JPH03200097A - Control system for concentration of combustible gas in atomic power plant - Google Patents

Abstract

PURPOSE:To absorb the hydrogen generated in the event of a loss of coolant accident by a hydrogen absorbing device without delay by providing the hydrogen absorbing device which absorbs the hydrogen in a combustible gas sent into the device by a blower by a hydrogen absorbing alloy. CONSTITUTION:A hydrogen absorbing line 11 is so mounted as to bypass a stop valve 10 provided between the blower 2 and a heater 3. The hydrogen absorbing device 12 for ordinary use and the hydrogen absorbing device 13 for spare are provided in parallel at the intermediate point of the hydrogen absorbing line 11. The hydrogen absorbing devices 12, 13 are constituted by housing the hydrogen absorbing alloys into hydrogen absorbing containers. The combustible gas generated in a reactor container 1 is sucked by the blower 2 when a sepn. valve 8 is opened and the stop valve 10 is closed and the blower 2 starts operating in the event of the generation of the loss of coolant accident in the atomic power plant. The gas is introduced through a stop valve 14 installed in the hydrogen absorbing line 11 into the hydrogen absorbing device 12. The combustible gas introduced into the hydrogen absorbing device 12 is subjected to the absorption of the hydrogen contained therein by the hydrogen absorbing alloy.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to an improvement of a combustible gas concentration control device in a nuclear power plant, and in particular, to an improvement of a combustible gas concentration control device equipped with a hydrogen absorption device. Regarding control systems.

(Prior Art) When a loss of coolant accident occurs in a nuclear power plant, hydrogen and oxygen are generated due to a water-metal reaction or radiolysis of water. Generally, a combustible gas containing hydrogen and oxygen has a risk of spontaneous combustion if the hydrogen and oxygen are above the flammability limit (oxygen concentration is 5% or more and hydrogen concentration is 4% or more).

Therefore, in order to prevent the concentration from reaching this range and maintain the integrity of the reactor containment vessel, nuclear power plants
A flammable gas concentration control system has been installed to recombine the flammable gases (hydrogen, oxygen) generated within the containment vessel.

In this case, in order to maintain safety in the event of an accident, the combustible gas concentration control system is divided into two completely independent systems with 100% capacity.
They are installed and used in parallel.

Figure 3 shows an example of a nuclear power plant equipped with a conventional combustible gas concentration control system. ,
In both cases, combustible gas (hydrogen, oxygen) generated in the reactor containment vessel 1 is sucked in by a blower 2, guided to a recombination device 4 via a heater 3, and water vapor generated by the recombination reaction is transferred to a cooling device 5. After cooling and condensing the gas, a steam separator 6 removes moisture, and the remaining gas is returned to the reactor containment vessel 1 through a suppression chamber 7. 8.9
indicates an isolation valve (normally open).

If a loss of coolant accident occurs in a nuclear power plant equipped with a flammable gas concentration control system configured as described above, the flammable gas concentration control system (system A, system B) will be operated from the central control room (not shown). According to the instruction, heating of the recombination device 4 was started by manual operation approximately 30 minutes after the loss of coolant accident occurred, and the warm-up operation was completed within approximately 3 hours and the system was in a state where it could perform the gas concentration control function. Become.

Therefore, the isolation valve 8.9 is opened, and the flammable gas in the reactor containment vessel 1 is sucked in by the blower 2, heated by the heater 3, and guided to the recombination device 4, where the hydrogen and oxygen in the gas are recombined. I will let you do it.

(Problem to be Solved by the Invention) However, in conventional nuclear power plants configured as described above, after a loss of coolant accident occurs, it is difficult for the flammable gas concentration control system to reach a state where it can perform its functions. has the disadvantage that it takes a considerable amount of time and is troublesome to start up.

The present invention eliminates the above-mentioned drawbacks in the prior art,
The object of the present invention is to provide a combustible gas concentration control system that can function quickly.

[Structure of the Invention] (Means for Solving the Problems) A flammable gas concentration control system in a nuclear power plant according to the present invention includes a blower that sucks combustible gas in a reactor containment vessel;
A combustible gas concentration control system comprising a recombination device for recombining hydrogen and oxygen in the combustible gas, a hydrogen absorption system in which hydrogen in the combustible gas sent by the blower is absorbed by a hydrogen absorption alloy. It is characterized by the addition of a device.

(Function) In the flammable gas concentration control system of the present invention configured as described above, when a loss of coolant accident occurs in a nuclear power plant, combustible gas containing hydrogen and oxygen generated in the reactor containment vessel is The gas is sucked by a blower and introduced into the hydrogen absorption device, and the hydrogen in the combustible gas is absorbed and removed by the hydrogen absorption alloy.

(Example) The present invention will be described in detail below with reference to FIGS. 1 and 2. In these figures, the same parts as in FIG. 3 are denoted by the same reference numerals, and their explanation will be omitted.

In Fig. 1, the combustible gas concentration control system (only the A system is shown in detail, but the B system has the same configuration) includes:
An on-off valve 10 is interposed between the blower 2 and the heater 3, and a hydrogen absorption line 11 is installed so as to bypass this on-off valve 10.

In the middle of this hydrogen absorption line 11, a regular hydrogen absorption device 12 and a standby hydrogen absorption device 13 are inserted in parallel. A stop valve 14.15 is inserted before and after each hydrogen absorption device 12.13, respectively.

As shown in FIG. 2, the hydrogen absorption device 12.13 is a hydrogen absorption container 20 containing a hydrogen absorption alloy 21, and the upper and lower openings of the container 20 are connected to the on-off valve 10 via the hydrogen absorption line 11. are connected before and after.

In the flammable gas concentration control system of the present invention having the above configuration, when a loss of coolant accident occurs in a nuclear power plant, the isolation valve 8 opens and the on-off valve 10 opens the flammable gas generated in the reactor containment vessel 1. When the blower 2 is closed and starts operating, hydrogen is sucked in and guided to the hydrogen absorption device 12 through the stop valve 14 installed in the hydrogen absorption line 11. The hydrogen contained in the combustible gas introduced into the hydrogen absorption device 12 is absorbed by the hydrogen absorption alloy 21 .

Hydrogen that cannot be completely absorbed by the hydrogen absorption device 12 is introduced into the recombination device 4 through the heater 3 of the combustible gas concentration control system, and is recombined with oxygen, as in the conventional case. After the water vapor generated by the recombination reaction is cooled and condensed in a cooler 5 and moisture is removed in a steam separator 6, the remaining gas is returned to the reactor containment vessel 1 through a suppression chamber 7.

In the above, two combustible gas concentration control systems (A system,
System B) is configured as a control system with 100% processing capacity in one system. In addition, the hydrogen absorption device 12 is also
3 is installed, and two are installed in parallel so that one of them can be used at all times.

Regarding hydrogen-absorbing alloys, in recent years, extensive research has been conducted on hydrogen transport technology using metal hydrides, and in particular, Mg-based alloys have been developed as high bulk density alloy hydrogen-absorbing materials. These research results can be used.

Note that the hydrogen absorption capacity of the hydrogen absorption device 12.13 is set according to the output scale of the nuclear power plant,
When this set capacity reaches its limit, the hydrogen absorbing alloy 21
Since the hydrogen absorption capacity expands approximately three times as much as when the hydrogen absorption degree is 0, the hydrogen absorption container 20 also needs to be sized to take this expansion into account.

In addition, in FIG. 2, the chain line 22 indicates the assumed fat expansion line of the hydrogen absorbing alloy 21 after absorbing hydrogen.

Further, when the hydrogen absorbing alloy 21 reaches its absorption capacity and becomes unable to absorb hydrogen, it becomes sand-like.

In this case, the hydrogen-absorbing alloy 21, which has become sand-like after completing its absorption action, can be reused by being reprocessed after being taken out from the container 20 and regenerated into its original shape.

The control system of the present invention is activated by a command from the central control room, but the actual operation is performed by the valve 14 installed in the absorption line 11.
There is no need for multiple operations like in conventional combustible gas concentration control systems.

In addition, since it is activated immediately after a loss of coolant accident, the amount of hydrogen gas generated within the reactor containment vessel 1 can be reduced, and safety within the reactor containment vessel 1 can be maintained at a higher level.

Conventional combustible gas concentration control systems are manually activated approximately 30 minutes after the occurrence of a coolant loss accident and function after warm-up approximately 3 hours, but according to the control system of the present invention, warm-up Hydrogen can be absorbed during operation.

In addition, since the absorption action by the hydrogen absorption alloy 21 in the control system of the present invention is only the operation of the valve 14 installed in the absorption line 11, high reliability can be obtained with respect to its operation. It also becomes possible to rationalize the concentration control system.

[Effects of the Invention] As described above, according to the present invention, hydrogen generated during a loss of coolant accident can be absorbed by the hydrogen absorption device without delay, so the safety inside the reactor containment vessel is increased. It is maintained.

In addition, even if the hydrogen absorption alloy becomes incapacitated, the gas can be processed by the recombination device as in the past, and the reactor containment vessel can be reused in the event of a loss of coolant accident. Safety can be maintained.

[Brief explanation of drawings]

Fig. 1 is a schematic system diagram showing an embodiment of the present invention, Fig. 2 is a partially longitudinal explanatory diagram illustrating a hydrogen absorption device used in the present invention, and Fig. 3 is a conventional nuclear power plant in which combustible gas FIG. 2 is a schematic system diagram showing a concentration control system. 1... Reactor containment vessel 2... Blower 3... Heater 4... Recombination device 5...... Cooling device 6... Steam water separator 7... Suppression chamber 8.9.
...Isolation valve 10...Opening/closing valve 11...Hydrogen absorption line 12.13...
・Hydrogen absorption device 14.15...Stop valve 20...Hydrogen absorption container 21......Hydrogen absorption alloy gauze 2 diagram

Claims (1)

[Claims] In a combustible gas concentration control system that includes a blower that sucks combustible gas in a reactor containment vessel and a recombination device that recombines hydrogen and oxygen in the combustible gas, the A combustible gas concentration control system in a nuclear power plant, characterized by adding a hydrogen absorption device that absorbs hydrogen in combustible gas using a hydrogen absorption alloy.