A method for improving explosion safety of nuclear power plants

Abstract

The invention relates to a method for reducing the impact of explosive loads on industrial sites. The technical effect of the invention is to reduce the impact of the explosion wave formed during an emergency explosion of a fuel and air mixture on the walls and ceilings of the protected site. This effect is achieved by placing obstacles in the form of elastic shells filled with non-combustible substances in front of the protected surface and collapsing at the moment they come into contact with the front of the explosion wave, and after the detection of dangerous concentrations of combustible gases in the space in front of the protected object, these shells are filled with substances that do not support combustion.

Description

Technical Field

[0001] The present invention relates to methods of reducing the effects of blast loads on industrial sites, including those associated with nuclear power plants and large chemical industries. Background of the Invention

[0003] Methods and devices are known for attenuating shock waves using foam or porous materials, but without using any additional fire extinguishing mechanisms (Kudinov VM, Palamarchuk BI, Gelfand BE, Gubin SA Shock wave parameters during explosion of explosive charge in foam / / "Reports of the USSR Academy of Sciences". Vol. 228. 1974.4. pp. 555-558. 2. Gelfand BE, Gubanov AV, Timofeev EI Interaction of shock waves with porous screens / / "Izvestia of the USSR Academy of Sciences". 1983.4. pp. 79-84).

[0004] However, such devices are characterized by low efficiency and high consumption of consumables, which significantly limits the possibilities of their practical application.

[0005] In order to reduce the intensity of the shock wave, screens made of porous material with an open honeycomb structure (eg foam rubber) filled with a non-flammable liquid are also used [RU 2150669, F 42B 33 / 00, F 42 D 5 / 04, 15.03.1999].

[0006] However, the use of this method in industrial locations is ineffective, since the presence of liquid in the porous screen leads to the formation of increased humidity and therefore corrosion, as well as increased weight loads on the walls and ceilings of the protected room.

[0007] The closest to the claimed invention for its intended purpose and a set of essential features is a method for increasing explosion safety. An obstacle is placed in front of the protected surface in the form of an elastic shell. The elastic shell filled with a non-flammable liquid is intended to attenuate the blast wave and was presented as a prototype [RU2125232, F42B39 / 00, F42B33 / 00, 23.09.1997].

[0008] A disadvantage of the prototype and its analogues is the constant static load on the walls and ceiling of the protected room. Summary of the invention

[0009] The object of the claimed invention is to increase explosion safety.

[0010] The technical effect of the present invention is to reduce the impact of the blast wave formed during an emergency explosion of a fuel and air mixture on the walls and ceilings of the protected location.

[0011] In order to achieve this technical effect, in the known method of increasing explosion safety by reducing the impact of the combustion wave or shock wave on the protected surface, it is proposed to use a non-combustible gas as a substance for filling the shell, the shell itself being made of a material that collapses during the movement of the shell surface along the front Gorenger wave or shock wave and under the action of the movement. Moreover, after a dangerous concentration of combustible gas is detected in the space in front of the protected object, the shell is immediately filled with non-combustible gas. Helium is used to fill the elastic shell as a substance that does not support combustion. The elastic shell is placed in front of the protected surface in at least two layers. Each subsequent layer of the elastic shell is located in the depression of the previous layer. In order to fill the elastic shell as a substance that does not support combustion, a mixture of air and helium with a helium content of at least 50% by volume is used. In front of the shell filled with helium, there is a shell filled with air. The total thickness of the elastic shell filled with non-combustible substance along the normal to the protected surface exceeds two critical detonation diameters of the stoichiometric composition of the mixture in free space.

[0012] The set of characteristics claimed enables a highly efficient method for reducing the high blast and thermal effects of the blast wave on spatially extended flat and curved surfaces which bound the protected room.

[0013] In the known methods for reducing the effects of blasts on protected surfaces, no combination of essential features corresponding to the features claimed has been found. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] exist Figure 1 and Figure 2 The proposed method of attenuating the impact of blast waves on the protected surface is explained in.

[0015] Figure 1 One of the possible options for implementing the claimed method is shown;

[0016] Figure 2 Shown is a schematic diagram of a blast chamber in which the effectiveness of shock wave attenuation was experimentally tested. DETAILED DESCRIPTION

[0017] according to Figure 1 , in the protected room (1) there are: sensors (2) for determining the concentration of explosive gases, a controller (3) which activates the gas supply mechanism (4) when necessary, cylinders for storing compressed gas (5), a gas distribution system (6), an elastic housing (7) and a compressor (8).

[0018] Protection of surfaces of nuclear power plant premises from the effects of explosive loads is as follows. From sensors (2), a controller (3) continuously receives signals about the concentration of combustible gas, for example, hydrogen, in a protected room of a nuclear power plant. When the controller (3) registers an unacceptable concentration of combustible gas (in an emergency), the controller (3) issues a command to the gas supply mechanism (4) and fills the elastic shell (7) with non-combustible gas from the tank (5) through the distribution system (6), for example if the concentration of combustible gas in the room (1) can be reduced to a safe level (for example, as a result of the operation of the ventilation system and the system of chemical oxidation of the combustible gas, not shown in the above picture), then from the shell (7) when explosive combustion occurs in the room (1), the combustion wave (or shock wave), approaches the elastic shell (7), destroys them, and continues its movement in the non-combustible (inert) gas environment, which leads to a reduction of its force effect on the walls and, in particular, on the dome of the room (1).

[0019] The effectiveness of shock wave attenuation was tested in a large-scale experiment of a partial volume explosion of a hydrogen-air mixture in a spherical explosion chamber (9) with a diameter of 12 meters, the scheme of which is as follows Figure 2 As shown. A premixed combustible mixture is injected into a latex shell (10) (balloon probe) with a volume of up to 40 cubic meters. With the help of a charge of agglomerated explosive (11), combustion or detonation takes place in the center. Pressure sensors (12D1-4) and ionization sensors (12I1-4) are located inside and partially outside the shell, respectively.

[0020] With respect to the external object, which in the simplest case is represented by a limiting surface, a spherical volume (10) located in the wall area simulates the accumulation of a flammable hydrogen-air mixture in the inner space of a nuclear power plant. Four pressure sensors (13) for registering the explosion load are placed on the surface of the blast chamber, as Figure 2 As shown in the right part of the diagram. As pressure sensor (13), a sensor of the RSV113 model was used, which was openly installed in a 6 mm thick steel plate with dimensions of 0.52 x 0.65 m2 (not shown in the figure). On part of the sensor (13), an elastic shell (7) filled with helium or air with a gas layer thickness of 0.6 m, or filled with a two-layer air-helium system with the same total gas layer thickness and a one-to-one ratio of layer thickness was installed. In the experiment, the pressure recorded by the sensor (13) was compared in two variants, with partial protective shells (7) and without them' as Figure 2 shown.

[0021] Pressure drop comparison table

[0022]

[0023] These studies showed that the most effective pressure reduction is provided by an elastic shell filled with helium. The specified thickness of the gas layer in the elastic shell in the path of the blast wave propagation is 0.6 m, with at least two critical detonation diameters in free space for a mixture of the chemical composition of hydrogen and air.

Claims

1. A method for increasing the safety of an enclosed space from explosions by reducing the impact of a combustion wave or a shock wave on a protected surface, comprising placing an obstacle in front of the protected surface in the form of an elastic shell filled with a substance that does not support combustion, characterized in that Non-combustible gas is used as a substance for filling an elastic shell, the elastic shell itself being made of a material that collapses during and under the action of the movement of a combustion wave or a shock wave along the surface of the elastic shell, and the elastic shell is filled with non-combustible gas immediately after a dangerous concentration of combustible gas is detected in the space in front of the protected object, wherein the elastic shell is located in front of the protected surface in at least two layers and each subsequent layer of the elastic shell is located in a recess of the previous layer.

2. The method according to claim 1, characterized in that Helium is used to fill an elastic shell which is a substance that does not support combustion.

3. The method according to claim 1, characterized in that To fill the elastic shell as a non-combustion-supporting substance, a mixture of air and helium is used, the helium content of which is at least 50% by volume.

4. The method according to claim 2, characterized in that: The elastic shell filled with air is located in front of the elastic shell filled with helium.

5. The method according to claim 1, characterized in that The total thickness of the elastic shell filled with the incombustible substance along the normal to the protected surface exceeds two critical detonation diameters in free space of the stoichiometric mixture.

Images