JPH02140695A - Overpressure preventing device for control rod driving system - Google Patents

Abstract

PURPOSE:To prevent the damage of a hydraulic control unit and the mulfunction of a control rod by connecting a driving water piping and a nuclear reactor return piping, and a cooling water piping and the nuclear reactor return piping, by a driving water bypass tube and a cooling water bypass tube, respectively. CONSTITUTION:To a driving water piping 14, one end of a driving water bypass tube 30 is brought to branch connection, and the other end is brought to confluence to a nuclear reactor return piping 31. A driving water bypass solenoid valve 32 and a before-and-after valve 33 of a manual type for isolating it are inserted through the bypass tube 30. A cooling water piping 13 and the nuclear reactor return piping 31 are connected by a cooling water bypass tube 34. A cooling water bypass solenoid valve 35 and a before-and-after valve 36 of a manual type for isolating it are inserted through this bypass tube 34. Also, an inter- driving water/nuclear reactor differential pressure gauge 19 and an inter-cooling water/nuclear reactor differential pressure gauge 20 are installed in the piping system, outputs of these differential pressure gauges 19, 20 are led to the solenoid valve 32 or the solenoid valve 35 through an inter-driving water/nuclear reactor differential pressure switch 40 or an inter- cooling water/nuclear reactor differential pressure switch 42, and when pressure of the piping 14 or the piping 13 exceeds the set value, the solenoid valve 32 or the solenoid valve 35 is closed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an overpressure prevention device that prevents overpressure in a control rod drive system that manually adjusts the output of a nuclear reactor.

(Prior Art) In general, nuclear power generation facilities are provided with a control rod drive system for manually adjusting the output of a nuclear reactor in addition to various automatic control systems.

Figure 2 shows the schematic configuration of this control rod drive system.
A control rod drive mechanism 2 is installed at the bottom of the reactor pressure vessel 1 .

This control rod drive mechanism 2 has a lower chamber 3a and an upper chamber 3b divided by a driving water piston 4 that moves up and down in a cylinder 3.
An insertion pipe 5 and a withdrawal pipe 6 are connected to the pistons 5 and 6, respectively, so that water pressure can be applied to either the top or bottom of the driving water piston 4. The water pressure applied to the drive water piston 4 is obtained by pressurizing condensate supplied from the condensate tank 7 via the pump suction pipe 8 with the control rod drive water pump 9.

The condensate pressurized by the control rod drive water pump 9 passes through a flow rate adjustment section 11 and is divided into a cooling water pipe 13 and a drive water pipe 14 by a pressure regulation valve 12 consisting of an electric valve.

A part of these cooling water pipes 13 and drive water pipes 14 are made into ladders, and the vicinity of their tips are divided into the number of control rods (usually 185), and each of them is connected to the insertion pipe 5 of the water pressure control unit 15. Or connected to the four-way control valve 16. In addition, a drainage pipe 17 from the four-way control valve 16 (
The entrance section is also divided into 185 sections. ) is connected to a part of the header of the cooling water pipe 13.

Note that 18 indicates a stabilizing valve connected in parallel to the pressure regulating valve 12, and 1 and 20 indicate a driving water/reactor differential pressure gauge and a cooling water/reactor differential pressure gauge, respectively.

In the control rod drive system configured as described above, the cooling water flowing through the cooling water pipe 13 normally enters the cylinder 3 of the control rod drive mechanism 2 through the insertion pipe 5, and the cooling water flows through the control rod drive mechanism 2.
enters reactor 1 while cooling.

When there is no control rod operation, the cooling water from the cooling water pipe 13 flows through the insertion pipe 5 and the control rod drive mechanism 2 to a pressure of about 1.0 mm below the reactor pressure. (1 kg/c - flows into the reactor 1 at high pressure.

On the other hand, when the control rod insertion operation is performed, the pressure regulating valve 12 closes, and driving water with a pressure approximately 18.3 kg/c higher than the reactor pressure flows through the driving water piping 14, four-way control valve 16, and insertion piping 5. and flows into the lower chamber 3a of the cylinder 3. This causes the drive water piston 4 to rise and insert the control rod into the reactor core.

In this case, the water above the driving water piston 4 is drawn out from the piping 6,
It passes through the four-way control valve 16 and the drain pipe 17, and then returns to the reactor 1 again via the cooling water pipe 13 of another control rod and the control rod drive mechanism 2.

In the case of a control rod withdrawal operation, contrary to the above-mentioned insertion operation, the driving water is changed into a reverse flow by the four-way control valve 16 and is sent to the upper chamber 3b of the cylinder 3 through the withdrawal pipe 6. and pushes down the driving water piston 4. At this time, water in the cylinder lower chamber 3a passes through the insertion pipe 5, the drainage pipe 17, and returns to the reactor 1 through the cooling water plumber 3 of the other control rod.

During the insertion and withdrawal operations described above, the stabilizing valve 18 operates so that the system flow rate and pressure do not fluctuate, thereby stabilizing the outlet flow rate and pressure of the flow rate: A adjustment section 11. Further, the driving water pressure and the cooling water pressure are monitored by a driving water/reactor differential pressure gauge 19 and a cooling water/reactor differential pressure gauge 20, respectively.

(Problem 8 to be Solved by the Invention) In the control rod drive system described above, during repair work, etc., all hydraulic control units 15 (185 units) are isolated and repaired, but when the system is restored after the repair is completed,
The control rod-driven water pump 9 is kept operating to also fill the water pressure control unit with water.

If one hydraulic control unit is restored in this state, the pressure of the remaining 184 units will be concentrated in one unit.

Normally, the outlet pressure of the control rod-driven water pump 9 is approximately 130 kg.
/c-, and since the reactor pressure is atmospheric pressure,
At the time of restoration, a very large pressure difference is applied to the driving water piston 4 and the four-way control valve 16, which may cause the control rod to malfunction or damage the four-way control valve 16.

The present invention has been made to solve the above problems, and in any case, when abnormal pressure is applied to the driving water piping or the cooling water piping, this pressure is released to others automatically or manually, and the water pressure control unit The object of the present invention is to provide a control rod drive system overpressure prevention device that can reliably prevent damage to component equipment and malfunction of control rods.

[Configuration of the Invention (Means for Solving the Problems) The control rod drive system overpressure prevention device of the present invention pressurizes condensate from a condensate tank with a control rod drive water pump, and transfers it to the drive water piping or In the control rod drive system leading to the hydraulic control unit of each control rod drive mechanism via the cooling water pipe, the drive water pipe and the reactor return pipe are connected by a drive water bypass pipe equipped with a drive water bypass solenoid valve. At the same time, the cooling water pipe and the reactor return pipe are connected by a cooling water bypass pipe equipped with a cooling water bypass solenoid valve, and the piping system is connected to a drive water/reactor differential pressure gauge and a cooling water/reactor return pipe. The outputs of these differential pressure gauges are sent to the driving water bypass solenoid valve or the cooling water bypass solenoid valve via the driving water/reactor differential pressure switch or the cooling water/reactor differential pressure switch. The invention is characterized in that the driving water bypass solenoid valve or the cooling water bypass solenoid valve is opened when the pressure in the driving water piping or the cooling water piping exceeds a set value.

(Function) In the control rod drive system overpressure prevention device of the present invention configured as described above, when the differential pressure between the cooling water pipe and the reactor increases abnormally, the control rod drive system overpressure prevention device installed in the cooling water bypass pipe A solenoid valve opens, returning pressure to the reactor return line. Additionally, if the differential pressure between the drive water pipe and the reactor increases abnormally, a solenoid valve installed in the drive water bypass pipe opens to release pressure to the reactor return pipe. Therefore, damage to equipment in the control rod drive system and malfunction of the control rods are prevented.

(Example) Next, the present invention will be explained in detail with reference to FIG.

In FIG. 1, the same parts as in FIG. 2 are given the same reference numerals, and to avoid duplication, explanations of the same parts will be omitted unless necessary.

FIG. 1 shows a schematic configuration of a control rod drive system equipped with a control rod drive system overpressure prevention device according to the present invention, in which one end of a drive water bypass pipe 30 is branched and connected to the drive water pipe 14.
The other end joins the reactor return pipe 31. The driving water bypass pipe 30 includes a driving water bypass solenoid valve 32,
A manual front and back valve 33 is inserted to isolate it.

The cooling water pipe 13 and the reactor return pipe 31 are connected by a cooling water bypass pipe 34. This cooling water bypass pipe 3
4, a cooling water bypass solenoid valve 35 and a manual front and rear valve 36 for isolating the valve are inserted.

A driving water/reactor differential pressure switch 40 is connected to the driving water/reactor differential pressure gauge 19, and its output is sent to the driving water bypass solenoid valve 3 along with an electric signal from the manual switch 41.
2. Further, a cooling water/reactor differential pressure switch 42 is connected to the cooling water/reactor differential pressure gauge 20, and its output is transmitted to the cooling water bypass solenoid valve 35 together with an electric signal from a manual switch 43. .

In the device of the present invention having such a configuration, the drive water pipe 14
When the pressure rises abnormally, this is converted into an electrical signal by the drive water/reactor pressure difference gauge 19 and transmitted to the drive water/reactor pressure difference switch 40 . When the input signal exceeds a preset value, the drive water/reactor differential pressure switch 40 sends an open signal to the drive water bypass solenoid valve 32, opens the drive water bypass solenoid valve 32, and returns water to the reactor. Piping 31
The pressure in the drive water pipe 14 is reduced.

Furthermore, when the pressure in the driving water piping 14 decreases, a closing signal is transmitted from the driving water/reactor differential pressure switch 40 to the driving water bypass solenoid valve 32, and the driving water bypass solenoid valve 32 is fully closed.

On the other hand, when the pressure in the cooling water piping 13 rises abnormally, this is converted into an electrical signal by the cooling water/reactor pressure difference gauge 20 and transmitted to the cooling water/reactor pressure difference switch 42 . The cooling water/reactor differential pressure switch 42 activates the cooling water bypass solenoid valve 35 when the human input signal exceeds a preset value.
An open signal is sent to the reactor, the cooling water bypass solenoid valve 35 is opened, and the pressure in the cooling water pipe 13 is released to the reactor return pipe 31. Furthermore, when the pressure in the cooling water pipe 14 decreases, a closing signal is sent from the cooling water/reactor differential pressure switch 42 to the cooling water bypass solenoid valve 3.
5, and the drive water bypass solenoid valve 35 is fully closed.

Note that the driving water bypass solenoid valve 32 and the cooling water bypass solenoid valve 35 are each equipped with manual switches 41 and 43, so by operating these manual switches, the driving water bypass solenoid valve 32 and the cooling water bypass solenoid valve 32 and the cooling water bypass The solenoid valve 35 can be isolated from the system.

[Effects of the Invention] As explained above, the control rod drive system overpressure prevention device according to the present invention can quickly respond to abnormal pressure increases in cooling water piping and drive water piping, regardless of the simple equipment. Since the pressure in these piping is lowered, equipment damage and control rod malfunction can be reliably prevented.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a control rod drive system showing an embodiment of the control rod drive system overpressure prevention device of the present invention, and FIG. 2 is a system diagram of a conventional control rod drive system. 1...Reactor 2...Control rod drive mechanism 3...Cylinder 4...Drive water piston 5...Insertion piping 6...Removal piping 7...Condensate tank 8...Pump suction piping 9... Control rod driven water pump 11...
...Flow ff12 Adjustment section 12...Pressure adjustment valve 13...Cooling water piping 14...Drive water piping 15. ......Water pressure control unit 16...
...Four-way control valve 17...Drainage piping 18...Stability valve 19...Driving water/reactor difference Pressure gauge 20・
......Cooling water/reactor differential pressure gauge 30...
...... Drive water bypass pipe 31 ...... Reactor return pipe 32 ...... Drive water bypass solenoid valve 33.36 ... Front and rear valves 34 ... ...Cooling water bypass pipe 35...
...Cooling water bypass solenoid valve 40...
・Driving water/reactor differential pressure switch 41.43...Manual switch 42...Cooling water/reactor differential pressure switch Representative Patent attorney Noriyuki Chika Ken Daishimaru

Claims (1)

[Claims] In a control rod drive system in which condensate from a condensate tank is pressurized by a control rod drive water pump and is guided to a water pressure control unit of each control rod drive mechanism via drive water piping or cooling water piping, the drive water piping and the reactor return pipe are connected by a drive water bypass pipe equipped with a drive water bypass solenoid valve, and between the cooling water pipe and the reactor return pipe,
A cooling water bypass pipe equipped with a cooling water bypass solenoid valve is connected, and a driving water/reactor differential pressure gauge and a cooling water/reactor differential pressure gauge are installed in the piping system, and the outputs of these differential pressure gauges are connected to the driving water. /The pressure in the driving water piping or the cooling water piping exceeds a set value by guiding it to the driving water bypass solenoid valve or the cooling water bypass solenoid valve via the inter-reactor differential pressure switch or the cooling water/reactor-to-reactor differential pressure switch. 1. A control rod drive system overpressure prevention device, characterized in that the drive water bypass solenoid valve or the cooling water bypass solenoid valve is configured to open when the drive water bypass solenoid valve or the cooling water bypass solenoid valve is opened.