RU2059303C1 - Float valve of immersing type - Google Patents

Abstract

FIELD: nuclear power engineering. SUBSTANCE: invention is meant for provision of safety during operation of nuclear reactors. Float valve of immersing type has rigidly ribs inside and is fitted with end cap to pump in counterpressure. Lower part of it has ring tongue for metal bolt. EFFECT: improved operational reliability. 4 dwg

Description

 The invention relates to ensuring safety in the operation of nuclear reactors and can be used in an emergency reactor cooling system in the event of a rupture of a regular circulation loop pipeline.

There are various float valves and devices used in hydraulic systems and plumbing [1]
However, these devices cannot be used in the emergency reactor cooling system due to the fact that these structures are inoperative under conditions of high pressures (100-200 atm) and high flow rates of the bypassed liquid (hundreds of kg / s).

 Known ball float valve of submersible type used in high pressure balloons of the emergency cooling system of the VVER-440 reactor [2] The ball valve consists of a housing, a limiting buffer, a seat, a float and a housing. The float is made in the form of a metal ball, into which a breathing tube is welded, connecting the cavity of the ball with the gas cavity of the hydroballon. This allows you to unload the ball from the pressure of the medium and obtain the necessary buoyancy of the valve.

 However, this thin-walled ball valve has low sealing qualities of a ball-cone pair, since the ball consists of two stamped hemispheres, and the throat cone lined with stainless steel sheet serves as a seat without subsequent mechanical processing. This valve flaw determines a significant residual water level. In addition, a ball with a diameter of 435 mm and a wall thickness of 2 mm does not have sufficient rigidity and strength during impact landing in the saddle in an emergency. With increasing wall thickness, the buoyancy of the ball is lost. A 5 m long breathing pipe does not have a reliable buffer in case of a sharp ascent when filling the hydro-balloon with water from the neck side, therefore it is subject to deformation and failure.

 Thus, the ball valve is practically a one-time valve and its use in high pressure reactors (such as RBM-K) is extremely difficult and inefficient.

 The aim of the invention is to increase the service life of the valve in a wide range of pressures.

 For this, the float is made in the form of a cylinder with stiffening ribs inside and is equipped in the upper part with a sealed plug for backpressure injection, and in the lower part with an annular whisker for a movably fixed plate self-installing metal shutter.

 In FIG. 1 shows a cross-sectional view of a float valve in an open position; in FIG. 2 the same, in a closed position in a section; in FIG. 3 node I in FIG. 2; in FIG. 4, the proposed scheme with shut-off float valves (left side) and the existing scheme (for the RBM-K reactor) with fast-acting shut-off valves (circled by a dashed line).

 The float valve (Fig. 1) contains a hollow sealed float 1 in the form of a cylinder, hardened by internal stiffening ribs 2. Outside, the float is equipped with cuffs 3, spring rings 4 fixed to its body.

 On the lower end part by means of an annular whisker 5 on a float 1 a disk-shaped self-locking shutter 6 is fixed. This connection allows the liquid to freely enter the cavity 7 through the annular gap 8.

 The float 1 is placed in the housing 9, consisting of a buffer 10, a guide pipe 11 and a saddle 12, which is welded to the bottom of the pressure gauge 13 at the outlet pipe 14.

 The guide tube has windows 15 for the passage of water into the drain neck and slots 16 for removing water from the housing 9.

 In the upper part of the float 1 has a plug 17 for injecting gas under pressure into the inner cavity 18 of the float, if necessary, create backpressure to the environment in order to reduce the weight of the float.

 The float valve operates as follows.

 In the initial state (Fig. 1), the float 1 is in a floated state and abuts against the buffer 10. The poppet 6 is held by an annular mustache 5.

 The pressure in the reservoir 13 is supported by the supply of gas to the cavity of the container above the water level (pressure is supplied from the receiver).

 In the case of a high pressure of the liquid in the hydrogallon 13 into the internal cavity 18 of the float 1 through the hole of the plug 17 ends the necessary backpressure.

 When the emergency cooling system of the reactor is triggered, water from the hydroballon 13 under the influence of gas pressure rushes through the windows 15 into the drain pipe and then through pipelines to the reactor core.

 As a result of the emptying of the pressure gauge to the desired residual level, the float 1 sits with a poppet 6 in the seat 12.

 The residual water level serves as a hydraulic shutter and prevents gas from entering the reactor.

 The small service life of ball float valves makes it difficult to use them in emergency cooling systems of multiple reactors. Therefore, in emergency cooling systems of domestic reactors (such as RBM-K), these valves are not used.

Existing emergency reactor cooling systems are configured as shown in FIG. 4 (circled by dashed lines), which includes a large number of hydroballoons (with a capacity of 25 m ³ each), high-speed shut-off valves, level sensors with automatic exposure to the high-speed shut-off valve and throttle profiling washers.

 Such a complex hydraulic system, saturated with unique high-speed fittings and automation, does not allow the maximum use of the water supply in the hydraulic tanks.

 The proposed valve makes it possible to simplify the emergency cooling circuit of the reactor by eliminating shut-off mechanical quick-acting valves, level control sensors with appropriate automation, profiling washers, and reducing the number of hydraulic balloons by approximately 20% due to more complete use of the emergency water supply in them.

 In addition, the proposed float valve in comparison with the known float type valve allows the possibility of its multiple actuation in conditions of high pressures and fluid flow.

Claims (1)

 SUBMERSIBLE VALVE VALVE for emergency cooling system of a high pressure reactor, comprising a housing defining a buffer, a seat and a float, characterized in that, in order to increase the valve's operating life in a wide pressure range, the float is made with stiffeners inside and equipped with a plug in the upper part for injection of back pressure, and in the lower part with an annular mustache for a movably fixed disk-shaped self-installing metal shutter.

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