U236-destroying heavy rare gas coolant reactor, U236-containing nuclear fuel rod (301), radioactive landmines / radioactive minefields

Abstract

When using a small modular reactor (SMR), the spent nuclear fuel contains uranium-236. Because U236 is more easily fissionable than U238, it cannot be disposed of as general waste. [Solution] By using a heavy rare gas reactor, in which the cooling water in a conventional boiling water reactor is replaced with a heavy rare gas heavier than helium, such as neon, krypton, or argon, when an SMR is introduced, the uranium-236 contained in the spent nuclear fuel is burned and annihilated by fast neutron fission.

Description

Technical Field

[0001] Nuclear fission is a phenomenon in which heavy atomic nuclei such as uranium react with neutrons or protons and split into two or more light atomic nuclei. At that time, two or more neutrons are released. Uranium-235 forms a compound nucleus with slow neutrons and undergoes significant nuclear fission. Uranium-238 hardly undergoes nuclear fission with slow neutrons. However, it undergoes nuclear fission with fast neutrons. In the United States, small modular reactors (SMRs) are being promoted. There are various types of SMRs. Here, a small and mass-producible one uses medium-enriched oxide nuclear fuel with a uranium-235 concentration of about 20 wt% to 60 wt% (uranium-238 ratio of 80 wt% to 40 wt%) and helium coolant and solid moderator to carry out nuclear fission combustion. Since the ratio of uranium-238 is small, the production amount of plutonium will be small. Many atomic bombs cannot be made. However, since it is possible to make an atomic bomb with low efficiency even with medium-enriched nuclear fuel, in order not to allow the production of a large number of low-efficiency atomic bombs, it is meaningless not to prohibit the production of medium-enriched nuclear fuel and instead import it from the United States. If there is a low-efficiency atomic bomb, a low-efficiency hydrogen bomb can be made using lithium-6 deuteride. Experimental machines and products end immediately when one is made and the performance that meets the initial specifications is obtained. Then, it is decided whether to mass-produce according to the requirements of the times. There is research on high-temperature reactors, but high temperatures can be achieved using the electricity generated by light water reactors, and electric steelmaking is a typical example. The significance of high-temperature reactors is unclear. Radioactive waste is generated from high-temperature reactors.

Background Art

[0002] [ [[ID=二十三]] [ When medium-enriched nuclear fuel is burned using helium coolant and solid moderator, uranium-234 (U234) and uranium-236 (U236) are produced. Figure 1 shows the neutron energy dependence η of U234, U235, U236, and U238 , , , g , g , , ,

[0002] is. If the neutrons do not slow down, then η gThis is a neutron energy-dependent, leakage-free, no-deceleration, infinite multiplication factor kinf g That is the case. U238, U234, U235, and U236 also have neutron energies above 2 MeV. g ≒kinf g It is significantly above 1.0. U236 is only slightly above U238, and because it undergoes some fission, it is difficult to handle. It cannot be thrown away as garbage. Above 10.5 MeV, the η is large. g It is thought that this would be the value, but I cannot find a reliable nuclear combustion calculation code. [Disclosure of the Invention] [Problems that the invention aims to solve]

[0003] To emphasize safety, the reactors were miniaturized and built in large batches, aiming to cut costs through mass production, but it seems that this is less economical than large reactors. The US company that came up with the idea (a company structure similar to Apple, where they design but other companies manufacture the products; this structure is probably the only option due to the extremely strict product liability laws. There are animals like koalas that feed on eucalyptus leaves, which contain toxins) seems to be withdrawing from the small modular reactor market. Even the nuclear industry, in order to maintain its long-standing status, will likely continue to build modular reactors. The problem then becomes what to do with spent nuclear fuel. In particular, the fate of uranium-236 remains unclear. [Means for solving the problem]

[0004] Method 1 is a U236 extinction heavy noble gas cooled reactor. The core of a boiling water reactor is modified, which consists of a pressure vessel (10) filled with coolant, in which nuclear fuel rod assemblies are arranged in a square grid pattern adjacent to numerous cross-shaped control rods (22) arranged in a square grid pattern. The water coolant shall be a heavy noble gas coolant. The nuclear fuel rod assembly is a U236-containing nuclear fuel rod assembly (1). The U236-containing nuclear fuel rod assembly (1) is made up of a large number of U236-containing nuclear fuel rods (301) according to claim 2 arranged in a square lattice. At the center of the reactor core is a U236-containing nuclear fuel rod assembly (1) consisting of U236-containing nuclear fuel rods (301) manufactured from low-burnup spent nuclear fuel from a modular reactor. Starting from the center, U236-containing nuclear fuel rod assemblies (1) consisting of U236-containing nuclear fuel rods (301) manufactured from spent nuclear fuel with a high burnup rate in the modular reactor are loaded sequentially. A U236 annihilation heavy noble gas coolant reactor characterized by fast neutron fission of U236. If water is used as a coolant, the neutron velocity is significantly reduced, resulting in fewer fast neutrons needed to fission U236. Neutron velocity is also reduced if helium or carbon dioxide is used as a coolant. Heavy noble gases, such as neon, krypton, and argon, which are heavier than helium, do not reduce neutron velocity as much. Prior examples of the present invention include Patent Documents 1, 2, and 3. [Patent Document 1] Japanese Patent Application No. 2023-131719 [Patent Document 2] Japanese Patent Application No. 2023-189696 [Patent Document 3] Japanese Patent Application No. 2023-148573

[0005] Means 2 is the U236-containing nuclear fuel rod (301) of Means 1. Green nuclear fuel pellets (210) are short cylindrical nuclear fuel obtained by loading finely granulated nuclear fuel particles, which are made from pulverized spent nuclear fuel from simplified reprocessing, into a short cylindrical mold with a closed bottom, made of metallic depleted uranium or oxidized depleted uranium, with a height of 1 cm to 2 cm and a diameter of 1.5 cm to 2 cm, and then vibrating and filling it. The U236-containing nuclear fuel rod (301) of method 1 is characterized by being loaded by stacking a large number of green nuclear fuel pellets (210) inside a cladding tube (250), which is a long cylindrical sheath made of stainless steel, and sealing the upper and lower ends of the cladding tube (250). Simplified reprocessed spent nuclear fuel is obtained by removing volatile fission products from spent nuclear fuel from modular reactors, then removing light elements from the solid fission products, and crushing and granulating lumps containing U234, U235, U236, U238, MA, and heavy metals heavier than actinium. Heavy metals heavier than actinium are difficult to separate and are therefore left in the lumps.

[0006] Method 3 is radioactive landmines and radioactive landminefields. A radioactive minefield characterized by containing spent nuclear fuel generated in a modular reactor directly inside a stainless steel container, and numerous radioactive mines buried in a concrete floor. [Effects of the Invention]

[0007] Because of its simple structure, manufacturing and construction costs can be expected to decrease. Even if it is destroyed, demolition and clearing the land is easy and inexpensive. It can be rebuilt each time it is damaged by an earthquake. The demand for rebuilding will be positive for the Japanese economy. Since it seems possible to process spent nuclear fuel from modular reactors, this will help in the construction of the first modular reactor or an experimental reactor. [Best Mode for Carrying Out the Invention]

[0008] We were able to provide a reactor that can extinguish spent nuclear fuel generated from a modular reactor through nuclear combustion, and also utilize the heat generated during the nuclear combustion process for power generation. [Example 1]

[0009] Example 1 is the U236 extinction heavy noble gas cooled reactor of the present invention. Figure 2 is an overview diagram of the U236 extinction heavy rare gas cooled reactor of the present invention. This diagram shows a schematic representation of a conventional boiling water reactor with its nuclear fuel rod assembly loaded inside the pressure vessel (10) (Non-Patent Document 1, Non-Patent Document 2). The low-temperature, low-pressure heavy rare gases that have finished their work in the turbine are air-cooled and pass through the coolant supply pipe (17) to enter the lower core plenum (8) through the cooling inlet pipe (25) laid in the shroud-external coolant space (16) between the pressure vessel (10) wall and the shroud (18). In addition to the coolant supply pipe (17), the low-temperature, low-pressure heavy rare gases can also enter the lower core plenum (8) through the cooling inlet pipe (25) from the emergency core cooling system pipe (ECCS pipe). The lower core plenum (8) is surrounded by the bottom of the pressure vessel (10) and the core support plate (9) and is filled with high-pressure heavy noble gases. The core support plate (9) supports the U236-containing nuclear fuel rod assembly (1) of the present invention. The cold, heavy rare gas that enters the lower core plenum (8) enters the lower end of the U236-containing nuclear fuel rod assembly (1), absorbs heat from the nuclear fuel rods of the nuclear fuel rod assembly (1), and flows upward. The cold, heavy rare gas flowing through the gaps between the nuclear fuel rod assemblies flows upward through the leak coolant passage (20). High-temperature heavy rare gas leaking from the top of the U236-containing nuclear fuel rod assembly (1) and medium-temperature heavy rare gas leaking from the top of the leaking coolant passage (20) mix in the mixing region (19) and enter the coolant dome (11), then exit to the gas turbine through the high-temperature heavy rare gas pipe (14). The reactor output is controlled by cross-shaped control rods (22) that move up and down via a control rod drive device (23). Figure 3 is an overview perspective view of the present invention, which consists of a U236-containing nuclear fuel rod assembly (1) containing nuclear fuel material and cross-shaped control rods (22). The U236-containing nuclear fuel rod assembly (1) has a large number of cylindrical U236-containing nuclear fuel rods (301) containing nuclear fuel material arranged in a square grid (rarely a triangular grid), with their lower ends inserted into a lower fuel tie plate (37), and the bundle of nuclear fuel rods (301) is covered on all four sides by a channel box (35) made of a zirconium alloy or stainless steel plate molded into a square frame. The U236-containing nuclear fuel rod assembly (1) is supported by a fuel rod assembly support fitting (50). Between the nuclear fuel rods (301) is a primary coolant passage (36), and heavy rare gas for extracting heat out of the reactor flows from bottom to top, absorbing heat from the nuclear fuel rods as it flows upward. Heavy rare gas flows in the leakage coolant passage (20) between adjacent U236-containing nuclear fuel rod assemblies (1). The cruciform control rod (22) can move up and down between the channel boxes (35). The cruciform control rod (22) is made of a thin hafnium plate, a substance with strong neutron-absorbing properties for controlling the reactor power. The cruciform control rod (22) moves up and down by a control rod drive device (23) housed in a control rod guide tube (26). The heavy rare gas in the lower plenum (8) of the reactor core enters the fuel rod assembly support fitting (50) from a coolant inlet (99) opened in the control rod guide tube ( 26), and then flows into the lower end of the U236-containing nuclear fuel rod assembly (1). The fuel rod assembly support fitting (50) is supported by the control rod guide tube (26) and the reactor core support plate (9). The arrows in the figure indicate the main flow direction of the coolant. Figure 4 is a plan view of the reactor core of the present invention, which consists of the U236-containing nuclear fuel rod assembly (1) and the cruciform control rod (22) obtained by modifying a boiling water reactor. Heavy rare gas flows into the leakage coolant passage (20) between adjacent U236-containing nuclear fuel rod assemblies (1) from the bottom and flows upward. The cruciform control rod (22) can move up and down in the leakage coolant passage (20). The reactor core surrounded by a stainless steel cylindrical shroud (18) consists of a U236-containing nuclear fuel rod assembly (1) containing nuclear fuel and a cruciform control rod (22) containing a neutron absorber. Between adjacent U236-containing nuclear fuel rod assemblies (1) is a leakage coolant passage (20) through which saturated water flows. In the central part of the reactor core, as 1, a U236-containing nuclear fuel rod assembly (1) composed of U236-containing nuclear fuel rods (301) manufactured from low-burnup used nuclear fuel of a modular reactor was loaded. It is manufactured from used nuclear fuel located at the upper and lower ends and the outer edge in the radial direction of the modular reactor. A large amount of uranium-235 remains unburned. The nuclear fission chain reaction is active even in a fast neutron atmosphere. Since there are few thermal neutrons, the conversion to uranium-236 is small. U236 also undergoes nuclear fission. There are also minor actinides (MA) represented by Pu, and plutonium increases as the reactor of the present invention operates. In the middle part of the reactor core, as 2, a U236-containing nuclear fuel rod assembly (1) composed of U236-containing nuclear fuel rods (301) manufactured from medium-burnup used nuclear fuel of a modular reactor was loaded. It is manufactured from used nuclear fuel located in the middle part in the height direction and the middle part in the radial direction of the modular reactor. There is MA, and plutonium increases. In the outer part of the reactor core, as 3, a U236-containing nuclear fuel rod assembly (1) composed of U236-containing nuclear fuel rods (301) manufactured from high-burnup used nuclear fuel of a modular reactor was loaded. It is manufactured from used nuclear fuel located in the central part in the height direction and the central part in the radial direction of the modular reactor. Almost no uranium-235 remains. MA is abundant, and plutonium increases. The outside of the shroud (18) is covered by a pressure vessel (10). The shroud outer coolant space (16) between the pressure vessel (10) and the shroud (18) is filled with a heavy rare gas. When the reactor is stopped, all of the cruciform control rod (22) groups are inserted into the reactor core. When the reactor is operating, most of the cruciform control rod (22) groups are withdrawn from the reactor core to below the reactor core, and several cruciform control rods (22) at the center are inserted into the reactor core.

Non-Patent Document 1

Non-Patent Document 2

Example 2

[0010] Example 2 is the U236-containing nuclear fuel rod (301) of the present invention. Figure 5 is an overview of the U236-containing nuclear fuel rod (301) of the present invention. It consists of a stainless steel cladding tube (41) which is a cylindrical sheath 1m to 2m in length, upper end plugs (42) and lower end plugs (43) which airtightly seal the upper and lower open ends of the cladding tube (41), a number of green nuclear fuel pellets (210) loaded inside the cladding tube (41), and a spring (45). The green nuclear fuel pellets (210) are 1cm to 2cm in height and 1.5cm to 2cm in diameter. The U236-containing nuclear fuel rod (301) according to claim 1 is characterized by being loaded with a large number of green nuclear fuel pellets (210) stacked inside a cladding tube (41), which is a long cylindrical sheath made of stainless steel, and having the upper and lower ends of the cladding tube (41) sealed. To increase the density of green nuclear fuel pellets (210), depleted uranium metal particles are sometimes mixed in. The diameter of these pellets is increased to further enhance density. Green nuclear fuel pellets (210) contain U234, U235, U236, U238, MA, and heavy metals heavier than actinium. [Example 3]

[0011] Example 3 is a radioactive landmine and a radioactive landminefield. Claim 1 provides protection against terrorism for a U236 extinction heavy rare gas coolant reactor power plant. U236 emits gamma rays when it absorbs spontaneous neutrons generated in MA (Magnetic Amplifier). Tank groups are vulnerable to attacks from approaching enemy soldiers if there are no defending soldiers in the gaps between the tanks. Therefore, tank groups can be repelled by slowing down the number and movement of defending soldiers. Defending soldiers who approach landmines unknowingly will gradually weaken or die. Defending soldiers protected by lead suits will move slowly. Spent nuclear fuel from light water reactors accumulating in Japan can be exported as radioactive landmines. Tanks move slowly on soft ground, so they should be laid on hard ground or solid roads. If spent nuclear fuel is mixed with tar or clay and hit a tank with it, the gamma rays will weaken the driver inside the tank. It is effective for defending existing nuclear power plants and borders. It will not launch an offensive, but it will not allow intrusion. The accumulated spent nuclear fuel assemblies, fuel rods, and low-dose radioactive waste from light water reactors can be used directly to create radioactive landmines or minefields. [Industrial applicability]

[0012] The initial sales volume is proportional to the population of the country of manufacture. If the initial sales and manufacturing plan in Japan is 10,000 units, it would be 100,000 units in China. Manufacturing costs are low. Therefore, the separation of design and manufacturing will continue for the time being. However, Japan's population is moderately large, so a reasonable production volume can be planned, and it would sell well domestically, so there is hesitation in large-scale production. However, it will lose out in overseas cost competition. Countries with large populations experience a rapid decline in sales once they stop selling. Japan is precisely the country best suited to the separation of design and manufacturing. Nuclear power plants are also designed in Japan and manufactured and sold overseas. From this perspective, it seems possible to market the design of this invention overseas. Development costs will be financed with government bonds. If the government debt becomes too high, the Bank of Japan can simply authorize the government to extinguish its own holdings of government bonds. This is similar to a corporation extinguishing its own shares. Government authorization would be gradually increased, starting with 2 billion yen in the first year, then 4 billion yen after six months, then 8 billion yen after another six months, and so on. If prefectural notes, similar to feudal domain notes, could be issued, it might be possible to cover some of the costs. These could potentially be used as collateral to purchase materials. [Brief explanation of the drawing]

[0013] [Figure 1] Reference neutron energy dependence ηg graphs for U234, U235, U236, and U238. [Figure 2] A schematic diagram of the U236 extinction heavy noble gas cooled reactor of the present invention. [Figure 3] A perspective view of the reactor core according to the present invention, comprising a nuclear fuel rod assembly (1) containing an allowable alloy related to the present invention that encloses nuclear fuel material, and a cross-shaped control rod (22). [Figure 4] A plan view of the reactor core of the present invention, which consists of a U236-containing nuclear fuel rod assembly (1) and a cross-shaped control rod (22) related to the present invention, modified from a boiling water reactor. [Figure 5]A schematic diagram of the U236-containing nuclear fuel rod (301) of the present invention. [Explanation of Symbols]

[0014] 1 is a U236-containing nuclear fuel rod assembly. 8 is the lower core plenum. 9 is the core support plate 10 is a conventional pressure vessel 11 is the coolant dome 14 is a high-temperature heavy noble gas pipe. 16 is the space for the coolant outside the shroud. 17 is the coolant supply pipe. 18 is Shroud 19 is a mixed region 20 is a leaking coolant passage. 22 is a cross-shaped control rod 23 is the control rod drive unit. 25 is the cooling inlet pipe. 26 is a control rod guide tube. 35 is the channel box 36 is the main coolant passage. 37 is the lower fuel type rate 42 is the upper end plug 43 is the lower end plug 45 is spring 50 is a support bracket for nuclear fuel rod assemblies. 99 is the coolant inlet. 210 is a green nuclear fuel pellet. 250 is a cladding pipe 301 is a nuclear fuel rod containing U236.

Claims

1. In the core of a boiling water reactor, which is a pressure vessel (10) filled with coolant, nuclear fuel rod assemblies are arranged in a square grid adjacent to a large number of cross-shaped control rods (22) arranged in a square grid, The water coolant will be a heavy rare gas coolant. The nuclear fuel rod assembly is a U236-containing nuclear fuel rod assembly (1), The U236-containing nuclear fuel rod assembly (1) is made up of a large number of U236-containing nuclear fuel rods (301) according to claim 2 arranged in a square lattice, At the center of the reactor core is a U236-containing nuclear fuel rod assembly (1) consisting of U236-containing nuclear fuel rods (301) manufactured from low-burnup spent nuclear fuel of a modular reactor. Starting from the center, U236-containing nuclear fuel rod assemblies (1) consisting of U236-containing nuclear fuel rods (301) manufactured from spent nuclear fuel with a high burnup rate in the modular reactor are loaded sequentially. A U236 annihilation heavy noble gas coolant reactor characterized by fast neutron fission of U236.

2. Green nuclear fuel pellets (210) are short cylindrical nuclear fuel obtained by loading finely pulverized spent nuclear fuel particles, obtained by simplified reprocessing, into a short cylindrical mold with a height of 1 cm to 2 cm and a diameter of 1.5 cm to 2 cm, made of metallic depleted uranium or oxidized depleted uranium, and then vibrating and filling it. The U236-containing nuclear fuel rod (301) according to claim 1 is characterized by being loaded with a large number of green nuclear fuel pellets (210) stacked inside a cladding tube (250), which is a long cylindrical sheath made of stainless steel, and having the upper and lower ends of the cladding tube (250) sealed.

3. A radioactive minefield characterized by the inclusion of spent nuclear fuel generated in a modular reactor inside a stainless steel container, and numerous other radioactive mines buried in a concrete floor.

Images