CN101266843B - Siphon breaker - Google Patents

Abstract

The invention provides a siphon destruction device that is simple in structure, safe and reliable, and can reduce the amount of sodium leakage and delay the development of the accident so that operators have enough time to deal with it when an accident occurs due to pipe rupture outside the reactor. The device includes a sodium intake pipe connected to a circulation pump through a pipe outside the reactor. The other end of the circulation pump is connected to a sodium return pipe through a pipe outside the reactor. The sodium intake pipe and sodium return pipe are fixed on the isolation plate and extend into two sides of the reactor respectively. In a protective sleeve, the inlet orifice plate is located at the lower end of the sodium pipe. The fracture structure of the protective sleeve that the sodium pipe extends into is a venturi tube, and four middle holes are opened around it; the inlet The hole diameter of the orifice plate is 45mm; lower the elevation of the sodium tube.

Description

Siphon breaker

technical field

The invention relates to the field of additional adjustment devices for flow, in particular to a siphon breaking device.

Background technique

The primary sodium of the reactor is purified outside the reactor, and the elevation of most of the pipes and equipment in the purification circuit is lower than that of the sodium liquid level in the reactor vessel. Once the pipeline outside the reactor breaks, the high-temperature and highly radioactive liquid sodium in the pool will be ejected from the pipeline breach under the joint action of the reactor pressure and siphon force, resulting in a sodium loss accident. This not only poses a threat to the safety of the reactor itself, but also the highly radioactive aerosol discharged with the liquid sodium will seriously pollute the surrounding environment.

Internationally, only Russia has proposed the preliminary design of the passive siphon breaker for pool-type fast reactors, but it has not yet been verified by experiments and applied in engineering. Through experiments, it is found that the performance of this design cannot meet the design requirements when the purification circuit is in normal operation and the accident of sodium loss from a large ^breach in the external reactor pipeline occurs. A gas-liquid two-phase foamy overflow occurs at the top of the outlet ring cavity of the pipe section (in the stack), and falls directly onto the free surface of the high-temperature liquid sodium in the hot sodium pool; (2) When the purification flow rate is ≥5m ³ /h, the purification circuit returns to A large amount of gas is entrained in the downcomer of the protective casing of the sodium pipe section. At the refueling level, the gas volume content is as high as 30%. Once the entrained gas enters the core through the cold pool and the main circulation pump, it will cause Serious problems such as reactor power oscillations, heat transfer deterioration, and cavitation of circulation pumps. In addition, due to the possible accumulation and rupture of gas in the cold pool, pressure pulsation will be generated and flow-induced vibration of reactor internals and core components will be induced, which will seriously affect the safe operation of the reactor; During the accident, the leakage of sodium was too large, which may expose the sodium inlet of the accident cooler (independent heat exchanger) to the gas, affecting its normal operation, and causing serious consequences due to the inability to discharge the waste heat of the reactor; (4) When a sodium loss accident occurs through a breach, the system lacks effective human intervention measures to make the accident end as soon as possible, but it can only be terminated naturally.

Contents of the invention

The present invention overcomes the shortcomings in the prior art, and provides a simple structure, safe and reliable siphon breakage that reduces the amount of sodium leakage and delays the development of the accident in the event of an accident of a pipeline rupture outside the reactor, so that the operator has enough time to deal with it device.

In order to solve the above-mentioned technical problems, the present invention is achieved through the following technical proposals: the device comprises a sodium pipe that is connected to a circulation pump through a pipeline outside the pile, and the other end of the circulation pump is connected with a sodium return pipe through a pipeline outside the pile, and the sodium pipe, The sodium return pipe is fixed on the isolation plate and extends into the two protective sleeves in the stack respectively. The inlet orifice is located at the lower end of the sodium extraction pipe. The fracture structure of the protective sleeve where the sodium extraction pipe extends is Venturi pipe, and have 4 middle holes around it; the aperture of the inlet orifice plate is 45mm; reduce the elevation of the sodium pipe.

In order to enable the system to operate more stably, eliminate the problems of gas-liquid two-phase overflow and entrained gas, and better play a role in safety protection, the present invention can also: the vertical opening of the outlet joint of the sodium return pipe is blinded, A small hole of 6 mm is opened in the center of the blind plate, and 16 side holes of 10 mm are uniformly opened in the circumferential direction of the sodium return pipe 5-7 mm higher than the blind plate. Add a 40mm orifice plate at the outlet of the protective sleeve of the sodium return pipe. The throat diameter of the Venturi tube is 50mm. The diameter of the middle hole is 20mm. The pipeline outside the pile is a double-layer pipeline.

Compared with the prior art, the present invention has the advantages of successfully solving the complex two-phase flow phenomenon when a large breach in the purification pipeline occurs in the large-scale reactor system, and making the sodium The reduction in leakage and the delay in the development of accidents allow operators to have enough time to deal with them and reduce the consequences of accidents.

Description of drawings

Fig.1 Simulation flow chart of siphon breaking device

Fig. 2 Structural sectional view of the outlet joint of the sodium return pipe

Fig. 3 takes the sectional view of the structure of the sodium nozzle

In the figure: Sodium extraction pipe 1 Sodium return pipe 2 Protective sleeve 3 Protective sleeve 4 Inlet orifice plate 5 Outer stack pipe 6 Circulation pump 7 Outlet joint 8 Small hole 9 Side hole 10 Venturi tube 11 Middle hole 12 Isolation plate 13

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

The device comprises that the sodium extraction pipe 1 is connected with the circulation pump 7 through the external pipeline 6, and the other end of the circulation pump 7 is connected with the sodium return pipe 2 through the external pipeline 6, and the sodium extraction pipe 1 and the sodium return pipe 2 are respectively fixed on the isolation plate 13, the sodium extraction pipe 1 extends into the protective sleeve 3 in the pile, the sodium return pipe extends into the protective sleeve 4, the inlet orifice 5 is located at the lower end of the sodium extraction pipe 1, and the sodium extraction pipe 1 extends The fracture structure of the inserted protective sleeve 3 is a Venturi tube 11 with a throat diameter of 50mm, and four 20mm middle holes 12 are opened around it. The aperture of the inlet orifice 5 is 45mm. Lower the elevation of the sodium pipe 1. The vertical opening of the outlet joint 8 of the sodium return pipe 2 is blinded, and a small hole 9 with a diameter of 6 mm is opened in the center of the blind plate, and at the same time, the side of the sodium return pipe 2 that is 5 to 7 mm higher than the blind plate is uniformly distributed in the circumferential direction. Open 16 side holes 10 with a diameter of 10mm; add a 40mm orifice plate at the outlet of the protective sleeve 4 of the sodium return pipe 2; the outer pipeline 6 is a double-layer pipe.

Because the sodium pipe 1 and the protective sleeve 3 form an annular gap, its liquid level is lower than the liquid level in the sodium pipe 1 during normal operation. A large amount of outflow causes the flow rate of sodium in the protective sleeve 3 to increase rapidly, and the resistance increases, so that the liquid level in the annular gap quickly drops to the fracture elevation, the air cavity gas flows out from the fracture, and the pressure drops rapidly. In this way, 5 inlet orifice plates are caused. The sodium flow is reduced, thereby stopping the further leakage of sodium and playing the role of safety protection for siphon damage.

Claims (4)

1. A siphon destroying device, comprising getting the sodium pipe and connecting it with the circulation pump through the pipeline outside the pile, the other end of the circulation pump is connected with the sodium return pipe through the pipeline outside the pile, getting the sodium pipe and returning the sodium pipe to be fixed on the isolation plate, respectively It extends into the two protective sleeves in the stack, and the inlet orifice is located at the lower end of the protective sleeve where the sodium intake pipe extends. It is characterized in that the fracture structure of the protective sleeve that the sodium intake pipe extends into is Venturi pipe, and have 4 middle holes around it, and the diameter of the middle holes is 20mm; the aperture of the inlet orifice is 45mm; reduce the elevation of the sodium pipe. 2. The siphon breaking device according to claim 1, characterized in that, the vertical opening of the outlet joint of the sodium return pipe is blinded, and a small hole with a diameter of 6mm is opened in the center of the blind plate, and at the same time, it is higher than the blind plate. 16 side holes with a diameter of 10mm are evenly opened on the side of the sodium return pipe with a thickness of 5-7mm. 3. The siphon breaking device according to claim 1, characterized in that the diameter of the venturi throat is 50 mm. 4. The siphon breaking device according to claim 1, characterized in that, the pipes outside the stack are double-layer pipes.

Images