• 专利附录
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    • 专利摘要:
    A fast neutron reactor core for improving safety by reducing the reactivity of combustion so as to reduce the reactivity applied to the core at the time of a UTOP while suppressing the increase in combustion. cavity reactivity. [Means of resolution] A core 10 of a fast neutron reactor comprises an internal core fuel zone 21 and an external core fuel zone 22 surrounding the internal core fuel zone 21 in the radial direction of the core and a fuel assembly in which MOX fuel is housed in a hexagonal tube is loaded into the inner core fuel zone 21 and the outer core fuel zone 22 and at least the fuel assembly loaded into the inner core fuel zone 21 includes inner cover fuel 31 comprising depleted uranium oxide containing minor actinide as fuel in an axially substantially central portion. [Selected design]
    公开号:FR3057988A1
    申请号:FR1759975
    申请日:2017-10-23
    公开日:2018-04-27
    发明作者:Kouji Fujimura；Katsuyuki Kawashima
    申请人:Hitachi GE Nuclear Energy Ltd；
    IPC主号:
    专利说明:

    [DESCRIPTION] [Title of the Invention] FAST NEUTRON REACTOR CORE [Technical Field]
    The present invention relates to a core of a fast neutron reactor for improving safety in order to prevent damage to the core in the event of an accident of inadvertent withdrawal of a control rod in a reactor. fast neutrons.
    [Prior state of the art]
    Regarding a new fuel assembly and a core of a fast neutron reactor, as described in the publication NPL 1, in a fast neutron breeder reactor, a core is placed in a reactor vessel and in the liquid sodium coolant. is brought to fill the reactor vessel. The fuel assembly loaded into the core includes a plurality of fuel rods in which depleted uranium (U-238) enriched in plutonium is enclosed, a hexagonal tube surrounding the plurality of fuel rods grouped in bundles, a nozzle inlet which supports the lower end portions of these fuel rods and a neutron shield located on the lower side of the fuel rods and a coolant outlet located on the upper side of the fuel rods.
    The core of the fast neutron breeder reactor includes a core fuel zone which includes an inner core fuel zone and an outer core fuel zone, a cover fuel zone surrounding the core fuel zone and a zone of 'protective screen surrounding the covering fuel area. In the case of a conventional homogeneous core, the enrichment in Pu of the fuel assembly loaded in the area of the outer core is higher than the enrichment in Pu of the fuel assembly loaded in the fuel zone of the inner core .
    As a result, the radial energy distribution of the heart is flattened.
    Examples of the shape of a nuclear fuel material housed in each fuel rod of the fuel assembly include a metal fuel, a nitride fuel and an oxide fuel. Of these, the oxide fuel is the one with the most experience.
    A mixed oxide fuel in which oxides of each of Pu and depleted uranium are mixed, namely MOX fuel pellets, is caused to fill an axially central part in the fuel rod at a height of about 80 to 100 cm. In addition, in the fuel rod, an axial cover area filled with a plurality of uranium dioxide pellets made of depleted uranium is disposed on both the upper and lower sides of an area filled with MOX fuel. . An inner core fuel assembly loaded into the inner core fuel zone and an outer core fuel assembly loaded into the outer core fuel zone includes a plurality of fuel rods filled with a plurality of MOX fuel pellets of this way.
    The enrichment in Pu of the fuel assembly of the outer core is higher than that of the fuel assembly of the inner core.
    In the cover fuel area surrounding the core fuel area, a cover fuel assembly comprising a plurality of fuel rods filled with a plurality of uranium dioxide pellets made of depleted uranium is loaded. Among the neutrons generated by nuclear fission that occurs in the charged fuel assembly in the core fuel zone, a neutron that leaks from the core fuel zone is absorbed by U-238 in each fuel rod. the cover fuel assembly loaded into the cover fuel area. As a result, Pu-239 which is a fissile nuclide is produced in each fuel bar of the cover fuel assembly.
    In addition, when starting and stopping the fast neutron breeder reactor and when adjusting the output from the nuclear reactor, a control bar is used. The control bar includes a plurality of neutron absorption bars in which boron carbide (B4C) pellets are enclosed in a cladding tube made of stainless steel and is designed such that these absorption bars neutrons are housed in a hexagonal tube having a regular hexagonal cross-section in the same manner as the inner core fuel assembly and the outer core fuel assembly. The control rod system consists of two independent systems: a main reactor shutdown system and a secondary reactor shutdown system and it is possible to perform an emergency shutdown of the fast neutron breeder reactor by a only from the main reactor shutdown system and the secondary reactor shutdown system.
    On the other hand, in general, the reactivity of the combustion of the fast neutron reactor is approximately Ak / kk 'of 3% and when an accident in which a withdrawal by mistake of a control rod and a failure emergency stop overlap (UTOP: unprotected transient overload, hereinafter called a “UTOP”) is presumed, it is possible that the power density in the vicinity of the control bar changes and that the linear power ( W / cm) may exceed the design limit. If such an increase in linear power during a UTOP can be avoided, a thermal margin can be increased and, moreover, the safety of the heart can be improved. In order to avoid the increase in linear power during a ÜTOP, it is effective to reduce the combustion reactivity so as to reduce the control reactivity required by control rod to compensate for the combustion reactivity.
    For example, the publication PTL 1 discloses that a combustible material in a combustible element (a fuel needle) housed in a fuel assembly loaded in a core of a fast neutron reactor is designed in such a way that enrichment in TRU (transuranic elements) containing a minor actinide (MA, hereinafter called a “MA”) is fixed at 5% to 30% and the enrichment in fissile Pu is fixed at 9% at 12%. It is described that, according to this, a fast neutron breeder reactor capable of supplying a required electrical power without refueling during the entire lifetime of the installation of a nuclear power plant can be achieved, the load factor is improved and the life of the fuel is extended and, therefore, the economic profitability can be greatly improved.
    [List of references cited] [Patent-type publications] [PTL 1] JP-A-5-52981 [Non-patent-type publications] [NPL 1] “Genshiro Butsuri Nyumon (Introduction of
    Nuclear Reactor Physics) "written by Naohiro Hirakawa and Tomohiko Iwasaki, Tohoku University Press, Sendai, pp. 279-286, October 2003 [NPL 2] Preparation of Fast Reactor Group Constant Sets UFLIB. J40 and JFS-3-J4.0 based on JENDL-4.0 data, Kazuteru Sugino, Tomoyuki Jin, Taira Hazama, Kazuyuki Numata, JAEA data / Code 2011-017, (2011) [NPL 3] “SLAROM-UF: Ultra Fine Group Cell Calculation Code for Fast Reactor — Version 20090113- ”, Taira Hazama, et al., UAEA-Review 2009-003, (2009) [NPL 4] TR Fowler, DR Vondy and GW Cunningham: Nuclear Reactor Code Analysis Code : QUOTE: ORNL / TM-2469
    Rev. 2 (1971) [Summary of the invention] [Technical problem]
    However, according to the configuration of publication PTL 1, the loading of MA into the core fuel of the fast neutron reactor results in a considerable increase in cavity reactivity. In addition, in the core of the fast neutron reactor during a UTOP, the reduction in combustion reactivity is needed, but however, in the publication PTL-1, this point is not considered at all.
    In view of this, the present invention provides a core of a fast neutron reactor making it possible to improve safety by reducing the reactivity of combustion so as to reduce the reactivity applied to the core for a UTOP while suppressing the increase of cavity reactivity. [Solution to the problem]
    In order to achieve the above objective, a core of a fast neutron reactor according to the present invention is characterized in that the core comprises an inner core fuel zone and an outer core fuel zone surrounding the zone of inner core fuel in the radial direction of the core and a fuel assembly in which MOX fuel is housed in a hexagonal tube is loaded into the inner core fuel area and the outer core fuel area and at least the assembly fuel loaded into the inner core fuel zone includes an inner cover fuel comprising depleted uranium oxide containing a minor actinide as a fuel in an axially substantially central portion.
    [Advantageous Effects of the Invention]
    According to the present invention, a core of a fast neutron reactor making it possible to improve safety by reducing the reactivity of combustion so as to reduce the reactivity applied to the core for a UTOP while suppressing the increase in cavity reactivity. can be provided.
    For example, as a core configuration, an axially heterogeneous core is adopted, an MA is loaded into the internal covering fuel and the MA content is optimized, whereby the absolute value of the combustion reactivity is set to 1 $ (dollar) or less and the absolute value of the responsiveness of the application can be reduced for an ÜTOP and therefore, the security of the heart can be improved.
    Objectives, configurations and effects other than those described above will be clarified by the following description of embodiments.
    [Brief description of the drawings] [FIG. 1] FIG. 1 is a vertical sectional view of a core of a fast neutron reactor of a first embodiment according to an embodiment of the present invention and is a view representing one half of the core.
    [FIG. 2] FIG. 2 is a horizontal sectional view of the core of the fast neutron reactor shown in FIG. 1 and is a view representing half a heart.
    [FIG. 3] FIG. 3 is an overall structural view of a nuclear power generation system with a fast neutron reactor comprising a core of a fast neutron reactor according to an embodiment of the present invention.
    [FIG. 4] FIG. 4 is a view showing the relationship between the reactivity of the combustion and an MA content in an internal covering in a core of a fast neutron reactor in which an MA is loaded in an internal covering fuel.
    [FIG. 5] FIG. 5 is a vertical sectional view of a variant of the core of the fast neutron reactor shown in FIG. 1 and is a view representing half a heart.
    [FIG. 6] FIG. 6 is a vertical sectional view of a core of a fast neutron reactor of a second embodiment according to another embodiment of the present invention and is a view representing one half of the core.
    [FIG. 7] FIG. 7 is a horizontal sectional view of the core of the fast neutron reactor shown in FIG. 6 and is a view representing half a heart.
    [Description of embodiments]
    FIG. 3 is an overall structural view of a nuclear power generation system with a fast neutron reactor comprising a core of a fast neutron reactor according to an embodiment of the present invention. As shown in FIG. 3, a nuclear power generation system with a fast neutron reactor 1 comprises a reactor vessel 2, a core 3 comprising a fissile material housed in the reactor vessel 2, an intermediate heat exchanger 5 and a circulation pump primary 7a connected in series from the reactor vessel 2 via a primary cooling system piping 4a and a steam generator 8 and a secondary circulation pump 7b connected in series from the heat exchanger intermediate heat 5 via secondary cooling system piping 4b. In addition, it also consists of a primary steam system piping 9a which sends steam produced by the steam generator 8 to a high pressure turbine 11a and a low pressure turbine 11b, a condenser 13 which condenses the steam after its passage through the high pressure turbine 11a and the low pressure turbine 11b to return it in the form of water, a piping of the feed water system and presumed 9b which returns the water condensed by the condenser 13 the steam generator 8, an electric generator 12 connected to the shafts of the high pressure turbine 11a and the low pressure turbine 11b and of a water supply pump 14 and of a water heating device supply 15 connected to the piping of the water supply and presumption system 9b on the downstream side of the condenser 13.
    Then, in the fast neutron reactor nuclear electric power generation system 1, a primary system coolant (for example liquid sodium) heated in the core 3 is caused to pass through the intermediate heat exchanger 5 to heat a secondary system coolant (e.g. liquid sodium) and, in addition, the secondary system coolant is passed through the steam generator 8 to produce steam in the main steam system piping 9a and this steam is guided to the high pressure turbine 11a and the low pressure turbine 11b and electricity is produced by the electric generator 12. The steam used in the production of electricity is condensed into water by the condenser 13 and it is subsequently heated and pressurized by passage through the water supply pump 14 and the water heating device. supply 15 and it is then supplied to the steam generator 8 in the same manner as in a nuclear electric power production system with a light water reactor of the boiling water reactor (BWR) type or of the pressurized water reactor type ( PWR).
    In core 3, a plurality of fuel core assemblies and control rods (described below) are loaded. The reactor vessel 2 in which the core 3 is housed is filled with the primary coolant and the primary coolant enters the core 3 from a lower part of the core 3, rises along the core fuel assemblies and circulates in the intermediate heat exchanger 5 placed outside the reactor vessel 2 passing through the primary cooling system piping 4a by means of the primary circulation pump 7a. According to this, a loop type fast neutron reactor is formed. Although in this description a loop type fast neutron reactor will be described by way of example, the present invention is not limited thereto and can also be applied to a closed core type fast neutron reactor in which the core 3, the primary main circulation pump 7a and the intermediate heat exchanger 5 are housed in a reactor vessel.
    Hereinafter, the core of the fast neutron reactor according to an embodiment of the present invention will be described with reference to the drawings.
    [First embodiment]
    FIG. 1 is a vertical sectional view of a core of a fast neutron reactor of a first embodiment according to an embodiment of the present invention and is a view showing one half of the core, FIG. 2 is a horizontal sectional view of the core of the fast neutron reactor shown in FIG. 1 and is a view representing half a heart and FIG. 4 is a view showing the relationship between the reactivity of the combustion and an MA content in an internal covering in a core of a fast neutron reactor in which an MA is loaded in an internal covering fuel.
    In FIG. 2, the heart is vertically symmetrical and therefore only half is shown. The core 10 of the fast neutron reactor in this embodiment is placed in the reactor vessel 2 (FIG. 3) of the fast neutron reactor and a core fuel zone is constituted by an internal core fuel zone 21 and an outer core fuel zone 22 surrounding the inner core fuel zone 21 in the radial direction. In the core fuel area, a plurality of control rod assemblies 24 are placed. In addition, the core 10 of the fast neutron reactor comprises a radial covering fuel zone 23 so as to surround the external core fuel zone 22 and a reflector zone 25 and a protective screen zone 2 6 on the outside the radial covering fuel area 23. In the radial direction of the core 10 of the fast neutron reactor, the reflector area 25 is adjacent to the radial covering fuel area 23 while surrounding the covering fuel area radial and the protective screen zone 26 surrounds the reflector zone 25. The core 10 of the fast neutron reactor of this embodiment is an axially heterogeneous core in which an internal covering fuel (described below) is placed in the internal core fuel zone 21 constituting the core fuel zone.
    As shown in FIG. 1, in the core 10 of the fast neutron reactor, an upper fuel 32 and a lower fuel 33 from the inner core fuel zone 21 (FIG. 2) and an outer core fuel 34 from the outer core fuel zone 22 (FIG. 2) are all MOX fuel in which plutonium oxide (PuOx) is mixed with depleted uranium oxide (UO2). The fuel of the inner cover fuel 31 is a fuel in which MA oxide (MAOx) is mixed with depleted uranium oxide (UO2). Furthermore, the fuels of an axially upper covering fuel 35, an axially lower covering fuel 36 and a radial covering fuel 37 are all depleted uranium oxide (UO2).
    In this regard, as shown in FIG. 1, in the inner core fuel zone 21 (FIG. 2), the axially lower covering fuel 36, the lower fuel
    33, the inner cover fuel 31, the upper fuel 32 and the axially upper cover fuel 35 are placed sequentially from the lower part to the upper part in the axial direction (from the upstream side to the downstream side along the direction of the flow of liquid sodium which is the primary coolant). For example, the axially lower covering fuel 36 has a height (a length along the axial direction) of about cm in the axial direction, the lower fuel 33 has a height of 40 cm, the inner covering fuel has a height of 20 cm, the upper fuel 32 has a height of 40 cm and the axially upper covering fuel 35 has a height of 30 cm (each height is a length along the axial direction). Therefore, the total height in the axial direction (the total length along the axial direction) of the lower fuel 33, the inner covering fuel 31 and the upper fuel 32 is about 100 cm. On the other hand, in the outer core fuel zone 22 (FIG. 2), the axially lower covering fuel 36, the outer core fuel 34 and the axially upper covering fuel 35 are placed sequentially from the lower part to the upper part in the axial direction (from the upstream side to the downstream side along the direction of the flow of liquid sodium which is the primary coolant). The outer core fuel 34 has a height (a length along the axial direction) of about 100 cm in the axial direction.
    In addition, the radial covering fuel 37 of the radial covering fuel zone 23 (FIG. 2) has a height (a length along the axial direction) of about 160 cm in the axial direction.
    The electrical production of the nuclear reactor is 750,000 kWe, a period of continuous operation is approximately 20 months, a refueling of fuel in 6 batches is adopted and an average combustion rate of the core fuel is approximately 150 GWj / t. As a parameter of the content (in% by weight) of MA contained in the internal covering fuel 31 of the core 10 of this embodiment, the content of
    MA (in% by weight) of the combustion reactivity (Ak / kk 'in%) was calculated and evaluated.
    In the evaluation, as indicated below, a standard analytical method for a fast neutron reactor is used. By using the nuclear data sets of 70 groups for fast neutron reactors based on the latest Japanese library of nuclear data, JENDL-4.0 (see publication NPL 2), the cross section of 70 groups of neutrons by energy was calculated by SLAROM-UF (see publication NPL 3), which is a program for the calculation of the cross section of a fast neutron reactor. By using the cross section, an equilibrium phase calculation is carried out in a two-dimensional RZ core system model of the CITATION neutron scattering calculation program (see publication NPL 4) which makes it possible to determine a factor effective neutron multiplication (keff) and Pu enrichment of the inner core fuel assembly loaded in the inner core fuel 21 and the outer core fuel assembly loaded in the outer core fuel zone 22 of so as to reach the criticality at the end of the equilibrium phase at a predefined combustion rate relative to a certain content of MA (in% by weight) is determined. At that time, by using the effective multiplication factor of the neutrons (keff) at the beginning of the equilibrium phase and at the end of the equilibrium phase, the reactivity of the combustion (Ak / kk 'in% ) is calculated. The above calculation is repeated for several MA contents and a curve of the relationship between the combustion reactivity (Ak / kk 'in%) and the MA content (in% by weight) is represented graphically. In this regard, the abovementioned standard analytical method for a fast neutron reactor has been sufficiently verified in a critical test simulating a fast neutron reactor or in a real fast neutron reactor.
    In FIG. 4, the results of the evaluation are shown. FIG. 4 is a view showing the relationship between the reactivity of the combustion and the content of MA in the internal covering fuel in the core 10 of the fast neutron reactor. In FIG. 4, the MA content (in% by weight) in the internal covering fuel is represented on the horizontal axis and the combustion reactivity (Ak / kk 'in%) is represented on the vertical axis and the relationship between the combustion reactivity and the MA content in the internal covering fuel is shown. The MA is Np, Am or Cm contained in spent fuel in a light water reactor with a fuel combustion rate of 60 GWj / t. As shown in FIG. 4, the combustion reactivity (Ak / kk 'in%) decreases as the content of MA (in% by weight) in the internal covering fuel 31 increases and it decreases almost to 0 when the content of MA increases around 40% by weight and becomes a negative value when the MA content (in% by weight) increases further. Here, when the MA content exceeds about% by weight, the combustion reactivity (Ak / kk 'in%) becomes a negative value, but however, it is because the reactivity at the end of the equilibrium phase is higher than the reactivity at the start of the equilibrium phase. When the MA content (in% by weight) is 35% by weight, the reactivity of the combustion becomes $ 1 and when the MA content (in% by weight) is 45% by weight, the reactivity of the combustion becomes less than or equal to -1 $. In other words, when the MA content (in% by weight) in the internal covering fuel 31 is in the range from 35% by weight to 45% by weight, the absolute value of the combustion reactivity becomes less than or equal to $ 1 and even if an accident in which a control rod withdrawal and an emergency stop failure overlap (UTOP: unprotected transient overload) is presumed, the linear power in the fuel assembly at vicinity of the control rod assembly 24 increases slightly and the integrity of the fuel is preserved. Here, the expression "the absolute value of the combustion reactivity is $" means that the effective delayed neutron rate is approximately 0.3%.
    FIG. 5 is a vertical sectional view of a variant of the core of the fast neutron reactor shown in FIG. 1 and is a view representing half a heart. As shown in FIG. 5, a core 10a of a variant fast neutron reactor comprises an inner core fuel 31a located at a predefined length (a distance) in a radial direction from an area adjacent to an inner covering fuel 31 d an inner core fuel zone 21 (FIG. 2) and in an axially substantially central part in an outer core fuel 34 of an outer core fuel zone 22 (FIG. 2). This inner covering fuel 31a in the outer core fuel 34 of the outer core fuel zone 22 is a fuel in which a minor actinide oxide (MA) (MAOx) is mixed with uranium oxide ( UO2) depleted in the same way as the inner cover fuel 31 of the inner core fuel zone 21. Therefore, also in the inner cover fuel 31a in the outer core fuel 34 of the outer core fuel zone
    22, the content of MA (in% by weight) is preferably fixed at 35% by weight to 45% by weight and the content of MA (in% by weight) is desirably brought to be the same in the fuel of internal covering 31 in the internal core fuel zone 21 and in the internal covering fuel 31a in the external core fuel 34 of the external core fuel zone 22.
    As described above, according to this embodiment, it becomes possible to provide a core of a fast neutron reactor making it possible to improve safety by reducing the reactivity of combustion so as to reduce the reactivity applied to the core at moment of a UTOP while suppressing the increase in cavity reactivity.
    More specifically, as a core configuration, an axially heterogeneous core is adopted, an MA is added to the internal covering fuel and the MA content is optimized, whereby the absolute value of the combustion reactivity is set at $ 1 (dollar) or less and the absolute value of the responsiveness of the application may be reduced at the time of presumption of UTOP and, therefore, the safety of the heart may be improved.
    [Second embodiment]
    FIG. 6 is a vertical sectional view of a core of a fast neutron reactor of a second embodiment according to another embodiment of the present invention and is a view representing one half of the core. FIG. 7 is a horizontal sectional view of the core of the fast neutron reactor shown in FIG. 6 and is a view representing half a heart. In the first embodiment, a configuration in which the axially upper covering fuel 35 and the axially lower covering fuel 36 are arranged in the inner core fuel zone 21 and the outer core fuel zone 22 as shown in the FIG. 1 was adopted. On the other hand, this embodiment is designed such that a sodium expansion chamber zone 45 is placed in an axially upper part of an upper fuel 42 and of an outer core fuel 44 without placing the axially upper covering fuel 35 and the axially lower covering fuel 36, which is different from the first embodiment. In addition, this embodiment is designed such that a gas expansion module (GEM, hereinafter called a “GEM”) 46 is placed between the external core fuel 44 and the radial covering fuel 47 , which is different from the first embodiment.
    In FIG. 7, the heart is vertically symmetrical and therefore only half is shown. A core 20 of the fast neutron reactor in this embodiment is placed in a reactor vessel 2 (FIG. 3) of the fast neutron reactor and a core fuel zone is constituted by an internal core fuel zone 21 and an outer core fuel zone 22 surrounding the inner core fuel zone 21 in the radial direction. In the core fuel area, a plurality of control rod assemblies 24 are placed. In addition, in the core 20 of the fast neutron reactor, a gas expansion module (GEM) 38 is loaded so as to surround the fuel zone of the external core 22 and the core 20 comprises a fuel zone of radial cover. 23, a reflector zone 25 and a protective screen zone 26 on the outside of the gas expansion module (GEM) 38. In the radial direction of the core 20 of the fast neutron reactor, the radial covering fuel zone 23 is adjacent to the gas expansion module (GEM) 38 while surrounding the gas expansion module (GEM) 38 and the protective screen area 2 6 surrounds the reflector area
    25. Here, the gas expansion module (GEM) 38 is a hollow tubular structure of which one end is closed and the other end is open and its external appearance is the same as that of a hexagonal tube of an assembly fuel loaded in the inner core fuel zone 21 and the outer core fuel zone 22. The core 20 of the fast neutron reactor of this embodiment is an axially heterogeneous core in which an internal covering fuel (described below) below) is placed in the internal core fuel zone 21 constituting the core fuel zone.
    As shown in FIG. 6, in the core 20 of the fast neutron reactor, an upper fuel 42 and a lower fuel 43 from the inner core fuel zone 21 (FIG. 7) and an outer core fuel 44 from the core fuel zone external 22 (FIG. 7) are all MOX fuel in which plutonium oxide (PuOx) is mixed with depleted uranium oxide (UO2). An internal cover fuel 41 is a fuel in which MA oxide (MAOx) in an amount of 35% by weight is mixed with depleted uranium oxide (UO2). In addition, the sodium expansion chamber zone 45 is placed in the axially upper part of the upper fuel 42 of the internal core fuel zone 21 (FIG. 7) and of the external core fuel 44 of the fuel zone. outer core 22 (FIG. 7). Here, the sodium expansion chamber area 45 is a space bounded by an inner wall surface of the hex tube in an upper portion of the core fuel (the upper fuel 42 and the outer core fuel 44). In addition, on the outside, radially, of the external core fuel 44, is the gas expansion module (GEM) 46 and, furthermore, on the outside, radially, of the gas expansion module ( GEM) 46, there is the radial cover fuel 47.
    In this regard, when an accident in which of the loss of coolant flow caused by the triggering of the primary circulation pump 7a (FIG. 3) due to the loss of external power input and the failure of emergency stop overlap (ULOF: loss of unprotected flow loss, hereinafter called “ULOF”) is presumed, even if the cavity reactivity is increased, the increase in the linear power of the fuel assembly in the vicinity of the fuel rod assembly 24 is removed by housing an empty space generated in the sodium expansion chamber area 45 located in the upper part of the core fuel (the upper fuel 42 and the core fuel external 44), and also by the internal covering fuel 41. Consequently, even if a configuration in which the gas expansion module (GEM) 46 is placed so as to be adjacent to the loaded fuel assembly in the outermost circumference of the outer core fuel zone 22 (FIG.
    7) is not always included, the aforementioned operational effect which cannot be manifested in the first embodiment can be manifested by the inclusion of the sodium expansion chamber zone 45.
    As shown in FIG. 6, in the internal core fuel zone 21 (FIG. 7), the lower fuel 43, the internal covering fuel 41, the upper fuel 42 and the sodium expansion chamber zone 45 are placed sequentially from the part lower than the upper part in the axial direction (from the upstream side to the downstream side along the direction of the flow of liquid sodium which is the primary coolant). For example, the lower fuel 43 has a height (a length along the axial direction) of about 35 cm in the axial direction, the inner cover fuel 41 has a height of 20 cm, the upper fuel 42 has a height 45 cm and the sodium expansion chamber area 45 has a height of 40 cm (each height is a length along the axial direction).
    Therefore, the total height in the axial direction (the total length along the axial direction) of the lower fuel 43, the inner covering fuel 41 and the upper fuel 42 is about 100 cm. On the other hand, in the outer core fuel zone 22 (FIG. 7), the outer core fuel 44 and the sodium expansion chamber zone 45 are placed sequentially from the lower part to the upper part in the axial direction (from the upstream side to the downstream side along the direction of the flow of liquid sodium which is the primary coolant). The outer core fuel 44 has a height (a length along the axial direction) of about 100 cm in the axial direction.
    In addition, the sodium expansion chamber area 45 has a height (a length along the axial direction) of about cm in the axial direction.
    In the core 20 of the fast neutron reactor in this embodiment, as described above, in the core of the first embodiment, the axial covering fuel (the axially upper covering fuel 35 and the axially lower covering fuel 36) is eliminated and, instead, the sodium expansion chamber area 45 is disposed in the upper part of the core fuel and, moreover, a configuration in which the gas expansion module (GEM) 46 is arranged on the outer circumference of the core fuel zone composed of the inner core fuel zone 21 and the outer core fuel zone 22, that is to say so as to be adjacent to the assembly fuel, and to surround it, loaded in the outermost circumference among the fuel assemblies loaded in the outer core fuel zone 22 is adopted.
    In the core 20 of the fast neutron reactor of this embodiment, in the same way as in the first embodiment, the integrity of the core fuel at the time of a UTOP is guaranteed and moreover the cavity reactivity is d '' about $ 2 to $ 3, which is much lower than that of a fast neutron reactor with the same production scale. In addition, when an accident in which of the loss of primary system coolant flow (eg liquid sodium) caused by the triggering of the primary circulation pump 7a due to the loss of external power input or the like and an overlapping emergency stop failure (ULOF) is assumed, due to the decrease in the primary system coolant flow (e.g. liquid sodium) in the fuel assembly loaded in the internal core fuel zone 21 and the outer core fuel zone 22, the power to flow ratio (P / F) of the fuel assembly will be unsuitable and the maximum temperature of the primary system coolant (for example liquid sodium) is increased. However, depending on the configuration of the core 20 of the fast neutron reactor of this embodiment, the extent of the neutron leak from the loaded fuel assembly into the inner core fuel zone 21 and the outer core fuel zone to the sodium expansion chamber area 45 and the gas expansion module (GEM) 46 is large and, by application of a negative reactivity, the boiling of the primary system coolant (e.g. liquid sodium) can be avoided and in addition the increase in thermal power of the core can be suppressed and, therefore, the integrity of the core fuel is maintained.
    In this regard, a plurality of fuel assemblies are placed in the circumferential direction so as to be adjacent to the gas expansion module (GEM) 46 and the plutonium enrichment (Pu enrichment) of the MOX fuel of the assembly. fuel loaded in the outermost circumference of the outer core fuel zone 22 can be set to be the highest. In other words, the plutonium enrichments (Pu enrichments) of the MOX fuels of the fuel assemblies loaded in the fuel zone of the outer core 22 and of the fuel assemblies loaded in the fuel zone of the inner core 21 with the exception of the assembly fuel loaded in the outermost circumference of the outer core fuel zone 22 (the outermost circumferential fuel assembly) are identical and the plutonium enrichment (Pu enrichment) of the MOX fuel the outermost circumferential fuel assembly is higher than the plutonium enrichment (Pu enrichment) of the MOX fuels of the fuel assemblies loaded in the fuel zone of the outer core 22 and of the fuel assemblies loaded in the fuel zone internal core fuel 21.
    As described above, according to this embodiment, in addition to the effect at the time of presumption of UTOP from the first embodiment, by adopting the configuration in which the sodium expansion chamber zone 45 is placed, when an accident in which of the loss of coolant flow caused by the triggering of the primary circulation pump 7a (FIG. 3) due to the loss of external power supply or the like and a failure of overlapping emergency stop (ULOF) is assumed, since the configuration in which the sodium expansion chamber zone 45 and the gas expansion module (GEM) 46 are placed in the reactor core fast neutrons is adopted, the extent of the neutron leakage from the loaded fuel assembly into the inner core fuel zone 21 and the outer core fuel zone 22 to the sodium expansion chamber zone 45 and the gas expansion module (GEM) 46 is large and, by applying a negative reactivity, the boiling of the primary system coolant (for example liquid sodium) can be avoided and in addition the increase in thermal power of the core can be suppressed and, therefore, the integrity core fuel can be stored.
    Incidentally, in the first embodiment and the second embodiment mentioned above, a case where a mixed oxide fuel (MOX) in which plutonium oxide (PuOx) is mixed with uranium oxide ( UO 2 ) depleted is used as fuel of the core is described by way of example, but however, the invention is not limited thereto. For example, a metallic fuel or a nitride fuel can be used and, in addition, a configuration in which also as a coolant (primary coolant), a liquid heavy metal such as lead or lead-bismuth is used instead sodium can be adopted.
    It should be noted that the present invention is not limited to the above-mentioned embodiments and that various variants are included in the present invention. For example, the above-mentioned embodiments are explained in detail in order to clearly explain the present invention, and the embodiments are not always limited to the embodiments including all of the configurations described. Part of the configuration of a certain embodiment can be replaced by the configuration of another embodiment. In addition, the configuration of another embodiment can also be added to the configuration of a certain embodiment.
    [List of reference numbers]: nuclear power generation system with fast neutron reactor: reactor vessel: core
    4a: primary cooling system piping 4b: secondary cooling system piping 5: intermediate heat exchanger
    7a: primary circulation pump
    7b: secondary circulation pump: steam generator
    9a: system piping steam primary 9b: system piping of water feed condensation 10, 10a, 20: heart lia : high pressure turbine 11b : low pressure turbine 12: electric generator
    : condenser: feed water pump: feed water heater
    21: zoned of combustible of internal heart 22: zoned of combustible of external heart 23: zoned of combustible radial coverage
    : control rod assembly: reflector area: protective screen area
    31, 31a: internal cover fuel upper fuel lower fuel outer core fuel axially upper cover fuel axially lower cover fuel radial cover fuel gas expansion module (GEM) internal cover fuel upper fuel lower fuel core fuel external sodium expansion chamber area gas expansion module (GEM) radial cover fuel
    权利要求:
    Claims (7)
    [1" id="c-fr-0001]
    [CLAIMS] [Claim 1]
    Core of a fast neutron reactor, characterized in that the core comprises an inner core fuel zone and an outer core fuel zone surrounding the inner core fuel zone in the radial direction of the core and a fuel assembly in which MOX fuel is housed in a hexagonal tube is loaded into the inner core fuel area and the outer core fuel area and at least the fuel assembly loaded into the inner core fuel area includes an inner cover fuel comprising depleted uranium oxide containing a minor actinide as a fuel in an axially substantially central portion.
    [Claim 2]
    Core of a fast neutron reactor according to claim 1, characterized in that in the internal covering fuel, the content of minor actinide is from 35% by weight to 45% by weight.
    [Claim 3]
    Core of a fast neutron reactor according to claim 2, characterized in that the fuel assembly loaded into the inner core fuel zone comprises an upper fuel comprising MOX fuel and an axially upper covering fuel comprising oxide depleted uranium as fuel on the upper side of the inner cover fuel and a lower fuel comprising fuel
    MOX and an axially lower cover fuel comprising depleted uranium oxide as fuel on the lower side of the internal cover fuel.
    [Claim 4]
    Core of a fast neutron reactor according to claim 3, characterized in that the MOX fuel is a fuel in which plutonium oxide is mixed with depleted uranium oxide and the plutonium enrichments of the upper fuel and the lower fuel of the fuel assembly loaded in the inner core fuel zone and the MOX fuel of the fuel assembly loaded in the outer core fuel region are identical.
    [Claim 5]
    Core of a fast neutron reactor according to claim 1, characterized in that the fuel assembly loaded in the inner core fuel zone and the outer core fuel zone comprises a sodium expansion chamber zone delimited by an internal wall surface of the hexagonal tube in an axially upper part of the MOX fuel.
    [Claim 6]
    Core of a fast neutron reactor according to claim 5, characterized in that a radial covering area positioned so as to surround the outer core fuel area is included and, between the radial covering area and the fuel area an outer core is a gas expansion module which is a hollow tubular structure with one end closed and the other end open.
    [Claim 7]
    Core of a fast neutron reactor according to claim 6, characterized in that a plurality of gas expansion modules are placed in the circumferential direction so as to be adjacent to the fuel assembly loaded in the most circumference outside the outer core fuel zone.
    [Claim 8]
    Core of a fast neutron reactor according to claim 7, characterized in that the MOX fuel is a fuel in which plutonium oxide is mixed with the depleted uranium oxide and the plutonium enrichments of the upper fuel and the lower fuel of the fuel assembly loaded in the inner core fuel zone and the MOX fuel of the fuel assembly loaded in the outer core fuel zone are identical.
    [Claim 9]
    Core of a fast neutron reactor according to claim 7, characterized in that a plurality of fuel assemblies are placed in the circumferential direction so as to be adjacent to the gas expansion module and the plutonium enrichment of the fuel MOX of the fuel assembly loaded in the outermost circumference of the outer core fuel zone is the highest.
    1/7 [FIG. 1]
    REACTOR CENTER
    [2" id="c-fr-0002]
    2/7 [FIG. 2] [3" id="c-fr-0003]
    3/7 [FIG. 3] [4" id="c-fr-0004]
    4/7 [FIG. 4] [5" id="c-fr-0005]
    5/7 [FIG. 5]
    JQa
    REACTOR CENTER
    [6" id="c-fr-0006]
    6/7 [FIG. 6] [7" id="c-fr-0007]
    7/7 [FIG. 7]
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    同族专利:
    公开号 | 公开日
    JP6753760B2|2020-09-09|
    JP2018071997A|2018-05-10|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    CN109215811B|2018-09-13|2020-01-14|中国核动力研究设计院|Hexagonal beryllium assembly and aluminum assembly nuclear design reliability inspection reactor core and adjusting method|
    CN109215812B|2018-09-13|2020-01-14|中国核动力研究设计院|Hexagonal casing type fuel aluminum component nuclear design reliability inspection reactor core and method|
    CN109192332B|2018-09-13|2020-01-07|中国核动力研究设计院|Hexagonal casing type fuel reactor core cobalt target assembly nuclear design inspection reactor core and method|
    法律状态:
    2018-09-28| PLFP| Fee payment|Year of fee payment: 2 |
    2019-09-16| PLFP| Fee payment|Year of fee payment: 3 |
    2020-09-29| PLFP| Fee payment|Year of fee payment: 4 |
    2021-09-27| PLFP| Fee payment|Year of fee payment: 5 |
    2021-11-19| PLSC| Publication of the preliminary search report|Effective date: 20211119 |
    优先权:
    申请号 | 申请日 | 专利标题
    JP2016208205A|JP6753760B2|2016-10-25|2016-10-25|Fast reactor core|
    JP2016208205|2016-10-25|
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