KR101815958B1 - Passive containment cooling system for pressurized water reactor using phase-change material - Google Patents

Abstract

The present invention relates to a passive containment cooling system for a pressurized light water reactor using a phase change material. Specifically, the present invention relates to a passive containment cooling system for a pressurized light water reactor using a phase change material which installs a cooler using a phase change material in a containment, thereby increasing a thermal safety margin by reducing the temperature and pressure in the containment while condensing steam since the phase change material absorbs heat when a nuclear accident occurs, and securing safety of a nuclear power plant through a passive means using a natural phenomenon which is latent heat of the phase change material.

Description

[0001] The present invention relates to a passive containment cooling system for pressurized water reactor using a phase change material,

The present invention relates to a pressurized light-water reactor type passive containment building cooling system using a phase change material, and more particularly to a cooling system in a containment building, The present invention relates to a cooling system of a pressurized light-water reactor type passive containment structure using a phase change material.

Nuclear power plants have played a major role in electricity production up to now, as demand for electricity production has increased rapidly throughout the world. Nuclear power generation is a strong support for the use of nuclear energy because of its economic advantages from low electricity production costs. Nuclear power generation uses electricity generated from the process of artificially fissuring fissile material such as uranium to generate electricity. It is very important to consider the safety of the risk of radioactive materials and radiation due to fission.

In the nuclear industry, the passive containment cooling system is widely used as a system to maintain the integrity of the reservoir in various reactors including the integrated reactor. If the pressure inside the containment building rises due to the release of cooling water or steam due to the loss of coolant or the breakage of the steam pipe, the building cooling system cools the steam and cools the internal air.

Generally, a heat exchanger in a passive containment building cooling system is disposed inside a containment building, and water is supplied from an external cooling water tank to cool the inside of the containment building using natural circulation. Even in this type of cooling system, when the temperature inside the containment building is higher than 100 ° C, it can exhibit normal performance and effectively reduce the maximum pressure of the containment building at the time of an accident.

However, since the cooling performance of the heat exchanger is significantly reduced in the latter half of the accident in which the temperature inside the containment building is reduced to less than 100 ° C. due to the rise in the temperature of the emergency cooling water, the pressure inside the containment building is reduced to 1 / 2 or less.

In addition, there is a limit to penetrate the containment building made of reinforced concrete to install a heat insulation pipe connecting the heat exchanger and the cooling water tank.

There has also been an attempt to apply ice as a coolant, but there is still a limit to use refrigerant and power to maintain the ice condition.

: Registration Patent No. 10-1242746 (Registered on Mar. 03, 2013)

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide a cooling device using a phase change material in a containment building to reduce the temperature and pressure in the containment building while the phase change material absorbs heat to condense the steam, The present invention provides a cooling system of a pressurized light water reactor type passive containment building using a phase change material that increases the thermal safety margin.

It is another object of the present invention to provide a cooling system of a pressurized light water reactor type passive containment structure using a phase change material that secures safety of a nuclear power plant through passive means using a natural phenomenon of latent heat of the phase change material.

A pressurized light water reactor type passive storage building cooling system using a phase change material according to an aspect of the present invention includes a reactor, a containment building surrounding the reactor, a steam generator injecting coolant into the reactor through a hot tube, And a cooler formed inside the containment structure for cooling and condensing the inner vapor and the non-condensable gas in the containment structure.

The cooler of the present invention may comprise a phase change material.

The cooler of the present invention further includes a fin, and the side surface of the fin may be formed to be non-uniform or porous.

One side of the pin of the present invention may be exposed to the outside of the container so as to be in contact with the outside atmosphere, and the other side may be connected through the phase change material.

The phase change material of the present invention is a saturated hydrocarbon having 26 to 31 carbon atoms, and the saturated hydrocarbon is preferably any one selected from the group consisting of normal, iso, and cyclic.

Preferably, the phase change material of the present invention uses sodium hydroxide hydrate (NaOH.H2O) or sodium acetate hydrate (CH3COONa.3H2O).

The phase change material of the present invention is characterized by having a latent heat of 240 to 275 kJ / kg.

The cooler of the present invention further includes a heat transfer structure, wherein the heat transfer structure may be formed into a net structure or a plate shape.

The cooling system of the pressurized light-water reactor type passive containment building using the phase change material according to the present invention is provided with a cooler using a phase change material in the containment building so that the phase change material absorbs heat when a nuclear accident occurs and condenses the steam, It has the effect of increasing the thermal safety margin by reducing the temperature and pressure.

In addition, the pressurized light water reactor type passive storage building cooling system using the phase change material according to the present invention has an effect of securing the safety of a nuclear power plant through passive means using latent heat of the phase change material.

1 is a schematic configuration diagram of a pressurized light water reactor using a cooler according to an aspect of the present invention.
2 is a schematic configuration diagram of a cooler according to an embodiment of the present invention.
3 is a pin-shaped enlarged view of a cooler according to an embodiment of the present invention.
4 is a schematic configuration diagram of a cooler according to the second embodiment of the present invention.
5 is an enlarged view of a pin shape of a cooler according to the second embodiment of the present invention.
6 is a schematic configuration diagram of a cooler according to the third embodiment of the present invention.
7 is a schematic configuration diagram of a cooler according to four embodiments of the present invention.
8 is a graph showing the average condensed heat transfer coefficient according to the second embodiment of the present invention.
FIG. 9 is an image and a graph showing the thermal conductivity according to the width of the phase change material and the inner fin using the cooler according to the second embodiment of the present invention (FIGS. 9a to 9c are graphs showing the relationship between the heat flux at the right wall of the heat transfer structure 3,000 W / m ² · the temperature distribution shown image within K) have given time, the phase change material and the heat transfer structure to Fig 9d is a maximum temperature at when different heat flux to the right wall surface of the heat transfer structure, the heat transfer structure wall Fig.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

Hereinafter, the present invention will be described in detail.

1, a pressurized light water reactor type passive storage building cooling system using a phase change material according to an aspect of the present invention includes a reactor 10, a containment building 20, a steam generator 30, a pressurizer 40, And a cooler 50.

The reactor 10 refers to a device capable of continuously maintaining and controlling the fission chain reaction.

The containment building 20 surrounds the reactor 10 and serves as a final barrier to prevent leakage of radioactive material from the nuclear reactor to the external environment.

The steam generator (30) injects coolant into the reactor (10) through a hot tube (11).

The pressurizer (40) regulates the amount of coolant stock and the pressure through a pressurized connection pipe (41) connected to the hot pipe (11).

The cooler (50) is formed inside the containment building (20) to cool and condense the internal vapor and the non-condensable gas in the containment building (20).

Hereinafter, a configuration of a cooler 50 according to the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a schematic configuration diagram of a cooler according to an embodiment of the present invention, FIG. 3 is a pin-shaped enlarged view of a cooler according to an embodiment of the present invention, FIG. 6 is a schematic structural view of a cooler according to a third embodiment of the present invention, and FIG. 7 is a schematic view of a cooler according to an embodiment of the present invention Fig. 5 is a schematic configuration diagram of a cooler according to four embodiments of Figs.

2 to 7, the cooler 50 is comprised of a fin 51, a phase change material 52, a heat transfer structure 53, and a vessel 54.

Conventionally, the water in the heat exchanger installed in the containment building and the water in the cooling water tank outside are cooled by the natural circulation method to cool the inside of the containment building. In order to install the heat insulation pipe to connect the heat exchanger and the cooling water tank, It is necessary to penetrate the containment building to expose it to the risk of leakage of radioactivity through the through hole when a nuclear accident occurs.

Therefore, the cooler 50 of the present invention does not need to install the heat exchanger, the cooling water tank, the heat insulation tube, and the like in the containment building 20, and can save the installation or maintenance cost have. In addition, the cooler 50 is formed inside the containment building 20, so that leakage of radioactivity can be prevented when a nuclear accident occurs. 1, the cooler 50 can be installed on the inner wall of the containment structure 20, and a cradle can be placed in the empty space of the containment building 20 using a cradle such as a shelf, The cooler 50 can be installed.

One side of the fin (51) is exposed to the outside of the container (54) so as to be in contact with the outside atmosphere, and the other side passes through the phase change material (52).

As shown in FIGS. 2 and 4, the shape of the fin 51 may be a cylindrical or square pillar shape, but is not limited thereto. In addition, the side surface of the fin 51 may be formed in a non-uniform pattern.

3 and 5, the side surface of the fin 51 may be formed of a porous material. When the side surface of the fin 51 is formed of a porous material, the porous material may be a circle, an ellipse, Is preferable. When the fin 51 is formed on the side surface of the fin 51 as described above, the specific surface area of the fin 51 is increased, and the internal steam and the non-condensing gas of the containment building 20 can be condensed rapidly.

The phase change materials (PCM) 52 are materials that can absorb or emit a large amount of heat while changing phases from solid to liquid, or from liquid to gas, or vice versa, without changing the temperature at a specific temperature it means.

When the phase change material 52 accumulates and emits heat at the time of phase change, the heat at this time is referred to as latent heat, and the latent heat has an energy storage capacity superior to sensible heat. When stored as latent heat accompanied by the phase change of the material, the volume of the thermal storage medium and the space therefrom become very small and the heat can be released or absorbed at a constant temperature. Since heat exchange is performed with the inner atmosphere of the containment building 20 through the heat absorption of the phase change material 52, the cooling can be performed even when the non-condensing gas and the steam are mixed.

The phase change material 52 has a melting point of 49 to 80 DEG C and a latent heat of 180 to 280 kJ / kg. In general, a phase change material having a melting point of -10 ° C or more and less than 49 ° C is used for cooling, but when the nuclear accident occurs, the atmospheric conditions in the containment building 20 melt at 0.4 MPa (design pressure) and 49 ~ 143.3 ° C, A phase change material having a temperature of 10 ° C or more and less than 49 ° C does not meet the above conditions.

The phase change material 52 is a saturated hydrocarbon having 26 to 31 carbon atoms and the saturated hydrocarbon may be any one selected from the group consisting of normal, iso, and cyclo, or sodium hydroxide hydrate that the NaOH · H ₂ O) or sodium acetate hydrate _{(CH 3 COONa · 3H 2 O} ) is preferred.

As shown in FIGS. 2 through 5, the heat transfer structure 53 is formed of a net structure to cover the phase change material 52, As shown in FIG. 6, the heat transfer structure 53 may be formed in a plate shape so that the phase change material 52 and the heat transfer structure 53 may be alternately stacked in a sandwich form. As shown in FIG. 7, And the heat transfer structure 53 may be formed on one side of the phase change material 52. 6 and 7, the fin 51 and the heat transfer structure 53 may be integrally formed and formed on one side of the phase change material 52.

The fin 51 and the heat transfer structure 53 may be made of the same material and may be formed of any one selected from the group consisting of copper, gold, silver, aluminum, and iron having excellent thermal conductivity.

The present invention calculates the average condensation heat transfer coefficient with a cooler according to the second embodiment.

&Quot; F. P. Incropera, D. P. Dewitt, T. L. Bergman, and A. S. Lavine, Fundamentals of Heat and Mass Transfer, John Wiley & Sons, New York, The average condensation heat transfer coefficient was calculated based on the literature, and the formula for the calculation is shown below. The design conditions for calculation and the atmospheric conditions inside the containment are shown in Table 1 below.

<Formula 1>

<Formula 2>

<Expression 3>

<Formula 4>

<Expression 5>

<Expression 6>

Value or range Pin bottom Width (m) 0.1 to 2 Height (m) 0.1 to 2
pin Thickness (m) 0.001 Width (m) 0.3 Height (m) 0.1 to 2
Condition Target heat capacity (Mw) 20 Storage pressure inside containment (MPa) 0.74 Storage temperature inside the building (℃) 167.2

As shown in FIG. 8, the average condensed heat transfer coefficient according to the second embodiment of the present invention is shown. As a result of the calculation, as the height of the pin having the target heat capacity in the design condition decreases, And the average condensation heat transfer coefficient increases. Conversely, the direction in which the height of the fin increases is limited to meet the target heat capacity, but it can be seen that the number of fins and the pin bottom area decrease and the average condensation heat transfer coefficient increases.

The present invention has evaluated the thermal conductivity effect of the phase change material and the width of the heat transfer structure (inner fin) with the cooler according to the second embodiment. The formula for the purging is shown below, and the phase change material, heat transfer structure, and heat flux conditions for the calculation are shown in Table 2 below.

<Expression 7>

<Expression 8>

<Expression 9>

Value or range Phase change material
(Sodium acetate _{hydrate, CH 3 COONa · 3H 2 O} ) Width (m) 0.15-0.29 Height (m) 0.1 Thermal conductivity (W / m · k) 0.25
Heat transfer structure (copper) Width (m) 0.01 to 0.15 Height (m) 0.1 Thermal conductivity (W / m · k) 401
Condition The heat flux (W / m ² · K) at the right wall surface of the heat transfer structure 3,000 / 4,000 / 5,000

As shown in FIGS. 9a to 9c, the temperature distribution in the phase change material and the heat transfer structure was calculated when given a constant heat flux (3,000 W / m ² · K) at the right wall surface of the heat transfer structure. As a result of the calculation, it can be seen that as the width of the heat transfer structure increases, both the maximum temperature at the wall surface and the maximum temperature at the boundary between the phase change material and the heat transfer structure are lowered.

Also, as shown in FIG. 9 (d), it can be seen that the maximum temperature at the wall surface of the heat transfer structure is almost constant when the width of the heat transfer structure is greater than about 0.5 m even if the heat flux is differently distributed on the right wall surface of the heat transfer structure.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

10: Reactor 20: containment building
30: steam generator 40: pressurizer
50: cooler

Claims (8)

nuclear pile;
A containment building surrounding the reactor;
A steam generator in which a coolant is injected into the reactor through a hot tube;
A pressurizer for regulating a coolant stock amount and a pressure through a pressurized connection pipe connected to the hot pipe; And
And a cooler formed inside the containment structure for cooling and condensing the inner vapor and the non-condensable gas in the containment structure,
The cooler is configured to form a phase change material inside a container having a predetermined shape, and a heat transfer structure of the net structure surrounds the phase change material. The cooler is exposed to the outside of the container so that one side of the fin, And the other side of the pin is connected to the phase change material through the through hole.
nuclear pile;
A containment building surrounding the reactor;
A steam generator in which a coolant is injected into the reactor through a hot tube;
A pressurizer for regulating a coolant stock amount and a pressure through a pressurized connection pipe connected to the hot pipe; And
And a cooler formed inside the containment structure for cooling and condensing the inner vapor and the non-condensable gas in the containment structure,
The cooler includes a phase change material formed inside a container having a predetermined shape, a heat transfer structure in which the phase change material is alternately stacked in a sandwich form, And the other side of the pin passes through the heat transfer structure and is integrally connected to the other side of the heat transfer structure.
nuclear pile;
A containment building surrounding the reactor;
A steam generator in which a coolant is injected into the reactor through a hot tube;
A pressurizer for regulating a coolant stock amount and a pressure through a pressurized connection pipe connected to the hot pipe; And
And a cooler formed inside the containment structure for cooling and condensing the inner vapor and the non-condensable gas in the containment structure,
The cooler includes: a phase change material formed inside a container having a predetermined shape; a heat transfer structure coupled to the phase change material in a plate shape; and a heat transfer structure having one side of the fin formed in a side surface thereof exposed to the outside of the container And the other side of the pin is connected to the heat transfer structure through the phase change material.
4. The method according to any one of claims 1 to 3,
Wherein the phase change material is a saturated hydrocarbon having a carbon number of 26 to 31, and the saturated hydrocarbon is any one selected from the group consisting of normal, iso, and cyclic type hydrocarbons.
4. The method according to any one of claims 1 to 3,
The phase change material is sodium hydrate (NaOH · H ₂ O) or sodium acetate hydrate _{(CH 3 COONa · 3H 2 O} ) PWR passive containment cooling system, characterized in that.
4. The method according to any one of claims 1 to 3,
Wherein the phase change material has a melting point of 49 to 80 DEG C and a latent heat of 180 to 280 kJ / kg.
4. The method according to any one of claims 1 to 3,
Wherein the temperature of the boundary between the phase change material and the heat transfer structure decreases as the width of the heat transfer structure increases.
4. The method according to any one of claims 1 to 3,
Wherein the heat transfer structure has a constant temperature at a wall surface of the heat transfer structure at a width of 0.5 m or more.

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