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 block ice containing a water-soluble polymer stored in a basket provided in an ice condenser chamber is provided, the method comprising a step of melting the block ice while preventing gelation of the water-soluble polymer, and a step of removing water of the melted block ice out of the ice condenser chamber.SELECTED DRAWING: Figure 5

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 circumference of a cylindrical block of ice containing borax 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 nuclear reactors where it is expected that the reactor containment vessel will be filled with high-temperature steam in the event of an abnormality, ice condensers are sometimes installed to cool and condense the high-temperature steam with ice that absorbs a large amount of heat. In such ice condensers, 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 and turns 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. 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] However, the water vapor produced by the sublimation of the ice circulates within the ice condenser chamber, where it is cooled again and becomes frost, which then 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.

[0006] As methods for removing ice from the basket, there are two methods: removing the ice individually and melting the ice to remove it as water. The former method places a heavy burden on workers, while the latter method requires the disposal of a large amount of melted liquid when melting ice in bulk. As mentioned above, when polyvinyl alcohol (PVA), a water-soluble polymer film, is used, depending on the melting temperature, the PVA reacts with borax to generate a gel-like solid, making it difficult to remove the ice as water. As methods for removing stuck ice, there are two methods: individually releasing the stuck ice and adjusting the temperature of the ice condenser chamber to melt the ice. In this case, too, the former method places a heavy burden on workers, while the latter method requires the suppression of the generation of a gel-like solid.

[0007] 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]

[0008] In order to achieve the above-mentioned object, a method for removing ice from an ice condenser according to one embodiment of the present disclosure is a method for removing block ice from an ice condenser in which block ice containing a water-soluble polymer is stored in a basket placed in a cooling chamber, the method including the steps of melting the block ice while preventing gelation of the water-soluble polymer, and removing water from the melted block ice to the outside of the cooling chamber. Effect of the Invention

[0009] The present disclosure provides a method for reducing the burden on workers and making it easier to remove ice. [Brief description of the drawings]

[0010] [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 flowchart of a method for removing ice from an ice condenser according to an embodiment. [Figure 6] FIG. 6 is a flowchart of another ice removal method for an ice condenser according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 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.

[0012] FIG. 1 is a schematic diagram of a reactor containment vessel to which the ice condenser of the embodiment is applied.

[0013] 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.

[0014] 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.

[0015] 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 (also called block ice) 14, a duct 15, and an air conditioner 16.

[0016] 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.

[0017] A support grid 12 is disposed within the ice condenser chamber 11 between the upper deck door 11A and the lower deck door 11B.

[0018] 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.

[0019] As shown in FIG. 3, the block ice 14 is formed into a cylindrical shape. The block ice 14 is arranged in a vertically stacked manner 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 (cruciform) 18 are inserted from the side of the wire 17 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 from the side of the wire 17 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] However, in the ice condenser 10, there are several thousand baskets 13 and the total weight of the block ice 14 is several thousand tons, so the work of removing the block ice 14 is very burdensome. Also, 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 turns into frost, which adheres to the block ice 14 and basket 13 and hardens, so it can be difficult to remove the block ice 14 from the basket 13.

[0024] Therefore, the ice condenser 10 of the embodiment includes a configuration for easily taking out and removing the block ice 14. As shown in Fig. 2, the ice condenser 10 includes a water collecting section 21, a storage section 22, a delivery section 23, and the air conditioner 16 described above.

[0025] The water collecting portion 21 constitutes a funnel extending downward from the lower portion of the support grid 12 .

[0026] The reservoir 22 is a container connected to the lower part of the water collecting part 21 .

[0027] The delivery section 23 includes an external storage section 23A provided outside the ice condenser chamber 11, a delivery pipe 23B connecting the external storage section 23A and the storage section 22, and a pump 23C provided on the delivery pipe 23B.

[0028] FIG. 5 is a flowchart of a method for removing ice from an ice condenser according to an embodiment.

[0029] As shown in FIG. 5, in the ice removal method for the ice condenser 10 of the embodiment, first, the ice condenser chamber 11 is set to a predetermined temperature (step S1). The predetermined temperature is a temperature that melts the block ice 14 while preventing gelation of the water-soluble polymer. Specifically, the predetermined temperature is greater than 0° C. and less than 20° C. In addition, the predetermined temperature is preferably within the above range of 5° C.±5° C. As a result, only a part (adhered part) or all of the block ice 14 melts and turns into water (melt water), which is collected by the water collecting section 21 and stored in the storage section 22. When only a part of the block ice 14 is melted, the remaining part is removed in ice form.

[0030] Next, the water in the melted block ice 14 is removed to the outside of the ice condenser chamber 11 (Step S2). In Step S2, pump 23C of delivery unit 23 is operated to send the water in storage unit 22 to external storage unit 23A via delivery pipe 23B. The ice removal method repeats the operations of Steps S1 and S2 until all of the block ice 14 has melted and been removed (Step S3: Yes).

[0031] FIG. 6 is a flowchart of another ice removal method for an ice condenser according to an embodiment.

[0032] In another ice removal method, as shown in FIG. 6, when the block ice 14 is removed in chunks (step S11: Yes), if the block ice 14 is not stuck and can be removed in chunks (step S12: Yes), the block ice 14 is removed as usual (step S13-1), and this is continued until all the block ice 14 is removed (step S10: Yes). Also, if the block ice 14 is stuck and cannot be removed in chunks (step S12: No), the block ice 14 is individually released (step S14: Yes) or multiple blocks are released at the same time (step S14: No). In the former case (step S14: Yes), the ice is released using a release tool or the like (step S15), and the block ice 14 is removed (step S13-2). In the latter case (step S14: No), the ice condenser chamber 11 is set to a predetermined temperature (step S16). The predetermined temperature is a temperature at which the block ice 14 melts while preventing the water-soluble polymer from gelling. Specifically, the predetermined temperature is higher than 0°C and lower than 20°C. The predetermined temperature is preferably within the above range of 5°C±5°C. As a result, a part or all of the block ice 14 melts and becomes water (melt water), which is collected by the water collecting unit 21 and stored in the storage unit 22. When only a part of the block ice 14 is melted (step S17: Yes), the remaining part is taken out in ice form (step S13-3). Some of the water in the melted block ice 14 is taken out of the ice condenser chamber 11. On the other hand, when the entire block ice 14 is melted (step S17: No), the water in the melted block ice 14 is taken out of the ice condenser chamber 11 (step S18). To take the water in the block ice 14 out of the ice condenser chamber 11, the pump 23C of the delivery unit 23 is operated to send the water in the storage unit 22 to the external storage unit 23A via the delivery pipe 23B. In the other ice removal method, the operations from step S14 to step S18 are repeated until all the blocks of ice 14 have melted and removal is complete (step S10: Yes).

[0033] On the other hand, in another ice removal method, as shown in FIG. 6, when the block ice 14 is not removed in chunks (step S11: No), the ice condenser chamber 11 is set to a predetermined temperature (step S19). The predetermined temperature is a temperature that melts the block ice 14 while preventing the water-soluble polymer from gelling. Specifically, the predetermined temperature is greater than 0° C. and less than 20° C. In addition, the predetermined temperature is preferably within the above range of 5° C.±5° C. As a result, the block ice 14 melts and turns into water, which is collected by the water collection section 21 and stored in the storage section 22.

[0034] Next, in the other ice removal method, the water in the melted block ice 14 is removed outside the ice condenser chamber 11 (step S20). In step S20, pump 23C of delivery unit 23 is operated to send the water in storage unit 22 to external storage unit 23A via delivery pipe 23B. Then, in the other ice removal method, the operations from step S19 to step S20 are repeated until all of the block ice 14 has melted and been removed (step S10: Yes).

[0035] Thus, the ice removal method for an ice condenser in this embodiment is a method for removing block ice 14 in an ice condenser 10 in which block ice 14 containing a water-soluble polymer is stored in a basket 13 arranged in an ice condenser chamber 11, and includes a step of melting the block ice 14 while preventing gelation of the water-soluble polymer, and a step of removing the water from the melted block ice 14 to the outside of the ice condenser chamber 11.

[0036] According to this method for removing ice from an ice condenser, the block ice 14 is melted while preventing gelation of the water-soluble polymer, so the generation of solid matter is reduced, and the block ice 14 can be removed as water, making it easy to remove the ice. Moreover, according to this method for removing ice from an ice condenser, the block ice 14 can be removed as water, so the human load of removing the block ice 14, which weighs a total of several thousand tons, can be reduced, reducing the load on workers and making it easy to remove the ice. Moreover, according to this method for removing ice from an ice condenser, the block ice 14 can be removed as water, so even if the block ice 14 is solidified with frost, it can be melted and the ice can be easily removed.

[0037] In the method for removing ice from an ice condenser in the embodiment, the temperature inside the ice condenser chamber 11 is set to above 0°C and below 20°C.

[0038] According to this method for removing ice from an ice condenser, by setting the temperature inside ice condenser chamber 11 to above 0°C and below 20°C, gelation of the water-soluble polymer can be reduced.

[0039] The ice removal method for an ice condenser in the embodiment further includes a step of removing the unmelted block ice 14 and the melted block ice 14, or the water in the melted block ice 14, from the basket 13.

[0040] According to this method for removing ice from an ice condenser, by removing the block ice 14 from the basket 13, the burden of treating the melted water can be reduced compared to removing all of the ice with water.

[0041] The method for removing ice from an ice condenser in the embodiment includes a step of storing water inside the ice condenser chamber 11 and a step of pumping the water out of the ice condenser chamber 11.

[0042] According to this method for removing ice from an ice condenser, water is stored inside the ice condenser chamber 11 and then pumped out of the ice condenser chamber 11, thereby reducing the impact on existing drainage equipment compared to discharging melted water outside the ice condenser chamber 11.

[0043] In the ice condenser ice removal method in the embodiment, a temperature difference is created between the upper and lower parts of the ice condenser chamber 11, making the lower part hotter than the upper part. Specifically, in the ice condenser ice removal method, heat is input from the lower part of the ice condenser chamber 11. For example, heat is input to the lower part of the ice condenser chamber 11 by taking in outside air using a heater or a blower. Alternatively, for example, a heat source such as a heater is installed in the lower part of the ice condenser chamber 11. This makes it easier to melt the block ice 14 at the lower part that has adhered to the basket 13.

[0044] The present disclosure includes the following inventions. [Invention 1] 1. A method for removing block ice from an ice condenser in which block ice containing a water-soluble polymer is stored in a basket disposed in a cooling chamber, comprising: melting the block ice while preventing gelation of the water-soluble polymer; removing the water from the melted block ice to the outside of the cooling chamber; 16. A method for removing ice from an ice condenser, comprising: [Invention 2] The temperature inside the cooling chamber is set to more than 0°C and less than 20°C. A method for removing ice from an ice condenser as described in Invention 1. [Invention 3] The method further includes a step of removing the block ice before melting and the melted block ice, or the water of the melted block ice from the basket. A method for removing ice from an ice condenser according to claim 1 or 2. [Invention 4] storing the water within the cooling chamber; pumping the water out of the cooling chamber; Including, A method for removing ice from an ice condenser according to any one of claims 1 to 3. [Invention 5] A temperature difference is generated between the upper and lower parts of the cooling chamber, making the lower part hotter than the upper part. A method for removing ice from an ice condenser according to any one of claims 1 to 4. [Explanation of symbols]

[0045] 10 Ice Condenser 11 Ice Condenser Room 13. Basketball 14 Block Ice

Claims

1. 1. A method for removing block ice from an ice condenser in which block ice containing a water-soluble polymer is stored in a basket disposed in a cooling chamber, comprising: melting the block ice while preventing gelation of the water-soluble polymer; removing the water from the melted block ice to the outside of the cooling chamber; 16. A method for removing ice from an ice condenser, comprising:

2. The temperature inside the cooling chamber is set to more than 0°C and less than 20°C.

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

3. The method further includes a step of removing the block ice before melting and the melted block ice, or the water of the melted block ice from the basket.

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

4. storing the water within the cooling chamber; sucking and pumping the water out of the cooling chamber; Including, 2. The method for removing ice from an ice condenser according to claim 1.

5. A temperature difference is generated between the upper and lower parts of the cooling chamber, making the lower part hotter than the upper part.

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

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