JPH1090484A - Hydrogen/oxygen injection system of boiling water reactor plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably maintain oxygen concentration at the outlet of recombiner of gas waste processing system by varying oxygen injection rate following the change of oxygen concentration and flowrate at the outlet. SOLUTION: In the case hydrogen temporarily stagnates and discharges in the main condenser 4, for example, the recombining amount of hydrogen and oxygen in a recombiner 8 of a gas waste processing system varies with it. The state can be known from the oxygen concentration at the outlet of the recombiner 8 of a gas waste processing system. Upon receiving the oxygen concentration change, oxygen concentration is detected without delay with an oxygen concentration detector 11 and an oxygen concentration measuring device 12, which is input in a hydrogen / oxygen injection rate controller 19. In the hydrogen / oxygen injection rate controller 19, control signal for varying the opening of an oxygen injection rate control valve 18 can be sent through a specific operation. Repeated operation of this, as the results, comes to stabilize oxygen concentration at the outlet of the recombiner 8 of a gas waste processing system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for injecting hydrogen into a primary coolant of a nuclear reactor and converting the non-condensable gas extracted by a main condenser into a gas waste treatment system before reaching a gas waste treatment system recombiner. The present invention relates to a system for performing a hydrogen / oxygen injection operation in a boiling water nuclear power plant that injects oxygen for processing excess hydrogen in a processing system, and in particular, an oxygen concentration in a gaseous waste processing system recombiner outlet gas. The present invention relates to a hydrogen / oxygen injection system for a boiling water nuclear power plant, which can stabilize a fuel cell to avoid the danger of reaching a hydrogen explosion concentration range and ensure the safety of a nuclear power plant.

[0002]

2. Description of the Related Art In a boiling water nuclear power plant, the primary coolant of a reactor becomes steam in a reactor, and the generated steam works in a turbine and is condensed in a main condenser. The condensed water is supplied again to the reactor, while the non-condensed gas extracted in the main condenser is guided to a gaseous waste treatment system for treatment. This non-condensable gas is mainly composed of primary coolant in a nuclear reactor, that is, hydrogen and oxygen generated by radiolysis of water.

[0003] The hydrogen / oxygen injection operation in the boiling water nuclear power plant is intended to reduce the oxygen concentration of the reactor water and to suppress the corrosion of structural materials in the reactor. All of the hydrogen injected into the coolant is transferred to the steam side before the reactor and is led to the gaseous waste treatment system as a non-condensable gas through the main condenser. In order to recombine this hydrogen with oxygen, just before the gas waste treatment system recombiner, enough oxygen is injected into the non-condensed gas to recombine the injected hydrogen, and the gas waste treatment system recombiner At the outlet, the oxygen concentration is monitored to confirm the achievement of the recombination.

In the operation of the hydrogen / oxygen injection system of such a conventional boiling water nuclear power plant, the gas concentration at the outlet of the recombiner of the gaseous waste treatment system changes when the pressure in the main condenser changes. Therefore, there is a problem that the oxygen concentration is reduced and the hydrogen concentration is increased in conjunction therewith. This is because when the pressure changes in the main condenser, the transition speed of the non-condensable gas waste treatment system fluctuates transiently, and the ratio of the hydrogen flow rate and oxygen flow rate reaching the recombiner However, even if the hydrogen concentration rises, the state where the explosion level is lower than the lower limit (4%) must be avoided as a nuclear power plant.

[0005] Such a change in the pressure of the main condenser may be caused by a change in the degree of vacuum caused by a change in the temperature of the cooling water (seawater) of the main condenser or a change in the main condenser in addition to the failure or accident of the main condenser. Occurs as a temporary pressure change when performing routine plant operation, such as cleaning the condenser cooling water pipe. At this time, the plant operator changes the operation of the hydrogen / oxygen injection system (increases the oxygen injection flow rate) while paying attention to the change in the oxygen concentration value at the outlet of the gaseous waste treatment system recombiner. The display of the oxygen concentration value has a problem that there is a time delay of several minutes or more in the oxygen concentration change behavior of the actual gas waste treatment system.

In other words, the conventional oxygen concentration measuring device at the outlet of the gaseous waste treatment system recombiner has various problems such as exposure of workers at the time of calibrating the oxygen concentration detector and a device which is not robust in pressure resistance. The pipe is branched from the outlet pipe of the gas waste treatment system recombiner, and the pipe is led to the outside of the gas waste treatment system room surrounded by the shielding wall, and is led to the oxygen concentration measurement device. It takes time to introduce gas from the outlet of the recombiner to this measuring device position, and most of the above-described time delay of several minutes or more is time for introducing gas to this measuring device position.

For this reason, for example, even if the plant operator confirms a decrease in the oxygen concentration and then changes the operation of the hydrogen / oxygen injection system, the oxygen concentration in the gas waste treatment system at the same time is changed. If the decrease event (in some cases, the increase in hydrogen concentration) has progressed considerably before that, or if the oxygen concentration has already returned to a normal value or more and the system flow rate has exceeded the normal value, gas There is a problem that the design flow rate of the waste treatment system is temporarily exceeded.

[0008]

As described above, in the hydrogen / oxygen injection system of the conventional boiling water nuclear power plant, the oxygen concentration measurement at the outlet of the recombiner in the gaseous waste treatment system is performed as follows.
Because it was conducted by an oxygen concentration measurement device installed by guiding the pipe to the outside of the gas waste treatment system room that was branched from the gas waste treatment system recombiner outlet pipe and surrounded by a shielding wall,
There is a problem that it takes time to guide the gas from the gaseous waste treatment system recombiner outlet to this measuring device position, and a time delay of several minutes or more occurs in the oxygen concentration change behavior of the actual gaseous waste treatment system. .

The present invention has been made to solve such a conventional problem, and it is possible that the oxygen at the outlet of the gas waste treatment system recombiner is consumed and the hydrogen concentration starts to increase with a change in the operating conditions of the plant. To detect the change in oxygen concentration at the outlet of the gaseous waste treatment system recombiner, a series of operations such as calculating the oxygen injection flow rate commensurate with the change amount and controlling the flow rate control device and changing the flow rate are performed. An object of the present invention is to provide a hydrogen / oxygen injection system for a boiling water nuclear power plant, which stabilizes the oxygen concentration at the outlet of a gaseous waste treatment system recombiner by performing the operation automatically and continuously.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above objects, the present invention provides: (1) Injecting hydrogen into a primary coolant of a nuclear reactor and adding gas to a non-condensable gas extracted by a main condenser. In a system that performs hydrogen / oxygen injection operation at a boiling water nuclear power plant that injects oxygen to treat excess hydrogen in a gaseous waste treatment system before reaching a waste treatment system recombiner Oxygen concentration measurement device that measures the oxygen concentration in the non-condensed gas after passing through the waste treatment system recombiner with the oxygen concentration detector directly attached to the gas waste treatment system recombiner outlet pipe, and the gas waste treatment system Oxygen injection amount control device that calculates and changes the oxygen injection flow rate to oxygen based on the oxygen concentration value, and hydrogen that controls the oxygen injection flow rate by automatically changing the opening of the control valve according to a signal from the oxygen injection amount control device. Injection flow control valve and A hydrogen / oxygen injection system for a boiling water nuclear power plant. (2) Inject hydrogen into the primary coolant of the reactor, and add excess hydrogen to the non-condensed gas extracted by the main condenser in the gas waste treatment system before reaching the gas waste treatment system recombiner. In a system for performing hydrogen / oxygen injection operation at a boiling water nuclear power plant that injects oxygen for treating wastewater, a flow measurement device that measures the gas flow rate at the outlet pipe of a gaseous waste treatment system recombiner, and a gaseous waste An oxygen injection amount control device that calculates and changes the oxygen injection flow rate to the processing system based on the flow rate value, and automatically controls the oxygen injection flow rate by automatically changing the opening of the control valve according to a signal from the oxygen injection amount control device. A hydrogen / oxygen injection system for a boiling water nuclear power plant, comprising: an oxygen injection flow control valve.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the hydrogen / oxygen injection system of a boiling water nuclear power plant according to the present invention, the ratio of the flow rate of hydrogen and oxygen reaching the gas waste treatment system recombiner is changed by changing the operating conditions of the plant. When a change occurs, the amount of hydrogen injected into the primary coolant of the reactor is maintained by following and changing the oxygen injection flow rate from the change in oxygen concentration and flow rate at the outlet of the gaseous waste treatment system recombiner. In addition, the oxygen concentration at the outlet of the gaseous waste treatment system recombiner can be kept stable.

[0012]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 schematically shows a hydrogen / oxygen injection system of a boiling water nuclear power plant, in which steam generated in a nuclear reactor 1 rotates a turbine 3 via a main steam pipe 2 to complete work. Is condensed by the main condenser 4, is pressurized by the water supply pump 6 through the water supply pipe 5, and is supplied to the reactor 1.

The main condenser 4 is connected to a gas waste treatment system recombiner inlet pipe 7 and guides non-condensed gas to the gas waste treatment system recombiner 8. The gaseous waste treatment system recombiner outlet pipe 9 is used to remove the non-condensed gas that has not been recombined by the gaseous waste treatment system recombiner 8 from a flow meter 10, an oxygen concentration measurement device 12 having an oxygen concentration detector 11, and the like. This leads to an unillustrated gaseous waste treatment system.

A hydrogen supply pipe 13 is connected to the water supply pipe 5,
Hydrogen is injected from the hydrogen supply facility 14 via the hydrogen injection flow control valve 15. Further, an oxygen supply pipe 16 is connected to the gas waste treatment system recombiner inlet pipe 7, and oxygen is injected from an oxygen supply facility 17 through an oxygen injection flow control valve 18.

The hydrogen / oxygen injection amount control device 19 includes the flow meter 1
In response to 0 or a signal from the oxygen concentration measuring device 12, the amount of oxygen for processing excess hydrogen in the gaseous waste treatment system is calculated, and a control signal is supplied to the oxygen injection flow control valve control valve 18. The hydrogen / oxygen injection amount control device 19 receives a signal from the flow meter 10 or the oxygen concentration measurement device 12,
If necessary, the hydrogen injection flow control valve 15 is also automatically changed to control the hydrogen injection flow. During normal operation of the plant, hydrogen and oxygen are supplied from the hydrogen gas supply equipment 14 and the oxygen gas supply equipment 17, and are controlled by a control signal from the hydrogen / oxygen injection quantity control device 19 to control the hydrogen injection flow control valve 15 and the oxygen injection flow rate. The valve 18 controls the injection volume.

This hydrogen is injected into the primary coolant of the reactor, melts, flows into the reactor 1, passes through the main steam pipe 2, passes through the turbine 3, the main condenser 4, and recombines with the gas waste treatment system. To the vessel 8.

Oxygen is supplied to the gaseous waste treatment system recombiner 8.
It is implanted before and contributes to the recombination of the implanted hydrogen.

Here, for example, in the case where hydrogen temporarily stays and releases in the main condenser 4, the recombination amount of hydrogen and oxygen in the gas waste treatment system recombiner 8 is The situation can be known from the change in the oxygen concentration at the outlet of the gas waste treatment system recombiner 8. That is, when the injection volume flow ratio of hydrogen and oxygen is 2: 1, the gas composition at the outlet of the gas waste treatment system recombiner 8 is almost equal to the air flowing into the gas waste treatment system, and theoretically, the oxygen The concentration is about 21%. However, when the amount of oxygen injected into the gaseous waste treatment system is constant and the amount of hydrogen injected into the gaseous waste treatment system decreases, the oxygen concentration increases, and the amount of hydrogen reaches a large amount. Occasionally, the oxygen concentration decreases, and after oxygen depletion, the hydrogen concentration, which was not present before, begins to increase.

The first embodiment of the present invention is a system for immediately changing the oxygen injection flow rate in response to this change in oxygen concentration. The oxygen concentration detector 11 is provided in the gas waste treatment system outlet pipe 9 with the oxygen concentration detector 11. The measuring device 12 is directly attached, the oxygen concentration is detected without delay, and the detected oxygen concentration is input to the hydrogen / oxygen injection amount control device 19.

An example of the calculation and control method of the oxygen concentration input value will be described below.

The oxygen concentration (O ₂ ) at the outlet of the gaseous waste treatment system recombiner is generally expressed by the following equation.

(O ₂ ) = ｛(Air) × 0.21 + (O _2in )
−0.5 × (H _2in )｝ / ｛(Air) + (O _2in ) −0.5
× (H _2in )｝ where (Air) is the inflow air flow rate in the gaseous waste treatment system,
(O _2in ) is the attained flow rate of the injected oxygen (oxygen injection flow rate),
(H _2in ) indicates the reached flow rate of the injected hydrogen, and 0.21 indicates the oxygen abundance ratio in the air.

Here, since (Air) is a parameter with little variation during the rated operation of the plant, it can be considered as a constant. Therefore, under steady operation of hydrogen / oxygen injection, the change of (O ₂ ) is the change of (H _2in ). Is shown. In the hydrogen-oxygen injection rate control unit 19, the value of (O _2), or (O ₂₎
(O) at regular time intervals so that the range of change becomes a constant value.
Calculates the value of _{2i n),} it is possible to send a control signal for changing the opening degree of the oxygen injection flow control valve 18. The operation of repeating this operation stabilizes the oxygen concentration at the outlet of the gaseous waste treatment system recombiner as a result.

As shown in the example of FIG. 2, the oxygen concentration measuring device 12 is provided to prevent the oxygen concentration detector 11 from leaking out of the system when the pressure of the gas waste treatment system piping is increased.
1 is provided, and a pressure gauge 22 and a pressure correction calculator 23 are provided to correct the influence of a change in the oxygen concentration value due to a change in pressure of the gaseous waste treatment system.

In the second embodiment, instead of detecting the oxygen concentration at the outlet of the gaseous waste treatment system recombiner, the flow rate at the outlet of the gaseous waste treatment system recombiner shown in FIG. The fact that the detection value of the total 10 changes is used.

Since the denominator of the above equation corresponds to the gaseous waste treatment system recombiner outlet flow rate (Q), it is expressed by the following equation, so that (Q) is the same as in the first embodiment. change in it is shown that due to a change in (H _{2i n).}

(Q) = (Air) + (O _2in ) −0.5 × (H _2in ) where (Air) is the flow rate of air flowing into the gas waste treatment system,
(O _2in ) is the attained flow rate of the injected oxygen (oxygen injection flow rate),
(H _2in ) indicates the flow rate of the injected hydrogen.

In the hydrogen / oxygen injection amount control device 19,
Control to change the opening of the oxygen injection flow control valve 18 by calculating the value of (O _2in ) at regular time intervals so that the value of (Q) or the range of change of (Q) becomes a certain value. You can send a signal. The operation of repeating this operation stabilizes the oxygen concentration at the outlet of the gaseous waste treatment system recombiner as a result.

[0030]

According to the present invention, when the ratio of the flow rates of hydrogen and oxygen reaching the gas waste treatment system recombiner changes due to a change in the operating conditions of the plant, etc., the gas waste treatment system By changing the oxygen injection flow rate by following the change in the oxygen concentration at the outlet of the coupler, the amount of hydrogen injected into the primary coolant of the reactor is maintained, and the oxygen concentration at the outlet of the gaseous waste treatment system recombiner is stabilized. It is possible to carry out the hydrogen / oxygen injection operation in which the hydrogen and oxygen are maintained.

Further, according to the present invention, when the ratio of the flow rate of hydrogen and oxygen reaching the gas waste treatment system recombiner changes due to a change in the operating conditions of the plant, etc., the gas waste treatment system By changing the flow rate of the oxygen injection from the change in the flow rate at the outlet of the coupler, the amount of hydrogen injected into the primary coolant of the reactor is maintained and the oxygen concentration at the outlet of the gaseous waste treatment system recombiner is kept stable.・ Oxygen injection operation can be performed.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a hydrogen / oxygen injection system according to the present invention.

FIG. 2 is a conceptual diagram of an apparatus for measuring the concentration of acid rope according to claim 2 of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor, 2 ... Main steam pipe, 3 ... Turbine, 4 ... Main condenser, 5 ... Water supply pipe, 6 ... Water supply pump, 7 ... Gas waste treatment system recombiner inlet piping, 8 ... Gas waste Processing recombiner,
9: gas waste treatment system recombiner outlet pipe, 10: flow meter, 11: oxygen concentration detector, 13: hydrogen supply pipe, 12 ...
Oxygen concentration measuring device, 14: hydrogen gas supply equipment, 15: hydrogen injection flow control valve, 16: oxygen supply pipe, 17: oxygen gas supply equipment, 18: oxygen injection flow control valve, 19: hydrogen / oxygen injection amount control device , 21 ... partition wall, 22 ... pressure gauge, 23 ...
Pressure compensation calculator.

Claims (2)

[Claims] 1. Injecting hydrogen into a primary coolant of a nuclear reactor and removing excess gas from a non-condensable gas extracted by a main condenser in a gas waste treatment system before reaching a gas waste treatment system recombiner. In a system for injecting hydrogen and oxygen at a boiling water nuclear power plant that injects oxygen to process hydrogen, the concentration of oxygen in non-condensed gas after passing through a gas waste treatment system An oxygen concentration measurement device that measures with an oxygen concentration detector directly attached to the treatment system recombiner outlet pipe, and an oxygen injection amount control that calculates and outputs the oxygen injection flow rate to the gaseous waste treatment system based on the oxygen concentration value Hydrogen in a boiling water nuclear power plant, comprising: an oxygen injection flow control valve for automatically changing an opening of a control valve by an output signal of the oxygen injection amount control device to control an oxygen injection flow rate. ·oxygen Injection system. 2. Injecting hydrogen into the primary coolant of the nuclear reactor and removing excess condensate from the non-condensed gas extracted by the main condenser in the gas waste treatment system before reaching the gas waste treatment system recombiner. A system for performing hydrogen / oxygen injection operation at a boiling water nuclear power plant that injects oxygen for treating hydrogen, comprising: a flow measuring device that measures a gas flow rate at an outlet pipe of a gas waste treatment system recombiner; and An oxygen injection amount control device that calculates and changes the oxygen injection flow rate to the waste treatment system based on the flow rate value, and automatically changes the opening of the control valve according to a signal from the oxygen injection amount control device to change the oxygen injection flow rate. A hydrogen / oxygen injection system for a boiling water nuclear power plant, comprising: an oxygen injection flow control valve for controlling.