JPS59180497A - Reactor presscre 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 [Technical Field of the Invention] The present invention relates to a reactor pressure control device in a nuclear power generation facility equipped with a boiling water reactor.

[Technical background of the invention and its problems]

A nuclear power generation facility equipped with a boiling water reactor is constructed as shown in FIG. That is, 1 in the figure is a reactor pressure vessel, and this reactor pressure vessel 1 is a reactor containment vessel 2.
is housed within. Steam generated in the reactor core 3 housed in the reactor pressure vessel 1 is sent to the turbine 5 via the main steam pipe 4, which drives the turbine 5 and generates a generator (
(not shown) is configured to rotate to generate electricity. The steam initially discharged from the turbine 5 is condensed in a condenser 6, and the condensed water is returned to the reactor pressure vessel 1. Main steam isolation valves 7 and 8 are provided at the portion where the main steam pipe 4 penetrates the reactor containment vessel 2, and in the event of an accident, the entire reactor will be scrammed and the main steam pipe 4 will pass through the reactor containment vessel 2. Close the steam isolation valves 7 and 8 and close the reactor containment vessel 2.
to prevent the spread of radioactive materials. Further, a control valve 9 is provided at the inlet of the turbine 5, and the control valve 9 is operated to control the amount of steam supplied to the turbine 5.

Further, 10 is a turbine bypass pipe, which communicates the upstream side of the control valve 9 with the condenser 6.

A bypass valve 1 is provided in this turbine bypass pipe 10.
By opening this bypass valve 11, excess steam is condensed. , missed by ÷6. In addition, in the actual one, a plurality of the main steam pipes 4 are provided,
In addition, main steam isolation valves 7, 8. Adjustment valve9. A plurality of bypasses 3P1 are also provided.

By the way, in a boiling water reactor, the coolant (light water) uses a moderator, which slows down the fast neutrons generated by the nuclear reaction to a thermal neutron state, causing a second nuclear reaction. Therefore, if the amount of coolant present in the reactor core 3 increases, the moderation effect of neutrons becomes stronger, the reactivity increases, and the output increases, and if the amount of coolant present in the core 3 decreases, The moderating effect of neutrons becomes smaller, the reactivity becomes smaller, and the output decreases. In addition, in a boiling water reactor, the coolant boils within the reactor core 3 and flows as a two-phase flow of water and steam. ), when the output of the core 3 increases for some reason, the amount of steam generated increases, and the ratio of steam to water in the core 3, that is, the void ratio, becomes negative, and the cooling existing in the core 3 increases. The amount of material decreases and the output decreases. Conversely, when the output of the core 3 decreases, the void ratio decreases and the output increases. Therefore, the steam bubbles or voids within the core 3 serve to stabilize the output. Furthermore, by changing the flow rate of the coolant flowing through the core 3, the void ratio can be changed and the output can be controlled.

However, since this void ratio changes due to fluctuations in the pressure within the reactor pressure vessel 1, that is, the reactor pressure, it is necessary to control the reactor pressure to a predetermined pressure in order to perform stable control. For this reason, a reactor pressure control device No. 2 is provided, and its entire configuration will be explained below. That is, numeral 13 in the figure is a reactor pressure detector, which detects the reactor pressure within the reactor pressure vessel l. Further, 14 is a turbine inlet pressure detector, which detects the pressure of main steam supplied to the turbine 5. The reactor pressure signal S from the reactor pressure detector 13 and the turbine inlet pressure signal S2 from the turbine inlet pressure detector Z4 are sent to the pressure control circuit 15. This pressure control circuit I5 is The above-mentioned reactor pressure signal S or turbine inlet pressure signal S,
Based on 11. It outputs a good word S3 and sends it to the valve control circuit 16. This valve control circuit 16 receives the control signal S,
Based on this, the regulator valve 9 and bypass valve 1) are controlled to control the reactor pressure to a predetermined pressure. Further, this pressure control circuit 15 can be arbitrarily set to a reactor dome pressure control mode in which control is performed based on the reactor pressure signal S, and a turbine inlet pressure control mode in which control is performed based on the turbine input pressure signal S2. It is configured to be switched.

By the way, in order to ensure safety in such nuclear power generation equipment, the main steam isolation valve 7.8 and the control valve 9.8 are closed during operation. When a surveillance test to test the operation of the bypass valve 11 was carried out, the reactor pressure volume and the main steam flow rate sent from S1 to the turbine 5 suddenly changed (((()), the control of the reactor pressure became unstable, and this reactor pressure The reactor pressure increases transiently, and this increase in reactor pressure reduces the void fraction, resulting in a drop in output and potentially causing the reactor to scram unnecessarily.

That is, when this nuclear power generation facility is operated in the turbine inlet pressure control mode, the main steam isolation valve 7,
When carrying out a surveillance test of 8.1 with all valves closed,
This main steam isolation valve? , 8 fully opens the main steam pipe 4.
As the pressure loss increases, the reactor pressure temporarily increases and the turbine inlet pressure decreases. Then, in order to compensate for this decrease in turbine inlet pressure, the regulator valve 9 or the bypass valve 11 is throttled, and as a result, the pressure loss in the main steam pipe 4 becomes even larger, and the reactor pressure further increases. Due to the transient characteristics that promote the disturbance, the reactor pressure temporarily increases significantly and the output increases significantly.In this case, the output of the reactor core 3 increases as shown by the broken line in Figure 2. In other words, the neutron flux temporarily increases significantly and exceeds the scram set value A, causing the reactor to scram. If the surveillance test of .8 is conducted, the increase in reactor pressure will cause the control valve 9 to compensate for the increase in reactor pressure.
．． Since the bypass valve 11 is opened, the pressure loss in the main steam pipe 4 is reduced, and the transient rise in reactor pressure is suppressed to a low level. Therefore, in this case, the transient increase in neutron flux is suppressed to a low level as shown by the solid line in FIG. 2, and a scram does not occur. In addition, if a surveillance test with one valve of the regulator valve 9 fully idle is performed during operation in the reactor dome pressure control mode, the turbine inlet pressure and the reactor pressure will increase due to this one valve fully idle of the regulator valve 9. However, since the main steam pipe 4 is long, there is a certain time delay before the reactor pressure rises. Therefore, a time delay occurs before the other control valves 9 and bypass valves 11 are opened to compensate for the increase in reactor pressure. In addition, this control valve 9 and bypass valve 11
Similarly to the above, there is a time delay between when the reactor is opened and when the reactor pressure drops. As a result, the reactor pressure overshoots due to this time delay, and as shown by the broken line in Figure 3, the transient output, that is, the increase in neutron flux increases, exceeding the scram set value A and causing the reactor to scram. Put it away. On the other hand, when a surveillance test is carried out with one valve of the regulator valve 9 fully idle while operating in the turbine inlet pressure control mode, the turbine inlet pressure immediately increases due to one valve of the regulator valve 90 being fully idle. However, to compensate for this, the other control valves 9 and bypass valves 11 are immediately opened. Therefore, in this case, there is no time delay as mentioned in 1.
Since no reactor pressure overshoot occurs, the transient increase in neutron flux is suppressed to a low level, as shown by the solid line in FIG. 3, and a scram does not occur.

Therefore, in order to conduct a surveillance test without scramming the reactor during operation, it is necessary to switch the pressure control mode in accordance with the type of valve on which the surveillance test is to be performed. However, switching the pressure control mode takes a long time for the nuclear power generation equipment to stabilize, which significantly reduces the work efficiency of surveillance tests.

For this reason, conventionally the pressure control mode was not switched.
Surveillance tests were carried out with the reactor output reduced to around 50 centimeters to prevent the reactor from scramming unnecessarily. For this reason, there was a problem that the operating rate of the reactor decreased.

[Purpose of the invention]

The present invention was made based on the above circumstances, and it is possible to conduct surveillance tests without switching the pressure control mode and without reducing the reactor output, thereby improving the operating rate of nuclear power generation equipment. The objective is to provide a nuclear reactor pressure control device that can.

[Summary of the invention]

The present invention includes a reactor pressure detector for detecting reactor pressure, a turbine inlet pressure detector for detecting turbine inlet pressure, and receiving a reactor pressure signal from the reactor pressure detector and the turbine inlet pressure signal. The system is equipped with a signal synthesis circuit that synthesizes these signals and outputs a composite pressure signal, and a valve control circuit that controls the regulator valve of the turbine and the bypass valve of the turbine bypass system based on this composite pressure signal. . Therefore, by combining the reactor pressure signal and the turbine inlet pressure signal, characteristics that promote disturbance and inconvenient characteristics such as time delay are canceled out during resurveillance tests, and the Nol 1 pressure control mode is switched. Surveillance tests can be carried out without reducing reactor output, without reducing reactor output, and without causing unnecessary scrams, thereby improving the operating capacity of nuclear power generation equipment.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 4 to 7. In the figure, 101 is a reactor pressure vessel, and this reactor pressure vessel 101 is housed 41 in a reactor containment vessel 102. I housed in this reactor pressure vessel 101
7 and steam generated in the reactor core 103; J main steam pipe 104
is sent to the turbine 105, and this turbine 105
f and %, power generation 5: rotates the number (t not shown), 'C starts', E is divided as &t, and tt. The steam discharged from this turbine 105 is condensed in an ascites 106.
t.

The compressed territorial water is returned to the inside of the reactor pressure vessel 101). And, in the part where the main steam pipe 1θ4 penetrates the reactor containment vessel 102,
, 108 were installed, and the reactor was scrammed and main steam isolation valves 107 and 108 were closed to isolate the reactor containment vessel 102. , to prevent the spread of dispersible material 'rBl'.Also, a regulating valve 1θ9 is provided at the inlet of the terpino 105, and the amount of steam supplied to the turbine 105 is controlled by this regulating valve 1θ9. is a turbine bypass pipe, which connects the downstream side of the control valve 1θ9 to the condenser 106.
We communicate with each other. The Kubin bypass pipe 110 is provided with a bypass valve 111, and by opening the bypass valve 111, the remaining steam is released to the condenser 106. In the actual system, a plurality of F exhaust steam pipes 104 are provided, and main steam isolation valves 107, 108. Kajo dialect 109. A plurality of bypass valves 11] are also provided 3, and this nuclear power plant equipment is equipped with a Jf and a sub-reactor pressure control device 112.
The configuration is explained below. In the figure, 113 is a reactor pressure detector, which detects the reactor pressure inside the reactor pressure vessel 101. Further, 114 is a turbine inlet pressure detector, which detects the pressure of main steam supplied to the turbine 105. The reactor pressure signal S11 outputted from the reactor pressure detector 113 and the turbine artificial pressure signal S12 outputted from the turbine inlet pressure detector 114 are sent to the pressure control circuit 115. This pressure control circuit 115 combines the reactor pressure signal SI+ and the turbine inlet pressure signal "r812", and outputs a combined control signal S21 based on this combined signal.This combined control signal S21 is sent to the valve control circuit 116. The valve control circuit 116 controls the control valve 109 and the bypass valve 111 based on the composite control signal S21, and is configured as a button to control the reactor pressure to a predetermined pressure.

The pressure control circuit U'' is constructed as shown in FIG. 5, and the construction of this pressure control circuit 115 will be explained below. That is, 120 is a signal synthesis circuit, which combines the reactor pressure signal Sl+ and the turbine inlet pressure (No. i S
, 2 are input to this signal synthesis circuit 120. This signal synthesis circuit 120 synthesizes the reactor pressure signal 811 and the turbine inlet pressure signal S, 2, and outputs a composite pressure signal S13. The signal synthesis circuit 120 weights both signals when synthesizing the reactor pressure signal Sl+ and the turbine inlet pressure signal S12, and is configured to be able to arbitrarily change the weighting ratio. . This combined pressure signal S Ill is then sent to the deviation circuit 121 . This deviation circuit 12) includes two subtracters 122@, 12
2b, and the composite pressure signal 813 is input to these subtracters 122a and 122b, respectively. Further, a bias signal S14 for equipment maintenance CG, for example, is input to one subtractor 122a, and the other subtractor 1
A reference letter S, 5 from the pressure setting device 123 for setting and changing the reactor pressure is input to 22b. The bias signal S14, the deviation signal S15+S+7 between the reference signal S15 and the composite pressure signal S13 are output from the subtracters 122a and 122b, respectively. These deviation signals S16+817 are each sent to the gain corrector 124a.

124b, lead/lag circuit 125a as a filter.

125b to the high value priority circuit 126.

This high value priority circuit 126 has deviation No. 45 S76. It is configured to give priority to the higher value of S and 7 and send it to the valve control circuit 116 as a composite control signal S21.

In one embodiment of the present invention configured as described above, the reactor pressure is controlled based on a composite pressure signal S, which is a composite of the reactor pressure signal S++ and the turbine inlet pressure signal S,2. Since the flow of main steam is almost steady under normal operating conditions, there is a certain relationship between the reactor pressure and the turbine inlet pressure, and the reactor pressure is determined based on the composite pressure signals s, 3r, and c. There is no problem with controlling it. In addition, when conducting surveillance tests, the reactor pressure signal S
++ or 1) if the control is performed only based on the turbine input pressure signal S12? ■As mentioned above, transient characteristics that promote disturbances and overshoot due to time delay appear when conducting a surveillance test, but in this example, the reactor pressure signal S I+ and the turbine inlet pressure 11 Since the control is performed based on the composite pressure signal SI3 of signals S and 2, such characteristics are canceled out. Therefore, even if surveillance tests are conducted on various valves without reducing the reactor output while operating in a single mode based on this composite pressure/No. 15 S13, there will be no transient increase in the reactor pressure. The width is kept low and the reactor does not scram.

Incidentally, FIGS. 6 and 7 show transient characteristics when a surveillance test is carried out with the reactor output set as the rated output in this embodiment. In other words, the solid line in Section 6 is the result when a surveillance test was conducted with all main steam isolation valves 107 and 108 closed, and the transient increase in neutron flux was suppressed to a low level and exceeded the scram set value A. There are no words. Incidentally, the broken line in FIG. 6 shows the characteristics when a one-nerverance test of the valve is carried out on the king steam valve in the conventional turbine inlet pressure control mode. In addition, the solid line in FIG. 7 shows the transient characteristics when conducting a one-valve-all-off surveillance test of the control valve 109, and the transient increase in neutron flux is suppressed to a low level and the scram set point A is not exceeded. There isn't. Incidentally, the broken line in FIG. 7 shows the characteristics when a surveillance test with one regulating valve fully closed is carried out in the conventional reactor dome pressure control mode.

〔Effect of the invention〕

As described above, the present invention includes a reactor pressure detector for detecting the reactor pressure, a turbine inlet pressure detector for detecting the turbine inlet pressure, 2. A signal synthesis circuit that receives the turbine inlet pressure from the turbine inlet pressure sensor and synthesizes these signals to produce a composite pressure signal, and this composite upper blade (based on the name of the turbine) It is equipped with a valve control circuit that controls the regulator valve and the bypass valve of the turbine bypass system.Therefore, it is possible to combine the reactor pressure signal and the turbine entry pressure signal to avoid disturbances during the Elisurveillance test. Inconvenient features such as special ordering and time delays are eliminated without switching pressure control modes, without reducing reactor power, and causing unnecessary scrams. The effects are significant, such as being able to conduct surveillance tests without having to use nuclear power plants, and improving the operating rate of nuclear power generation facilities.

[Brief explanation of drawings]

1 to 3 show conventional examples, with FIG. 1 being a schematic configuration diagram, and FIGS. 2 and 3 being diagrams showing transient characteristics during surveillance and test leprosy. 4 to 7 show an embodiment of the present invention, FIG. 4 is a schematic diagram, FIG. 5 is a schematic diagram of a pressure control circuit, and FIGS. 6 and 7 show a valve surveillance test. It is a diagram showing transient characteristics when implemented. 10...Reactor pressure vessel, 1θ3...Reactor core, 10
4...Main steam pipe, 105...Turbine, 102°10
8. Main steam isolation valve, 109. Adjustment valve, 11 bypass valve, 112 - Reactor pressure control device, 113.. Reactor pressure detector, 114.. Turbine inlet pressure detector, 115
-Pressure control circuit, 120...signal synthesis circuit.

Claims (1)

[Claims] a reactor pressure detector for detecting reactor pressure; a turbine inlet pressure detector for detecting turbine inlet pressure; a reactor pressure signal from the reactor pressure detector; and a turbine inlet signal from the turbine inlet pressure detector. A signal synthesis circuit that receives pressure signals, synthesizes these signals, and outputs a composite pressure signal; and a valve control circuit that controls a turbine control valve and a turbine bypass valve based on the composite pressure signal. A nuclear reactor pressure control device characterized by: