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Nuclear power unit steam generator mechanism model building method and system thereof

A technology of steam generator and mechanism model, applied in general control system, control/regulation system, instrument, etc., can solve problems such as increase of water loading in SG, melting of core, deterioration of core waste heat export function, etc.

Active Publication Date: 2018-08-31
SOUTHEAST UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If the water level is too low, it will cause local exposure of U-shaped tube bundles, cause thermal shock of SG heat transfer tubes, and may even cause water hammer phenomenon in water supply pipelines, and the export function of core waste heat will deteriorate
In severe cases, the temperature of the coolant in the primary circuit will rise and the core will melt
If the water level is too high, it will affect the work of the steam-water separator, make the water content of the steam exceed the standard, aggravate the erosion of the turbine blades, affect the life and normal operation of the steam turbine, and even damage the steam turbine unit
Moreover, if the water level is too high, the amount of water in the SG will increase, and under the accident condition of steam pipe rupture, it will cause excessive cooling of the core and lead to the occurrence of reactive accidents.
If the rupture accident occurs in the containment, a large amount of steam will cause the pressure and temperature of the containment to rise rapidly, endangering the sealing of the containment

Method used

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  • Nuclear power unit steam generator mechanism model building method and system thereof
  • Nuclear power unit steam generator mechanism model building method and system thereof
  • Nuclear power unit steam generator mechanism model building method and system thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0226] Example 1: The secondary circuit feedwater flow is subjected to step disturbance:

[0227] Model response plots and analysis are described below:

[0228]When the model is running stably for the 50th second, the feedwater flow of the secondary circuit is disturbed step by step. At this time, the total heat transferred from the metal wall to the secondary circuit is almost unchanged, resulting in an increase in the underenthalpy of the hot water section, a decrease in the volume of the air bubbles in the working fluid, and a temporary drop in the water level, that is, a "false water level". At the same time, the pressure in the steam chamber will also drop. However, with the increase of the feed water flow rate, the recirculation water volume increases, and the water level will continue to rise (such as Figure 10 shown).

[0229] At the same time, the chamber pressure will also increase continuously, and the final pressure mainly depends on the heat absorbed and the ...

Embodiment 2

[0230] Embodiment 2: steam flow step disturbance:

[0231] Model response plots and analysis are described below:

[0232] When the model runs steadily for the 50th second, the steam flow is disturbed step by step. At the moment when the steam flow increases, the SG pressure has an instantaneous decrease in theory, but in fact, due to the buffering effect of a large number of steam drums in the fluid and a large amount of steam stored in the pipeline, the pressure decreases slowly and tends to a new equilibrium (with Figure 13 match);

[0233] However, the volume of the steam drum in the fluid increases when the pressure decreases, resulting in a short-term rise in the water level, that is, the "false water level", but due to the imbalance between the feed water flow and the steam flow, the water level will gradually decrease, and there is no self-balancing ability (such as Figure 12 match). The simulation is consistent with the theoretical analysis, and the model is reas...

Embodiment 3

[0234] Example 3: Step disturbance of primary circuit coolant temperature

[0235] Model response plots and analysis are described below:

[0236] When the model runs steadily for the 50th second, the temperature of the coolant in the primary circuit increases step by step. The temperature difference between the first and second circuits increases, the heat transfer increases, and the volume of the air bubbles in the fluid of the second circuit increases sharply, resulting in a temporary false high of the water level. At the same time, the steam production increases, which causes the pressure in the chamber to increase and the working The increase of mass and metal heat storage balances the pressure (such as Figure 15 ).

[0237] The pressure difference between the chamber and the steam main pipe increases, the steam flow rate increases, and the recirculation water volume decreases accordingly, and the difference between the feed water flow rate and the steam flow rate caus...

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Abstract

The invention discloses a nuclear power unit steam generator mechanism model building method and a system thereof; the method comprises the following steps: building mechanism models for nuclear powerunit steam generator segments; integrally processing the built segment models; dynamic model structure processing; dynamic model verification, respectively step disturbance for three inputs includingfeed water flow, steam flow and coolant temperature, analyzing to obtain a response curve, determining whether the curve trends is consistent with theory or not, and verifying the model building rationality and accuracy. The method combines segment and lumped parameters to carry out mechanism modeling, uses a special solution aiming at a DAE differential equation in a MATLAB, redistributes ODE resolver quality matrix parameters, and converts the differential algebraic equation into a non-linear state space form, thus realizing differential algebraic equation accurate solving, and finally verifying the accuracy of the built models.

Description

technical field [0001] The invention relates to a thermal control and thermal modeling method, in particular to a method and system for establishing a steam generator mechanism model of a nuclear power unit. Background technique [0002] According to statistics, about one-fourth of the unplanned outage accidents in foreign pressurized water reactor nuclear power plants are related to steam generators. It can be seen that the safe and reliable operation of SG has an important impact on the safety and economy of nuclear power plants. An important operating parameter of SG is its water level, that is, the water level of the SG secondary circuit. If the water level is too low, it will cause partial exposure of the U-shaped tube bundle, cause thermal shock of the SG heat transfer tube, and may even cause water hammer phenomenon in the water supply pipeline, and the export function of the core waste heat will deteriorate. In severe cases, the temperature of the coolant in the pri...

Claims

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Application Information

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IPC IPC(8): G05B17/02
CPCG05B17/02
Inventor 魏志伟王明春耿健王馥郁
Owner SOUTHEAST UNIV
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