JPS63313094A - Device for supplying purging water to control rod driving mechanism - Google Patents

Abstract

PURPOSE:To prevent the inflow of reactor water into control rod driving mechanisms at the time of insertion and operation of the control rod driving mechanisms by providing a bypass piping to the down stream side of a flow rate control valve and bypassing the purging water at the flow rate in excess of the ordinary flow rate of the purging water. CONSTITUTION:The purging water to be supplied to the control rod driving mechanisms 3, many pieces of which are provided to the lower part of a reactor pressure vessel 1, is boosted by a boosting pump 6 and is supplied after the flow rate is controlled by the flow rate control valve 13. The bypass piping 15 having a bypass valve 17 is provided on the down stream side of the flow rate control valve 13. Of the purging water on the down stream side of the flow rate control valve 13, the purging water of the volume in excess of the volume of the ordinary purging water is bypassed from the bypass piping and the remaining purging water is supplied as the ordinary purging water to the control rod driving mechanisms 3 in the cases in which the control rod driving mechanisms 3 are not operated and in which a pulling operation is executed. The bypass valve 17 is closed by the input of the signal for the loading operation of the control rod driving mechanisms and the bypassed purging water is supplied to the control rod driving mechanisms 3 when the control rod driving mechanisms 3 are subjected to the loading operation.

Description

[Detailed description of the invention] [Object of the invention] (Field of application in GI industry) The present invention supplies purge water to a control rod drive mechanism provided in large numbers at the bottom of a reactor pressure vessel of a boiling water reactor. The present invention relates to a control rod drive mechanism purge water supply device.

(Prior Art) Generally, a large number of control rod drive mechanisms (hereinafter referred to as CRDs) are provided in the lower part of the reactor pressure vessel of a boiling water reactor for inserting and withdrawing control rods into the reactor core. During normal operation, this CRD is driven by a control rod drive mechanism electric motor (hereinafter referred to as CRD-motor), and during an emergency stop (hereinafter referred to as scram), it is driven by a control rod drive hydraulic device (hereinafter referred to as CRD hydraulic device). There is.

FIG. 3 is a configuration diagram showing the CRD hydraulic device.

Reactor pressure vessel 2 provided in reactor containment unit 1
A large number of CRDs 3 are provided at the bottom of the CRD 3, and a CRD hydraulic system v14 is provided connected to the CRD 3.

This CRD water pressure device 4 includes a water pressure control unit (hereinafter referred to as ICU) 5 that controls the pressure of the water supplied to the CRD 3, and a and II water pressure units that increase the pressure of the water supplied to the CRD 3.
A control rod hydraulic pump (hereinafter referred to as a driving water pump) 6 is provided.

A plurality of HCUs 5 are provided, and usually one ICU 5 is provided for each two CRDs 3.

1-I CU 5 includes an accumulator 8 that stores the supply water sent from the driving water pump 6 through the filling water header 7, and a scram that supplies the supply water stored in the accumulator 8 to the CRr) 3 at the time of scram. A valve 9 is provided.

The driving water pump 6 is connected to the condensate desalination device outlet and the condensate storage pool (C8P) 10, and a minimum flow line 11 is connected from the pump outlet side to the condensate storage pool 10 for pump protection. In addition, a barge water distribution 'Q12 to the CRD3 is connected from the discharge side of the driving water pump 6,
A flow control valve 13 is interposed in this purge water pipe 12 .

The flow rate control valve 13 automatically adjusts the valve opening based on the differential pressure between the discharge side pressure of the driving water pump 6 and the pressure inside the reactor pressure vessel 2, and supplies a predetermined flow rate of purge water to the CRD 3. It has become.

In the CRD hydraulic device 4 configured as described above, the supply water sucked in by the drive water pump 6 from the condensate storage pool 10J3 and the condensate desalination device is pressurized by the drive water pump 6 and then pumped into the HCLJ 5. It is stored in the accumulator 8. During scram, the scram valve 9 is closed, so that the high pressure water stored in the accumulator 8 is supplied to the CRD 3, and the control rods are inserted into the reactor core all at once by this high pressure water.

In addition, during normal operation, purge water is supplied to the CRD 3 from the discharge side of the drive water pump 6 through the purge water pipe 12,
This purge water prevents foreign matter from settling inside the reactor pressure vessel 2.

(Problems to be Solved by the Invention) In this way, purge water is constantly supplied from the purge water pipe 12 to the CRD 3, but the CRD 3 by the CRD motor
Depending on the relationship between drive speed and barge water volume, reactor water may flow into the CRDa.

In other words, insertion and withdrawal are performed by driving the hollow piston in CRDa connected to the control rod, and in the case of insertion, the hollow piston in CRDa is inserted into the reactor pressure vessel 2 as the control rod is inserted. Therefore, the amount of water corresponding to the volume moved by the hollow piston is calculated as CRD.
It is necessary to supply within a.

In this case, if the CRD3 drive speed is relatively slow, purge water is supplied into the CRD3, thereby preventing reactor water from flowing into the CRD3, but if the CRD3 drive speed is relatively fast, In this case, purge water was not supplied in time and reactor water flowed into CRDa.

If reactor water flows into the CRDa, it will not affect the performance of CRD3, but when workers work inside the lower pedestal of the reactor pressure vessel during regular reactor inspections, the CRD
The radiation ω from 3 increases, which is unfavorable in terms of preventing workers from being exposed to radiation.

In order to prevent reactor water from flowing into the CRD 3, it is possible to supply a large amount of purge water to the CRD 3 regardless of the operating state of the CRD 3. It is not preferable to let it flow in because it causes a decrease in the furnace output.

The present invention has been made in consideration of the above circumstances, and can be used to drive the i and lJ control rods even when the control rod drive mechanism is inserted without flowing multi-R purge water into the reactor pressure vessel. An object of the present invention is to provide a control rod drive mechanism purge water supply device that can prevent reactor water from flowing into a reactor and protect workers from radiation exposure.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a control rod drive mechanism provided in large numbers at the bottom of a reactor pressure vessel, a booster pump that backpressures purge water supplied to the control rod drive mechanism, and a booster pump that backpressures purge water supplied to the control rod drive mechanism. In a control rod drive mechanism purge water supply device equipped with a flow control valve that adjusts the flow rate of purge water supplied from a pressure pump to the control rod drive i structure, the purge water on the downstream side of the flow control valve is A bypass pipe is provided to bypass purge water exceeding the normal purge water flow rate, and a bypass valve is interposed in the bypass pipe to perform a closing operation when a control rod drive mechanism insertion operation signal is input.

(Function) When the llJ control rod side rod drive mechanism is not operated or when it is pulled out, the purge water that exceeds the normal purge water flow rate among the purge water on the downstream side of the flow m control valve is bypassed from the bypass piping, and the remaining purge water is supplied to the control rod drive mechanism as normal purge water. When the control rod drive mechanism is inserted, the bypass valve receives a control rod drive mechanism insertion operation signal and performs a closing operation.

In this manner, the bypass valve closes, and the purge water that has been bypassed is supplied to the control rod drive mechanism. Therefore, reactor water is prevented from flowing into the control rod drive mechanism.

(Embodiment) - An embodiment of the control rod drive mechanism purge water supply device according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, the purge water supply system 2 boosts the pressure of purge water supplied to the control rod drive f, IJ mechanism (hereinafter referred to as CHD) 3 and its CRD 3, which are provided in large numbers at the bottom of the reactor pressure vessel 2. A control rod driven water pump (hereinafter referred to as a driven water pump) 6 as a pressure boosting pump, and a flow m control valve 13 for adjusting the vtR of purge water supplied from the driven water pump 6 to the CRD 3 are provided. A bypass piping 15 is provided to bypass the purge water exceeding the normal purge water flow rate among the purge water on the downstream side of the flow m control valve 13, and when the control rod drive mechanism insertion operation signal 16 is input to the bypass piping 15. A bypass valve 17 is interposed which performs a closing operation. Portions in FIG. 1 that are the same as those in FIG. 3 are designated by the same reference numerals and their explanations will be omitted.

The flow ffi f, IJ all valve 13 is adjusted to flow purge water at a flow rate that exceeds the normal purge water flow rate. Further, the bypass pipe 15 is provided to connect the purge water pipe 12 on the downstream side of the flow control valve 13 and the condensate storage pool 10 . This bypass piping 15 may be provided by attaching a part of the minimum flow line 11. Bypass valve 17
is normally in an open state, and closes when a control rod insertion operation signal 16 is input from a control rod operation panel (not shown). As the bypass valve 17, an air-operated valve that opens and closes using air from an instrument air system (IA system) or a solenoid valve that opens and closes using electric power is used. An orifice 18 or a throttle valve for adjusting the flow rate may be provided near the bypass valve 17.

Next, the operation of the above embodiment will be explained.

When the CRD 3 is not operated or when the CRD 3 is withdrawn, the purge water on the downstream side of the flow rate control valve 13 that exceeds the normal purge water flow rate is bypassed from the bypass pipe 15 and the bypass valve 17 in the open state is bypassed. and flows into the condensate storage pool 10. Then, purge water at a normal flow rate is supplied to the CRD 3 through the purge water pipe 12, and the purge water prevents foreign matter from settling in the reactor pressure vessel 2.

On the other hand, when the CRD 3 is inserted, the bypass valve 17 inputs the control rod insertion operation signal 16 from the control rod operation panel and performs the closing operation. When the bypass valve 17 closes, the purge water that has been bypassed is supplied to the CRD 3 through the purge water pipe 12. Therefore, even when the hollow piston inside CRDa moves when the CRD3 is inserted, it is possible to supply the amount of purge water corresponding to the volume moved by the hollow piston, and the CRD3 is inserted into the CRDa.
It is possible to prevent reactor water from flowing into the RDa.

Next, another embodiment of the present invention will be described using FIG. 2.

This example is bypass distribution S! 15 flows ffi siri control valve 1
The purge water pipe 12 on the downstream side of 3 and the pipe connected to the reactor pressure vessel 2 (condensate water supply pipe 20 or condensate water supply pipe 20
A bypass valve 17 and a flow control valve 22 are provided in series to this bypass pipe 15.

In this embodiment, the flow level control valve 22 automatically adjusts its opening degree based on the differential pressure between the discharge pressure of the drive water pump 6 and the pressure inside the reactor pressure vessel 2, and the bypass valve Even when 17 is open, the bypass flow rate can be adjusted to a predetermined flow rate to prevent unnecessary low-temperature purge water from flowing into the reactor pressure vessel 2, thereby making it possible to further reduce the influence on the plant output. Other effects similar to those of the embodiment described above are obtained.

〔Effect of the invention〕

Vlull rod drive machine lateral drive mechanism according to the present invention Purge water supply device A bypass piping is provided to bypass the purge water that exceeds the normal purge water flow rate among the purge water downstream of the control valve, and this bypass piping is provided with a control rod drive mechanism. Since a bypass valve is installed that closes when a mechanism insertion operation signal is input, control can be performed even when the control rod drive mechanism is inserted without injecting a large amount of purge water into the reactor pressure vessel. This has the effect of preventing reactor water from flowing into the rod drive flJ mechanism and protecting workers from radiation exposure.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a configuration diagram showing one embodiment of the control rod drive mechanism purge water supply device according to the present invention, FIG. 2 is a configuration diagram showing another embodiment of the present invention, and FIG. The figure is a configuration diagram showing a control rod drive hydraulic system. 1... Reactor containment vessel, 2... Reactor pressure vessel, 3
... I, IJ n-frame drive mechanism, 4... Control rod drive water pressure device, 5... Water pressure control unit, 6... Control rod drive water pump, 7... Filling water header, 8... - Accumulator, 9... Scram valve, 10... Condensate storage pool, 11... Minimum flow line, 12... Purge water piping, 13... Flow rate control valve, 15... Bypass piping, 16... Control rod drive mechanism insertion operation signal, 17.
... Bypass valve, 18 ... Orifice, 20 ... Condensate water supply pipe, 21 ... Reactor water purification system return pipe, 22 ...
...Flow R control valve.

Claims (1)

[Claims] 1. A control rod drive mechanism provided in large numbers at the bottom of the reactor pressure vessel, a boost pump that boosts the pressure of purge water supplied to the control rod drive mechanism, and a booster pump that drives the control rods. In a control rod drive mechanism purge water supply device that is equipped with a flow rate control valve that adjusts the flow rate of purge water supplied to the mechanism, a purge that exceeds the normal purge water flow rate of the purge water downstream of the flow rate control valve. A control rod drive mechanism purge water supply device comprising a bypass pipe for bypassing water, and a bypass valve that performs a closing operation when a control rod drive mechanism insertion operation signal is input to the bypass pipe. . 2. The control rod drive mechanism purge water supply device according to claim 1, wherein the bypass pipe is provided to connect the downstream side of the flow control valve and the condensate storage pool. 3. The bypass pipe is provided to connect the downstream of the flow control valve and the reactor water purification system return pipe.
Control rod drive mechanism purge water supply device as described in .