JPH06281101A - Steam generating device for pressurized water reactor - Google Patents

Abstract

(57) [Summary] [Purpose] Prevents accidents in which the primary coolant containing radioactivity leaks into the secondary coolant that does not contain radioactivity, and efficiently transfers the heat of the primary coolant to the secondary coolant. (EN) A steam generator for a pressurized water reactor capable of being obtained. A primary coolant chamber, in which a primary coolant flow is circulated, which is separated from each other by a partition wall, a secondary coolant chamber, in which a secondary coolant and steam are circulated, and a heat disposed through the partition wall. And a heat pipe, wherein the heat pipe is arranged such that the evaporation portion is inside the primary coolant chamber, the aggregating portion is inside the secondary cooling chamber, and the intermediate heat insulating portion is inside the partition wall. is there.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam generator for a pressurized water reactor, and more particularly to a steam generator for preventing accidental leakage of a primary coolant into a secondary coolant.

[0002]

2. Description of the Related Art Heat naturally flows from a high temperature portion to a low temperature portion under a finite temperature difference, as is derived from the second law of thermodynamics. Therefore, such a flow of heat (heat transfer) is an irreversible process and thermodynamically causes an increase in the amount of entropy.

Generally, when considering the transfer or transfer of thermal energy, a process by so-called "heat transport" in which some kind of fluid medium (gas, liquid, etc.) serves as a carrier and is transported by receiving another power, and thermal energy are generally considered. It is roughly divided into the so-called "heat transfer phenomenon" process in which it naturally transfers and moves into another medium under a finite temperature difference.

In a pressurized water reactor, the heat generated by nuclear fission in the core is transferred to the steam generator by the primary coolant, and the heat transfer phenomenon in the steam generator heats the secondary coolant to generate steam. To occur.

FIG. 2 is an explanatory view schematically showing the structure of a steam generator used in a conventional pressurized water reactor. As shown in the figure, the primary coolant 3a heated by the heat generated in the pressurized water nuclear reactor core 1 is circulated through the steam generator 2 and the core 1 via the primary pipe 3 by the primary coolant pump 4.

The heated primary coolant 3a is the steam generator 2
When it passes through the heat transfer tube group 2a composed of a large number of U-shaped thin tubes in the upper part of the above, it gives heat to the secondary coolant 5a introduced from above and is discharged from the lower part.

The secondary coolant 5a takes away heat to become steam 5b, which is introduced into the turbine 6 through the secondary system pipe 5 to generate electric power, condensed by the condenser 7 and condensed by the feed water pump 8 again by the steam generator. Guided to 2.

[0008]

In such a pressurized water reactor, in a heat transfer tube composed of a large number of thin tubes of a steam generator, a primary coolant passing through the narrow tubes is fissioned into a secondary coolant flowing outside the narrow tubes. Since the heat generated by the reaction is transferred, it has a structural weak point in the pressurized water reactor. That is,
The damage to the tubules may cause the primary coolant containing radioactivity to leak into the secondary coolant containing no radioactivity, with the worst possible release of radioactivity into the atmosphere.

The present invention prevents an accident in which a primary coolant containing radioactivity leaks into a secondary coolant containing no radioactivity,
An object of the present invention is to obtain a steam generator for a pressurized water reactor capable of efficiently transferring the heat of the primary coolant to the secondary coolant.

[0010]

In the steam generator for a pressurized water nuclear reactor according to the invention described in claim 1, the secondary coolant is steamed by the heat of the high-temperature primary coolant circulating in the pressurized water nuclear reactor. In the steam generator to be converted, a primary coolant chamber in which primary coolant flows separated from each other by a partition wall are circulated,
It has a secondary coolant chamber in which a secondary coolant and steam are circulated, and a heat pipe arranged so as to penetrate through the partition wall, wherein the heat pipe has an evaporator in the primary coolant chamber and an agglomeration unit. Is disposed in the secondary cooling chamber, and the intermediate heat insulating portion is disposed in the partition wall.

In the steam generator for a pressurized water reactor according to the present invention as defined in claim 2, in the steam generator for a pressurized water reactor according to claim 1, H _{2 is used} as a heat transport medium for the heat pipe. It contains a medium selected from one or more of O, K, Na, and Hg.

[0012]

According to the present invention, the primary coolant chamber, in which the primary coolant flow is circulated, which is separated from each other by the partition wall, the secondary coolant chamber in which the secondary coolant and steam are circulated, and the partition wall are penetrated. The heat pipes are arranged so that the evaporating section is in the primary coolant chamber, the aggregating section is in the secondary cooling chamber, and the intermediate heat insulating section is in the partition wall. Since it is installed, the primary coolant containing radioactivity and the secondary coolant not containing radioactivity do not directly transfer heat through the heat transfer wall, and the radiation into the secondary coolant is eliminated. It is possible to prevent accidental leakage of Noh.

Since a heat pipe is used, a large amount of heat can be transported with a slight temperature difference by utilizing latent heat and capillarity due to vapor or cohesion of the heat transport medium itself, and a power for transporting Since the pump is not required, the heat of the primary coolant can be efficiently transferred to the secondary coolant.

The heat pipe is structurally composed of an evaporating portion, an aggregating portion, and a heat insulating portion in the middle thereof, and the heat transport medium is enclosed in the pipe in which the porous material is provided along the inner wall surface. Has been done. In operation, the filled heat transport medium is heated and evaporated in the evaporator, and the vapor flows through the core in the central portion and flows into the agglomerate and agglomerates. The medium liquefied in the aggregating part is returned to the evaporating part by the capillary action of the porous material and a circulating flow is formed.

At the gas-liquid interface in the evaporation section (heating), the liquid surface is dented by evaporation of the liquid. Therefore, if the surface tension of the liquid surface and the radius of curvature of the liquid at that time are σ _b and γ _e , the porous material hydraulic internal as vapor pressure p _ve, given by p _ve -2σ _b / γ _e.

On the other hand, in the agglomerated portion (heat dissipation), since the gas-liquid interface portion becomes nearly flat, the liquid surface radius of curvature of the agglomerated portion is similarly γ _c.
As a result, the liquid pressure in the porous material is p _vc −2σ _b / γ _c .

After all, the pump pressures for pushing the liquid back from the coagulation part to the evaporation part are the heads of the liquid level h _e and h _c , respectively.
If the average density of the medium is ρ _tg , then 2σ _b (1 / γ _e −1 / γ _c ) − (p _vc −p _ve ) −ρ _tg
(H _e −h _c ), and if the following condition p _vc −p _ve ≧ 0 γ _e γ _c is considered, it is possible to make the pump pressure positive, and the power from the outside is controlled in the sealed pump. A circulation flow is formed without.

Therefore, since the heat pipe uses latent heat due to evaporation / aggregation, a large amount of heat can be transported, and a power or pump for transporting the heat pipe is not required. Therefore, the heat of the primary coolant is secondarily cooled. Can be efficiently transmitted to the material.

Specifically, one or more heat pipes are preferably arranged in the steam generator, and these heat pipes generate vibrations due to movement of fluids of the primary coolant and the secondary coolant. So that they can withstand each other.

As a specific heat transport medium for a heat pipe, since the water temperature of the primary coolant is about 300 to 350 ° C., one or more of H ₂ O, K, Na, and Hg are selected. Any medium containing the selected medium can be used.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view schematically showing the construction of one embodiment of the steam generator of the present invention. As shown in the figure, the steam generator 11 includes a primary coolant chamber 13 in which a high temperature primary coolant 12 on the left side is circulated, and a secondary coolant in which a right side secondary coolant 14 and steam 15 are circulated. The chamber 16 is separated by a thick partition wall 17.

At least one or more heat pipe mounting holes 18 are provided in the partition wall 17. The mounting holes 18 are provided.
A heat pipe 19 is horizontally attached to the. Further, the heat pipes 19 are connected to each other by a narrow tube holding member 20 which is laterally crossed with each other so as to withstand vibrations and the like generated by movement of fluids of the primary coolant and the secondary coolant.

The heat pipe 19 has a structure in which a heat transport medium is enclosed in a pipe in which a porous material is provided along the inner wall surface, and is composed of an evaporation part, an agglomeration part and a heat insulating part in the middle thereof. Therefore, in the heat pipe 19, the part exposed in the primary cooling material chamber 13 is the evaporation part, the part exposed in the secondary cooling chamber 16 is the aggregating part, and the part contained in the partition wall 17 is intermediate heat insulation. It becomes a part. The ratio of the three parts is an optimum ratio depending on conditions such as the number of heat pipes 19 arranged, the water temperatures of the primary and secondary coolants, and the thickness of partition walls.

As the heat transport medium enclosed in the heat pipe 19, the optimum heat transport medium is selected according to the water temperature of the primary coolant / secondary coolant, that is, the operating temperature, but the water temperature of the primary coolant is Since it is about 300-350 ° C, H ₂
It is possible to use one selected from O, K, Na, and Hg or two or more thereof.

Therefore, in the heat pipe 19, the heat transport medium is heated and evaporated by the heat of the primary coolant, and the vaporized heat transport medium passes through the intermediate heat insulating section and releases the heat to the secondary coolant to be condensed. The agglomerated heat transport medium passes through the intermediate adiabatic portion by the capillary action of the porous material, moves to the primary coolant side, and repeats this. The steam generated in the heat pipe 19 is discharged from the upper part of the steam generator.

The present steam generator can reduce the trouble that the primary coolant leaks to the secondary side for the following reasons. (1) Since the partition wall that separates the primary coolant and the secondary coolant can be made sufficiently thick, it is unlikely that a radiation accident will occur due to damage to the partition wall. (2) Even if the primary coolant side of the heat pipe is damaged and the primary coolant leaks into the heat pipe, in order to leak into the secondary coolant, damage to the heat pipe on the secondary coolant side is also required. Must occur. That is, the primary coolant does not leak into the secondary coolant unless the secondary damage occurs.

[0027]

As described above, according to the present invention, a primary coolant chamber, in which a primary coolant flow separated by a partition wall is circulated, a secondary coolant chamber in which a secondary coolant and steam are circulated, A heat pipe arranged so as to penetrate through the partition wall, wherein the heat pipe has an evaporation section in the primary coolant chamber, an agglomeration section in the secondary cooling chamber, and an intermediate heat insulation section in the partition wall. The primary cooling material that contains radioactivity and the secondary cooling material that does not contain radioactivity do not directly transfer heat through the heat transfer wall, and the secondary cooling It is possible to prevent the accident of leakage of radioactivity into the material.

Further, since the heat pipe is used, the latent heat and the capillary phenomenon due to the vapor or agglomeration of the heat transport medium itself are utilized to enable a large amount of heat transport with a slight temperature difference, and a power for transporting or Since no pump is required, the heat of the primary coolant can be efficiently transferred to the secondary coolant.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing a configuration of an embodiment of a steam generator of the present invention.

FIG. 2 is an explanatory diagram schematically showing a configuration of a steam generator used in a conventional pressurized water nuclear reactor.

[Explanation of symbols]

 11 ... Steam generator, 12 ... Primary coolant, 13 ... Primary coolant chamber, 14 ... Secondary coolant, 15 ... Steam, 16 ... Secondary coolant chamber, 17 ... Partition wall, 18 ... Mounting hole, 19 ... Heat Pipe, 20 ... Capillary holding material,

Claims (2)

[Claims] 1. A steam generator in which a secondary coolant is vaporized by the heat of a high-temperature primary coolant circulating in a pressurized water nuclear reactor, in which primary coolant streams separated from each other by partition walls are circulated. A chamber, a secondary coolant chamber in which a secondary coolant and steam are circulated, and a heat pipe arranged so as to penetrate through the partition wall, wherein the heat pipe has an evaporator in the primary coolant chamber. ,
A steam generator for a pressurized water reactor, wherein the aggregating portion is arranged in the secondary cooling chamber, and the intermediate heat insulating portion is arranged in the partition wall. 2. The steam generator for a pressurized water reactor according to claim 1, wherein H ₂ O, K and N are used as a heat transport medium of the heat pipe.
A steam generator for a pressurized water nuclear reactor, comprising a medium selected from the group consisting of a and Hg.