JP2006047062A - Irradiation test reactor and fuel assembly for it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an irradiation test reactor where an irradiation field on the same condition of neutron-beam or gamma-ray irradiation is formed mutually in each in-pile loop and which enables tests under the environment of temperature, pressure and an atmospheric medium that are independent from an object for loops to be irradiated that is located in each in-pile loop and under the same condition of neutron-beam or gamma-ray irradiation and fuel assemblies for the irradiation test reactor. <P>SOLUTION: The irradiation test reactor 1 includes a reactor vessel 2, a core tank 3 which is stowed in the vessel 2 and where a core 32 is composed and in-pile loops 4 which are inserted and located in the tank 3 and guides an atmospheric medium to the core 32 and enables the irradiation of the object TR to be irradiated that is located in the core 32. Additionally, the reactor 1 is characterized in that the core tank 3 is so constituted that the layout of the fuel assemblies 10 is identical as viewed from each in-pile loop 4 by locating the in-pile loops 4 in the core tank 3 and laying out fuel assemblies 10 around the in-pile loops 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an irradiation test reactor and a fuel assembly for an irradiation test reactor. Irradiation fields having the same neutron or gamma irradiation conditions are formed in each in-pile loop, and are arranged in each in-pile loop. The present invention relates to an irradiation test furnace and an irradiation test furnace fuel assembly that can be tested under an environment of independent temperature, pressure, and atmospheric medium, and under the same neutron or gamma irradiation conditions.

  In nuclear power facilities such as nuclear reactors, an irradiation test is performed on the structural materials constituting the nuclear reactor and the fuel for the nuclear reactor. Such an irradiation test is performed in an irradiation test furnace capable of forming a predetermined irradiation field. As a conventional irradiation test reactor, JMTR (Japan Materials Testing Reactor) of the Japan Atomic Energy Research Institute is known (see Non-Patent Document 1).

  In a conventional irradiation test reactor, an in-pile loop is inserted into a reactor vessel core, and a plurality of fuel assemblies are arranged in the reactor core so as to surround the in-pile loop. The core was configured. In such a conventional irradiation test furnace, a high-temperature and high-pressure atmosphere medium (coolant such as water or gas) circulates in the inpile loop, so that the atmosphere medium is guided into the core through the inpile loop. Thereby, an irradiation environment close to an actual nuclear reactor is simulated with a simple and inexpensive configuration.

  Here, in a conventional irradiation test reactor, a plurality of in-pile loops may be arranged in the reactor vessel, but only one in-pile loop is arranged in the reactor core. The fuel assemblies were arranged in an annular shape with respect to a single impile loop.

  Further, in the conventional irradiation test furnace, a fuel assembly is configured by laminating thin plate-like fuel plates. Such fuel assemblies are arranged to constitute a core, and a capsule insertion tube is disposed around the core. The irradiated body (irradiated body for insertion tube) was accommodated in the capsule and placed in the capsule insertion tube, and irradiation was performed at this position.

Japan Atomic Energy Research Institute Oarai Research Institute JMTR brochure

  In the present invention, an irradiation field having the same neutron or gamma irradiation condition is formed in each in pile loop, and independent temperature and pressure are applied to the loop irradiation object arranged in each in pile loop. Another object of the present invention is to provide an irradiation test furnace and a fuel assembly for the irradiation test furnace that can perform tests under the environment in an atmospheric medium and under the same neutron or gamma irradiation conditions.

  In order to achieve the above object, an irradiation test reactor according to the present invention is installed in a reactor vessel, a reactor core vessel that is housed in the reactor vessel and constitutes a reactor core, and is inserted into the reactor vessel. And an in-pile loop that guides the atmosphere medium to the core, and in an irradiation test reactor capable of irradiating an irradiated object arranged in the core, a plurality of the in-pile loops are provided in the core tank. The core tank is configured so that the fuel assemblies are arranged around the in-pile loop, and the arrangement of the fuel assemblies is the same as viewed from each in-pile loop. To do.

  In this irradiation test reactor, the core tank is configured so that the arrangement of the fuel assemblies is the same as seen from each in-pile loop. Therefore, in each in-pile loop, the same neutron or gamma-ray irradiation conditions are mutually applied. An irradiation field is formed. Therefore, an irradiation field having the same neutron or gamma irradiation condition is formed in each impile loop, and the temperature, pressure, and atmosphere independent of the loop irradiation object disposed in each impile loop. There is an advantage that the test can be performed under the environment in the medium and under the same neutron or gamma irradiation conditions.

  Further, in the irradiation test reactor according to the present invention, the core tank is configured so that the core tank has a substantially cylindrical shape, and the array including the impile loop and the fuel assembly is substantially circular as a whole. Yes.

  Further, in this irradiation test furnace, the core tank has a substantially cylindrical shape, and the core tank is configured so that the array of the impile loop and the fuel assembly is substantially circular as a whole. Such a configuration has an advantage that the configuration of the irradiation test reactor can be downsized because the arrangement space loss in the reactor core tank can be reduced when the impile loop and the fuel assembly are arranged.

  Further, in the irradiation test reactor according to the present invention, the core tank is configured such that a plurality of fuel assemblies can be arranged in a ring shape and one of the impile loops is surrounded by the arranged fuel assemblies.

  In the irradiation test furnace 1, a plurality of fuel assemblies are arranged in an annular shape so as to surround one impile loop in the fuel assembly arrangement state. In such a configuration, since the fuel assemblies are arranged in an annular shape, neutrons or gamma rays are irradiated from around the irradiated object for the loop in the in-pile loop. Thereby, there exists an advantage which can implement | achieve efficient irradiation.

  Further, in the irradiation test furnace according to the present invention, fuel assemblies having a hexagonal cross section can be arranged, and six fuel assemblies can be arranged in an annular shape by adjoining the sides of the hexagons. And the said core tank is comprised so that the said impile loop may be inserted in the ring which consists of this fuel assembly.

  Further, in this irradiation test reactor, fuel assemblies having a hexagonal cross section are arranged in the arrangement state of the fuel assemblies, and the six fuel assemblies have their hexagonal sides adjacent to each other. An in-pile loop is inserted into a ring composed of these fuel assemblies. In such a configuration, the number of fuel assemblies surrounding one impile loop is small as compared to a configuration in which a large number of small-diameter fuel assemblies are used to surround the impile loop. As a result, the fuel rods are densely arranged in the core tank, and the core is constituted by a small number of fuel assemblies. Therefore, there is an advantage that the configuration of the core is simplified. In this irradiation test furnace, the following fuel assembly is preferably employed (hereinafter the same). That is, the fuel assembly is configured by bundling a plurality of fuel rods. Further, the fuel rod is composed of, for example, low enriched uranium dioxide having a concentration of less than 20% as a fuel material. In addition, each fuel rod is arranged so that three adjacent rods form an equilateral triangle in a plan view (triangular arrangement), and are bundled and arranged so as to form a hexagonal lattice structure as a whole.

  Further, in the irradiation test reactor according to the present invention, the ring composed of the six fuel assemblies can be continuously arranged in plural while sharing a fuel assembly constituting a part thereof with an adjacent ring. In addition, the core tank is configured such that the impile loops are respectively arranged with respect to these rings.

  Further, in this irradiation test reactor, in the fuel assembly arrangement state, the ring composed of the six fuel assemblies described above shares the fuel assembly constituting a part thereof with the adjacent ring. A plurality of them are continuously arranged, and an impile loop is arranged for each of these rings. In such a configuration, a plurality of impile loops are surrounded by a smaller number of fuel assemblies as compared to a configuration in which a plurality of rings each composed of fuel assemblies are arranged separately and independently. As a result, the fuel assemblies are densely arranged in the core tank, and such an arrangement is constituted by a small number of fuel assemblies. Therefore, there is an advantage that the configuration of the core is simplified.

  In the irradiation test reactor according to the present invention, the fuel assemblies arranged in the reactor core tank have a hexagonal lattice structure as a whole of a plurality of fuel rods made of low enriched uranium dioxide having an enrichment of less than 20%. In addition, an insertion hole for the irradiated object for the assembly is formed on the central axis thereof.

  In this irradiation test reactor, an insertion hole (capsule insertion hole) is formed on the central axis of the fuel assembly arranged in the core tank. In such a configuration, a uniform and high-quality high-density neutron or gamma irradiation field is formed in the insertion hole. Thus, there is an advantage that an efficient irradiation test can be performed on the assembly irradiation object arranged in the insertion hole and a high-quality test result can be obtained.

  The fuel assembly for an irradiation test reactor according to the present invention is configured by bundling a plurality of fuel rods made of low enriched uranium dioxide having an enrichment of less than 20% so as to form a hexagonal lattice structure as a whole. And the insertion hole of the to-be-illuminated object for aggregate | assembly is formed on the central axis, It is characterized by the above-mentioned.

  In addition, in this fuel assembly for an irradiation test reactor, an insertion hole (capsule insertion hole) is formed on the central axis thereof, so that a uniform, high-quality and high-density radiation irradiation field can be formed in the insertion hole during use. It is formed. Thus, there is an advantage that an efficient irradiation test can be performed on the assembly irradiation object arranged in the insertion hole and a high-quality test result can be obtained.

  According to the irradiation test reactor according to the present invention, since the core tank is configured such that the arrangement of the fuel assemblies is the same as viewed from each in-pile loop, the same neutron is mutually contained in each in-pile loop. Alternatively, an irradiation field of gamma ray irradiation conditions is formed, and the same neutron or gamma ray irradiation conditions are used in an environment with independent temperature, pressure, and atmospheric medium for the loop irradiation object arranged in each impile loop. There is an advantage that can be tested.

  Further, in the fuel assembly for an irradiation test reactor according to the present invention, since the insertion hole is formed on the central axis, a uniform and high-quality high-density neutron or gamma irradiation field is formed in the insertion hole at the time of use. There is an advantage that an effective irradiation test can be performed on the formed object to be irradiated, which is formed and arranged in the insertion hole, and a high-quality test result can be obtained.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements of the embodiments described below include those that can be easily replaced by those skilled in the art or those that are substantially the same.

[Irradiation test furnace]
FIG. 1 is a longitudinal sectional view showing an irradiation test furnace according to an embodiment of the present invention. 2 to 4 are an A sectional view (FIG. 2), a B sectional view (FIG. 3), and a C sectional view (FIG. 4) showing the irradiation test furnace shown in FIG. FIG. 5 is an explanatory view showing the configuration of the in-pile loop of the irradiation test furnace shown in FIG. 6 and 7 are a perspective view (FIG. 6) and a cross-sectional perspective view (FIG. 7) showing a fuel assembly used in the irradiation test furnace shown in FIG. FIG. 8 is an explanatory diagram showing the core configuration of the irradiation test reactor shown in FIG. FIG. 9 is an explanatory view showing a modification of the core configuration shown in FIG.

  The irradiation test furnace 1 is a test furnace capable of performing an irradiation test on materials and fuels. For example, the irradiation test reactor 1 can acquire irradiation test data necessary for the development of a nuclear power plant by irradiating the structural material of the nuclear reactor and the irradiated object T of the fuel with neutrons with a high density of neutron flux. The irradiation test furnace 1 has not only such applications but also a plurality of application fields such as production of radioisotopes used in the manufacturing industry or medical care, and academic research support using neutrons and gamma rays. In this respect, the irradiation test furnace 1 is particularly excellent in terms of usability and versatility as compared with the conventional irradiation test furnace.

  The irradiation test reactor 1 includes a nuclear reactor vessel 2, a core tank 3, and an in-pile loop 4 (see FIG. 1). In the irradiation test furnace 1 having such an in-pile loop 4, a high-temperature and high-pressure atmosphere medium (coolant such as water or gas) circulates in the in-pile loop 4, so that the atmosphere medium passes through the in-pile loop 4. The irradiation field of the high density neutron flux is partially formed in the core 32 by being guided into the core 32. Thereby, an irradiation environment close to an actual nuclear reactor is simulated with a simple and inexpensive configuration.

  The nuclear reactor vessel 2 includes a vessel main body 21 and a vessel lid 22 (see FIG. 1). The container main body 21 is a substantially cylindrical container having a dome-shaped bottom 23, and is installed with its side surfaces supported by support legs 26 while its longitudinal direction is set up vertically. In addition, container pipes 24 and 25 for circulating cooling water are connected to the sides of the container body 21. In the container main body 21, the cooling water is always circulated during operation by supplying the cooling water from one container pipe 24 and discharging the cooling water from the other container pipe 25. The container lid 22 has a substantially dome shape and is detachably installed in the opening of the container body 21. By attaching the vessel lid 22, the reactor vessel 2 is held in a sealed state. In addition, the container lid 22 is configured to be independent of and independent of other components (for example, the impile loop 4 and the loop pipes 41 and 42) that constitute the irradiation test furnace 1. Therefore, the container lid 22 can be attached to and detached from the container main body 21 by itself without removing other components. The container lid 22 is fixed to the container body 21 by, for example, bolt coupling.

  The bottom of the reactor core 3 is supported by the lower reactor core plate 31 and accommodated in the reactor vessel 2 (see FIG. 1). In the reactor core 3, a plurality of fuel assemblies 10 are accommodated with their longitudinal directions set vertically, and arranged in a predetermined arrangement structure. And the impile loop 4 is penetrated by these 10 groups of fuel assemblies, and the core 32 is comprised (refer FIG.2, FIG3 and FIG.8). In the irradiation test furnace 1, a rod-shaped fuel assembly 10 having a hexagonal lattice structure is used (see FIG. 6). The reactor core 3 is configured so that the cooling water in the reactor vessel 2 flows around the outer periphery thereof, and the surrounding water is cooled by the cooling water when the irradiation test reactor 1 is operated.

  The impile loop 4 is formed of a long cylindrical member, and is installed in the reactor vessel 2 with its longitudinal direction set up vertically (see FIGS. 1 to 4). The inpile loop 4 is inserted into the core tank 3 and passes through the core 32, and is fixed to the lower core plate 31 at the bottom thereof. Thus, the fuel assembly 10 is disposed so as to be surrounded by the fuel assembly 10 (see FIGS. 2 and 3). Further, in this irradiation test furnace 1, three impile loops 4 are installed independently of each other. These three impile loops 4 are arranged point-symmetrically in the reactor vessel 2 so as to constitute the vertices of the triangle in a horizontal sectional view (see FIGS. 2 to 4). . Further, these impile loops 4 are completely accommodated in the reactor vessel 2, and the upper opening thereof is located in the reactor vessel 2. A loop lid 44 is detachably attached to the upper opening portion of the impile loop 4, and the inside of the impile loop 4 is sealed by the loop lid 44.

  Further, loop pipes 41 and 42 are connected to the upper side and the bottom of each impile loop 4 (see FIG. 5). A high temperature and high pressure atmosphere medium is supplied and circulated in the impile loop 4 through these loop pipes 41 and 42. Here, the upper side loop pipe 41 extends in the horizontal direction from the connection position with the impile loop 4, and is drawn out from the side surface of the reactor vessel 2 to the outside through the switching valve 43. It is connected to a supply source (not shown). On the other hand, the loop piping 42 at the bottom passes through the lower core plate 31 and makes a U-turn at the bottom in the reactor vessel 2, and passes upward through the gap between the side surface of the reactor core 3 and the inner wall surface of the reactor vessel 2. It is extended. The bottom loop pipe 42 is refracted in the horizontal direction in the vicinity of the upper side loop pipe 41, drawn out from the side of the reactor vessel 2, and connected to the switching valve 43 and the atmosphere medium supply source. ing.

  In the impile loop 4, the flow direction of the atmospheric medium inside is switched by an external switching valve 43. Specifically, by changing the flow direction of the atmospheric medium using the switching valve 43, (1) a configuration in which the atmospheric medium flows in the in-pile loop 4 from above to below, or (2) from below to above. It can be configured to flow. In the former, (1) the atmosphere medium enters the inpile loop 4 from the upper side loop pipe 41 and exits from the bottom loop pipe 42. In the latter, (2) the atmosphere medium passes from the bottom loop pipe 42. It becomes the structure which enters in the in-pile loop 4 and exits from the loop piping 41 of an upper side part. In addition, a well-known thing is employ | adopted for the switching valve 43 within the range obvious to those skilled in the art.

[Core configuration]
Here, in this irradiation test reactor 1, the core 32 is configured as follows. That is, in this irradiation test furnace 1, six fuel assemblies 10 form a ring formed by joining hexagonal sides (side surfaces of a hexagonal lattice) in a horizontal sectional view (1 at the center). They are arranged so that there is a gap between the body parts (see FIG. 8). Then, a total of 15 fuel assemblies 10 are continuously arranged, so that three rings composed of six fuel assemblies 10 are formed in point symmetry so as to form a triangle. In addition, these three rings share a part of the fuel assembly 10 with the adjacent rings. And the impile loop 4 is inserted and arrange | positioned at these three rings, respectively. As a result, the three in-pile loops 4 are arranged in point symmetry (120-degree symmetry or one-third symmetry) so as to form the vertices of an equilateral triangle in a horizontal sectional view. 4 is configured so as to be surrounded by six fuel assemblies without gaps.

  In the irradiation test furnace 1, first, the irradiated object T is placed in the in-pile loop 4. Hereinafter, the irradiated object T arranged in the impile loop 4 is referred to as a loop irradiated object TR. The loop irradiated body TR is inserted into the impile loop 4 from above with the loop lid 44 removed. When the irradiation test furnace 1 is in operation (at the time of the irradiation test), a high-temperature and high-pressure atmosphere medium is supplied from an external supply source into the in-pile loop 4 through the loop pipes 41 and 42 and circulates. Fission reaction occurs in the fuel assembly 10 around the impile loop 4, and an irradiation field of high-density neutron flux is partially formed in the core 32. As a result, the irradiation object for loop TR is irradiated. During operation, the core 32 is cooled by cooling water supplied into the reactor vessel 2 via the vessel piping 24.

[effect]
The irradiation test reactor 1 is configured such that the arrangement positions of the fuel assemblies 10 in the reactor core 3 are the same as viewed from the respective impile loops 4 in a horizontal sectional view (see FIG. 3 and FIG. 3). (See FIG. 8). Specifically, the three in-pile loops 4 are installed, and the arrangement (core structure) of these in-pile loops 4 and the fuel assemblies 10 is point-symmetric (120-degree symmetry or one-third symmetry). It is comprised so that it may become. Accordingly, irradiation fields under the same neutron or gamma irradiation conditions are formed in each impile loop 4. As a result, it is possible to perform the test under the same neutron or gamma ray irradiation conditions in an environment of independent temperature, pressure, and atmospheric medium for the irradiated object TR for the loop disposed in each impile loop 4. There is.

  Further, in this irradiation test reactor 1, the reactor core 3 (reactor vessel 2) has a substantially cylindrical shape, and the array composed of the impile loop 4 and the fuel assembly 10 is generally circular as a whole. (See FIGS. 1 to 4 and FIG. 8). Such a configuration has an advantage that the configuration of the irradiation test reactor 1 can be reduced in size since the arrangement space loss in the reactor core 3 can be reduced when the impile loop 4 and the fuel assembly 10 are arranged.

  Further, in the irradiation test furnace 1, the core tank is configured such that each impile loop 4 is surrounded by a plurality of fuel assemblies 10 (see FIGS. 3 and 8). In such a configuration, since the fuel assemblies 10 are arranged in a ring shape, neutrons or gamma rays are irradiated from around the irradiation target TR for the loop in the in-pile loop 4. This has the advantage that efficient neutron or gamma irradiation can be achieved.

  Further, in this irradiation test furnace 1, a fuel assembly 10 having a hexagonal cross section (hexagonal lattice structure) is adopted, and six fuel assemblies 10 are arranged in the hexagonal side in a horizontal sectional view. Are arranged in an annular shape by adjoining each other, and an impile loop 4 is inserted into a ring formed of these fuel assemblies 10 (see FIGS. 6 and 8). In such a configuration, the number of the fuel assemblies 10 surrounding one impile loop 4 is small as compared to a configuration surrounding the impile loop 4 using a large number of small-diameter fuel assemblies. As a result, the fuel rods 101 can be densely arranged around the impile loop 4, and such an arrangement can be constituted by a small number of fuel assemblies 10, so that there is an advantage that the configuration of the core 32 is simplified. Moreover, since the loss of the arrangement | positioning space in the reactor core tank 3 can be reduced in arrangement | positioning of the impile loop 4 and the fuel assembly 10 by this, there exists an advantage which can reduce the irradiation test reactor 1 in size.

  Further, in the irradiation test reactor 1, the ring composed of the six fuel assemblies 10 is continuously plural while sharing the fuel assemblies 10 constituting a part thereof with the adjacent rings. The impile loops 4 are arranged with respect to these rings (see FIG. 8). In such a configuration, the plurality of impile loops 4 are surrounded by a smaller number of fuel assemblies 10 as compared to a configuration in which a plurality of rings each composed of the fuel assemblies 10 are arranged separately and independently. As a result, the fuel rods 101 are densely arranged in the core tank 3 and the core is constituted by a small number of fuel assemblies 10, so that there is an advantage that the configuration of the core 32 is simplified. Moreover, since the loss of the arrangement space in the core tank 3 can be reduced when arranging the impile loop 4 and the fuel assembly 10, there is an advantage that the configuration of the irradiation test reactor 1 can be reduced in size.

[Modification of core configuration]
In the irradiation test reactor 1, 15 fuel assemblies 10 having a hexagonal cross section as described above are used, and three impile loops 4 are surrounded by the fuel assemblies 10 to form a core 32. (See FIG. 8). Thereby, since the impile loop 4 and the fuel assembly 10 are efficiently arranged, there is an advantage that the configuration of the core 32 is simplified. However, the present invention is not limited to this, and the fuel assembly 10 may not have a hexagonal cross section (hexagonal lattice structure), and the arrangement structure of the fuel assembly 10 is not particularly limited.

  For example, 30 fuel assemblies 10 having a hexagonal cross section as described above (31 in the configuration in which the fuel assemblies 10 are arranged in the center) are used, and six in piles are formed by these fuel assemblies 10. The core 32 may be configured by surrounding the loop 4 (see FIG. 9). Such an array structure is configured by six impregnating loops 4 surrounded by six fuel assemblies 10 and the arrays of the impile loops 4 and the fuel assemblies 10 are continuously arranged in a ring shape. Is done. Further, in such an arrangement structure, the ring of the fuel assemblies 10 surrounding each impile loop 4 shares a part of the fuel assemblies 10 that are constituent elements between the adjacent impile loops 4. . Such a configuration also has the advantage that the configuration of the core 32 is simplified by efficiently arranging the impile loop 4 and the fuel assembly 10. In the general irradiation test furnace 1, if too many fuel assemblies 10 are arranged, the amount of heat generated during operation becomes enormous. For this reason, in the normal irradiation test reactor 1, the core configuration in which the three impile loops 4 are surrounded by the 15 fuel assemblies 10 as described above is a necessary and sufficient configuration and is preferable.

[Fuel assembly]
In the irradiation test furnace 1, it is preferable to employ the following fuel assembly 10. That is, the fuel assembly 10 is configured by bundling a plurality of fuel rods 101. The fuel rod 101 is composed of, for example, low enriched uranium dioxide having a concentration of less than 20% as a fuel material (see FIG. 7). Each fuel rod 101 is arranged so that three adjacent rods form an equilateral triangle in a plan view (triangular arrangement), and are bundled and arranged so as to form a hexagonal lattice structure as a whole. The bundled fuel assembly 10 is constituted by tie rods 102 on each side of the hexagonal lattice, and both ends thereof are fastened by fixing metal fittings 103.

  A capsule insertion hole 104 is formed at the center of the fuel assembly 10. The irradiated object T can be disposed in the capsule insertion hole 104. Hereinafter, the irradiated object T disposed in the capsule insertion hole 104 (fuel assembly 10) is referred to as an irradiated object TS for the assembly. Note that the capsule insertion hole 104 is configured such that the opening thereof opens on the fixing metal fitting 103 (see FIG. 6). Therefore, the irradiation capsule can be inserted into the capsule insertion hole 104 without disassembling the fuel assembly 10. Further, in the fuel assembly 10, control rod guide thimbles 105 are partially arranged in place of the fuel rod 101.

  In the irradiation test furnace 1, the assembly irradiated object TS is placed in a container called an irradiation capsule (not shown), and the irradiation capsule is inserted into the capsule insertion hole 104 of the fuel assembly 10. The fuel assembly 10 is arranged in the core 32 with the irradiation capsule inserted. Then, irradiation of the aggregate irradiation object TS is performed by the operation of the irradiation test furnace 1. It should be noted that the irradiated object TS for the assembly is normally taken out of the core 32 together with the fuel assembly 10 at the time of fuel replacement, with a test period (irradiation period) for the irradiated object set for each cycle of fuel replacement.

  In the irradiation test furnace 1, since the capsule insertion hole 104 is formed in the fuel assembly 10 (the central axis of the fuel assembly 10), a uniform and high-quality irradiation field is formed in the capsule insertion hole 104. Is done. Thereby, there is an advantage that an irradiation test can be efficiently performed and a high-quality test result can be obtained.

  Further, in this irradiation test furnace 1, the capsule insertion holes 104 are formed in all the fuel assemblies 10, and therefore, the assembly irradiated object TS can be arranged for all the fuel assemblies 10. . Thereby, since an irradiation test can be simultaneously performed with respect to a several to-be-irradiated body, there exists an advantage which can perform an irradiation test more efficiently.

  Moreover, in this irradiation test furnace 1, since the capsule insertion hole 104 has a large diameter as compared with the capsule insertion tube of the conventional irradiation test furnace, the advantage that an irradiation capsule equipped with a neutron instrumentation monitor and a thermocouple can be arranged. There is.

[Additional items]
Moreover, in this irradiation test furnace 1, since the impile loop 4 has a long structure compared with the conventional irradiation test furnace (refer nonpatent literature 1), with respect to the irradiation object TR for longer loops, There is an advantage that an irradiation test can be performed. Further, the long in-pile loop 4 constitutes a core 32 that can acquire a uniform neutron flux in a wide range in the axial direction. Thereby, there is an advantage that an irradiation test can be efficiently performed and a high-quality test result can be obtained.

  Moreover, in this irradiation test furnace 1, compared with the conventional irradiation test furnace (refer nonpatent literature 1), since the impile loop 4 has a large diameter, it irradiates with respect to the irradiated body TR for larger loops. There is an advantage that a test can be performed. In addition, the large-diameter in-pile loop 4 has an advantage that an irradiation test can be performed on the loop irradiation object TR having various shapes.

  In this irradiation test furnace 1, a plurality (three) of the in-pile loops 4 are installed independently of each other, so that the loop irradiation object TR can be arranged in each in-pile loop 4. Accordingly, there is an advantage that an independent irradiation test can be performed for each impile loop 4 simultaneously and under individual conditions.

  Further, in JMTR (see Non-Patent Document 1), since the maximum temperature and the maximum pressure of the irradiation field are configured for a boiling water reactor, there is a problem that an irradiation test for a pressurized water reactor cannot be performed. is there. In this respect, since the irradiation test reactor 1 can perform an irradiation test under high temperature and high pressure conditions by adopting the in-pile loop 4, irradiation is performed for both boiling water reactors and pressurized water reactors. There is an advantage that the test can be performed. In boiling water reactors, light water is used as a reactor coolant and reactor moderator, and this light water is boiled in the core to generate steam directly, and this steam is guided to a turbine generator for power generation. Reactor. The pressurized water reactor uses light water as the reactor coolant and reactor moderator, and this light water is used as high-temperature and high-pressure water that does not boil over the entire core (reactor system: primary cooling system). It refers to a nuclear reactor that sends high-temperature and high-pressure water to a steam generator (primary system) for heat exchange to generate steam (steam system: secondary cooling system) and sends this steam to a turbine generator to generate power.

  In the irradiation test furnace 1, a switching valve 43 is installed between the loop pipes 41 and 42 of the inpile loop 4 and the supply source of the atmospheric medium. The flow direction of the atmospheric medium can be switched (see FIG. 5). Thereby, since the suitable irradiation environment according to a use is realizable, there exists an advantage which can improve test data quality. Specifically, in an irradiation test for a liquid-cooled nuclear reactor, a configuration in which the atmospheric medium flows from the lower side to the upper side in the in-pile loop 4 is preferable in order to simulate the cooling conditions of the actual nuclear reactor. In an irradiation test for a nuclear reactor, a configuration in which the atmosphere medium flows from the upper side to the lower side in the in-pile loop 4 is preferable in order to suppress the floating or vibration caused by the cooling gas flowing at high speed with a simple configuration. .

  As described above, the irradiation test reactor and the fuel assembly for the irradiation test reactor according to the present invention have the irradiation fields of the same neutron or gamma irradiation conditions formed in each in-pile loop, and each in-pile loop. It is useful in that the test can be performed on the irradiation object for the loop arranged in the environment under an independent temperature, pressure, atmosphere medium environment and the same neutron or gamma irradiation conditions.

It is a longitudinal cross-sectional view which shows the irradiation test furnace concerning Example 1 of this invention. FIG. 2 is a cross-sectional view of the irradiation test furnace shown in FIG. FIG. 2 is a B cross-sectional view showing the irradiation test furnace shown in FIG. 1. FIG. 2 is a cross-sectional view of the irradiation test furnace shown in FIG. It is explanatory drawing which shows the structure of the inpile loop of the irradiation test furnace described in FIG. It is a perspective view which shows the fuel assembly used for the irradiation test furnace described in FIG. It is a cross-sectional perspective view which shows the fuel assembly used for the irradiation test furnace described in FIG. It is explanatory drawing which shows the core structure of the irradiation test reactor described in FIG. It is explanatory drawing which shows the modification of the core structure described in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Irradiation test reactor 2 Reactor vessel 21 Vessel main body 22 Vessel lid 23 Bottom 24 Vessel piping 25 Vessel piping 26 Support leg 3 Reactor core 31 Lower core plate 32 Reactor core 4 Impile loop 41, 42 Loop piping 43 Switching valve 44 Loop lid 10 Fuel assembly 101 Fuel rod 102 Tie rod 103 Fixing bracket 104 Capsule insertion hole 105 Control rod guide thimble T Irradiated object TR Loop irradiated object TS Assembled irradiated object

Claims (7)

A reactor vessel, a reactor core vessel that is housed in the reactor vessel and that constitutes a reactor core, and an inpile loop that is inserted into the reactor vessel and that guides an atmosphere medium to the reactor core, In an irradiation test reactor capable of irradiating the irradiated object arranged in the core,
A plurality of the impile loops are arranged in the core tank, fuel assemblies are arranged around the inpile loops, and the arrangement of the fuel assemblies is the same as viewed from the respective inpile loops. An irradiation test reactor characterized in that the core tank is configured as follows.   2. The irradiation test reactor according to claim 1, wherein the core tank is configured so that the core tank has a substantially cylindrical shape, and the array of the impile loop and the fuel assembly is substantially circular as a whole.   3. The irradiation test reactor according to claim 1, wherein the core tank is configured such that a plurality of fuel assemblies can be annularly arranged and one of the impile loops is surrounded by the arranged fuel assemblies.   A fuel assembly having a hexagonal cross section can be arranged, and six fuel assemblies can be arranged in an annular shape by adjoining the sides of the hexagons, and the fuel assembly has a ring formed of the fuel assemblies. The irradiation test reactor according to claim 1, wherein the core tank is configured such that the impile loop is inserted.   A ring composed of the six fuel assemblies can be continuously arranged in plural while sharing a fuel assembly constituting a part thereof with an adjacent ring, and for each of these rings, The irradiation test reactor according to any one of claims 1 to 4, wherein the core tank is configured so that the impile loop is disposed.   The fuel assemblies arranged in the reactor core tank are configured by bundling a plurality of fuel rods made of low enriched uranium dioxide having an enrichment of less than 20% so as to form a hexagonal lattice structure as a whole, and The irradiation test furnace according to any one of claims 1 to 5, wherein an insertion hole for the assembly irradiation object is formed on the central axis.   A plurality of fuel rods made of low enriched uranium dioxide having a concentration of less than 20% are bundled so as to form a hexagonal lattice structure as a whole, and on the central axis of the irradiated object for the assembly A fuel assembly for an irradiation test reactor, wherein an insertion hole is formed.

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