JP6238074B2 - Water stoppage method for underwater leakage - Google Patents

Description

  The present invention relates to a water stopping method for an underwater water leakage portion, in which the water leakage portion is stopped at a location where a water flow exists.

  For example, in a nuclear power plant, a very severe accident occurred, such as damage to the reactor pressure vessel or the containment vessel, or melting of nuclear fuel contained in the reactor pressure vessel. In some cases, it is necessary to repair or remove them. Since these severe troubles may occur simultaneously or in combination, it is required to repair damaged parts in each container when taking out fuel debris generated by melting of nuclear fuel.

  Here, for example, when a reactor pressure vessel (hereinafter sometimes abbreviated as “pressure vessel”) is damaged and leakage of cooling water occurs, a reactor containment vessel (hereinafter, referred to as “pressure vessel”) is accommodated. Cooling water flows from the dry well (which may be abbreviated as a containment vessel) into the pressure suppression chamber through the vent pipe. Furthermore, the cooling water flows out from a part of the pressure suppression chamber, so that the floor of the building where the containment vessel is installed may be flooded with the cooling water. Such a large amount of leaked water is undesirable from the viewpoint of workability at the time of accident convergence work and environmental conservation. It is necessary to perform repair work.

  The leakage water due to the damage of the containment vessel as described above flows out from the downcomer communicated with the vent pipe, and the pressure suppression chamber is flooded. In such a case, in order to stop the leaked water, it is necessary to block the downcomer or the like that is the leak path in the leaked water flooded in the pressure suppression chamber. Examples of such a method for stopping the water leakage portion existing in water include a method of embedding the water leakage portion by placing a mortar material in the water and stopping the water, for example, water that hardens in water. It is conceivable to use non-separable mortar (see, for example, Patent Documents 1 and 2). In this case, the underwater inseparable mortar before curing needs to have sufficient proof strength against the water pressure acting in the water leakage part. It is necessary to make it thick so that the water pressure can be resisted by the weight of the inseparable mortar in water.

  However, when the cooling water W2 leaks from the dry well 102 to the pressure control unit 103 as in the storage container 100 shown in FIG. 4, the cooling water WR of the downcomer 106 serving as the water leakage part of the cooling water WA When the water pressure becomes very high, it is necessary to sufficiently counter the water pressure by the weight of the underwater non-separable mortar MR by placing a huge amount of underwater inseparable mortar MR and forming it thick. . On the other hand, depending on the location of the water leaking part 106a in the containment vessel 100, there are places where it is difficult to place the underwater non-separable mortar MR thickly. As a result, it may be difficult to repair the damaged part.

JP 63-067311 A JP 2009-184891 A

  The present invention has been made in view of the above problems, and even if water leaks due to damage to the container and there is a water leakage portion in the water, water can be reliably stopped by a simple method. It aims at providing the water stop method of an underwater leakage part.

First, the first invention of the present invention is a method for stopping water in water leakage portion of the water shut-off the leakage portion present in the water in the reactor containment vessel, the reactor containment, at least the leakage portion A primary placement step of placing an underwater inseparable mortar M1 so as to cover the water and forming a water-stopping layer; then, after the water-stopping layer is cured, the primary placement from the upstream side of the water leakage portion Aggregates having a larger average particle size than the aggregates contained in the underwater non-separable mortar M1 were contained so as to fill the water channel communicating with the water leakage portion generated in the water blocking layer after the step. And a secondary placement step of placing the underwater inseparable mortar M2.

According to the water stopping method of the underwater leakage portion having such a configuration, first, in the primary placing step, the underwater inseparable mortar M1 is placed in the reactor containment vessel with a thickness that covers the leakage portion. After forming the water-stopping layer, in the secondary casting process, from the upstream side of the water leakage part, the water channel communicating with the water leaking part generated in the water blocking layer after the primary casting process is filled with water. Since it is a method of placing the underwater inseparable mortar M2 containing an aggregate having an average particle diameter larger than that of the aggregate contained in the inseparable mortar M1, while suppressing the placement thickness of the underwater inseparable mortar. Sufficient yield strength can be ensured with respect to the water pressure acting in the water leakage portion. Thereby, in the reactor containment vessel, even when there is a water leakage part in a place where it is difficult to place the underwater inseparable mortar thickly, by placing the underwater inseparable mortar thinly, It is possible to easily form a water blocking layer having sufficient proof stress. Further, since it is not necessary to place an enormously heavy underwater non-separable mortar, the repair cost can be reduced. Therefore, even if water leaks due to damage to the reactor containment vessel and there is a water leakage portion in the water, it is possible to reliably stop the water by a simple method.

  Moreover, the second invention in the present invention is the water shutoff method for an underwater leakage portion configured as described above, wherein the underwater non-separable mortar M2 used in the secondary placing step is larger than the average pore diameter of the water channel. It contains an aggregate having an average particle size.

  According to the water stopping method of the underwater leakage portion having such a configuration, the secondary casting step includes an aggregate having an average particle size larger than the average pore size of the water channel generated after the primary casting step. By using the underwater inseparable mortar M2, it is possible to reliably embed the water channel, so that a reliable water stop treatment is possible.

  According to the water stoppage method of the underwater leakage portion according to the present invention, the above configuration first places the underwater non-separable mortar M1 in the container with a thickness that covers the leakage portion in the primary placement step. After forming the water-stopping layer, in the secondary casting process, from the upstream side of the water leakage part, the water channel communicating with the water leaking part generated in the water blocking layer after the primary casting process is filled with water. Since it is a method of placing the underwater inseparable mortar M2 containing an aggregate having an average particle diameter larger than that of the aggregate contained in the inseparable mortar M1, while suppressing the placement thickness of the underwater inseparable mortar. Sufficient yield strength can be ensured with respect to the water pressure acting in the water leakage portion. As a result, even if there is a water leaking part in a container where it is difficult to place the underwater inseparable mortar thickly, the underwater inseparable mortar can be provided with sufficient strength. It is possible to easily form a water-stopping layer comprising Further, since it is not necessary to place an enormously heavy underwater non-separable mortar, the repair cost can be reduced. Therefore, even if water leaks due to damage to the container and there is a water leaking part in the water, there is an excellent effect that water can be reliably stopped by a simple method.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining typically the water stop method of the underwater leakage part which is one Embodiment of this invention, and when stopping the water leak part which exists in water with a reactor containment vessel, an underwater non-separable mortar in a container It is the schematic which shows the water leak path | route in a container in the state before driving | running | working. It is a figure explaining typically the water stop method of the underwater leakage part which is one embodiment of the present invention, and in the primary placement process, it is an underwater non-separable mortar in a container so that the leakage part which exists in water may be covered. It is the schematic which shows the state which casted and formed the water stop layer. It is a figure explaining typically the water stop method of the underwater water leakage part which is one embodiment of the present invention, and occurs in the water stop layer after the primary placement process from the upstream side of the water leakage part in the secondary placement process. It is the schematic which shows the state which laid the underwater non-separable mortar containing an aggregate so that the water channel connected to the water leakage part may be filled. It is the schematic shown about the water stop method of the conventional underwater leakage part.

  Hereinafter, an example of the water stop method of the underwater leakage part which is embodiment of this invention is given, and the structure is explained in full detail, referring FIGS. 1-3.

  The water stopping method for the underwater water leakage portion of the present embodiment is a water stopping method for the underwater water leakage portion that stops the water leakage portion existing in the water in the container 1. And the water stop method of this embodiment is the primary placement process which forms the water stop layer 8 by placing the water non-separable mortar M1 in the container 1 so as to cover at least the water leakage part, After the water layer 8 is cured, it is contained in the underwater non-separable mortar M1 so as to be filled with a water channel 8A communicating with the water leakage portion generated in the water blocking layer 8 after the primary placing process from the upstream side of the water leakage portion. And a secondary placing step of placing an underwater inseparable mortar M2 containing an aggregate having an average particle size larger than that of the aggregate.

  Here, the water leakage part described in the present invention is an opening 6a of the downcomer 6 whose details will be described later. Although the detailed structure will be described later, the cooling water W2 from the dry well 2 constituting the container 1 should not be used. This is a portion that serves as a water outlet to the internal space of the pressure suppression chamber 3 through the vent pipe 4 when water leakage occurs.

[Vessel (Containment Vessel)]
As a container 1 to be repaired in the water stopping method of the present embodiment, for example, as shown in FIG. 1, in a nuclear power plant, a nuclear reactor house that houses a reactor pressure vessel 7 containing nuclear fuel therein. A container (PCV: Primary Containment Vessel) is mentioned.

  This container (containment vessel) 1 is disposed so as to surround a dry well 2 (Dry Well) 2 in which a reactor pressure vessel 7 is accommodated and a dry well 2 at the bottom of the vessel 1 as shown in the figure. An annular pressure suppression chamber (suppression pool) 3 and a vent pipe 4 provided between the dry well 2 and the pressure suppression chamber 3 are schematically configured. The container 1 is installed in a reactor building made of a reinforced concrete structure (not shown). In addition to an emergency core cooling system pump, the reactor building further includes a fuel pool and a purification facility. Etc. are accommodated and installed.

  As described above, the dry well 2 is a large steel vessel in which the reactor pressure vessel 7 is accommodated. In the illustrated example, the dry well 2 is configured as a round bottom flask.

  Although the pressure suppression chamber 3 is a steel container and detailed illustration is omitted, the vertical cross-sectional shape is circular and the plan view shape is circular so as to surround the lower portion of the dry well 2 as described above. Or it is comprised by the polygonal cyclic | annular form. Normally, a predetermined amount of stored water W1 is accommodated in the pressure suppression chamber 3. In the unlikely event that the pressure suppression chamber 3 is damaged in the container 1 and the internal pressure rises due to the generation of steam, the internal pressure of the pressure suppression chamber 3 is reduced by introducing the steam to the pressure suppression chamber 3 through a vent pipe 4 to be described later. Has the function of lowering. Furthermore, in the unlikely event that the reactor cooling function is lost due to a severe accident, the stored water W1 can be supplied as emergency cooling water.

  The vent pipe 4 is provided between the dry well 2 and the pressure suppression chamber 3 as described above, and is made of steel that guides the vapor to the pressure suppression chamber 3 when the vapor leaks from the dry well 2. It is piping. Although the detailed illustration of the vent pipe 4 is omitted, a plurality of vent pipes 4 are arranged at equal intervals in a plan view.

  A vent header 5 is connected near the tip of the vent pipe 4 accommodated in the pressure suppression chamber 3. The vent header 5 is a pipe arranged substantially concentrically with the pressure suppression chamber 3 in the inside of the pressure suppression chamber 3, and communicates with a plurality of vent pipes 4 in the vicinity of the tip of the vent pipe 4. To be connected.

  Further, a downcomer 6 is attached to the vent header 5. The downcomer 6 is a substantially inverted U-shaped (substantially inverted V-shaped) tubular member in the illustrated example, and both ends facing downward are openings 6a, and the top (intermediate portion) is The vent header 5 is connected to communicate with the vent header 5. Further, although the detailed illustration of the downcomer 6 is omitted, a plurality of downcomers 6 are arranged at equal intervals along the vent header 5 in plan view. Thereby, the container 1 is configured so that the internal space of the pressure suppression chamber 3 and the vent pipe 4 communicate with each other through the downcomer 6.

  Moreover, when the stored water W1 is accommodated in the pressure suppression chamber 3, the opening part 6a is arrange | positioned under the water surface. And the opening part 6a of the downcomer 6 becomes a water leak part covered with the underwater non-separable mortar by the water stop method of this embodiment.

  As described above, for example, when a severe accident occurs in a nuclear power plant and the container 1 is also damaged, depending on the damaged state, the cooling water W2 accommodated inside the pressure vessel 7 leaks out of the container. It is assumed that the reactor building will be flooded. At this time, the opening 6a of the downcomer 6 that is a water leakage part is in a state existing in the stored water W1, but in order to smoothly proceed with the work of extracting nuclear fuel in the pressure vessel 7 toward the convergence of the accident, It is necessary to repair the damaged portion after water-stopping the opening 6a and stopping the leakage of the cooling water W2.

  As described above, the water stop method according to the present embodiment stops high-pressure water leakage (cooling water W2) in the conventional water stop method in order to stop the opening 6a which is a water leak portion existing in the stored water W1. In order to increase the yield strength, the underwater inseparable mortar had to be cast thick, while the underwater inseparable mortar (water-stopping layer 8) was placed to This is a method that can provide sufficient yield strength. That is, even in the case where the opening 6a of the downcomer 6 serving as a water leaking portion exists in a portion where it is difficult to place a thick underwater non-separable mortar in the pressure suppression chamber 3 of the container 1, it is ensured by a simple method. It is a method that can stop the water.

[Water stop method]
Below, the procedure and conditions are explained in full detail about the primary placement process and secondary placement process with which the water stop method of the underwater layer water part of this embodiment is equipped.

(Primary placement process)
In the water stop method of the present embodiment, as shown in FIG. 2, first, in the primary placing step, the inside of the pressure suppression chamber 3 of the container 1 is thick enough to cover the opening 6 a of the downcomer 6 that becomes a water leakage portion. An underwater non-separable mortar M1 is cast to form the water blocking layer 8. At this time, for example, as shown in FIG. 2, a driving tube 9 is inserted from the internal space of the dry well 2 toward the vent tube 4, and the underwater inseparable mortar M <b> 1 is discharged through the driving tube 9. A method of performing placement can be employed. Further, the discharge speed of the underwater inseparable mortar M1 at this time can be set as appropriate.

  As shown in FIG. 2, the casting thickness of the underwater non-separable mortar M1 in the primary casting process may be such that the height of the water blocking layer 8 is slightly higher than the opening 6a facing downward. As long as it exceeds 500 to 1000 mm. Moreover, it does not specifically limit as the whole thickness of the water stop layer 8, It can set suitably according to the size of the container 1, ie, the pressure suppression chamber 3, and arrangement | positioning of the downcomer 6 inside.

  Here, in the primary placement process of the present embodiment, a condition is adopted in which a water groove 8A communicating with the opening 6a is easily generated by forming the water blocking layer 8 thin. For example, when the pressure vessel 7 is damaged and the cooling water W2 leaks out, the water channel 8 is connected to the cooling water W2 so as to communicate with the opening 6a of the downcomer 6 through the vent pipe 4 from the dry well 2. This occurs in the water stop layer 8 due to the high pressure of the water, and if it is left as it is, it causes water leakage. In the water stop method of the present embodiment, the water stop layer 8 is thinly formed, which is a condition in which the water channel 8A is likely to be generated. On the other hand, by embedding the water channel 8A in the secondary placing process described later, Sufficient yield strength can be obtained with respect to the water pressure of the cooling water W2 acting on the opening 6a.

(Secondary placement process)
In the water stopping method of the underwater formation water part of this embodiment, as shown in FIG. 3, a secondary placement process is further performed after the primary placement process of the said procedure. In this secondary casting process, after the water-stopping layer 8 formed in the primary casting process was hardened, it was generated in the water-stopping layer 8 after the primary casting process from the upstream side of the opening 6a which is a water leakage part. An underwater inseparable mortar M2 containing an aggregate having a larger average particle diameter than the aggregate contained in the underwater inseparable mortar M1 is placed so as to fill the water channel 8A.

  In the secondary placement process, as in the primary placement process described above, the underwater non-separable mortar M2 is discharged using the placement pipe 9 inserted from the internal space of the dry well 2 toward the vent pipe 4. Can be placed. At this time, as shown in FIG. 3, the non-separable mortar M2 after discharge is first embedded so as to cause clogging in the water channel 8A formed so as to communicate with the opening 6a. Furthermore, it is driven so as to enter the inside of the downcomer 6 from the opening 6a. Thereby, the opening 6a is completely blocked by the water-stopping layer 8 formed from the underwater non-separable mortar M2 and is in a water-stopped state. Here, similarly to the primary placing step, the discharge speed of the underwater non-separable mortar M2 at this time can also be set as appropriate.

(Combination of primary placement process and secondary placement process)
In the present embodiment, as described above, first, a method of completely embedding the water channel 8A in the secondary placement process while suppressing the placement thickness of the underwater non-separable mortar M1 in the primary placement process is adopted. Yes. Thereby, compared with the past (refer FIG. 4), it is with respect to the water pressure of the cooling water W2 which acts in the opening part 6a which is a water leakage part, although it is the conditions which form the water stop layer 8 thinly. It becomes possible to form the water blocking layer 8 having sufficient proof stress.

  Therefore, even in the case where the opening 6a of the downcomer 6 serving as the water leakage portion exists in the pressure suppression chamber 3 where it is difficult to place a thick underwater inseparable mortar, the underwater inseparable mortar M1 ( By placing M2) thinly, it becomes possible to easily form the water stop layer 8 having sufficient strength against the water pressure of the cooling water W2. Further, unlike the prior art, it is not necessary to place an enormously heavy underwater inseparable mortar M1 (M2), so that the repair cost can be reduced.

(Underwater inseparable mortar)
In the present embodiment, the underwater inseparable mortars M1 and M2 used for repairing / stopping water leakage are not particularly limited, and any common underwater inseparable mortar material used for the purpose of curing in water. Can be used without limitation. Examples of such underwater inseparable mortars include Taiheiyo Material Co., Ltd .: Preeurolex LC-MIX (registered trademark). Further, the underwater inseparable mortar M2 used in the secondary placement step contains an aggregate having an average particle size larger than that of the aggregate contained in the underwater inseparability mortar M1 used in the primary placement step.

  Furthermore, in this embodiment, about the water non-separable mortar M2 used in a secondary placement process, an average particle diameter larger than the average pore diameter of the water channel 8A formed in the water stop layer 8 after the primary placement process. It is preferable to contain the aggregate. Thus, in the secondary placing step, the water channel 8A is reliably embedded by using the underwater non-separable mortar M2 containing the aggregate having an average particle diameter larger than the average pore size of the water channel 8A. Therefore, a reliable water stop treatment is possible.

  Here, the pore diameter of the water channel 8A generated in the water blocking layer 8 varies depending on the casting conditions such as the thickness of the underwater inseparable mortar M1 and the curing conditions in the primary casting process. In this embodiment, if the average particle diameter of the aggregate contained in the underwater inseparable mortar M2 used in the secondary placing step is equal to or larger than the average pore diameter of the water channel 8A, the water channel 8A is reliably embedded. Can do.

  In addition, as above-mentioned, when the thing containing the aggregate more than the average pore diameter of water channel 8A is used as the underwater non-separable mortar M2 used in the secondary placement process, the underwater non-separation used in the primary placement process. As for the property mortar M1, the same as the underwater inseparable mortar M2 may be used.

[Function and effect]
As described above, according to the water stopping method of the underwater leakage part of the present embodiment, with the above-described configuration, first, in the primary placement step, with a thickness that covers the opening 6a of the downcomer 6 that becomes the leakage part, After the water non-separable mortar M1 is placed in the pressure suppression chamber 3 of the container 1 to form the water-stopping layer 8, the primary placement step is performed from the upstream side of the opening 6a in the secondary placement step. After that, the water containing the aggregate 8A having an average particle size larger than the aggregate contained in the underwater non-separable mortar M1 so as to fill the water channel 8A communicating with the opening 6a generated in the water blocking layer 8 is contained. Since it is a method of placing the non-separable mortar M2, it is possible to ensure a sufficient proof strength against the water pressure acting on the opening 6a while suppressing the casting thickness of the underwater non-separable mortar M1 (M2). Thereby, even in the case where the opening 6a of the downcomer 6 exists in a place where it is difficult to place the underwater inseparable mortar M1 (M2) thickly in the pressure suppression chamber 3, the underwater inseparable mortar By placing M1 (M2) thinly, it is possible to easily form the water stop layer 8 having sufficient proof stress. Further, since it is not necessary to place an enormously heavy underwater inseparable mortar M1 (M2), the repair cost can be reduced. Therefore, even if water leaks due to damage to the container 1 and there is a water leaking part in the water, there is an excellent effect that water can be reliably stopped by a simple method.

  In addition, each structure in those embodiment demonstrated above, those combinations, etc. are examples, and addition, omission, substitution, and other change of a structure are possible in the range which does not deviate from the meaning of this invention. Further, the present invention is not limited by the above-described embodiment, and is limited only by the scope of the claims.

  According to the water stopping method of the underwater leakage part of the present invention, by adopting the above configuration, it becomes possible to reliably stop the water leakage part at the location where the water flow exists, particularly in a nuclear power plant, In the unlikely event of a severe accident, the workability when repairing the reactor containment vessel is remarkably improved, and the accident convergence work can be carried out efficiently, contributing to environmental protection and other aspects. The degree is high.

1 ... Vessel (Reactor containment vessel, containment vessel)
2 ... Drywell,
3 ... Pressure suppression chamber,
4 ... vent pipe,
5 ... Vent header,
6 ... Downcomer,
6a ... Opening (water leakage part, water leakage part),
7 ... Reactor pressure vessel (pressure vessel),
8 ... water stop layer,
8A ... Mikami,
9 ... Laying pipe,
M1, M2 ... Underwater inseparable mortar,
W1 ... Reserved water,
W2 ... Cooling water.

Claims (2)

A water stopping method for an underwater water leakage portion that stops a water leakage portion existing in water in a reactor containment vessel,
A primary placement step of placing a water non-separable mortar M1 in the reactor containment vessel so as to cover at least the water leakage portion to form a water stop layer;
Then, after the water-stopping layer is cured, the underwater non-water-filling is filled from the upstream side of the water-leaking portion so as to fill a water channel communicating with the water-leaking portion generated in the water-stopping layer after the primary placing step. A secondary placing step of placing an underwater non-separable mortar M2 containing an aggregate having an average particle size larger than that of the aggregate contained in the separable mortar M1; Water-stopping method.   The underwater leakage according to claim 1, wherein the underwater separable mortar M2 used in the secondary placing step includes an aggregate having an average particle diameter larger than an average pore diameter of the water channel. Water-stopping method.

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