Method of removing ice from ice condenser

Abstract

To reduce the burden on operators and facilitate ice removal.SOLUTION: A method of removing block ice in an ice condenser having columnar block ice stored in a cylindrical basket provided in an ice condenser chamber is provided, the method comprising a separation step of separating the block ice from the basket using a cylindrical drill, and a removal step of removing the separated block ice form the basket.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a method for removing ice from an ice condenser. [Background technology]

[0002] For example, Patent Document 1 shows a configuration in which a water-soluble polymer film is attached to the outer periphery of ice formed as a cylindrical block ice body in order to prevent the ice filled in an ice condenser from being reduced due to sublimation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-147180 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a nuclear reactor where it is expected that the reactor containment vessel will be filled with high-temperature steam in the event of an abnormality, an ice condenser is sometimes installed to cool and condense the high-temperature steam with ice that absorbs a large amount of heat. In such an ice condenser, the ice in the ice condenser is exposed to circulating air so that the air inside the reactor containment vessel is always kept clean. Therefore, the ice sublimes into steam without melting, reducing its weight, and an appropriate condensing capacity cannot be obtained. Therefore, in the ice condenser, it is necessary to replace the lost ice to ensure the ice weight. However, the steam from the sublimated ice circulates inside the ice condenser, is cooled again and turns into frost, and adheres to the ice and the basket in which the ice is stored and hardens, making it difficult to remove the ice from the basket. In addition, after the plant operation is stopped, it is necessary to efficiently remove and dispose of the block ice in the ice condenser.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide an ice removal method for an ice condenser that reduces the burden on workers and allows ice to be easily removed. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, an ice removal method for an ice condenser according to one embodiment of the present disclosure is a method for removing cylindrical block ice from an ice condenser in which cylindrical block ice is stored in a cylindrical basket arranged in a cooling chamber, the method including a separation step of separating the basket and the block ice using a cylindrical drill, and a removal step of removing the separated block ice from the basket. Effect of the Invention

[0007] The present disclosure reduces the burden on workers and makes ice removal easier. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a reactor containment vessel to which the ice condenser of the embodiment is applied. [Diagram 2] FIG. 2 is a schematic diagram of the ice condenser according to the embodiment. [Diagram 3] FIG. 3 is a schematic diagram of a basket of the ice condenser according to the embodiment. [Figure 4] FIG. 4 is a schematic diagram of the wire of the ice condenser according to the embodiment. [Diagram 5] FIG. 5 is a schematic diagram of an ice removal mechanism of the ice condenser according to the embodiment. [Figure 6] FIG. 6 is a flowchart of a method for removing ice from an ice condenser according to an embodiment. [Figure 7] FIG. 7 is a process diagram of the ice removal method for an ice condenser according to the embodiment. [Figure 8] FIG. 8 is a process diagram of the ice removal method for an ice condenser according to the embodiment. [Figure 9]FIG. 9 is a process diagram of the ice removal method for an ice condenser according to the embodiment. [Figure 10] FIG. 10 is a process diagram of the ice removal method for an ice condenser according to the embodiment. [Figure 11] FIG. 11 is a process diagram of a method for removing ice from an ice condenser according to an embodiment. [Figure 12] FIG. 12 is a process diagram of the ice removal method for an ice condenser according to the embodiment. [Figure 13] FIG. 13 is a process diagram of a method for removing ice from an ice condenser according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present invention is not limited to these embodiments. In addition, the components in the following embodiments include those that are replaceable and easy for a person skilled in the art, or those that are substantially the same.

[0010] FIG. 1 is a schematic diagram of a reactor containment vessel to which the ice condenser of the embodiment is applied.

[0011] The ice condenser 10 of the embodiment is applied to a reactor containment vessel 100 as shown in Fig. 1. The reactor containment vessel 100 is surrounded by an external shielding wall 101 made of concrete, and has a concrete structure 102 inside. The concrete structure 102 has a cylindrical crane wall 103 that supports a crane 110 on its outer periphery, and the inside of the crane wall 103 is divided into a plurality of compartments in which a reactor 111, a primary coolant pump 112, a steam generator 113, and the like are respectively installed. The ice condenser 10 is provided inside the reactor containment vessel 100 so as to surround the outside of the crane wall 103.

[0012] Fig. 2 is a schematic diagram of the ice condenser of the embodiment, Fig. 3 is a schematic diagram of the basket of the ice condenser of the embodiment, and Fig. 4 is a schematic diagram of the wire of the ice condenser of the embodiment.

[0013] As shown in FIG. 2, ice condenser 10 includes an ice condenser chamber (cooling chamber) 11, a support grid 12, a basket 13, block ice 14, a duct 15, and an air conditioner 16.

[0014] The ice condenser chamber 11 is inside the reactor containment vessel 100 and constitutes a compartment surrounding the outside of the crane wall 103. The ice condenser chamber 11 is provided so that its upper part can communicate with an upper compartment inside the reactor containment vessel 100 via an upper deck door 11A. The ice condenser chamber 11 is also provided so that its lower part can communicate with a compartment inside the crane wall 103 via a lower deck door 11B provided at an opening 103a of the crane wall 103.

[0015] A support grid 12 is disposed within the ice condenser chamber 11 between the upper deck door 11A and the lower deck door 11B.

[0016] As shown in Fig. 3, the basket 13 is formed in a cylindrical shape with a bottom, with many through holes formed around the periphery and at the bottom. The basket 13 is supported by the support grid 12. The basket 13 has, for example, a diameter of about 30 cm and a vertical length of about 1500 cm, and about 2000 baskets are supported by the support grid 12 and arranged in a grid pattern when viewed from above.

[0017] The block ice 14 is formed into a cylindrical shape as shown in FIG. 3. The block ice 14 is arranged in a vertical stack inside the basket 13. Although not shown in the figure, a water-soluble polymer film is attached to the periphery of the block ice 14. The water-soluble polymer film is made of, for example, polyvinyl alcohol (PVA). Here, the basket 13 is inserted with a wire 17 from the top to the bottom, and the wire 17 has a plurality of fixing members 17a arranged at predetermined intervals in the vertical direction as shown in FIG. 4. In addition, as shown in FIG. 3, a plurality of support plates (cruciforms) 18 made of a magnetic material are inserted into the wire 17 from the side through slits 18a. The vertical position of each support plate 18 is determined and locked at the position of each fixing member 17a. In addition, a plurality of block ice 14 is inserted into the wire 17 from the side through slits 14a. The block ice 14 is supported by each support plate 18 in a state where multiple block ice 14 are stacked in the vertical direction. In this way, the block ice 14 is placed inside the basket 13 with multiple pieces inserted into the wire 17 and supported by the support plate 18. The block ice 14 is usually removed from the basket 13 while supported by the wire 17 and support plate 18 by pulling the wire 17 upward from the basket 13.

[0018] The ducts 15 are disposed inside the ice condenser chamber 11 so as to sandwich the support grid 12 between the outer side and the opposite side of the crane wall 103. Each duct 15 is configured to run from the upper side toward the lower side along the vertical direction of the support grid 12, turn around from the lower side, and return to the upper side.

[0019] The air conditioner 16 is, for example, an air handling unit (AHU). The air conditioner 16 is connected to one of the upper ports of each duct 15. The air whose temperature has been adjusted by the air conditioner 16 flows from the top to the bottom along the duct 15, turns around from the bottom and returns to the top, reaches the upper side of the inside of the ice condenser chamber 11, and is circulated throughout the inside of the ice condenser chamber 11. Therefore, in the ice condenser 10, the inside of the ice condenser chamber 11 is temperature-adjusted (cooled) by the air conditioner 16, and the block ice 14 is cooled.

[0020] For example, if a crack occurs in the reactor coolant circulation system, etc., and high-temperature and high-pressure coolant flows out and becomes high-temperature steam, a mixed fluid of this high-temperature steam and the internal atmosphere (air) of the reactor containment vessel 100 flows into the inside of the ice condenser chamber 11 of the ice condenser 10 through the lower opening 103a. The basket 13 inside the ice condenser chamber 11 allows the mixed fluid to flow in and out through the through holes, and the high-temperature mixed fluid flows upward while touching the block ice, and flows out into the upper section of the reactor containment vessel 100 through the opened upper deck door 11A. The block ice 14 takes heat as heat of fusion from the mixed fluid flowing inside the ice condenser chamber 11 and cools it. The cooled steam condenses and reduces the internal pressure of the reactor containment vessel 100. Even during normal times when there is no accident, the block ice 14 of the ice condenser 10 is in contact with the internal atmosphere of the reactor containment vessel 100, which causes it to sublimate and reduce its volume. For this reason, regular replacement is required to always maintain a sufficient level of condensation capacity during an accident.

[0021] However, in the ice condenser 10, the sublimated water vapor from the block ice 14 circulates inside the ice condenser chamber 11, is cooled again, and becomes frost, which adheres to and hardens on the block ice 14 and basket 13, so it can be difficult to remove the block ice 14 from the basket 13. Also, when using heat to melt the block ice, an enormous amount of heat is required because there are several thousand baskets 13 and the block ice 14 weighs several thousand tons in total, and the tip of the melted ice freezes again.

[0022] Therefore, the ice condenser 10 of the embodiment includes a configuration for easily taking out and removing the block ice 14. Fig. 5 is a schematic configuration diagram of an ice removal mechanism 20 of the ice condenser of the embodiment.

[0023] The ice removal mechanism 20 shown in FIG. 5 includes a drill 21 and a drive unit 22. The drill 21 is formed in a cylindrical shape. The drill 21 is formed so that its diameter is smaller than the inner diameter of the basket 13 so that it can be inserted inside the basket 13. The drill 21 has a cutting blade at the open lower end of the cylindrical shape. The drill 21 is formed so that the length of the cylindrical shape is at least the length of the columnar shape of the block ice. The drill 21 may be formed so that the length of the cylindrical shape can be extended. The drill 21 has a rotating shaft 21a that extends in the vertical direction at the center of the cylindrical shape of the closed upper end. The rotating shaft 21a may be formed so that its length can be extended. The drill 21 and the rotating shaft 21a are formed with a slit on the side so that the wire 17 can be passed through the inside. The driving device 22 rotates the drill 21 around the rotation shaft 21a and moves the drill 21 in the vertical direction along the rotation shaft 21a. In the embodiment, the driving device 22 includes a motor 22a, a gear 22b driven by the motor 22a, and a screw 22c provided on the rotation shaft 21a and meshing with the gear 22b. Thus, the driving device 22 drives the gear 22b by the motor 22a to rotate the screw 22c, thereby rotating and moving the drill 21 up and down. The ice removal mechanism 20 has a claw 21b that can advance and retreat inside the cylindrical shape of the drill 21. The claw 21b moves between a position where it retreats to the inner surface of the drill 21 and a position where it advances from the inner surface of the drill 21 by, for example, an actuator.

[0024] Fig. 6 is a flow chart of the method for removing ice from an ice condenser according to the embodiment. Fig. 7 to Fig. 13 are process diagrams of the method for removing ice from an ice condenser according to the embodiment.

[0025] In the embodiment, as a method for removing ice from the ice condenser 10, as shown in FIG. 6, if there are no blocks of ice 14 that cannot be removed (step S1: No), the blocks of ice 14 are removed as usual (step S2), and this is continued until all the blocks of ice 14 have been removed (step S3: Yes).

[0026] On the other hand, in the ice removal method, as shown in FIG. 7, if there is a block of ice 14 that cannot be removed due to the adhesion of frost 19 or the like (step S1: Yes), the drill 21 of the ice removal mechanism 20 is used to separate the basket 13 from the block of ice 14 (step S4). In the separation process for separating the basket 13 from the block of ice 14, as shown in FIG. 8, the drill 21 is lowered while rotating, and inserted between the basket 13 and the block of ice 14 that are stuck together. The drill 21 may be inserted into the basket 13 by the length of the single block of ice 14 at the top, or by the length of multiple block of ice 14, or may be inserted into the basket 13 up to the position of the support plate 18 at the top. FIG. 9 shows a state in which the drill 21 is inserted into the basket 13 by the length of the single block of ice 14 at the top, and the basket 13 and the block of ice 14 are separated.

[0027] Next, in the ice removal method, the basket 13 and the block ice 14 are separated as shown in FIG. 9, and then the separated block ice 14 is removed from the basket 13 as shown in FIG. 6 and FIG. 10 (step S5). In the removal process of removing the separated block ice 14 from the basket 13, if a single block ice 14 can be removed as it is in a cylindrical shape, the block ice 14 is removed as a cylindrical shape. In the removal process, if the stacked block ice 14 are stuck to each other, as shown in FIG. 10, the block ice 14 is split by driving a wedge into the slit 14a, and each split ice 14' is removed. In the removal process, if the stacked block ice 14 are stuck to each other and can be removed while stuck, the stacked block ice 14 is removed as it is. When removing the block ice 14 or the split ice 14', the operation is performed by a hand mechanism not shown. In this way, in the removal process, the block ice 14 is removed until the support plate 18 at the top is revealed, as shown in FIG. 11.

[0028] Next, in the ice removal method, as shown in Figs. 6, 12, and 13, the support plate 18 at the top is removed from the basket (step S6). In the removal process for removing the support plate 18 from the basket, since the support plate 18 is made of a magnetic material, a magnet (electromagnet) 23 is attached to the support plate 18, and the support plate 18 can be removed by pulling up the wire 23a that suspends the magnet 23. The support plate 18 can be removed from the basket by tilting it so that the wire 17 is pulled out from the slit 18a shown in Fig. 3. Also, in the removal process, if the support plate 18 is fixed to the basket 13 or the block ice 14 directly below, the support plate 18 can be removed by attaching a heater 24 to the support plate 18 to melt the frost. The heater 24 is suspended by a wire 24a, and is attached to the support plate 18 by this wire 24a.

[0029] In the ice removal method, the separation step in step S4, the removal step in step S5, and the removal step in step S6 are repeated until all of the block ice 14 has melted and removal is complete (step S3: Yes).

[0030] Thus, the ice removal method for an ice condenser in this embodiment is a method for removing block ice 14 from an ice condenser 10 in which cylindrical block ice 14 is stored in a cylindrical basket 13 arranged in an ice condenser chamber 11, and includes a separation process for separating the basket 13 and the block ice 14 using a cylindrical drill 21, and a removal process for removing the separated block ice 14 from the basket 13.

[0031] According to this ice removal method for an ice condenser, the basket 13 and the block ice 14 are separated by a cylindrical drill 21, so that the block ice 14 stuck to the basket 13 can be easily removed from the basket 13, reducing the burden on workers. Moreover, according to this ice removal method for an ice condenser, because the basket 13 and the block ice 14 are separated and removed by a drill 21, an enormous amount of heat is not required compared to, for example, melting the block ice 14 by heat, and it is also unnecessary to treat the water produced by melting the block ice 14, which amounts to a total of several hundred tons.

[0032] In the embodiment of the ice removal method for an ice condenser, the block ice 14 is stored in a basket 13 supported by support plates 18 attached at multiple points in the vertical direction of a hanging wire 17, and after the block ice 14 is removed from the basket 13, the method further includes a removal process of removing the support plates 18 supporting the removed block ice 14, and the separation process, removal process, and removal process are repeated.

[0033] According to this method for removing ice from an ice condenser, by removing the support plate 18 that supports the block ice 14, the block ice 14 underneath the support plate 18 can be removed.

[0034] In the ice removal method for an ice condenser in the embodiment, the support plate 18 is made of a magnetic material, and the removal step involves removing the support plate 18 by the magnet 23.

[0035] According to this method for removing ice from an ice condenser, the support plate 18 made of a magnetic material is removed by the magnet 23, so that the removal process can be easily performed.

[0036] In the ice removal method for an ice condenser in the embodiment, the drill 21 includes a claw 21b that can be engaged with the block of ice 14, and the removal step involves holding the block of ice 14 with the claw 21b and removing it.

[0037] According to this method for removing ice from an ice condenser, the block of ice 14 is held and removed by the claws 21b of the drill 21, so that the separation step and removal step can be carried out as a series of operations, thereby improving work efficiency.

[0038] The present disclosure includes the following inventions. [Invention 1] A method for removing cylindrical block ice from an ice condenser in which cylindrical block ice is stored in a cylindrical basket disposed in a cooling chamber, comprising: A separation step of separating the basket and the block of ice by a cylindrical drill; A removing step of removing the separated block of ice from the basket; 16. A method for removing ice from an ice condenser, comprising: [Invention 2] The block ice is supported by support plates fixed at multiple points in the height direction of the hanging wire and stored in the basket, The block ice is removed from the basket, and the support plate supporting the block ice is removed. A method for removing ice from an ice condenser as described in Invention 1. [Invention 3] The support plate is made of a magnetic material, The removing step removes the support plate by a magnet. A method for removing ice from an ice condenser according to claim 2. [Invention 4] the drill includes a claw capable of engaging with the block of ice; The removal step includes holding and removing the block of ice with the claws. A method for removing ice from an ice condenser according to any one of claims 1 to 3. [Explanation of symbols]

[0039] 10 Ice Condenser 13. Basketball 14 Block Ice 18 Support plate 21 Drill 21b Claws 23 Magnet

Claims

1. A method for removing cylindrical block ice from an ice condenser in which cylindrical block ice is stored in a cylindrical basket disposed in a cooling chamber, comprising: A separation step of separating the basket and the block of ice by a cylindrical drill; A removing step of removing the separated block of ice from the basket; 16. A method for removing ice from an ice condenser, comprising:

2. The block ice is supported by support plates fixed at multiple points in the height direction of the hanging wire and stored in the basket, The block ice is removed from the basket, and the support plate supporting the block ice is removed.

2. The method for removing ice from an ice condenser according to claim 1.

3. The support plate is made of a magnetic material, The removing step removes the support plate by a magnet. The method for removing ice from an ice condenser according to claim 2.

4. the drill includes a claw capable of engaging with the block of ice; The removal step includes holding and removing the block of ice with the claws.

2. The method for removing ice from an ice condenser according to claim 1.

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