JP2006003232A - Pressurized reactor and cooling method of pressurized reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize core cooling. <P>SOLUTION: A steam generator 1 is formed from a vessel body 3, many U-tubes 11 arranged in the vessel body 3, and liquid chambers 5, 6 arranged below the U-tubes 11 in the vessel body 3. The liquid chambers 5, 6 are constituted of a high-temperature side liquid chamber 5 and a low-temperature side liquid chamber 6. The steam generator 1 is equipped with a cooling acceleration portion for accelerating cooling of a cooling liquid inside a reaction vessel 2 in order to suppress siphon break at U-shaped parts 14 of the U-tubes 11. The siphon break can be suppressed by cooling acceleration, to thereby stabilize core cooling. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pressurized reactor and a cooling method for the pressurized reactor.

  With high economic growth, various forms of energy supply are required. Electrical energy is supplied by wind power generators, solar power generators, thermal power generators, and nuclear power generators. These devices are required to have higher efficiency. Next-generation nuclear reactors, particularly next-generation pressurized light water reactors, require core cooling with higher performance. As such core cooling, development of a cooling technique that eliminates the need for a high-pressure injection pump by using a steam generator has been proposed and known. The gas phase of the eluting non-condensable gas degrades the natural circulation of the liquid phase at the U-tube part of the steam generator. Gas phase separation is known as a general technique for suppressing such deterioration that lowers the cooling efficiency. As a technique for improving the cooling efficiency, it is known in Patent Document 1 to increase the area of the inner surface of the heat transfer tube.

  It is required to establish the concept of core cooling by improving the cooling efficiency of the steam generator. In order to establish this, it is important to stabilize the core cooling by increasing the cooling efficiency in order to improve the power efficiency.

JP-A-8-136177

  An object of the present invention is to provide a pressurized reactor for stabilizing core cooling and a cooling method for the pressurized reactor.

  The pressurized reactor according to the present invention comprises a reaction vessel (2), a steam generator (1), and legs (8, 9) connecting the reaction vessel (2) and the steam generator (1). ing. The steam generator (1) includes a container body (3), a number of U-tubes (11) disposed in the container body (3), and a U-shaped tube (11) in the container body (3). The liquid chamber (5, 6) disposed below and other devices are formed. The liquid chamber (5, 6) includes a high temperature side liquid chamber (5), a low temperature side liquid chamber (6), and other devices. The legs (8, 9) are composed of a high temperature side leg (8) for connecting the cooling liquid in the reaction vessel (2) to the high temperature side liquid chamber (5) and the low temperature side liquid chamber (6). (2) It is formed from the low temperature side leg (9) which returns circularly and other equipment. The steam generator (1) includes a cooling promotion portion that promotes cooling of the coolant inside the reaction vessel (2) in order to suppress siphon breaks in the U-shaped portion (14) of the U-shaped tube (11). Yes.

  Cooling of the reaction vessel including the core is extremely important for controlling the heat energy extraction cycle. Stabilization of the cooling control of the reaction vessel is realized by improving the cooling efficiency of the steam generator. The cooling promotion part is not provided to increase the output by improving the heat exchange rate of the secondary heat exchange in the steam generator, but as a result of stabilization of the heat flow in the steam generator. , Provided to stabilize core cooling. Heat exchange of the steam generator is performed by a U-shaped tube. The cooling promotion portion is a portion that suppresses or controls siphon breaks in the U-shaped portion of the U-shaped tube. Suppressing the siphon break is an important factor in stabilizing the smooth circulation flow of the coolant including the flow in the U-shaped tube. Such stabilization suppresses siphon breaks. Thus, suppression of siphon break and stabilization of the circulation flow have a cause-effect relationship with each other. The suppression of siphon break is the cause of the stabilization of the circulation flow and at the same time the result.

  The cooling promotion portion is formed as a fin (17) formed in the U-shaped tube (11). The formation of such a fin (17) is not for increasing the output. By improving the cooling performance by the U-shaped tube, it is possible to ensure the cooling capacity required when a siphon break occurs.

  The U-shaped pipe (11) includes a high temperature side straight pipe portion (12) opened in the high temperature side liquid chamber (5) and a low temperature side straight pipe portion (13) opened in the low temperature side liquid chamber (6). And a U-shaped portion (14) connecting the high temperature side straight pipe portion (12) and the low temperature side straight pipe portion (13). The fin (17) is formed in the low temperature side straight pipe portion (13). Such an asymmetrical fin arrangement makes the heat flux distribution uniform. It is wise to improve the heat exchange performance of the low temperature side straight pipe section (13). Although it is difficult to form the fin (17) in the U-shaped part (14), it is easy to form it in the low temperature side straight pipe part (13).

  It is preferable that the surface of the fin (17) is formed in parallel with the flow of the cooling liquid from the viewpoint of suppressing an increase in pressure loss. Reduction of pressure loss contributes to flow stabilization. Forming the fin on the inner surface side of the U-shaped tube facilitates drilling of the tube plate (15) that supports the U-shaped tube. The formation of the fins in a spiral shape is effective in both reducing the bubbles and collecting the bubbles on the center side, and can synergistically suppress siphon breaks.

  The U-shaped pipe (11) includes a high temperature side straight pipe portion (12) opened in the high temperature side liquid chamber (5) and a low temperature side straight pipe portion (13) opened in the low temperature side liquid chamber (6). And a U-shaped portion (14) connecting the high temperature side straight pipe portion (12) and the low temperature side straight pipe portion (13), and the cooling promoting portion is located outside the low temperature side straight pipe portion (13). It is formed on the side surface, and its outer surface is formed into a rough surface that increases the heat transfer coefficient. Steam generation efficiency is improved, the heat flux distribution on the secondary side is made uniform, and the heat flow is further stabilized.

  A plurality of steam generators (1-1, 2) are provided. A degree of 2 to 4 is common. The U-shaped pipe (11) includes a large-curvature radius pipe (11-out) having a larger curvature radius and a small-curvature radius pipe (11-in) having a smaller curvature radius at the U-shaped portion. In this case, the cooling promoting portion is formed as a liquid chamber structure of the high temperature side liquid chamber (5). The liquid chamber structure includes a first high temperature side liquid chamber (5-A) that communicates with the large curvature radius pipe (11-out), and a second high temperature side liquid chamber (5-B) that communicates with the small curvature radius pipe. And a separation plate (23) for separating the first high temperature side liquid chamber (5-A) and the second high temperature side liquid chamber (5-B). The first high temperature side liquid chamber (5-A) communicates with the second high temperature side liquid chamber (5-B) through the lower part of the separation plate (23), and the outlet of the high temperature side leg (8) is the first. 1 It is positioned in the high temperature side liquid chamber (5-A).

  The non-condensable gas bubbles are preferentially (selectively) guided to the large curvature radius tube (11-out), and siphon breaks in the small curvature radius tube (11-in) are effectively suppressed. The cooling performance of the small curvature radius tube (11-in) of the plurality of steam generators (1) is designed to be sufficiently large, so the large curvature radius tube (11-out) is actively sacrificed. Thus, the entire siphon break can be stably avoided.

  The cooling promotion part is formed as an arrangement structure of a large curvature radius tube (11-out) and a small curvature radius tube (11-in). As for the height position of the first opening portion where the large curvature radius pipe (11-out) opens in the high temperature side liquid chamber (5), the small curvature radius pipe (11-in) opens in the high temperature side liquid chamber (5). It is set to a position higher than the height position of the second opening part. Non-condensable gas bubbles are selectively introduced into the large radius of curvature tube (11-out).

  The high temperature side liquid chamber (5) is additionally provided with a guide body (26) in which the non-condensable gas bubbles in the high temperature side liquid chamber (5) are guided obliquely upward from the second opening toward the first opening. ing. The first opening and the second opening are positioned lower than the guide slope (25) which is the lower surface of the guide body (26). Non-condensable gas bubbles are selectively introduced into the large radius of curvature tube (11-out).

  The guide body (26) has a number of holes (27) penetrating in the vertical direction. Non-condensable gas bubbles are stored in the upper region of the high temperature side liquid chamber (5) through the hole (27), and are effectively suppressed from entering the U-shaped tube.

  The cooling promoting portion is formed as a bubble refining portion for refining a non-condensable gas bubble that enters the U-shaped tube (11). The bubble miniaturization site | part is formed in the inside of a U-shaped pipe (11) as a site | part which spiralizes the liquid flow of the cooling fluid in a U-shaped pipe (11). As described above, the spiral flow refines bubbles and has the gas-liquid separation effect described above.

  The cooling promotion portion is formed as a fin (31) that squeezes the coolant in the high temperature side leg (8) in the vicinity of the outlet of the high temperature side leg (8). The fin (31) is formed in the upper region of the high temperature side leg (8) on the inner surface near the outlet of the high temperature side leg (8). There is a bubble refinement effect.

  The cooling promotion portion is formed as a fin (32) that gives resistance to the coolant in the high temperature side leg (8) in the vicinity of the outlet of the high temperature side leg (8). The fin (32) is formed in the upper region of the high temperature side leg (8) on the inner surface near the outlet of the high temperature side leg (8). The upstream side surface (33) of the fin (32) is generally orthogonal to the mainstream flow of the coolant. There is a bubble refinement effect.

  The cooling promotion portion is formed as a spiral flow forming portion (35) that forms a spiral flow in the coolant flow in the high temperature side leg (8) in the vicinity of the outlet of the high temperature side leg (8). There is a bubble refinement effect.

  The cooling promoting portion is formed as an orifice (36) that provides resistance to the flow of the coolant in the high temperature side leg (8) in the vicinity of the outlet of the high temperature side leg (8). The opening side of the orifice (36) is located in the upper region of the high temperature side leg. There is a bubble refinement effect.

  The cooling promotion part is formed as the lower end part of the U-shaped tube (11), and the open end where the lower end part opens in the high temperature side liquid chamber (5) is positioned in the lower half region of the high temperature side liquid chamber (FIG. 12). ). There is a gas-liquid separation effect.

  A cooling promotion site | part is formed as a branch site | part (29) branched from a high temperature side leg (8). The branch portion (29) is formed as a branch pool that branches upward from the high temperature side leg (8) and stores non-condensable gas bubbles. There is a gas-liquid separation effect.

  According to the cooling method of the pressurized reactor according to the present invention, the cooling liquid is distributed in parallel from the reaction vessel to each of the high temperature side liquid chambers of the plurality of steam generators, and the cooling liquid in the high temperature side liquid chamber is passed through a U-shaped tube. Each of the steam generators is sent to a plurality of low temperature side liquid chambers, and the cooling liquid in the plurality of low temperature side liquid chambers is refluxed in parallel to a plurality of reaction vessels. The sending is to suppress siphon breaks in the U-shaped portion of the U-tube.

  Suppressing is to swirl the cooling liquid in the U-shaped tube to collect non-condensable gas bubbles eluted from the cooling liquid in the central line region of the U-shaped tube. The U-shaped tube includes a first U-shaped tube having a U-shaped portion having a larger radius of curvature and a second U-shaped tube having a U-shaped portion having a smaller radius of curvature. Suppression is to selectively introduce most of the non-condensable gas bubbles eluted from the coolant in the high temperature side liquid chamber into the first U-shaped tube.

  To suppress is to refine the non-condensable gas bubbles eluted from the coolant and to introduce the refined non-condensable gas bubbles into the U-shaped tube.

  The pressurized reactor and the cooling method for the pressurized reactor according to the present invention can stabilize the cooling of the core by suppressing siphon breaks.

  The best mode for carrying out the pressurized reactor according to the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the steam generator 1 is attached to the reaction vessel 2 and connected to the steam generator 1. A plurality of steam generators are shown as the steam generator 1. The some steam generator 1 is comprised from the 1st steam generator 1-1 and the 2nd steam generator 1-2. The first steam generator 1-1 and the second steam generator 1-2 are connected to the single reaction vessel 2 in parallel.

  The first steam generator 1-1 includes a first main body container 3-1, a first heat transfer tube group 4-1, a first high temperature side liquid phase chamber 5-1, and a first low temperature side liquid phase chamber 6-. 1. It is formed from other equipment. The first high temperature side liquid phase chamber 5-1 and the first low temperature side liquid phase chamber 6-1 are divided and divided by a central partition plate 7-1. The first inlet side opening end of the first heat transfer tube element of the first heat transfer tube group 4-1 opens in the first high temperature side liquid phase chamber 5-1, and the first heat transfer tube group 4-1 first transfer. The first outlet side opening end of the heat pipe element opens in the first low temperature side liquid phase chamber 6-1. The liquid phase water flowing into the first inlet side opening end from the first high temperature side liquid phase chamber 5-1 rises in the first heat transfer tube group 4-1, and flows through the first U-shaped tube portion. The direction is changed to descend in the first heat transfer tube group 4-1 and flows into the first low temperature side liquid phase chamber 6-1 from the first outlet side opening end. The upper layer part of the liquid phase cooling water in the reaction vessel 2 is connected to the first high temperature side liquid phase chamber 5-1 through the first hot leg 8-1. The lower layer portion of the liquid cooling water in the first low temperature side liquid phase chamber 6-1 is connected to the lower layer portion of the liquid cooling water in the reaction vessel 2 via the first cold leg 9-1. . The first hot leg 8-1 is provided with a pressurizing port of the pressurizer 10 for pressurizing the liquid phase cooling water in the first hot leg 8-1.

  The second steam generator 1-2 includes a second main body container 3-2, a second heat transfer tube group 4-2, a second high temperature side liquid phase chamber 5-2, and a second low temperature side liquid phase chamber 6-. 2. The second high temperature side liquid phase chamber 5-2 and the second low temperature side liquid phase chamber 6-2 are partitioned and divided by a central partition plate 7-2. The second inlet side opening end of the second heat transfer tube element of the second heat transfer tube group 4-2 is opened in the second high temperature side liquid phase chamber 5-2, and the second heat transfer tube group 4-2 has a second transfer. The second outlet side opening end of the heat pipe element is opened in the second low temperature side liquid phase chamber 6-2. The liquid phase water flowing into the second inlet side opening end from the second high temperature side liquid phase chamber 5-2 rises in the second heat transfer tube group 4-2 and flows through the second U-tube portion. The direction is changed to descend in the second heat transfer tube group 4-2, and flows into the second low temperature side liquid phase chamber 6-2 from the second outlet side opening end. The upper layer part of the liquid phase cooling water in the reaction vessel 2 is connected to the second high temperature side liquid phase chamber 5-2 via the second hot leg 8-2. The lower layer portion of the liquid cooling water in the second low temperature side liquid phase chamber 6-2 is connected to the lower layer portion of the liquid cooling water in the reaction vessel 2 via the second cold leg 9-2. .

An object of the present invention is to improve the cooling performance of the core, and the solution is to sufficiently improve the reliability of cooling of the steam generator. Specifically, the following three types of cooling means for sufficiently improving the reliability of cooling are provided.
(1) Improvement of steam generator cooling structure (2) Siphon break control of steam generator (3) Suppression of siphon break of steam generator (3-1) Refinement of gas phase (3-2) Gas phase Separation

Improved cooling structure:
FIG. 2 shows an improved example of the cooling structure of the heat transfer tube group. The heat transfer tube group described above (hereinafter, represented by the first heat transfer tube group 4-1, and the reference addition numbers "-1" and "-2" indicating the first and second are omitted) are configured as a bundle. A number of the thin tubes are hereinafter referred to as heat transfer tube elements 11. The heat transfer tube bundle is formed of a number of heat transfer tube elements 11. FIG. 2 shows one of them as an exaggerated representation. The heat transfer tube element 11 is formed of a high temperature side straight tube portion 12, a low temperature side straight tube portion 13 and a U-shaped tube portion 14. The U-shaped pipe part 14 connects the upper part of the high temperature side straight pipe part 12 and the upper part of the low temperature side straight pipe part 13. The lower end side portion of the high temperature side straight pipe portion 12 and the lower end side portion of the low temperature side straight pipe portion 13 penetrate the tube plate 15 in the vertical direction and are supported by the tube plate 15. As shown in FIG. 3, the tube plate 15 has a number of through holes 16 equal to twice the number of the many heat transfer tube elements 11. The heat transfer tube element 11 is passed through the through hole 16. A plurality of fins 17 are formed outside the heat transfer tube element 11. The fin 17 is formed over the entire length of the heat transfer tube element 11 along the central axis 18 of the heat transfer tube element 11. The heat transfer surface of the fin 17 is formed substantially parallel to the central axis 18. The through hole 16 has a hole surface corresponding to the outermost peripheral surface of the fin 17.

  FIG. 4 shows the best mode of implementation of the heat transfer tube element 11. In this embodiment, fins are not provided in the high temperature side straight tube portion 12 and the U-shaped tube portion 14, and fins 17 are formed only in the low temperature side straight tube portion 13.

Ｑ：熱流束（Ｗ／ｍ^２）
ｋ：熱貫流率（Ｗ／ｍ^２・Ｋ）
Ｔｈｏｔ：一次系流体温度（Ｋ）（＝伝熱管要素１１の中の流体温度）
Ｔｃｏｌｄ：二次系流体温度（Ｋ）（＝伝熱管要素１１の外の流体温度）
Ａ：伝熱面積：伝熱管要素１１の流体接触面積（ｍ^２）
伝熱管要素１１の外側表面と内側面積は異なるが、定数Ａは外側表面と内側面積が考慮される有効伝熱面積として扱われる。 In order to improve the cooling performance (heat removal performance), it is important to pay attention to a plurality of parameters of the heat passage type of heat passing from the primary system to the secondary system in the steam generator 1. The heat passage formula applied to the heat transfer tube element 11 is expressed as follows.

Q: Heat flux (W / m ² )
k: Heat flow rate (W / m ² · K)
Hot: Primary fluid temperature (K) (= fluid temperature in heat transfer tube element 11)
Tcold: secondary fluid temperature (K) (= fluid temperature outside the heat transfer tube element 11)
A: Heat transfer area: Fluid contact area of the heat transfer tube element 11 (m ² )
Although the outer surface and the inner area of the heat transfer tube element 11 are different, the constant A is treated as an effective heat transfer area in which the outer surface and the inner area are considered.

α_Ｈ：伝熱管内壁の熱伝達率（Ｗ／ｍ^２・Ｋ）
α_Ｃ：伝熱管外壁の熱伝達率（Ｗ／ｍ^２・Ｋ）
δ：伝熱管厚さ（ｍ）
λ：伝熱管の熱伝導率（Ｗ／ｍ・Ｋ） The heat transmissivity k is expressed by the following equation.

α _H : Heat transfer coefficient of heat transfer tube inner wall (W / m ² · K)
α _C : Heat transfer coefficient of heat transfer tube outer wall (W / m ² · K)
δ: Heat transfer tube thickness (m)
λ: Thermal conductivity of heat transfer tube (W / m · K)

  The fin 17 shown in FIG. 3 increases the parameter A of the equation (1). A larger A makes the heat flux Q larger. The larger heat flux Q increases the amount of heat exchange between the primary system and the secondary system, and the cooling efficiency of the fluid flowing through the heat transfer tube element 11 of the primary system is large. The temperature of the fluid flowing through the heat transfer tube element 11 is controlled to be lower, and the core cooling can be promoted. The fin 17 shown in FIG. 4 lowers the temperature of the fluid flowing in the low temperature side straight pipe portion 13 by lowering the temperature of the fluid in the high temperature side straight pipe portion 12, and thus reduces the temperature of the fluid flowing in the low temperature side straight pipe portion 13 more efficiently. The difference between the high temperature side heat flux of the secondary system corresponding to the pipe part 12 and the low temperature side heat flux of the secondary system corresponding to the low temperature side straight pipe part 13 becomes smaller, and the secondary system in the steam generator. The heat flux distribution of the fluid is made uniform. Such homogenization effectively suppresses the uneven distribution of heat, enables an increase in the amount of heat absorbed by the steam generator, and consequently promotes core cooling primarily.

  As shown in FIG. 3, the heat transfer surface of the fin 17 is parallel to the core axis 18, and disturbs the upward flow of the secondary heat exchange medium that rises at a high temperature around the heat transfer tube element 11. Therefore, the pressure loss is suppressed, the flow of the secondary heat exchange medium is smoothed, the bias of the heat distribution is effectively suppressed, and the heat absorption amount of the steam generator can be increased. Promote core cooling more effectively. Although it is difficult to bend the straight pipe in which the fins 17 are formed, the fin 17 shown in FIG. 4 is formed only in the straight pipe portion, and therefore there is no difficulty in bending the straight pipe. Forming the fins 17 on the inside of the low temperature side straight pipe part 13 maintains the above-described effectiveness of the low temperature side straight pipe part 13 that forms the fins 17 on the outside, and also provides a hole ( Circular) drilling is easy.

FIG. 5 is a developed oblique axis projection view showing another improved embodiment of the pressurized reactor according to the present invention. A plurality of multiple spiral grooves 19 are formed on the inner surface side of the high temperature side straight tube portion 12 and the inner surface side of the low temperature side straight tube portion 13, respectively. The fluid (liquid) passed through the high temperature side straight pipe part 12 and the low temperature side straight pipe part 13 is given a turning force by the multiple spiral groove 19. The bubbles of the non-condensable gas that is contained in the fluid and evaporates to become bubbles are confined in the central region inside the rotational flow of the liquid having a specific gravity larger than that of the bubbles, and the high-temperature side straight tube portion 12 and the low-temperature side straight tube portion. 13 does not touch. Bubbles with a small heat transfer coefficient do not contact the heat transfer surface, and a liquid with a large heat transfer coefficient contacts the heat transfer surface, so the bubbles do not cause a decrease in the heat transfer coefficient. In this embodiment, the heat transfer area A of the equation (1) is increased, the α _H of the equation (2) is not decreased, and the heat transmissivity k is not decreased. Removal, cutting, and heat passage Q can be increased. In order to make such an effect effective, it is important that the turning speed is slow and that more gas phase is collected in the central region. The angle between the tangent line contacting the center line of the spiral groove and the central axis 18 is preferably less than 45 °, and more preferably less than 30 °.

  In the form of FIG. 5, the multiple spiral groove 19 is not formed in the U-shaped tube portion 14, but is formed in the high temperature side straight tube portion 12 and the low temperature side straight tube portion 13 which are straight pipe portions. The pipe of the heat transfer tube after forming 19 is not bent, and there is no difficulty in bending. As described above, the drilling of the tube sheet 15 is easy.

FIG. 6 shows a further improvement of the implementation of the pressurized reactor according to the invention. The outer surface of the low temperature side straight pipe portion 13 is formed as a set of a large number of small protrusion concave surfaces 21 that are sharpened like a needle. A sharp cone surface is appropriate as the small protrusion concave surface 21. The small protrusion concave surface 21 can be easily formed by laser processing. The effect of increasing the parameter A in the equation (1) on the secondary low temperature side and the small heat flux distribution difference between the low temperature side and the high temperature side is as described above. Since the small protrusion concave surface 21 improves the formation of vapor bubbles of the secondary fluid (water) at the time of boiling, the external heat transfer coefficient α _C of the equation (2) is not reduced, and the heat passage of the equation (1) is prevented. It can be kept large. The small protrusion concave surface 21 is formed in the straight pipe portion, and there is no difficulty in bending the pipe.

Siphon break control:
FIG. 7 shows still another preferred embodiment of the pressure reactor according to the present invention. The heat transfer tube element 11 is classified into a large curvature radius thin tube 11-out in which the U-shaped tube portion 14 bends with a large curvature radius and a small curvature radius thin tube 11-in in which the U-shaped tube portion 14 bends with a small curvature radius. The large-curvature radius thin tube 11-out is disposed outside the small-curvature radius thin tube 11-in in terms of the arrangement structure. The high temperature side liquid phase chamber 5 is further divided in a divided manner by the bubble diversion partition plate 23. The high temperature side liquid phase chamber 5 is divided into a bubble concentration side high temperature side liquid phase chamber 5-A and a bubble non-concentration side high temperature side liquid phase chamber 5-B. The bubble concentration side high temperature side liquid phase chamber 5-A and the bubble non-concentration side high temperature side liquid phase chamber 5-B are connected to each other at a position lower than the lower end of the bubble diversion partition plate 23. The liquid phase injected from the hot leg 8 is divided into the bubble concentration side high temperature side liquid phase chamber 5-A and the bubble non-concentration side high temperature side liquid phase chamber 5-B. A part of the non-condensable gas contained in the liquid phase injected from the first hot leg 8-1 into the high temperature side liquid phase chamber 5 is eluted into the liquid phase to be bubbled. Most of the light non-condensable bubbles (group) 24 exit the hot leg 8 and concentrate in the bubble concentration side high temperature side liquid phase chamber 5-A. The amount of the non-condensable bubble 24 that enters the bubble non-concentrated high-temperature side liquid phase chamber 5-B is remarkable in comparison with the amount of the non-condensable bubble 24 that enters the bubble concentrated side high-temperature side liquid phase chamber 5-A. Very few.

  Most of the non-condensable bubbles 24 stay in the U-shaped tube portion 14 of the large-curvature radius thin tube 11-out. The amount of the non-condensable bubbles 24 staying at the U-shaped tube portion 14 of the heat transfer tube element 11-B is remarkably small. Even when the siphon break occurs in the U-shaped tube portion 14 of the large-curvature radius thin tube 11-out and the heat transfer coefficient of the U-shaped tube portion 14 of the large-curvature radius thin tube 11-out is extremely reduced, the small-curvature radius is also reduced. The siphon break does not occur in the U-shaped tube portion 14 of the thin tube 11-in, and the heat transfer coefficient of the U-shaped tube portion 14 of the small radius of curvature thin tube 11-in does not decrease. The number of installed steam generators 1 is about 2 to 4. The small radius of curvature thin tube 11-in of the steam generator 1 maintains the cooling performance as designed, and the small radius of curvature thin tube 11-in is as described above. Therefore, the cooling performance of the core is completely maintained within the design range. The necessary heat transfer area of the heat transfer tubes necessary for sufficiently cooling the core is designed to be about 60% of the total heat transfer area.

  FIG. 8 shows still another preferred embodiment of the pressure reactor according to the present invention. In this embodiment, the height position of the lower end of the heat transfer tube element 11-B is set to a position lower than the height position of the lower end of the heat transfer tube element 11-A. The non-condensable bubbles 24 are concentrated in the upper layer region in the high temperature side liquid phase chamber 5. The amount of the non-condensable bubble 24 that enters the small radius of curvature thin tube 11-in is significantly smaller than the amount of the non-condensable bubble 24 that enters the large radius of curvature thin tube 11-out. This embodiment is the same as the embodiment of FIG. 7 in that control is performed so that a siphon break does not occur.

  FIG. 9 shows still another preferred form of implementation of the pressurized reactor according to the present invention. This embodiment is the same as the embodiment of FIG. 9 in that the height position of the lower end of the heat transfer tube element 11-B is set to a position lower than the height position of the lower end of the heat transfer tube element 11-A. In this embodiment, a guide object 26 having a guide inclined surface 25 is disposed in the high temperature side liquid phase chamber 5. The guide object 26 guides the non-condensable bubble 24 more reliably and upwardly. The lower end of the small radius of curvature thin tube 11-in is set at a position lower than the guide inclined surface 25 in the vicinity of the portion where the small radius of curvature thin tube 11-in penetrates the guide object 26 and is guided by the guide inclined surface 25. The non-condensable bubbles 24 are effectively suppressed from entering from the lower end of the small radius of curvature thin tube 11-in. The separation effect of this embodiment is larger than that of the embodiment of FIG.

  FIG. 10 shows still another preferred form of implementation of the pressurized reactor according to the present invention. In this embodiment, a perforated plate inclined plate 26 ′ is used instead of the guide object 26 of FIG. 9. The perforated plate inclined plate 26 ′ has both an upper surface and a lower surface formed on an inclined surface. The lower side surface coincides with the guide inclined surface 25 described above. A large number of small diameter holes 27 penetrating in the vertical direction are formed in the guide inclined surface 25. A space between the tube plate 15 and the perforated plate inclined plate 26 ′ is used as a bubble reservoir. In this embodiment, the siphon break suppression effect of FIG. 9 is further enhanced.

  FIG. 11 shows still another preferred form of implementation of a pressurized reactor according to the present invention. In this embodiment, an orifice 28 is disposed near the outlet of the hot leg 8. The orifice 28 stores small bubbles. A large number of small bubbles stored in the orifice are combined to form a large bubble 24. The large bubbles 24 have a smaller specific gravity, the large bubbles 24 rapidly rise and rise, and most of them enter the large radius of curvature thin tube 11-out. The present embodiment can further exert its effect by being added to the embodiment of FIG. 7, the embodiment of FIG. 8, the embodiment of FIG. 9, and the embodiment of FIG.

Siphon break suppression (gas phase refinement):
FIG. 12 shows still another preferred form of implementation of the pressurized reactor according to the present invention. In this embodiment, the lower ends of all the heat transfer tube elements 11 protrude into the high temperature side liquid phase chamber 5 to a position where it is appropriately low. The lower end opening of the heat transfer tube element 11 is set at a position lower than the storage region where most of the non-condensable bubbles 24 are stored. Siphon breaks are suppressed for all the heat transfer tube elements 11. The form of FIG. 8 and the form of FIG. 10 have the siphon break suppression effect about the small curvature radius thin tube 11-in.

  FIG. 13 shows still another preferred embodiment of the pressure reactor according to the present invention. In this embodiment, a branch pipe 29 is added to the hot leg 8. The branch pipe 29 is disposed at a position higher than the main pipe that is the hot leg 8. The non-condensable bubbles 24 are stored in the branch pipe 29, and the amount of non-condensable gas entering the high temperature side liquid phase chamber 5 is remarkably small.

Siphon break suppression (gas phase separation):
FIG. 14 shows still another preferred embodiment of the pressure reactor according to the present invention. In this embodiment, the multiple spiral groove 19 having an inclination angle larger than the inclination angle of the multiple spiral groove 19 of FIG. 5 is formed inside the heat transfer tube element 11, particularly the low temperature side straight tube portion 13. By increasing the rotational speed, the relative speed between the gas phase and the liquid phase is increased, and the non-condensable bubbles are made smaller and finer. The fine bubbles have physical properties that are easy to follow the liquid flow, and such bubbles are guided by the liquid flowing in the U-shaped tube part 14, flow with the liquid, and are stored in the U-shaped tube part 14. Is effectively avoided and siphon breaks are effectively suppressed.

  FIG. 15 shows still another preferred embodiment of the pressure reactor according to the present invention. In this embodiment, a fin structure is added near the outlet of the hot leg 8. A large number of fins 31 are arranged in the circumferential direction in the upper half region inside the hot leg 8. The gap width between adjacent fins 31 is narrow, and the gas phase is divided between the fins and refined. The space between the fins is directed in the direction of flow in the hot leg 8, and pressure loss is suppressed. The small divided bubbles diffuse and flow into all the heat transfer tube elements 11 in a uniform distribution, but are not flowed into the liquid phase and stay in the U-shaped tube portion 14, and siphon breaks are effectively suppressed. The

  FIG. 16 shows still another preferred embodiment of the pressure reactor according to the present invention. In this embodiment, a fin structure is added near the outlet of the hot leg 8. A large number of fins 32 are arranged in the flow direction in the upper region inside the hot leg 8. As shown in FIG. 17, the fin 32 has a flow direction facing surface 33 and a flow direction wake side surface 34 orthogonal to the flow direction. The flow direction opposing surface 33 and the flow direction wake surface 34 form an acute angle. The bubbles are finely crushed and atomized at a sharp portion at the inner tip portion of the fin 32. The siphon break suppression effect due to the atomization of the bubbles is as described above.

  FIG. 18 shows still another preferred embodiment of the pressurized reactor according to the present invention. In this embodiment, a spiral groove 35 is formed on the inner surface side of the hot leg 8 in the vicinity of the outlet of the hot leg 8. The liquid flow passing through the hot leg 8 is formed into a spiral flow by the spiral groove 35. The gas phase is refined by the difference in swirling speed between the liquid phase and the gas phase. The siphon break suppression effect by the refinement of the gas phase is as described above.

  FIG. 19 shows still another preferred form of implementation of the pressurized reactor according to the present invention. In this embodiment, an orifice 36 is formed in the lower region in the hot leg 8 in the vicinity of the vicinity of the outlet of the hot leg 8. The opening portion of the orifice 36 is formed on the upper side in the hot leg 8. The gas phase bubbles flowing in the upper region in the liquid following the liquid phase in the hot leg 8 are subjected to squeezing resistance and are refined. The siphon break suppression effect by the refinement of the gas phase is as described above. The opening part of the orifice is on the upper side, the retention of bubbles is avoided, and miniaturization is possible.

  FIG. 20 shows still another preferred form of implementation of the pressurized reactor according to the present invention. In this embodiment, a plurality of (for example, four) bundle forming pipes 37 that are inscribed on the inner surface of the hot leg 8 and circumscribing each other are mounted in the hot leg 8. A spiral groove 38 is formed on the inner surface side of the bundle forming tube 37-T at an upper position through which most of the gas phase portion of the bundle forming tube 37 passes. The siphon break suppression effect due to the refinement of the bubbles by the generation of the swirling flow is as described above. Since a spiral groove is formed only in the upper bundle forming tube 37-T and no spiral groove is formed in the lower bundle forming tube 37-B, pressure loss can be reduced.

  FIG. 21 shows another bundle forming tube 37-T that is substituted for the bundle forming tube 37-T of FIG. A large number of fins 39 projecting sharply toward the center are arranged in the circumferential direction in the upper region inside the bundle forming tube 37-T on the upper side. The gap between the fins 39 adjacent in the circumferential direction extends smoothly in the flow direction. The bubbles flowing in the upper region in the bundle forming tube 37-T are finely pulverized and refined by the adjacent fins 39. The siphon break suppression effect due to the miniaturization of the bubbles is as described above, and the fin structure is limited to the upper tube, and therefore has a pressure loss suppression effect.

  Although the preferred forms of implementation described above each have the benefits as stated above, variations of those forms or combinations of these forms have further benefits. Change of the shape of the fin of FIG. 3, forming the fin in the high temperature side straight pipe part 12, using the spiral groove and the fin separately in the high temperature side straight pipe part 12 and the low temperature side straight pipe part 13, existence of the fin structure 7 is added, making the bubble fine structure and the gas-liquid separation structure compatible, the bubble fine structure of the hot leg 8 or the gas fine structure in the liquid phase chamber 5 Modifications such as combining the structure with the gas-liquid separation structure and combining all forms are effective in that the effect of suppressing siphon breakage can be enhanced.

FIG. 1 is a front sectional view showing a preferred embodiment of a pressurized reactor according to the present invention. FIG. 2 is a front sectional view showing the steam generator. FIG. 3 is a plan sectional view showing the tube sheet. FIG. 4 is a front sectional view showing the heat transfer tube element. FIG. 5 is a development view showing a portion of the heat transfer tube element. FIG. 6 is a cross-sectional plan view showing a portion of the heat transfer tube element. FIG. 7 is a front sectional view showing a preferred embodiment of the steam generator. FIG. 8 is a front cross-sectional view showing another preferred embodiment of the steam generator. FIG. 9 is a front sectional view showing still another preferred embodiment of the steam generator. FIG. 10 is a front sectional view showing still another preferred embodiment of the steam generator. FIG. 11 is a front sectional view showing still another preferred embodiment of the steam generator. FIG. 12 is a front sectional view showing still another preferred embodiment of the steam generator. FIG. 13 is a front sectional view showing still another preferred embodiment of the steam generator. FIG. 14 is a developed view showing the heat transfer tube element. FIG. 15 is a cross-sectional view showing a heat transfer tube element. FIG. 16 is a front sectional view showing still another preferred embodiment of the steam generator. FIG. 17 is a cross-sectional view showing a portion of FIG. FIG. 18 is a front sectional view showing still another preferred embodiment of the steam generator. FIG. 19 is a front sectional view showing still another preferred embodiment of the steam generator. FIG. 20 is a front sectional view showing still another preferred embodiment of the steam generator. FIG. 21 is a cross-sectional view showing a modification of part of FIG.

Explanation of symbols

1, 1-1, 2 ... Steam generator 2 ... Reaction vessel 3 ... Container body 5 ... Liquid chamber (high temperature side liquid chamber)
5-B ... 2nd high temperature side liquid chamber 5-A ... 1st high temperature side liquid chamber 6 ... Liquid chamber (low temperature side liquid chamber)
8 ... Leg (High temperature side leg)
9 ... Leg (low temperature side leg)
DESCRIPTION OF SYMBOLS 11 ... U-shaped pipe 11-out ... Large curvature radius pipe 11-in ... Small curvature radius pipe 12 ... High temperature side straight pipe part 13 ... Low temperature side straight pipe part 14 ... U-shaped part 17 ... Fin 23 ... Separation plate 26 ... Guide Body 27 ... Hole 29 ... Branching part 31 ... Fin 32 ... Fin 33 ... Upstream side face 35 ... Helix flow forming part 36 ... Orifice

Claims (22)

A reaction vessel;
A steam generator;
Comprising a leg connecting the reaction vessel and the steam generator;
The steam generator
A container body;
A number of U-tubes disposed in the container body;
A liquid chamber disposed below the U-shaped tube in the container body,
The liquid chamber is
A high temperature side liquid chamber;
A low temperature side liquid chamber,
The leg
A high temperature side leg connecting the coolant in the reaction vessel to the high temperature side liquid chamber;
A low temperature side leg that circulates the cooling liquid in the low temperature side liquid chamber back into the reaction vessel,
The steam generator includes a cooling promoting portion that promotes cooling of the cooling liquid inside the reaction vessel in order to suppress siphon breaks in the U-shaped portion of the U-shaped tube. The pressurized reactor according to claim 1, wherein the cooling promotion portion is formed as a fin formed in the U-shaped tube. The U-tube is
A high temperature side straight pipe portion that opens in the high temperature side liquid chamber;
A low-temperature-side straight pipe portion that opens in the low-temperature-side liquid chamber;
The U-shaped portion connecting the high temperature side straight pipe portion and the low temperature side straight pipe portion,
The pressurized reactor according to claim 2, wherein the fin is formed in the low temperature side straight pipe portion. The pressurized reactor according to claim 3, wherein a surface of the fin is formed in parallel with the flow of the cooling liquid. The pressurized reactor according to claim 4, wherein the fin is formed on an inner surface side of the U-shaped tube. The pressurized reactor according to claim 5, wherein the fin is formed in a spiral shape. The U-tube is
A high temperature side straight pipe portion that opens in the high temperature side liquid chamber;
A low-temperature-side straight pipe portion that opens in the low-temperature-side liquid chamber;
The U-shaped portion connecting the high temperature side straight pipe portion and the low temperature side straight pipe portion,
The pressurized reactor according to claim 1, wherein the cooling promotion portion is formed on an outer surface of the low temperature side straight pipe portion, and the outer surface is formed on a rough surface. The steam generator is provided with a plurality of units,
The U-shaped tube includes a large radius of curvature tube having a larger radius of curvature of the U-shaped portion and a smaller radius of curvature tube having a smaller radius of curvature of the U-shaped portion,
The cooling promotion part is formed as a liquid chamber structure of the high temperature side liquid chamber,
The liquid chamber structure is
A first high temperature side liquid chamber that communicates with the large radius of curvature tube;
A second high temperature side liquid chamber that communicates with the small radius of curvature tube;
A separation plate for separating the first high temperature side liquid chamber and the second high temperature side liquid chamber;
The first high temperature side liquid chamber communicates with the second high temperature side liquid chamber via a lower portion of the separation plate, and the outlet of the high temperature side leg is positioned in the first high temperature side liquid chamber. Item 1. The pressurized reactor of Item 1. The U-shaped tube includes a large radius of curvature tube having a larger radius of curvature of the U-shaped portion and a smaller radius of curvature tube having a smaller radius of curvature of the U-shaped portion,
The cooling promotion portion is formed as an arrangement structure of the large curvature radius tube and the small curvature radius tube,
The height position of the first opening portion where the large curvature radius tube opens in the high temperature side liquid chamber is higher than the height position of the second opening portion where the small curvature radius tube opens in the high temperature side liquid chamber. The pressurized reactor according to claim 1. The high temperature side liquid chamber includes a guide body in which the non-condensable gas bubbles in the high temperature side liquid chamber are guided obliquely upward from the second opening toward the first opening,
The pressurized reactor according to claim 9, wherein the first opening and the second opening are positioned lower than a guide slope that is a lower surface of the guide body. The pressurized reactor according to claim 10, wherein a number of holes penetrating in the vertical direction are formed in the guide body. The cooling promotion portion is formed as a bubble refining portion for refining a non-condensable gas bubble that enters the U-shaped tube,
The said bubble refinement | miniaturization site | part is formed in the inside of the said U-shaped tube as a site | part which spiralizes the liquid flow of the cooling fluid in the said U-shaped tube. Pressurized reactor. The cooling promoting portion is formed as a fin that squeezes the coolant in the high temperature side leg near the outlet of the high temperature side leg, and the fin is on the inner surface side near the outlet of the high temperature side leg and above the high temperature side leg. The pressurized reactor according to one of claims 1 to 12, wherein the pressurized reactor is formed in a region. The cooling promotion portion is formed as a fin that gives resistance to the coolant in the high temperature side leg near the outlet of the high temperature side leg, and the fin is on the inner surface side near the outlet of the high temperature side leg. The pressurized reactor according to claim 1, wherein an upstream side surface of the fin is substantially orthogonal to a flow of a main stream of the cooling liquid. The cooling promotion portion is formed as a spiral flow forming portion that forms a spiral flow in the flow of the cooling liquid in the high temperature side leg in the vicinity of the outlet of the high temperature side leg. The pressurized reactor according to claim. The cooling promoting portion is formed as an orifice that provides resistance to the flow of the coolant in the high temperature side leg near the outlet of the high temperature side leg, and the opening side of the orifice is located in an upper region of the high temperature side leg. The pressurized reactor according to claim 1, which is selected from claims 1 to 12. The cooling promotion portion is formed as a lower end portion of the U-shaped tube, and an opening end at which the lower end portion opens in the high temperature side liquid chamber is positioned in a lower half region of the high temperature side liquid chamber. The pressurized reactor according to claim 1, which is selected from 16. The cooling promotion part is formed as a branch part branched from the high temperature side leg, and the branch part is formed as a branch pool that branches upward from the high temperature side leg and stores non-condensable gas bubbles. The pressurized reactor according to claim 1, which is selected from ˜17. Distributing the cooling liquid in parallel from the reaction vessel to the high temperature side liquid chambers of the plurality of steam generators,
Sending the cooling liquid of the high temperature side liquid chamber to each of a plurality of low temperature side liquid chambers of the plurality of steam generators via a U-shaped tube;
Refluxing the cooling liquid in the plurality of low-temperature side liquid chambers in parallel to the plurality of reaction vessels,
The sending comprises: suppressing a siphon break of a U-shaped portion of the U-tube. Cooling method of a pressurized reactor. The suppression is to collect a non-condensable gas bubble eluted from the cooling liquid in a center line region of the U-shaped pipe by turning the cooling liquid in the U-shaped pipe. Cooling method for the pressurized reactor. The U-shaped tube includes a first U-shaped tube having a U-shaped portion having a larger radius of curvature, and a second U-shaped tube having a U-shaped portion having a smaller radius of curvature,
The suppression is to selectively introduce most of the non-condensable gas bubbles eluted from the cooling liquid in the high temperature side liquid chamber into the first U-shaped tube. Cooling method for pressure reactor. The suppression is
Miniaturizing non-condensable gas bubbles eluting from the coolant,
The method for cooling a pressurized reactor according to claim 19, further comprising introducing the refined non-condensable gas bubbles into the U-shaped tube.

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