Pressure release condensation heat transfer system for passive nuclear power station

Abstract

The invention provides a pressure release condensation heat transfer system for a passive nuclear power station. The system includes a steam header connected to a main automatic dropping valve and a closed natural circulation loop; the closed natural circulation loop includes a passive steam condensate heat exchanger, a heat transfer loop pipeline, a passive heat exchanger outside the shell and a heat transfer medium. The steam header is in a containment; the top of the steam header is provided with a steam discharge pipeline; the bottom of steam header is provided with a condensate water discharge pipeline; the heat transfer loop pipeline runs through the steam header and the containment; the passive steam condensate heat exchanger is arranged in the steam header and communicated with the heat transfer loop pipeline; the passive heat exchanger outside the shell is arranged outside the containment and communicates with the heat transfer loop pipeline; and the heat transfer medium absorbs heat from the passive steam condensate heat exchanger and transfers the heat to the passive heat exchanger outside the shell through the heat transfer loop pipeline, thereby establishing the closed natural circulation to facilitate continuous removal of core waste heat produced by core residue fission in the case of an accident.

Description

technical field [0001] The invention relates to a heat exchange system, in particular to a pressure relief condensation heat exchange system of a passive nuclear power plant. Background technique [0002] Safe nuclear power is a clean energy with high energy density, which plays an important role in protecting the ecological environment, adjusting the energy structure and ensuring energy security. However, once a safety problem occurs in a nuclear power plant, it will pose a huge threat to the staff, surrounding residents, and the ecological environment. Therefore, the safety of nuclear power plants is an important issue that people must consider when using nuclear power. At present, nuclear power plants tend to adopt passive safety technology to deal with accidents. The so-called passive safety technology refers to the use of natural forces to complete various cooling functions in the event of an accident. Natural forces can be generated by gravity, pressure of accumulato...

AI Technical Summary

Problems solved by technology

This will lead to the following problems: 1) The pressure inside the containment vessel will increase, which in turn will affect the pressure relief of the main circuit system and delay the start of the gravity injection of the main make-up water tank into the reactor pressure vessel. At this time, the first make-up water tank and the second make-up water tank The make-up water tank is basically emptied, and the reactor core is in the dangerous period when the liquid level is the lowest in the accident, and the delay of pressure relief at this time increases the risk of reactor core exposure

According to the test and analysis of the existing technology (see the literature published in "Nuclear Engineering and Design" in 1999, the author is David E. Bessette, MarinodiMarzo and the name is "Transition from depression to long term cooling in AP600 scaled integral test facilities"), the main automatic pressure relief valve is opened and the main water tank is safely injected During this transition period between start-ups, the lowest liquid level in the reactor core will occur, so for the existing passive safety technology, the depressurization process of the main loop system after the main automatic depressurization valve is opened is a dangerous stage to focus on

2) Since the containment cooling system of a passive nuclear power plant also adopts a passive method, after the cooling water outside the containment is drained (for example, the gravity flow of the cooling water outside the containment in the existing AP1000 technology can maintain for 72 hours, assuming that after 72 hours, the emergency outside the plant The long-term natural cooling stage that can provide power supply and restore the external cooling water supply), for example, can only rely on heat conduction and air natural convection to condense the steam in the containment, and the containment can maintain sufficient heat exchange capacity for a long time. challenge

3) It takes a period of time for the steam released by the pressure relief spray of the main automatic pressure-reducing valve to condense and flow back to the pit, especially if the cooling outside the containment is insufficient and the steam in the shell is not condensed in time, the liquid level of the pit will drop, causing the reactor core to Reduced natural circulation cooling flow

These will put the cooling of the reactor core at risk

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