JP2993744B2 - Reactor containment vessel decompression device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates relates to a containment vessel decompressor, in particular, to depressurize the nuclear reactor containment vessel when the pressure of the reactor containment vessel has occurred event such as exceeding the design value The present invention relates to a decompression device for a containment vessel that performs a gas filtration and discharge operation .

[0002]

2. Description of the Related Art A conventional decompression system for a reactor containment vessel has a structure in which a wet type washer and a radioactive substance adsorption filter device are installed in at least one vent line as described in, for example, Japanese Patent Application Laid-Open No. 63-253295. The wet scrubber decontaminates radioactive materials and debris entrained in the gas released from the containment vessel, and the filter unit removes finer particulate radioactive materials that could not be removed by the wet scrubber. Perform decontamination.

[0003]

However, the above-mentioned conventional reactor containment vessel decompression device has the following problems in the wet cleaning device and the filter device, respectively.

[0004]

First, the flow in the pool water is disturbed by the gas decontaminated by the pool water, and the amount of droplet particles scattered on the pool water surface is increased due to the abnormal rise of the pool water level and the disturbance of the pool water surface. As a result, the pool entrainment amount (gas entrainment amount of gas) becomes large, and there is a possibility that water may enter the subsequent filter device. This causes an increase in pressure loss in the filter section and a decrease in filter decontamination efficiency.

[0006] Therefore, in this case, there is a problem that the amount of radioactive substances released to the surrounding environment together with the exhaust gas without being captured by the filter device may be increased.

Next, with respect to the filter device, when the flow rate of the gas discharged from the containment vessel decreases,
Since the cooling effect of the exhaust gas is reduced, the filter may be melted by the heat generated by the radioactive material captured by the filter. As a result, there is a problem that the radioactive substance attached to the filter re-suspends and is released to the surrounding environment together with the exhaust gas.

Accordingly, the present invention is to provide a reactor containment vessel pressure reducing device for reducing the emission of radioactive material into the surrounding environment as a common object, in particular, increase in the pool water level of the wet scrubber and Puruen A first object is to suppress the amount of the tracement, and a second object is to prevent the radioactive substance captured by the filter device from re-floating.

[0009]

[0010]

In order to achieve the first object, the present invention relates to a method of forming a branch pipe, which is connected to a vent line and has gas discharge nozzles formed at equal intervals, at the bottom of a wet type washer. The lower end is separated from the bottom of the wet washer and the upper end is a water circulation path formed by equally disposing cylindrical plates located below the pool surface between the branch pipes. It is provided. In another embodiment of the present invention for achieving the first object, a cylindrical plate having a lower end separated from a bottom surface of the wet cleaning device and an upper end positioned below the pool water surface is concentrically different. A plurality of gas discharge nozzles are installed in the branch pipe communicating with the vent line, and the gas discharge nozzles are arranged radially at every other interval of the cylindrical plate at the lower position of the cylindrical plate, and in the circumferential direction. Is provided with a water circulation path formed so as to be evenly arranged.

Further , in order to achieve the second object, the present invention comprises means for washing the radioactive substance adsorption filter device by passing washing water in a direction opposite to a gas filtering direction after a filtering and discharging operation. It is a thing.

[0012]

[0013]

According to the wet cleaning device of the present invention , by forming a water circulation path for circulating the pool water in the wet cleaning device, the flow in the pool water is stabilized, and the interference between the upward flow and the downward flow is eliminated. . As a result, abnormal rise of the pool water level and disturbance of the pool water level are suppressed, the amount of scattered droplet particles on the pool water level is reduced, and the pool entrainment amount can be reduced. Further, by providing the cooling means in a part of the water circulation path, the circulation of the pool water is performed more efficiently.

As described above, the burden on the filter device installed at the subsequent stage is reduced, and the amount of radioactive substances released to the surrounding environment is significantly reduced. Further, since the decrease in the pool water amount is prevented and the flow in the pool water can be stabilized, the wet cleaning device can be made compact.

Further, according to the filter device of the present invention, by washing the radioactive substance adsorption filter device, it is possible to prevent the radioactive substance captured by the filter from re-floating.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. First, an outline of a reactor containment vessel decompression device according to a first embodiment of the present invention will be described with reference to FIG. In FIG.
Reference numeral 1 denotes a reactor containment vessel, in which a pressure vessel 2 is housed. Further, the containment vessel 1 includes a pressure suppression chamber 3 forming a wet well and a dry well 4.
The pressure suppression chamber 3 is provided with a pressure suppression pool 5, and the dry well 4 and the pressure suppression pool 5 communicate with each other through a plurality of vent pipes 6.

The decompression device of this embodiment has a plurality of vent lines 7 to 10. If an event occurs in which the pressure inside the reactor containment vessel 1 exceeds a design value, the reactor containment vessel 1 may be damaged. In order to prevent this, the gas in the reactor containment vessel 1 is released from one of the vent lines 7 to 10 or a plurality of vent lines, and the reactor containment vessel 1 is depressurized. Vent lines 7 to 10 have isolation valves 11 to 1
Gas is released from the corresponding vent line by opening the isolation valves 11 to 14. In the vent lines 8 and 9 of the vent lines 7 to 10, the wet type washer 15, the filter device 16, the orifice 17 and the valve 18 are installed, and the surrounding environment is considered to be remarkably contaminated by radioactive substances accompanying the released gas. If possible, use vent lines 8 and / or 9 to
The gas inside is discharged from the exhaust tower 19 to the surrounding environment through the wet cleaning device 15 and the filter device 16.

In the depressurizing apparatus for the reactor containment vessel constructed as described above, the wet type washer 15 reduces the pool entrainment amount (gas droplet entrainment amount) of the gas decontaminated by the pool water therein. With water circulation means for the pool. By the combination of the wet cleaning device 15 and the filter device 16 having such a configuration, the amount of radioactive substances released into the surrounding environment is significantly reduced. Hereinafter, a specific configuration of the pool water circulation means will be described.

[0019]

[0020]

[0021]

[0022]

[0023] First, the pool water circulating means of the wet scrubber 15 will be described by way of examples of the wet scrubber 15G by FIG. In FIG. 2 , the pool water is filled at a predetermined water level in a container 15a of the wet cleaning device 15, and a vent pipe 29 connected to the vent lines 8 and 9 shown in FIG. The gas from the reactor containment vessel 1 is discharged from the nozzles 34 provided on the branch pipes extending radially and uniformly in four directions from the lower end of the reactor vessel. In the container 15a, the lower end of the container 15a is provided at four places in the circumferential direction between the branch pipes.
A relatively small cylindrical plate 35 whose upper end is located below the surface of the pool and is spaced apart from the bottom surface of the pool is installed in the container 15a.
5, that is, a pool water circulation path formed by an ascending flow path between the container 15 a and the cylindrical plate 3 and a descending flow path inside the cylindrical plate 35.

The gas discharged from the nozzle 34 the container 15
Fine bubbles or slugs (mass of large gas) are formed in the ascending flow path between the a and the cylindrical plate 35, and push up the surrounding pool water. When this bubble or slug reaches the pool surface, the gas is released to the top. On the other hand, the pushed-up pool water is sent to the lower part of the container 15a through the descending flow path in the cylindrical plate 35 . By forming the pool water circulation channel in this way, interference between the upward flow and the downward flow is eliminated, and abnormal rise of the pool water level and disturbance of the pool water level at the time of gas release are suppressed. As a result, the pool water level is reduced. The amount of scattered droplet particles on the surface is reduced, and the amount of pool entrainment can be reduced. In addition, since the flow in the pool water can be stabilized, the wet type washer 15 can be made compact from this point as well. In addition, such an upflow channel,
The water circulation in the descending flow path is a natural circulation due to a difference in gas-liquid density, and has an advantage that no power is required. This embodiment is
Is distributed after the stakes are distributed evenly around the circumference.
Gas can be supplied to filter device 16 with equal distribution
You.

[0025]

FIG . 3 shows an embodiment of a wet type washer 15H in which a plurality of cylindrical plates 36 are provided concentrically with the container and a water circulation path (downflow path) and a gas discharge path (upflow path) are separated. In this embodiment, since the gas is distributed evenly in the radial direction, the gas can be supplied to the subsequent filter device 16 with a uniform distribution.

Another embodiment of the present invention will be described with reference to FIG . In this embodiment, a means for cleaning the filter of the filter device is provided. In the drawing, members equivalent to those shown in FIG. 1 are denoted by the same reference numerals.

In FIG . 4 , the pressure reducing device of the present embodiment includes a water storage tank 37, a water supply line 38, a return line 39 to the reactor containment vessel 1, a pressure reducing line 40 and various valves 41 to 44 in the equipment shown in FIG. Is added.

The operation method of this embodiment will be described below. For example, now, the reactor vessel 1
When the gas inside is discharged, first, the isolation valve 12 is closed and the isolation valve 11 is opened for switching the vent line. next,
The valve 42 is closed, the water supply line 38 and the return line 39
Are opened. Thereby, the water in the water storage tank 37 is sent to the reactor containment vessel 1 through the water supply line 38 → the filter device 16 → the wet washer 15 → the return line 39. The water sent at this time is
Filter 16a of filter device 16 and wet cleaning device 1
5 has a role of returning the radioactive material captured by the filter 16a and the pool water 15b in the wet cleaning device to the reactor containment vessel 1. Here, the water supply from the water storage tank 37 is of a gravity type or an animal pressure type.

According to the present embodiment, the re-suspension of the radioactive substance captured by the filter can be prevented by washing the filter 16a of the filter device 16 which has absorbed the radioactive substance.

After the cleaning is sufficiently performed by the apparatus of this embodiment, the valves 41 and 43 are closed so that the filter 16a is immersed in water. As a result, it is possible to cool the residual radioactive material that could not be decontaminated by the backwashing means of this embodiment. After the filter 16a is immersed in water, if the pressure in the container of the filter device 16 increases due to the generation of steam due to the heat generated by the remaining radioactive material, the valve container is depressurized by opening the valve 44. can do.

FIG . 5 shows a modification of the embodiment of FIG.
The cleaning means of the present invention is applied to a decontamination device in which a filter device and a wet cleaning device are integrated. That is, the pool water 39a as the wet cleaning device is filled in the wet cleaning device / filter device 39, and the filter 39b is integrally incorporated. Then, a water storage tank 37, a water supply line 38, and a reactor containment vessel 1 similar to the embodiment of FIG.
Return line 39, pressure reduction line 40 and various valves 4
1 to 44 are additionally provided. According to this embodiment, the same effect as that of the embodiment of FIG. 4 can be obtained.

[0033]

Since the present invention is configured as described above, the following effects are obtained.

(1) During operation of the reactor containment pressure reducing device,
It is possible to prevent re-evaporation of the radioactive material captured by the wet cleaning device. Also, since the pool water volume does not decrease, it always exerts a good radioactive substance removal function.

(2) During operation of the reactor containment pressure reducing device,
Since the abnormal rise of the pool water level in the wet cleaning device and the disturbance of the pool water level are suppressed, and the amount of scattered droplet particles on the pool water level is reduced, the pool entrainment amount can be reduced. In addition, it is possible to cool a part of the water circulation path and efficiently circulate the pool water.

(3) According to the above (1) and (2), the burden on the filter device installed at the subsequent stage can be reduced. In addition, the reduction of the pool water amount and the stabilization of the flow of the pool water in the cleaning device container can make the wet cleaning device compact.

(4) Since the radioactive substance attached to the filter can be washed, it is possible to prevent the radioactive substance from re-evaporating from the filter.

(5) By the above (1) to (4), the amount of radioactive substances released to the surrounding environment can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view of a reactor containment vessel decompression device according to an embodiment of the present invention.

FIG. 2 is a view showing an embodiment (circumferential plural cylindrical plate installation system) of the pool water circulation means of the wet cleaning device shown in FIG.

FIG. 3 is a view showing another embodiment of the pool water circulation means of the wet type washer (a concentric plural cylindrical plate installation system).

FIG. 4 is a schematic view of a reactor containment vessel decompression device according to another embodiment of the present invention.

FIG. 5 is a schematic view of a reactor containment vessel decompression device according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor containment vessel 7-10 Vent line 15 (15G, 15H) Wet washing machine 15a Washing machine vessel 16 Filter device 35 Cylindrical plate (pool water circulation means) 36 Cylindrical plate (pool water circulation means) 37 Water storage tank (cleaning means) 38 Water supply line (washing means) 39 Return line (washing means)

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tate, etc. 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Hitachi, Ltd. Inside the Hitachi Plant (72) Inventor Hidetoshi Karasawa 1168 Moriyama-cho, Hitachi-shi, Ibaraki Hitachi, Ltd. Energy Research Laboratories (72) Inventor Kenichi Kawabe 3-1-1 Sachimachi, Hitachi City, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant (56) References JP-A-63-253295 (JP, A) JP-A-2-13897 (JP, A) JP-A-63-124991 (JP, A) JP-A-6-101621 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G21C9 / 00 G21F 9/02 521 G21F 9/02 551 B01D 53/34

Claims (3)

(57) [Claims] 1. A reactor containment pressure reducing device for performing a gas filtration and discharge operation so as to reduce the pressure of a reactor containment vessel when an event occurs in which the pressure in the reactor containment exceeds a design value. A vent line, a wet washer and a radioactive substance adsorption filter device installed in the vent line, and a branch pipe in which gas discharge nozzles are drilled at equal intervals in communication with the vent line. A cylindrical plate having a structure in which the lower end is spaced apart from the bottom of the wet washer and the upper end is located below the surface of the pool at an equal interval is evenly arranged between the branch pipes. A decompression device for a reactor containment vessel, comprising a water circulation path formed by: 2. A reactor containment pressure reducing device for performing a gas filtration and discharge operation to reduce the pressure of the reactor containment when an event occurs in which the pressure in the reactor containment exceeds a design value. A cylindrical plate comprising: a vent line; a wet cleaning device and a radioactive substance adsorption filter device installed in the vent line; a lower end separated from the bottom surface of the wet cleaning device and an upper end positioned below the pool water surface. Are disposed on the concentric axis with different diameters, and a gas discharge nozzle drilled in a branch pipe communicating with the vent line is radially arranged at a position below the cylindrical plate at a position below the cylindrical plate. A reactor containment pressure reducing device, comprising: water circulation paths formed alternately and equally in the circumferential direction. 3. A reactor containment pressure reducing device for performing a gas filtration and discharge operation to reduce the pressure of the reactor containment when an event occurs in which the pressure in the reactor containment exceeds a design value. The vent line, the wet cleaning device and the radioactive substance adsorption filter device installed in the vent line, and the radioactive substance adsorption filter device by passing the cleaning water in the direction opposite to the gas filtration direction after the filtration and discharge operation. A decompression device for a reactor containment vessel, comprising: means for cleaning.