JPS581375B2 - Hydrogen detection device for fast reactor plants - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrogen detection device for a fast reactor plant that can continuously measure the concentration of hydrogen contained in a fluid.

For example, if a small water leak occurs in a steam generator in a metal sodium cooled fast reactor plant, there is a risk that adjacent heat transfer tubes will be damaged and a large-scale leakage accident will occur.

Therefore, it is necessary to quickly detect small water leaks and prevent accidents from occurring.

To detect this water leak, it is required that the sensor has high sensitivity and stability, can be used for a long time, and has a short response delay.

Therefore, various means have been considered for detecting water leakage, and among them, means for detecting hydrogen released into sodium or cover gas during the reaction between sodium and water is suitable.

To detect this hydrogen, a hydrogen detection device consisting of a diffusion membrane, a vacuum gauge, and an exhaust device is used.

An example of the configuration of a prior art device related to this is shown in FIGS. 1 and 2 of the accompanying drawings to clarify the problem.

In FIG. 1 and FIG. 2, elements given the same number are the same elements.

FIG. 1 shows an example of the configuration of a hydrogen detection device using a forced circulation method.

That is, by connecting the inlet pipe 3 of the detection device to the wall surface 1 of the fluid to be measured storage section of the steam generator, the fluid to be measured, for example, a mixed gas of argon and hydrogen containing sodium vapor, is supplied at a constant flow rate through the inlet valve 4. and introduce it into the detection device.

The gas to be measured that has passed through the inlet valve 4 is indirectly heated by the heater 16 via the inlet pipe 5, and is sent into the cylindrical container 6 at a constant temperature.

Here, the hydrogen concentration in the gas to be measured is measured by a hydrogen detection and measurement section 15 that includes a tubular body 12 having a sleeve-shaped diffusion membrane section 11, a sensor 13 consisting of a vacuum gauge or an ion pump, and its controller 14. .

The diffusion membrane portion 11 is made of nickel, palladium, iron, or the like that selectively transmits hydrogen.

After measuring the hydrogen concentration, the paper trap 22 removes sodium vapor from the gas to be measured, which may damage the circulation pump 24.
The residual gas is then removed by a filter 23 and returned to the steam generator by a circulation pump 24 through an outlet valve 8 and an outlet pipe 9.

The flow rate of the gas to be measured is controlled to a constant flow rate using a circulation pump 24 according to instructions from a flow meter 25.

The temperature of the diffusion film section 11 is controlled to a constant temperature by the heat of the gas to be measured heated by the first heater 16.

Further, in order to prevent the diffusion film section 11 from being cooled from the outside via the tubular body 12, the second heater 17 maintains the tubular body 12 at the same temperature as the diffusion film section.

The heaters 16 and 17 are adjusted to predetermined temperatures by temperature control devices 20 and 21 to which electromotive force is supplied from thermocouples 18 and 19, respectively, using output signals thereof.

On the other hand, FIG. 2 shows an example of the configuration of a hydrogen detection device using a natural convection method.

That is, a flange 26 is horizontally attached to the wall surface 1 of the fluid to be measured storage part of the steam generator, and a cylindrical container 6 through which the fluid to be measured, for example, a mixed gas of argon and hydrogen containing sodium vapor flows, is installed in the flange 26. Fixed.

A tubular body 12 made of, for example, stainless steel is suspended in the container 6 through the upper end opening 28 of the container 6 and is attached to a flange 26 .

A sleeve-shaped diffusion membrane portion 11 is connected to this tubular body from the center downward.

As the diffusion membrane portion 11, palladium, iron, nickel, or the like, which selectively transmits hydrogen, is used.

The upper and lower portions of the diffusion film portion 11, that is, the tubular body near the upper end opening 28 of the cylindrical container 6 and the lower end opening 27 of the cylindrical container 6.
A second heater 17 and a first heater 16 are respectively disposed inside.

The heaters 16 and 17 are adjusted to predetermined temperatures by temperature control devices 20 and 21 to which electromotive force is supplied from thermocouples 18 and 19, respectively, by means of their output signals.

A sensor 13 is connected above the flange 26 via the tubular body 12.

The sensor 13 is controlled by a hydrogen detector controller 14.

In this device, when the gas to be measured flows in from the lower end opening 27 of the cylindrical container 6, hydrogen is absorbed into the diffusion membrane section 11.
The hydrogen is detected by the sensor 13, that is, by the hydrogen detection section 15.

This hydrogen detection section 15 is carried out by, for example, measuring the ion current or the degree of vacuum, and the controller 14 includes:
For example, an ion pump controller and a vacuum gauge controller are incorporated.

In this conventional hydrogen detection device, the gas to be measured is
The gas is heated to a predetermined temperature by the heater 16, rises inside the cylindrical container 6 due to the buoyancy of the heated and expanded gas, and is discharged from the upper end opening 28 to the outside of the apparatus.

The diffusion film portion 11 is heated by the heated gas rising.

On the other hand, the tubular body 12 is cooled from the outside via the flange 26, and a second heater 17 is provided near the upper end opening 28 of the cylindrical container 6 to prevent heat from escaping from the diffusion membrane portion 11.
The tubular body 12 is heated and maintained at the same temperature as the control temperature of the diffusion membrane section 11.

As already mentioned, the hydrogen detection device is a very important piece of equipment from the standpoint of safe operation of the fast reactor steam generator.

Therefore, it is a matter of course that this detection device has sufficient detection performance, but it is also essential that it always operate normally throughout the life of the nuclear reactor.

In order to satisfy this condition, it is necessary to develop detectors with excellent durability and few failures, as well as the lifespan of the reactor (approximately 30
As long as it is impossible to manufacture equipment that will never break down over a long period of time (years), it is important that in the event of a breakdown, it can be quickly repaired or replaced with a new one.

However, research and development have so far been focused on the performance aspects of detectors, and at present little consideration has been given to durability, maintainability, reliability, etc.

Therefore, the problems with the conventional technology will be described below.

That is, in the hydrogen detection device using the forced circulation method shown in FIG. 1, by closing the inlet and outlet valves 4 and 8, the diffusion membrane section 11
Although it has the advantage that maintenance such as replacement can be performed, it has the disadvantage that it is extremely complicated and large.

Furthermore, since the device has a large number of components, the device as a whole lacks reliability.

In addition, the hydrogen detection device using the natural convection method shown in FIG. 2 does not require the circulation pump 24, paper trap 22, filter 23, etc. in the forced circulation method shown in FIG. 1, so it is smaller. However, there are problems as described below.

That is, the heaters 16, 17 and the electrical wiring attached thereto are directly exposed to high temperature gas containing corrosive sodium vapor, resulting in poor durability.

Furthermore, due to the structure in which the hydrogen detection device is directly inserted into the steam generator through the flange 26, the diffusion membrane section 11, heaters 16, 17, thermocouple 18, etc.
, 19 cannot be maintained, and in the case of replacement, it is necessary to stop the operation of the steam generator.

However, in a large-scale facility such as an actual nuclear reactor, stopping the steam generator is a difficult task, and if it is to be stopped, the operation of the reactor must be stopped for quite a long time.

This reduces the operating rate of the reactor, resulting in a very large loss.

For this reason, there is a need for a small and highly reliable hydrogen detection device that allows easy maintenance such as replacement of the diffusion membrane even while the steam generator is in operation.

In other words, the forced circulation system shown in Figure 1 and the second
What is needed is a hydrogen detection device that combines the advantages of the natural convection method shown in the figure.

The present invention has been made in response to such requirements, and allows for easy maintenance such as replacing the diffusion membrane part even during operation of the reactor in a fast reactor, and also enables a small and highly reliable fast reactor. The present invention provides a hydrogen detection device for flint.

Hereinafter, the present invention will be explained in detail with reference to an embodiment shown in FIG.

In FIG. 3, the same parts as in FIGS. 1 and 2 are indicated by the same reference numerals, and the explanation of the overlapping parts is omitted.

That is, the present invention includes an inflow pipe 5 connected to the wall surface 1 of the fluid storage part to be measured via the inlet valve 4, a cylindrical container 6 connected to the inflow pipe 5, and a cylindrical container 6 housed within the cylindrical container 6. an outflow pipe 7 connected from the upper part of the cylindrical container 6 to the storage wall 1 at a different position from the inflow pipe 5 through an outlet valve 8; This is a hydrogen detection device for a fast reactor plant, characterized in that it is equipped with heaters 16 and 17 provided in the first section, and allows the fluid to be measured to flow through natural convection due to a temperature difference.

Here, in this invention, the fluid to be measured passes through the inlet pipe 3 and the artificial valve 4, and is indirectly heated from the outside via the inflow pipe 5 by the first heater 16 provided in the middle of the inflow pipe 5 to a predetermined temperature. maintained at temperature.

The heated and expanded fluid to be measured reaches the diffusion membrane 11 inside the cylindrical container 6 due to the buoyancy due to the temperature difference, hydrogen is detected, and the fluid to be measured passes through the outflow pipe 7, the outlet valve 8, and the outlet pipe 9. It is returned to the storage section.

The temperature of the diffusion film section 11 is maintained at a constant temperature by the heat of the fluid to be measured, which is heated by the first heater 16 and rises.

On the other hand, in order to prevent the diffusion film section 11 from being cooled from the outside via the tubular body 12, a second
The tubular body 12 is heated by the heater 17 and maintained at the same temperature as the control temperature of the diffusion membrane section 11 .

Here, since the first heater 16 and the second heater 17 are installed outside the inflow pipe 5 and the cylindrical container 6, respectively, corrosion due to, for example, sodium or sodium vapor does not occur.

Further, by performing maintenance such as replacing the diffusion membrane portion 11 after closing the inlet valve 4 and the outlet valve 8, it is possible to easily perform maintenance even during operation of the nuclear reactor.

Furthermore, since it uses a natural convection method, there is no need for circulation pumps, flow meters, paper traps, etc., resulting in a smaller size and improved reliability.

FIG. 4 shows a hydrogen detection device in which a third heater 29 is provided on the outer wall of the outflow pipe 7. After hydrogen is detected, the fluid to be measured is further heated by the third heater 29 to increase the temperature difference and increase the flow rate. This is an example of a hydrogen detection device used to increase hydrogen.

For example, if the temperature of the fluid storage part to be measured is high, the first heater 1
This is used in cases where heating by No. 6 does not provide a sufficient temperature difference and the flow rate of the fluid to be measured decreases.

Further, in this example, the flow rate can be controlled by controlling the temperature of the fluid to be measured using the third heater 29.

FIG. 5 shows an example in which the hydrogen detection device is attached to the upper part of the fluid storage section to be measured.

Since the height of the inlet 2 and outlet 10 of the fluid to be measured is the same,
A cooler 32 is provided on the outer wall of the outflow pipe 7, and the temperature difference between the gas to be measured inside the inflow pipe 5 and the inside of the outflow pipe 7 causes convection.

As the cooler 32, for example, a combination of fins made of metal with high thermal conductivity and an air blower is used.

In this example as well, as in the example shown in FIG. 4, by controlling the temperature of the cooler 32, it is possible to control the flow rate of the fluid to be measured.

In this manner, according to the present invention, maintenance such as replacement of the diffusion membrane portion can be easily performed even during operation of a fast reactor, and a small and highly reliable hydrogen detection device can be provided.

Further, in the apparatus shown in FIGS. 3 to 5, if an argon gas system and a vacuum system, which are used only during maintenance such as replacing the diffusion membrane section, are provided via valves, maintenance etc. will be further facilitated.

[Brief explanation of drawings]

1 and 2 are partial vertical sectional views showing an example of the configuration of a conventional hydrogen detection device, and FIGS. 3 to 5 show respective embodiments of the hydrogen detection device for a fast reactor plant according to the present invention. FIG. 2 is a configuration diagram partially shown in longitudinal section. 1... Wall surface of the fluid storage section to be measured, 2...
Inflow port, 3... Inlet piping, 4... Inlet valve, 5... Inflow pipe, 6... Cylindrical container, 7...・Outflow pipe, 8...outlet valve, 9...outlet piping, 10...outlet,
11... Diffusion membrane part, 12... Tubular body,
13...Sensor, 14...Hydrogen detector control, 15...Hydrogen detection measurement section, 1
6...First heater, 17...Second heater, 18, 19...Thermocouple, 20,21...
... Temperature control device, 22 ... Paper trap, 23 ... Filter, 24 ... Circulating pump, 25 ... Flow meter, 26 ...・・・・・・
Flange, 27...Lower end opening, 28...
...Top opening, 29...Third heater, 30.
...Thermocouple, 31 ...Temperature control device, 3
2...Cooler.

Claims (1)

[Claims] 1. An inflow pipe connected to the wall surface of the fluid storage part to be measured via an inlet valve, a cylindrical container connected to this inflow pipe, a diffusion membrane section housed in this cylindrical container, and the cylindrical container. an outflow pipe connected to a wall surface of the storage section at a position different from the inflow pipe from the upper part of the cylindrical container via an outlet valve; and a heater provided at the upper and lower parts of the cylindrical container. A hydrogen detection device for fast reactor plants that is characterized by circulating the measured fluid through natural convection due to temperature differences.