and calculates the set value of the reactor output at the time of shutdown and outputs the deviation between the two, a control rod sequencer that converts the deviation signal from this controller into a control rod operation signal, and this control rod operation signal. A nuclear power generation plant comprising: a control rod drive device that inserts or withdraws a selected control rod in accordance with the received control rods.