JP2014106041A - Nuclear reactor containment and method of constructing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide nuclear reactor containment capable of suppressing erosion of a concrete layer by a meltdown object to secure soundness during a severe accident such as meltdown, and a method of constructing the same capable of applying to existing nuclear reactor containment.SOLUTION: Nuclear reactor containment includes: a reactor pressure vessel 4; a pedestal 5 that is provided on a foundation part 2a so as to support the reactor pressure vessel 4; and a concrete layer 6 having a lower side first concrete layer 22 that is provided on the foundation part 2a in the pedestal 5 and includes concrete using limestone as aggregate and an upper side second concrete layer 23 including concrete using aggregate whose generation rate of a gas during thermal decomposition is smaller than limestone.

Description

  The present invention relates to a reactor containment vessel and a construction method thereof.

  The reactor containment vessel, which is one of the engineering safety equipment of nuclear power plants, is required to maintain the function of confining radioactivity even in the event of an accident in the reactor.

  In the unlikely event that a severe accident occurs in which the core in the reactor pressure vessel stored inside the reactor containment vessel melts, the core melt will be transferred from the reactor pressure vessel to the concrete of the foundation of the reactor containment vessel. May fall on top. If the core melt falls on the concrete, the core melt may erode the concrete, impairing the sealing property of the reactor containment vessel, and may impair the soundness of the reactor containment vessel. In addition, non-condensable gases such as carbon dioxide and hydrogen are generated by the reaction between the core melt and concrete. Since these non-condensable gases increase the pressure in the reactor containment vessel, the soundness of the reactor containment vessel may be impaired when the pressure limit is exceeded.

  As countermeasures against such severe accidents, techniques described in Patent Documents 1 to 3 have been proposed.

  The technique described in Patent Document 1 provides a core catcher having a steel main body portion that is located below a reactor pressure vessel and has a plurality of cooling channels in which cooling water flows.

  In addition, the technique described in Patent Document 2 uses a heat-resistant material on the inner wall of the pedestal, the lower part of the outer wall, and the pedestal floor installed in the reactor containment vessel, and the floor in the reactor containment vessel and the lower part of the inner wall. It is laid.

  In addition, the technique described in Patent Document 3 includes a coarse aggregate made of a high-melting-point and high-density material in a wall surface and a floor surface structure forming a pedestal region located below the reactor pressure vessel. It is formed from concrete.

JP 2007-225356 A Japanese Patent Application Laid-Open No. 5-5795 JP 2005-337733 A

  If the technique described in Patent Document 1 is applied to an existing reactor containment vessel, a control rod drive mechanism and instrumentation piping are arranged below the reactor pressure vessel, so that the installation space May not be secured.

  Moreover, although the technique of patent document 2 is applicable to the existing reactor containment vessel with little installation space, since the heat-resistant tile used as a heat-resistant material is a block shape, the joint between each heat-resistant material is made into heat-resistant. Additional work is required to plug with some filler. Further, it is difficult to mechanize the laying operation of the heat resistant tile because the space in the pedestal is narrow, and there is a problem that the laying operation takes time and cost.

  In addition, the technique described in Patent Document 3 uses a concrete having a coarse aggregate made of a high-melting-point and high-density material when the core melt erodes the concrete, so that the gap between the concrete and the core melt is reduced. In addition, a solid crust (lower crust) with good thermal insulation is formed to suppress erosion of concrete. Specifically, an aggregate made of a mixture of a high melting point and high specific gravity material such as W or Ta and concrete having a decomposition temperature and density lower than that of the aggregate are integrally formed at the bottom of the reactor containment vessel. By providing in the corresponding part, the eutectic mixture of the aggregate component and the core melt is formed at the boundary between the concrete and the core melt.

  In this way, it is described that the particulate concrete decomposition product does not prevent the cooling water from penetrating the upper surface of the core melt by depositing on the upper surface of the core melt, but this phenomenon may occur. There is only in the vicinity of the side wall where the core melt is less likely to fall, and the core melt continues to fall mainly from the bottom of the reactor pressure vessel located at the center of the pedestal region, so this technology It is not enough to prevent the formation of a solid crust (upper crust) formed on the upper part.

  Since the core melt is mainly cooled from the upper surface, if the upper part of the core melt is cooled by water injection to form a solidified crust with good thermal insulation, sufficient cooling from the upper surface of the core melt is hindered. Thus, there is a possibility that the erosion of the concrete cannot be suppressed even if the lower crust is formed.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to suppress the erosion of the concrete layer by the core melt in a severe accident such as core melting and to ensure soundness. The present invention provides a reactor containment vessel that can be applied to an existing reactor containment vessel and a method for constructing the same.

In order to solve the above problems, for example, the configuration described in the claims is adopted.
The present application includes a plurality of means for solving the above-mentioned problems. To give an example, a reactor pressure vessel, a pedestal installed on a base so as to support the reactor pressure vessel, and the pedestal The first concrete layer on the lower side including concrete using limestone as an aggregate, and an aggregate that generates less gas than limestone when pyrolyzed are provided on the foundation portion inside. And a concrete layer having an upper second concrete layer containing concrete.

According to the present invention, the concrete layer is composed of a first concrete layer on the lower side using limestone as an aggregate and an upper side using an aggregate that generates less gas than limestone when pyrolyzed. In the unlikely event of an accident where the core melt falls into the concrete layer, the erosion of the concrete layer by the core melt is suppressed and the reactor containment vessel is sound. Sex can be secured.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is a schematic cross-sectional view of an improved boiling water reactor building to which a first embodiment of a reactor containment vessel of the present invention is applied. It is an expanded sectional view which shows the concrete layer which comprises 1st Embodiment of the nuclear reactor containment vessel of this invention shown in FIG. It is the top view which looked at the concrete layer which comprises 1st Embodiment of the nuclear reactor containment vessel of this invention from the III-III arrow of FIG. It is explanatory drawing which shows the erosion state by the core melt of the concrete layer which comprises 1st Embodiment of the nuclear reactor containment vessel of this invention. It is an expanded sectional view which shows the concrete layer which comprises the modification of 1st Embodiment of the nuclear reactor containment vessel of this invention. It is the top view which looked at the concrete layer which comprises the modification of 1st Embodiment of the nuclear reactor containment vessel of this invention from the VI-VI arrow view of FIG. It is an expanded sectional view which shows the concrete layer which comprises 2nd Embodiment of the nuclear reactor containment vessel of this invention. It is the top view which looked at the concrete layer which comprises 2nd Embodiment of the nuclear reactor containment vessel of this invention from the VIII-VIII arrow of FIG. It is an expanded sectional view which shows the concrete layer which comprises 3rd Embodiment of the nuclear reactor containment vessel of this invention. It is an expanded sectional view which shows the concrete layer which comprises the modification of 3rd Embodiment of the nuclear reactor containment vessel of this invention.

Hereinafter, embodiments of a reactor containment vessel and a construction method thereof according to the present invention will be described with reference to the drawings.
1 to 3 show a first embodiment of a reactor containment vessel according to the present invention. FIG. 1 shows an improved boiling water type to which the first embodiment of a reactor containment vessel according to the present invention is applied. 2 is a schematic cross-sectional view of the reactor building, FIG. 2 is an enlarged cross-sectional view showing a concrete layer constituting the first embodiment of the reactor containment vessel of the present invention shown in FIG. 1, and FIG. 3 is an arrow III-III in FIG. It is the top view which looked at the concrete layer which comprises 1st Embodiment of the nuclear reactor containment vessel of this invention from the view.

  In FIG. 1, a reactor containment vessel 2 is installed in a reactor building 1 of an improved boiling water reactor (ABWR). In this example, the reactor containment vessel 2 is made of reinforced concrete lined with a steel liner 3, and sealability and pressure resistance are ensured.

  A reactor pressure vessel 4 containing a core (not shown) is stored in the reactor containment vessel 2. The reactor pressure vessel 4 is supported by a substantially cylindrical pedestal 5 erected on the base portion 2 a of the reactor containment vessel 2. The pedestal 5 is provided with an opening (not shown) so that an operator can enter the pedestal 5 at the time of inspection or the like. A pedestal cavity 9 is formed below the reactor pressure vessel 4 inside the pedestal 5.

  A control rod drive mechanism 7 for driving the control rod and an instrumentation pipe (not shown) are arranged below the reactor pressure vessel 4. A diaphragm floor 8 is bridged between the side wall 2 b of the reactor containment vessel 2 and the pedestal 5. The diaphragm floor 8 divides the inside of the reactor containment vessel 2 into a dry well 10 and a wet well 11.

  The dry well 10 is a space around the reactor pressure vessel 4 above the diaphragm floor 8. The wet well 11 is a space around the pedestal 5 below the diaphragm floor 8. The dry well 10 and the wet well 11 communicate with each other through a vent pipe 13. The vent pipe 13 guides the steam from the dry well 10 to the wet well 11 when the steam flows into the dry well 10 due to a coolant loss accident or the like. The steam guided to the wet well 11 is condensed by the suppression pool water 12 of the wet well 11 and the pressure increase in the reactor containment vessel 2 is suppressed.

  A water supply pipe 14 is connected to the reactor pressure vessel 4, and during normal operation, water from a condenser (not shown) installed in the turbine building via the water supply pipe 14 is supplied to a water supply pump (not shown). ) To the reactor pressure vessel 4. The water supply pipe 14 is provided with a connection plug 15 that can be connected to a fire hose so that cooling water can be alternatively injected into the reactor pressure vessel 4 from a water source outside the power plant in the event of an accident.

  The reactor pressure vessel 4 is connected to an emergency core cooling system pipe 16. The piping 16 is for injecting cooling water into the reactor pressure vessel 4 at the time of an accident.

  A spray nozzle 17 of a reactor containment vessel spray system is installed on the upper part of the reactor containment vessel 2. The spray nozzle 17 is for spraying the cooling water into the reactor containment vessel 2 at the time of the accident, and the steam generated at the time of the accident is condensed by the spraying of the cooling water, and the pressure rise in the reactor containment vessel 2 is suppressed. The

  The emergency core cooling system and the containment vessel spray system are cooled by an emergency diesel pump (not shown) using the condensate or suppression pool water 12 stored in a condensate storage tank (not shown) in the event of an accident as a water source. It has a structure where water is supplied. Moreover, the emergency core cooling system and the reactor containment vessel spray system have a structure in which cooling water can be supplied from a water source outside the power plant using a fire hose or the like even when the emergency diesel pump does not operate.

  The water supply pipe 14, the pipe 16, and the spray nozzle 17 provided with the connection plug 15 function as a coolant supply unit that supplies coolant to the inside of the pedestal 5 from a water source outside the power plant at the time of an accident in which the core melts.

  A gas composition analysis sensor 18 is installed on the side wall 2 b of the reactor containment vessel 2 and the inner wall of the pedestal 5. The gas composition analysis sensor 18 measures the concentration of gas components (for example, hydrogen, carbon monoxide, carbon dioxide, etc.) in the reactor containment vessel 2.

  A concrete layer 6 is provided on the foundation portion 2 a of the reactor containment vessel 2 inside the pedestal 5. The concrete layer 6 receives the core melt 101 when a severe accident in which the core melts occurs and the core melt 101 falls from the reactor pressure vessel 4 into the pedestal cavity 9.

Next, the detailed structure of the concrete layer 6 mentioned above is demonstrated using FIG.2 and FIG.3.
2 and 3, the concrete layer 6 has a first concrete layer 22 on the lower side and a second concrete layer 23 on the upper side. The concrete layer 6 has reinforcing bars 21 arranged therein.

  The first concrete layer 22 on the lower side is formed of concrete using an aggregate (for example, limestone) that generates a large amount of gas when pyrolyzed. Limestone is a sedimentary rock mainly composed of calcium carbonate (CaCO3). When limestone comes into contact with the high-temperature core melt 101, a large amount of non-condensable gas such as carbon monoxide and carbon dioxide and water vapor are generated.

  The second concrete layer 23 on the upper side is made of concrete using an aggregate (for example, basalt) that generates a small amount of gas when pyrolyzed, and has a thickness of about 30 to 60 cm. Basalt is an igneous rock containing about 50% silicon dioxide (SiO 2) and containing magnesium oxide (MgO), iron oxide (FeO), calcium oxide (CaO) and the like. Even if the basalt comes into contact with the high-temperature core melt 101, the amount of non-condensable gas generated is small.

  The present embodiment can be applied to a new reactor containment vessel, and has a concrete layer formed of concrete using aggregate (for example, limestone) that generates a large amount of gas when pyrolyzed. It can be applied to existing reactor containment vessels. The construction method of this embodiment in these cases will be described.

  In the case of a new reactor containment vessel, after the pedestal 5 is installed in the reactor containment vessel 2, the reinforcing bars 21 are arranged on the foundation 2 a of the reactor containment vessel 2 inside the pedestal 5. Next, concrete mixed with limestone, cement, sand, and water is placed on the arranged foundation portion 2a. When the concrete is hardened, the first concrete layer 22 on the lower side is formed.

  Thereafter, concrete mixed with basalt, cement, sand, and water is placed on the first concrete layer 22 on the lower side. As the concrete hardens, a second concrete layer 23 on the upper side is formed. In this way, the concrete layer 6 is formed in an upper and lower two-layer structure in which reinforcing bars 21 are arranged.

  In the case of an existing reactor containment vessel, equipment necessary for the construction of the concrete layer 6 is carried into the pedestal 5 from an opening (not shown) of the pedestal 5. Next, the existing concrete layer is used as the first concrete layer 22 on the lower side, and the reinforcing bars 21 are arranged on the first concrete layer 22 on the lower side (existing concrete layer).

  Then, concrete using basalt as aggregate is placed on the first concrete layer 22 (existing concrete layer) on the lower side. As the concrete hardens, a second concrete layer 23 on the upper side is formed. In this way, the concrete layer 6 is formed in an upper and lower two-layer structure in which the existing concrete layer is the first concrete layer 22 on the lower side and the reinforcing bars 21 are arranged.

Next, the operation of the first embodiment of the reactor containment vessel of the present invention during a severe accident will be described with reference to FIGS. 1 and 4.
FIG. 4 is an explanatory view showing an erosion state of the concrete layer constituting the first embodiment of the reactor containment vessel of the present invention by the core melt. In FIG. 4, the same reference numerals as those shown in FIGS. 1 to 3 are the same parts, and detailed description thereof is omitted.

  As shown in FIG. 1, when a severe accident occurs in which the operation of multiple safety devices fails more than expected at the time of design due to a transient event or a loss of coolant accident due to pipe breakage, etc., the core (not shown) ) Melts and melts the liquid, solid, or mixed core melt 101 in the instrumentation pipe (not shown) and the control rod drive mechanism 7 installed in the lower part of the reactor pressure vessel 4. It is assumed that the concrete layer 6 falls. Specifically, this is a case where the DC power source is lost due to a tsunami or the like, and the emergency diesel pump fails to start and water cannot be injected into the reactor pressure vessel 4.

  When such a severe accident occurs, alternative injection for supplying cooling water from an external water source such as a fire hydrant to the water supply pipe 14 and the piping 16 of the emergency core cooling system is performed by a fire hose or the like. This alternative injection is defined as accident management (AM).

  The cooling water, which is alternatively injected into the reactor pressure vessel 4 by the accident management, cools the core melt 101 spread on the second concrete layer 23 on the upper side from the upper surface. Further, cooling water from an external water source is sprayed from the spray nozzle 17 and a part of this cooling water falls into the pedestal cavity 9 to cool the core melt 101 from the upper surface.

  At this time, the second concrete layer 23 on the upper side of the concrete layer 6 is eroded by the heat of the core melt 101, but the second concrete layer 23 on the upper side uses basalt as an aggregate. Even if the core melt 101 is decomposed by heat, the amount of non-condensable gas generated is small. For this reason, the pressure rise in the reactor containment vessel 2 is suppressed.

  If the core melt 101 is sufficiently cooled by the above-described alternative water injection while the erosion of the concrete layer 6 by the core melt 101 remains in the second concrete layer 23 on the upper side, the inside of the reactor containment vessel 2 The increase in pressure is suppressed, and the soundness of the reactor containment vessel 2 is ensured.

  On the other hand, as shown in FIG. 4, even if the core melt is cooled from the upper surface by the above-described alternative water injection, if the solid upper crust 102 having high thermal insulation is formed on the core melt 101, the cooling is performed. There is a possibility that heat transfer between the water 104 and the core melt 101 is hindered by the upper crust 102 and the core melt 101 cannot be sufficiently cooled from the upper surface.

  In this case, the core melt 101 erodes and penetrates the second concrete layer 23 on the upper side and reaches the first concrete layer 22 on the lower side of the concrete layer 6. On the other hand, the solid upper crust 102 is separated from the core melt 101 and remains in the upper second concrete layer 23 so as to close the opening of the eroded portion of the upper second concrete layer 23. . For this reason, a space 103 is formed between the core melt 101 and the upper crust 102.

  When the core melt 101 reaches the first concrete layer 22 on the lower side, the aggregate (limestone) of the first concrete layer 22 on the lower side reacts with the core melt 101 to generate a large amount of non-condensable gas. To do. This non-condensable gas passes through the core melt 101 and is discharged into the space 103. For this reason, the upper crust 102 is pressed from the inside by an increase in the pressure in the space 103, and finally, the pressure exceeds the yield stress of the upper crust 102, and the upper crust 102 is damaged.

  When the upper crust 102 is damaged, a part of the core melt 101 and high-temperature gas flow out from the damaged hole of the upper crust 102 and the cooling water 104 flows into the space 103 from the damaged hole of the upper crust 102. As a result, the cooling of the core melt 101 is promoted, so that the erosion of the lower first concrete layer 22 by the core melt 101 is suppressed, and the soundness of the reactor containment vessel 2 is ensured.

  In this process, a large amount of non-condensable gas is generated. When the core melt 101 erodes the concrete layer 6 and penetrates the wall of the reactor containment vessel 2, contaminated water containing radionuclides is stored in the reactor. Because there is a risk of being released to the outside of the vessel 2, the method of stopping the erosion of the concrete layer 6 by the core melt 101 rather than the suppression of the pressure increase in the reactor containment vessel 2 in which other pressure suppression means such as a vent exist. is important.

  Further, the concentration of the gas component in the reactor containment vessel 2 is measured by the gas composition analysis sensor 18 installed in the reactor containment vessel 2 and the pedestal 5. By analyzing this measured value, the erosion state of the concrete layer 6 by the core melt 101 is grasped. For example, when the concentration of non-condensable gases such as carbon monoxide and carbon dioxide has not risen above a predetermined value during a severe accident, the core melt 101 remains in the second concrete layer 23 on the upper side. Determined. On the other hand, when the concentration of the non-condensable gas rises above a predetermined value, it is determined that the core melt 101 has reached the first concrete layer 22 on the lower side.

  As described above, according to the first embodiment of the reactor containment vessel of the present invention and the construction method thereof, the concrete layer 6 is composed of the first concrete layer 22 on the lower side using limestone as an aggregate, Since it was formed with the second concrete layer 23 on the upper side using an aggregate that generates less gas than limestone when pyrolyzed, accidents such as the core melt 101 falling on the concrete layer 6 occur. Even when one occurs, the erosion of the concrete layer 6 by the core melt can be suppressed and the soundness of the reactor containment vessel 2 can be ensured.

  Furthermore, according to the present embodiment, the concrete layer 6 uses limestone and basalt as aggregates, and therefore is less expensive than those using a high melting point, high-density metal material or the like as aggregates.

  Moreover, according to this Embodiment, since concrete is cast on the existing concrete layer and the concrete layer 6 is formed, it can be applied to an existing reactor containment vessel at a low cost and in a short period of time.

  Furthermore, according to the present embodiment, the floor surface of the concrete layer 6 applied to the existing reactor containment vessel is higher than the floor surface of the existing concrete layer, and the concrete volume increases. The time that can be spent increases, and the risk that the core melt 101 reaches the foundation portion 2a of the reactor containment vessel 2 can be reduced.

  Moreover, according to this Embodiment, the erosion state of the concrete layer 6 by the core melt 101 can be grasped | ascertained by measuring the density | concentration of the gas component in the reactor containment vessel 2 with the gas composition analysis sensor 18. FIG. .

  Furthermore, according to the present embodiment, since the cooling water 104 is supplied from the external water source to the inside of the pedestal 5 through the water supply pipe 14, the pipe 16 and the spray nozzle 17 as the coolant supply unit, the core melts. Cooling of the thing 101 is accelerated | stimulated and the soundness of the reactor containment vessel 2 can further be ensured.

Next, a modification of the first embodiment of the reactor containment vessel of the present invention will be described with reference to FIGS.
FIG. 5 is an enlarged cross-sectional view showing a concrete layer constituting a modification of the first embodiment of the reactor containment vessel of the present invention, and FIG. 6 is a view of the reactor containment vessel according to the present invention from the VI-VI arrow in FIG. It is the top view which looked at the concrete layer which comprises the modification of 1st Embodiment of this. 5 and FIG. 6, the same reference numerals as those shown in FIG. 1 to FIG. 4 are the same parts, and detailed description thereof is omitted.

  The modification of the first embodiment of the reactor containment vessel of the present invention shown in FIGS. 5 and 6 is configured in substantially the same way as the first embodiment, but the first of the lower side of the concrete layer 6 is configured. The difference is that a plurality (six in FIG. 6) of temperature detectors 51 for measuring the temperature in the concrete layer 6 are installed between the concrete layer 22 and the second concrete layer 23 on the upper side.

  The temperature detector 51 includes a measurement plate 52, a plurality of thermocouples 53 (two or three in FIG. 6) as temperature detectors attached to the measurement plate 52, and an instrumentation device connected to the thermocouple 53. Lead wire 54. The measuring plate 52 is made of a material having a heat insulating property, and protects the lead wire 54. The lead wire 54 is connected to a thermocouple temperature measuring device (not shown) so that the temperature of the observation point can be measured.

Next, the construction method of the modified example of 1st Embodiment of the reactor containment vessel of this invention mentioned above is demonstrated.
Similar to the construction method of the first embodiment described above, the lower first concrete layer 22 is formed. Thereafter, a plurality of temperature detectors 51 are installed on the surface of the first concrete layer 22 on the lower side. Next, the second concrete layer 23 on the upper side is formed on the first concrete layer 22 on the lower side where the temperature detector 51 is installed, as in the construction method of the first embodiment. In this manner, a plurality of thermocouples 53 are embedded between the first concrete layer 22 on the lower side of the concrete layer 6 and the second concrete layer 23 on the upper side.

  According to the modification of the first embodiment of the reactor containment vessel of the present invention described above and the construction method thereof, in the unlikely event that an accident in which the core melt 101 falls on the concrete layer 6 occurs, the concrete The temperature in the layer 6 can be measured by the thermocouple 53. As a result, the erosion state of the concrete layer 6 by the core melt 101 and the deterioration state of the concrete of the concrete layer 6 due to the thermal effect of the core melt 101 can be estimated from the temperature measurement values in the concrete layer 6.

  In addition, according to the present embodiment, since the temperature detector 51 having a plurality of thermocouples 53 is installed, a plurality of thermocouples 53 can be installed at one time, and the number of local work man-hours is more than installing one thermocouple 53 one by one. Can be reduced.

Next, a second embodiment of the reactor containment vessel of the present invention will be described with reference to FIGS.
FIG. 7 is an enlarged cross-sectional view showing a concrete layer constituting the second embodiment of the reactor containment vessel of the present invention, and FIG. 8 is a second view of the reactor containment vessel of the present invention from the arrow VIII-VIII in FIG. It is the top view which looked at the concrete layer which comprises this embodiment. 7 and 8, the same reference numerals as those shown in FIGS. 1 to 6 are the same parts, and detailed description thereof is omitted.

  The second embodiment of the reactor containment vessel of the present invention shown in FIGS. 7 and 8 is when the first concrete layer 22 on the lower side of the concrete layer 6 of the first embodiment is pyrolyzed. It is made entirely of concrete using aggregates that generate a large amount of gas (for example, limestone), whereas aggregates that generate a small amount of gas when pyrolyzed (for example, basalt) are used. By excavating a plurality of holes in the central part of the concrete that is formed entirely, and filling those holes with concrete using aggregate (for example, limestone) with a large amount of gas generation when pyrolyzed, The difference is that the first concrete layer 22 on the lower side is formed.

  Specifically, a plurality of first concrete layers 22 on the lower side are arranged at intervals in the central portion inside the pedestal 5 and aggregates (for example, limestone) that generate a large amount of gas when pyrolyzed. A concrete using a first concrete part 31 formed of concrete using slag and an aggregate (for example, basalt) which is disposed around the first concrete part 31 and generates a small amount of gas when pyrolyzed. It is comprised with the formed 2nd concrete part 32. FIG.

  The first concrete portion 31 is arranged at a position where the core melt 101 is assumed to expand in a severe accident. When the core melt 101 erodes to the first concrete layer 22 on the lower side, the core melts. It reacts with the product 101 to generate a large amount of non-condensable gas.

  Since this embodiment can be applied to an existing nuclear reactor containment vessel provided with a concrete layer formed of concrete using aggregate (for example, basalt) that generates less gas when pyrolyzed, The construction method of this embodiment in this case will be described.

  In the center of an existing concrete layer (concrete layer formed of concrete using aggregate (for example, basalt) that generates little gas when pyrolyzed), a plurality of the concrete layers are spaced apart from each other while avoiding the reinforcing bars 21 The hole 33 is drilled. Each hole 33 is filled with concrete using an aggregate that generates a large amount of gas when pyrolyzed. When the concrete is hardened, the first concrete portion 31 is formed, and the first concrete layer 22 on the lower side composed of the first concrete portion 31 and the second concrete portion 32 is formed.

  Next, reinforcing bars 21 are arranged on the first concrete layer 22 on the lower side, and the concrete using the aggregate that generates less gas when pyrolyzed is placed on the first concrete layer 22 on the lower side. The second concrete layer 23 on the upper side is formed by casting.

  According to the second embodiment of the reactor containment vessel of the present invention and the construction method thereof, the same effects as those of the first embodiment and the construction method described above can be obtained.

Next, a third embodiment of the containment vessel of the present invention will be described with reference to FIG.
FIG. 9 is an enlarged cross-sectional view showing a concrete layer constituting the third embodiment of the reactor containment vessel of the present invention. In FIG. 9, the same reference numerals as those shown in FIGS. 1 to 8 are the same parts, and detailed description thereof is omitted.

  The third embodiment of the reactor containment vessel of the present invention is that the concrete layer 6 of the first embodiment has an upper and lower two-layer structure, whereas the concrete layer 6 has an upper and lower three-layer structure. Different.

  9 includes a first concrete layer 22 on the lower side, a second concrete layer 23 on the upper side, and a third concrete located below the first concrete layer 22 on the lower side. Layer 24. The third concrete layer 24 is a concrete layer in an existing reactor containment vessel, and is formed of concrete using an aggregate (for example, basalt) that generates a small amount of gas when pyrolyzed.

  This embodiment is applied when there is sufficient space in the pedestal cavity 9 in the existing reactor containment vessel to which the second embodiment can be applied.

  In the present embodiment, the lower first concrete layer 22 and the upper concrete layer 22 are formed on the existing concrete layer (third concrete layer 24) in the same manner as in the construction method of the first embodiment described above. By forming the second concrete layer 23, the concrete layer 6 having an upper and lower three-layer structure is formed.

  According to the third embodiment of the reactor containment vessel of the present invention described above, the same effect as that of the first embodiment described above can be obtained.

  Further, according to the present embodiment, excavation of a hole is made in an existing concrete layer (third concrete layer 24) formed of concrete using aggregate that generates less gas when pyrolyzed. Therefore, the construction work of the concrete layer 6 can be performed in a shorter period of time and at a lower cost.

  In addition, according to the present embodiment, the floor surface of the concrete layer 6 is higher than the floor surface of the concrete layer composed of two layers, and the concrete volume increases, so that time that can be spent on accident management is increased. Furthermore, the risk that the core melt 101 reaches the base portion 2a of the reactor containment vessel 2 can be further reduced.

Next, a modification of the third embodiment of the reactor containment vessel of the present invention will be described with reference to FIG.
FIG. 10 is an enlarged cross-sectional view showing a concrete layer constituting a modification of the third embodiment of the reactor containment vessel of the present invention. In FIG. 10, the same reference numerals as those shown in FIGS. 1 to 9 are the same parts, and detailed description thereof is omitted.

  The third embodiment of the reactor containment vessel of the present invention shown in FIG. 10 is configured in substantially the same manner as the third embodiment, but the first concrete layer 22 on the lower side of the concrete layer 6 and the upper part thereof. A plurality of temperature detectors 51 for measuring the temperature in the concrete layer 6 are installed between the second concrete layer 23 on the side and between the first concrete layer 22 and the third concrete layer 24 on the lower side. Is different.

  According to the modification of the third embodiment of the reactor containment vessel of the present invention described above, between the first concrete layer 22 on the lower side of the concrete layer 6 and the second concrete layer 23 on the upper side, and Since the thermocouple 53 is installed between the first concrete layer 22 and the third concrete layer 24 on the lower side, the temperature in the concrete layer 6 can be measured in more detail. As a result, it becomes easier to grasp the erosion state of the concrete layer 6 by the core melt.

  In the modification of the first to third embodiments described above, an aggregate that generates a small amount of gas when the second concrete layer 23 on the upper side is pyrolyzed is used. Although an example in which only the concrete is formed is shown, the second concrete layer 23 on the upper side is a bone that generates a small amount of gas when the portion where the core melt 101 is expanded in a severe accident is thermally decomposed. What is necessary is just to be formed with the concrete using a material. For example, the central portion of the second concrete layer 23 is formed of concrete using an aggregate that generates a small amount of gas when pyrolyzed, and the portion surrounding the central portion generates gas when pyrolyzed. It can also be made of concrete using a lot of aggregate.

  Moreover, in 2nd Embodiment mentioned above, although the example which has arrange | positioned the 1st concrete part 31 with the space | interval in the center part inside the pedestal 5 was shown, one 1st concrete part 31 is shown. It can also arrange | position so that the whole center part may be occupied.

  In the second embodiment described above, an example in which a plurality of first concrete portions 31 are arranged at intervals in the central portion has been shown. However, the first concrete portion 31 is a base portion inside the pedestal 5. A plurality can be arranged on the entire surface of 2a at intervals.

  Also in the second embodiment described above, a temperature detector can be installed in the concrete layer 6.

  In the modification of the first and third embodiments described above, an example in which the thermocouple 53 is used as the temperature detector is shown, but a resistance thermometer or the like can also be used as the temperature detector.

  Further, the present invention is not limited to the modifications of the first to third embodiments described above, and includes various modifications. The above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to the one having all the configurations described. For example, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is also possible to add, delete, or replace another configuration for a part of the configuration of each embodiment.

2 Reactor containment vessel 2a Foundation part 4 Reactor pressure vessel 5 Pedestal 6 Concrete layer 14 Water supply pipe (coolant supply part)
15 Connection plug 16 Piping (coolant supply part)
17 Spray nozzle (coolant supply part)
18 Gas composition analysis sensor 22 1st concrete layer 23 2nd concrete layer 24 3rd concrete layer 31 1st concrete part 32 2nd concrete part 33 Hole 51 Temperature detection body 53 Thermocouple (temperature detector)
101 Core melt 104 Cooling water (coolant)

Claims (9)

A reactor pressure vessel;
A pedestal installed on the foundation to support the reactor pressure vessel;
A first concrete layer on the lower side provided on the foundation portion inside the pedestal and containing concrete using limestone as an aggregate, and an aggregate that generates less gas than limestone when pyrolyzed. A reactor containment vessel comprising a concrete layer having an upper-side second concrete layer containing the used concrete. The reactor containment vessel according to claim 1,
The reactor containment vessel characterized in that the second concrete layer is made of concrete using basalt as an aggregate. The reactor containment vessel according to claim 2,
A reactor containment vessel, characterized in that a temperature detector is installed between the first concrete layer and the second concrete layer. The reactor containment vessel according to claim 2 or 3,
The first concrete layer is disposed at least in the center, and is disposed around the first concrete part formed of concrete using limestone as an aggregate, and basalt as an aggregate. A reactor containment vessel characterized by comprising a second concrete portion formed of concrete using slag. The reactor containment vessel according to claim 2 or 3,
The concrete layer further includes a third concrete layer formed of concrete using an aggregate that generates less gas than limestone when pyrolyzed under the first concrete layer. Characteristic reactor containment vessel. The reactor containment vessel according to claim 2 or 3,
A reactor containment vessel further comprising a gas composition analysis sensor for measuring a concentration of an internal gas component. The reactor containment vessel according to claim 2 or 3,
A reactor containment vessel further comprising a coolant supply unit that supplies coolant from an external water source into the pedestal during an accident. A method for constructing a reactor containment vessel in which concrete is placed on a foundation in a pedestal that supports a reactor pressure vessel,
Placing concrete using limestone as an aggregate on the foundation inside the pedestal to form a first concrete layer on the lower side;
At least a second concrete layer on the upper side is formed on the first concrete layer on the lower side by placing concrete using an aggregate that generates less gas than limestone when pyrolyzed. A method for constructing a reactor containment vessel, comprising: a process. In the construction method of the containment vessel according to claim 8,
Installing a temperature detector on the surface of the lower first concrete layer;
And a step of forming the second concrete layer on the upper side on the first concrete layer on the lower side on which the temperature detector is installed.

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