JPS6371693A - Control rod drive - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to the boiling water reactor (hereinafter referred to as BWR)
l H? ! The present invention relates to a drive device, and particularly relates to a device that prevents a situation II in which when a scram signal is output, adjacent control rod drive al1 mechanisms become unable to scram at the same time.

(Conventional example) 8 to VR generally have the following configuration.

A coolant and a reactor core are housed in the reactor pressure vessel, and the reactor core is composed of a plurality of fuel assemblies, control rods, and the like. The coolant flows upward through the reactor core and is elevated by the heat of the nuclear reaction in the reactor core. The heated coolant enters a two-phase flow state of water and steam, causing two phases to flow above the core.
The water is introduced into the steam/moisture pre-vessel. Water and steam are separated in this steam/water preparator, and the separated steam is introduced into a 32-part steam dryer above the steam dryer. It is dried in this steam dryer to become dry steam, which is transferred to the turbine system via the main steam pipe connected to the reactor pressure vessel and used for power generation.

In a BW R having such a configuration, the core power is controlled by adjusting the recirculation flow rate by the recirculation system and by adjusting the degree of insertion of the V control rods into the core. The control rod drive device performs this control.

The control rod drive device has a configuration as shown in FIG. Number 1 in Figure 2 is the water source.

A master control unit 3 is connected to this water supply source 1 via a driving water supply pump 2.

This master control unit 3 adjusts the pressure of the driving water supplied via the driving water supply pump 2 in three ways. This master control unit 3 is connected to three headers 5.6.7 that are shared by a plurality of control rod drive devices t1, and the master control unit 3 is connected to each of these three headers 5.6.7. Supply pressure driven water. In addition, only one control rod drive mechanism 4 is shown in the figure. A header 8 is also provided as another header. The header 5.6.7 has a filling water supply pipe 9, a drive water pipe 10, and
A cooling water pipe 11 is connected.

In the figure, only one rod is shown corresponding to one control rod drive mechanism 4. Further, a drainage pipe 12 is connected to the header 8.

A check valve 13 is connected to the filling water supply pipe 9 from the header 5 side.
An accumulator 14 is inserted, and gas supply for emergency insertion if! ! 15 are connected. The emergency insertion driving water in the accumulator 14 is pressurized by nitrogen gas supplied from the emergency insertion gas supply device 15. A check valve 16 is inserted into the driving water pipe 10, and is connected in parallel to the directional control valves 18 and 19 of the directional control valve unit 17. The direction control valve 18 is connected to the insertion port 21 of the II rod drive example 4 through an insertion pipe 20. On the other hand, the direction control valve 19 is connected to the control valve 19 through a pull-out pipe 22. It is connected to the extraction port 23 of the Azusa drive structure 4.

The cooling water pipe 11 is connected to the header 7 and the insertion pipe 20.
A check valve 24 is inserted. A scram pipe 25 is disposed between the downstream side of the check valve 13 of the filling water supply pipe 9 and the downstream side of the check valve 24 of the cooling water pipe 11. An inlet valve 26 is inserted.

The drainage pipe 12 (J is connected in parallel to the directional control valves 27 and 28 of the directional control valve unit 17. The directional control valve 27 is connected to the insertion pipe 20, and the directional control valve 28 is It is connected to the drawn-out pipe 22. A scram discharge header 30 is also connected to the drawn-out pipe via a scram discharge pipe 29, and a scram outlet valve 31 and a check valve 32 are connected to the two scram discharge pipes. The scram inlet valve 26 and the scram outlet valve 31 are normally kept closed by i!2i pressure air supplied through the scram pilot valve 33. The high-pressure air is exhausted by the scram signal 838 output from the reactor depth j device 38, and the scram inlet valve 26 and the scram outlet valve 31 are opened.

In addition, the υ1 rotary drive mechanism 4 can be slid into the control rod drive mechanism housing 35 fixed to the bottom 34 of the reactor pressure container, and within this control rod drive mechanism housing 35! i2, the piston 36, etc.
A rod 37 υj12a is connected to.

The operation will be explained based on the above configuration. First, the driving water pressurized from the water supply a1 via the driving water supply pump 2 is adjusted to three different pressures by the master control unit 3 and is supplied to the headers 5, 6.7. The drive water supplied via the header 5 is stored in the accumulator 14 via the filling water pipe 9 as drive water for emergency insertion. The drive water supplied through the header 7 is supplied as cooling water through the cooling water pipe 11 and the insertion pipe 20 through the insertion port 20 of the tll 18 Azusa drive example structure 4.

When inserting the control II rod 37 into the reactor core, the directional control valves 18 and 28 are opened. As a result, the driving water supplied from the header 6 is transferred to the driving water piping 10 and the check valve 16.
, direction υ1tID valve 18, ' is supplied from the insertion port 21 to the lower surface side of the piston 36 via the insertion pipe 20. This causes the piston 36 to rise and the control rod 37 to be inserted into the reactor core. At that time, the water on the upper surface side of the piston 36 is removed from the extraction port 2.
3 and returns to the header 8 via the withdrawal pipe 22, the directional control valve 28, and the drainage pipe 12.

Next, the case where the control rod 37 is pulled out will be explained.

In this case, the directional control valves 19 and 27 are opened.

As a result, the driving water supplied from the header 6 acts on the upper surface side of the piston 36 from the extraction port 23 via the driving water piping 10, the check valve 16, the directional control valve 19, and the extraction piping 22. As a result, the piston 36 descends and the control rod 37 is pulled out from the core. At that time, the water on the lower surface side of the piston 36 flows through the insertion port 21, the insertion pipe 20, the direction control valve 27, and the drain pipe 1.
2 into header 8.

Next, we will explain the case of reactor emergency shutdown (scram). At this time, first, a scram signal s38 is output from the reactor maintenance equipment 38. The scram pilot valve 33 is operated by the output of the scram signal s38. This exhausts the high pressure air and opens the scram inlet valve 26 and the scram outlet valve 31. As a result, the driving water stored in the accumulator 14 is pushed out by the nitrogen gas from the emergency insertion gas supply device 15 and flows through the scram inlet valve 26, the insertion pipe 20, and the insertion port 21 to the lower surface side of the piston 36. act. This allows the piston 36
The control rods 37 are inserted into the reactor core at high speed through. As a result, the reactor undergoes an emergency shutdown.

At this time, water on the upper surface side of the piston 36 flows out from the withdrawal port 23 and is discharged into the discharge header 30 via the withdrawal pipe 22, two scram discharge pipes, the scram outlet valve 31, and the check valve 32.

The above configuration has the following problems. In other words, when assuming a situation where the emergency insertion gas supply device 15 fails (for example, nitrogen gas leaks), even if the reactor protection device 3
Even if the scram signal s38 is output from the reactor 8, the drive water stored in the accumulator 14 cannot be supplied and the control rods 37 cannot be inserted into the reactor core at high speed. Ta. In particular, if two adjacent control rod drive mechanisms 4 become unable to scram together, it is expected that the safety of the nuclear reactor will be impaired, and a solution to this problem has been required.

(Problem to be solved by the invention) As described above, in the conventional control rod drive device, if the emergency insertion gas supply device does not operate at all, the scram operation of the control rod cannot be performed. If this happens between adjacent control rods at the same time, there is a problem that the health and safety of the plant will be impaired.The present invention was made based on this point and has achieved its purpose. The objective is to provide a control rod drive device that can maintain plant health and improve safety by preventing a situation in which adjacent control rod drive mechanisms become incapable of scramming at the same time. be.

[Structure of the Invention] (Means for Solving the Problems) That is, the control rod drive device according to the present invention is connected to a control rod drive mechanism via an insertion pipe and a withdrawal pipe, and is controlled by switching the flow path of driving water. The valve unit is inserted into the direction valve unit that inserts and pulls out the rods into the reactor core, and is inserted into the scram piping connected to the insertion piping and withdrawal piping, and is normally closed to receive the scram signal from the reactor protection device. A scram inlet valve and a scram outlet valve that open according to the output; an accumulator that supplies driving water for emergency insertion to the control rod drive mechanism via the scram inlet valve; A gas supply device for emergency insertion uses high pressure gas to pressurize the drive water in the system, and the gas pressure inside this gas supply device for emergency insertion is monitored and an alarm signal is output when the pressure falls below a preset standard (Nitsu). A pressure detector and an alarm signal are input from the pressure detector and an alarm signal is output from a pressure detector installed in another control rod drive structure adjacent to the control rod drive mechanism corresponding to the alarm signal. The apparatus is characterized by comprising a signal processing device that evaluates whether or not the control rod is present and outputs a signal that causes the control rod to be inserted into either one of the υ1till suspension bridges when the signal is output. be.

(Function) In other words, a pressure detector detects the gas pressure of the emergency insertion gas supply device installed for each control rod drive mechanism, and when the pressure falls below a preset reference value, an alarm signal is sent to the signal processing device. Output. There is another control rod drive 14I in the signal processing device.
The configuration is such that a similar signal is input from the pressure detector installed corresponding to one mechanism, and if any
*If an alarm signal is output from the pressure detector corresponding to the drive mechanism, the 11Jtll rod drive J! Evaluate whether or not an alarm signal is output from the pressure detector corresponding to the other υ control rod drive mechanism adjacent to the 71 mechanism, and if it is output, the control rod drive mechanism of either one This outputs a signal that causes the bridge to perform the control rod insertion operation.

(Example) An example of the present invention will be described below with reference to FIG. 1.

It should be noted that the same parts as in the prior art are denoted by the same reference numerals and the explanation thereof will be omitted. Reference number 101 in FIG. 1 is a pressure detector. This pressure detector 101 monitors the gas pressure of the emergency gas supply system 15, and when the pressure falls below a preset reference range, a signal is sent. The processing device 10 outputs an alarm signal s101. The pressure detector 101 is installed for each emergency insertion gas supply device 15 installed corresponding to each control rod drive mechanism 4. Similar alarm signals s 101 from the plurality of pressure detectors 101 are input to the signal@processing 'A H 102. When an alarm signal s 101 is output from the pressure detector 101 corresponding to any control rod drive mechanism 4, the signal processing device 102 transmits the control rod drive mechanism 4 to another control rod drive mechanism 4 adjacent to the control rod drive mechanism 4. It is evaluated whether or not the alarm signal 5101 of f1 is output from the pressure detector 101 corresponding to f1. If it is determined that the control rod is being outputted, a signal 3102 is output to the reactor protection device 38 to cause the adjacent rod drive machine TL 4 to insert the control rod, and the reactor maintenance system is activated. @38 outputs scram (a-s38).This reactor protection device 38 is configured so that it can perform a scram operation on each of the demolition drive units 1 and 4 individually.In addition, in this case,
As shown in the image, the gas pressure of the emergency insertion gas supply 〇115 corresponding to the adjacent control rod drive U structure 4 was also 11111m.
However, the pressure remains to the extent that the scrum operation is performed at a slower speed than the normal scrum operation, and as such, the upper &! A standard value shall be set. Further, the gas pressure recovery operation is performed in the second insertion gas supply mW115 corresponding to the pressure detector from which the alarm signal 6101 was first output.

The operation will be explained based on the above configuration. First, the pressure detector 101 corresponding to any control rod drive mechanism 4 indicates that the pressure of the emergency insertion gas supply device 15 has fallen below the W single chain.
! ? Suppose that the signal S 101 is output to the No.
Other controls adjacent to the control fI drive 11 even 4 corresponding to the pressure detector 101 that outputs! 'a Alarm signal 5101 from the pressure detector 101 corresponding to the 11 pier drive units
Evaluate whether or not is output. If it is output, what is the adjacent constraint? A signal 51 is sent to the reactor protection device 38 to cause the I drive system 4 to perform a scram operation.
Outputs 02. As a result, the reactor protection device 38 outputs a scram signal s38, and a scram operation is performed. This scram operation is as described in the description of the conventional example. Further, the scram operation at this time is slower than the normal scram operation because the pressure of the emergency insertion gas supply device 15 corresponding to the control rod drive mechanism 4 is below the reference value. On the other hand, in the emergency insertion gas supply device 15 corresponding to the pressure detector 101 that first outputs the alarm signal 8101, a gas pressure recovery operation is performed. Even if an emergency situation were to occur in this state and the original scram signal was output, both adjacent control rod drive mechanisms 4 would not be able to perform a scram operation, and the control rod 37 would remain pulled out, causing the There is a situation where the output does not decrease for
It won't happen. That is, as described above, one control rod drive has already performed the control rod insertion operation for the mechanism 4. Therefore, the safety of the nuclear reactor can be significantly improved. Furthermore, when the recovery of the gas pressure in the emergency insertion gas supply device 15 that first outputs the alarm signal 5101 is completed, a signal is output to the other control rod drive 114 to cause the control rod to retract. 37 is pulled out. Then, the gas pressure recovery operation of the emergency insertion gas supply device 15 is performed.

According to this embodiment, the following effects can be achieved.

(2) That is, even if a scram signal is output, a situation in which both adjacent control rod drive structures 4 are incapable of scram operation is avoided. This constantly monitors the gas pressure of the emergency insertion gas supply device 15 using the pressure detector 101, and if the pressure falls below a reference value, the signal processing device 102 outputs an alarm signal 5101. The signal processing device 102 determines whether the alarm signal S101 is output from the pressure detector 101 corresponding to the control rod drive mechanism 4 adjacent to the control rod drive mechanism 4 corresponding to the pressure detector 101 that outputs the alarm signal 5101. It is evaluated whether or not it is output, and if it is output, a signal 5102 is output to the reactor maintenance 7s device 38. As a result, the adjacent control rod drive mechanism 4 performs a scram operation and inserts the control rod 37. This is because the control rod 37 has already been inserted into the adjacent one. Therefore, the safety of the nuclear reactor can be greatly improved.

■Also, another way of thinking from this practical example is to insert all control rods when the gas pressure in the emergency insertion gas supply device 15 drops, but this would unnecessarily reduce the reactor output. This results in a decrease in On the other hand, in the case of this embodiment, only one of the adjacent ones is inserted, so that the influence on the reactor output is small and the operating rate is improved.

It should be noted that the present invention is not limited to the one embodiment described above; for example, in the one embodiment described above, another adjacent control rod drive mechanism is caused to perform the scram operation, but the reverse may be possible. Furthermore, the signal processing device may output an image signal f3 to switch the flow path to the control rod extension side to the directional control valve unit, instead of outputting a signal to the reactor protection device, and the same effect can be obtained. Qin can.

[Effects of the Invention] As detailed above, according to the control rod drive device according to the present invention, it is possible to reliably prevent a situation in which adjacent control rod drive mechanisms become unable to scram at the same time, and the safety of the plant is greatly improved. The effects are great, such as making it possible to improve

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a control rod drive device showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional control rod layer vJ necking device. 4... Control rod drive mechanism, 14... Accumulator,
15... Gas supply device for emergency insertion, 17... Directional control valve unit, 21... Insertion piping, 22... Pulling out piping, 26... Scram inlet valve, 31... Scram exit valve , 38...Reactor protection device, 101...Pressure detector, 1'02...Signal processing measures.

Claims (3)

[Claims] (1) A directional control valve unit that is connected to the control rod drive mechanism via insertion piping and withdrawal piping and inserts and withdraws the control rods into the reactor core by switching the flow path of driving water;
A scram inlet valve and a scram outlet valve that are inserted into the scram piping connected to the insertion piping and withdrawal piping, are normally closed, and open when a scram signal is output from the reactor protection device; and the scram inlet valve. an accumulator that supplies drive water for emergency insertion to the control rod drive mechanism through the
An emergency insertion gas supply device is connected to this accumulator and pressurizes the emergency insertion drive water stored in the accumulator using high pressure gas, and the gas pressure inside this emergency insertion gas supply device is monitored and set in advance. A pressure detector that outputs an alarm signal when the pressure falls below a reference value, and a pressure detector that receives an alarm signal from this pressure detector and is installed in another control rod drive mechanism adjacent to the control rod drive mechanism that corresponds to the alarm signal. and a signal processing device that evaluates whether or not an alarm signal is output from the pressure detector and outputs a signal that causes one of the control rod drive mechanisms to perform a control rod insertion operation if an alarm signal is output. A control rod drive device characterized by: (2) The signal processing device causes the reactor protection device to output a scram signal when it is determined that an alarm signal is being output from a pressure detector installed in another adjacent control rod drive mechanism. A control rod drive device according to claim 1, characterized in that: (3) When the signal processing device determines that an alarm signal is output from a pressure detector installed in another adjacent control rod drive mechanism, the signal processing device provides a control rod insertion flow path in the directional control valve unit. 2. The control rod drive device according to claim 1, wherein the control rod drive device outputs a signal indicating that the control rod drive device is switched to the control rod drive device.