JPH08338892A - Helium cooling high-temperature gas reactor - Google Patents

Abstract

PURPOSE: To make it possible to show the excellence from the viewpoint of energy resources and the global environment and desalt seawater at the same time because of its higher safety, high total thermal efficiency and no emission of carbon dioxide from all circuits. CONSTITUTION: An intermediate heat exchanger 9 separates a primary circuit including a reactor from a secondary circuit including a heat exchanger for supplying the heat capacity needed for a turbine system and a seawater desalting device in order not to leak any radioactive substances in the atmosphere. A heat exchanger of a helical-tube type is used in the intermediate heat exchanger 9. Moreover, the temperature of helium at the exit of the reactor is set at 950 deg.C and that at the entrance at 450 deg.C rather than a conventionally proposed temperature, 400 deg.C. In this case, in order to secure the integrity of the reactor according to the rise in the temperature at the entrance, the temperature of a pressure vessel is lowered by installing an inner heat-insulating layer with a metal corrugated sheet structure inside the reactor vessel to separate the thermal boundary and the pressure boundary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses helium gas as a coolant for a primary circuit and a secondary circuit, and provides a gas turbine power generation system and a desalination system in the secondary circuit.
Further, the present invention relates to a high temperature gas reactor system with improved safety by providing a heat insulating layer on the inner surface of the reactor vessel.

Since the high temperature gas reactor of the present invention uses helium which is chemically stable and contains almost no radioactive material as a coolant for the primary circuit and the secondary circuit, it is radioactive from the reactor system to the surrounding environment. Very little material leakage. Further, even in the event of an accident, no chemically active substance is produced like hydrogen, and the inherent safety is extremely high compared to a light water reactor. Also, it does not emit carbon dioxide at all. That is, it is a nuclear reactor excellent in safety and global environment. Therefore, it is desired to be used in the fields where high safety and global environment are required.

While the light water reactor has a thermal efficiency of about 35%, the high temperature gas reactor according to the present invention can effectively use about 90% of the reactor output for power generation and seawater desalination. Power generation to widely supply to the general public, and desalination to create fresh water from seawater for use in the livelihood of the location area (drinking water, cooling and heating, etc.) and for the agricultural industry (irrigation, greenhouse air conditioning, etc.) In addition to this, the exhaust heat of about 200 ° C. from the turbine can be used for multiple purposes in the chemical industry and the like. In addition, when a large amount of fresh water is required, it is possible to produce a large amount of fresh water by using the generated electric power or the like with an ion semipermeable membrane fresh water device.

In the high temperature gas reactor of the present invention, fissionable plutonium is burned and consumed by using uranium oxide and plutonium oxide separated from the spent fuel of the light water reactor by reprocessing. In other words, by burning and consuming the fissile plutonium produced by the light water reactor, Japan's supply and demand for plutonium will be adjusted so that plutonium will not be used for nuclear weapons. in this way,
By combining the HTGR according to the present invention with a light water reactor, the uranium cycle can be almost closed, and it is considered that it plays a useful role in ensuring the safety of nuclear energy.

[0005]

2. Description of the Related Art A graphite-moderated carbon dioxide cooling furnace was developed as a heat source for a steam power generation system mainly in England in the 1950s. This type of furnace has a total output of about 50 in England.
Although the development up to 00 MW, problems such as carbon separation in carbon dioxide due to abnormal temperature rise or long-term operation, carburizing steel and reacting with graphite became clear,
Development of a new carbon dioxide cooling furnace has stopped.

Next to the carbon dioxide cooling furnace, a new type high temperature gas furnace using helium as a coolant, which is chemically inert and has excellent heat transfer characteristics, was developed and operated in the United States and Germany. For example, in the United States, a reactor outlet temperature of 750 ° C, power generation efficiency of 39%, a reactor output of 330 MW high temperature gas reactor was constructed and operated, and in Germany, reactor outlet temperature of 750 ° C, power generation efficiency of 39%.
%, The THTR with a reactor output of 290 MW was constructed and operated, but due to various changes and improvements being made during development and the cost of power generation becoming expensive, the operation was completed around 1990.

At the Nuclear Research Institute in Jürich, Germany, in parallel with the development of the THTR, the research and development is being advanced with the aim of further improving the thermal efficiency and utilizing the thermal energy from the nuclear reactor in fields other than power generation. It was In particular, the high temperature gas experimental reactor AVR was constructed to carry out various R & D on fuels, and TRI was coated with SiC, carbon layers, etc.
We have developed excellent coated fuel particles called SO fuel. However, on the other hand, in the development of the helium gas turbine power generation system, the development of the blade material was not successful. Also,
It was found that excellent results were not obtained in the development of the coal gasification system and the long-distance transportation system of thermal energy, and the future could not be expected, so several years ago, including the shutdown of the experimental reactor AVR, Most research and development has been discontinued.

In Japan, one of the large-scale technological development projects of the Ministry of International Trade and Industry since 1970, research and development of direct iron making, which reduces raw iron ore by utilizing thermal energy of 1000 ° C. obtained from a HTGR, has been conducted. It was In this project, a high-temperature helium loop including important equipment required for direct steelmaking was developed, constructed and operated. This loop consisted of a primary helium circuit, a secondary helium circuit and a tertiary reducing gas production system. The test was carried out at the maximum temperature of the primary helium circuit of 1000 ° C., and the results satisfying the intended purpose were obtained. However, since the need for nuclear heat utilization in the steel industry decreased after that, the technology obtained in this project was transferred to the Japan Atomic Energy Research Institute, and then the Handel Loop (large-scale structural equipment demonstration test loop) Has been manufactured, and the development of equipment for high-temperature gas reactors and the research and development on safety have been conducted to date.

In 1990, based on the research results so far, in accordance with the "long-term plan for nuclear power development and utilization" formulated by the Atomic Energy Commission, the heat output of 30 MW at the Japan Atomic Energy Research Institute.
Construction of the High Temperature Engineering Test Reactor (HTTR) has been decided and started and is currently under construction. The HTTR is a research facility that aims to establish and improve the basic technology of helium-cooled high-temperature gas reactors and to conduct advanced research on high-temperature engineering. We are planning to examine the application fields. This test furnace is practically available based on the information of conventional gas furnaces, high temperature gas furnaces, etc.
The purpose is to establish the basic technology to operate a gas furnace at a high temperature of 0 ° C, and it is the only gas furnace currently built in the world and operated in the near future. In view of the purpose and the result of this test furnace, the present invention also sets the essential matters for the practical application of the high temperature gas reactor as the object and the constitution of the invention.

[0010]

A conventional nuclear reactor has a main purpose of performing power generation as a social role while hardly emitting global environmental pollutants such as carbon dioxide gas. Solving the two important purposes of producing fresh water from seawater using the exhaust heat of turbines and supplying it to civilian and agricultural areas where the power plant is located, and further, uranium and plutonium remaining in the spent fuel of the light water reactor. A fuel is produced from the fuel, and by using this fuel in the reactor of the present invention, the uranium fuel cycle is closed by burning and consuming the fissile plutonium almost completely, and the problem of supply and demand balance of plutonium in Japan. To solve.

Since the helium-cooled high temperature gas reactors proposed so far have been focused on economy, a direct cycle in which a helium turbine system is installed in a primary circuit is adopted. Moreover, the use of a compact plate heat exchanger is proposed as a regenerative heat exchanger for exhaust heat recovery of the turbine. However, compact plate heat exchangers are used in general industrial gas turbine cycles, fuel cell cycles, etc. when the operating pressure and the pressure difference between the primary side and the secondary side are both less than 1 MPa. As in the case of the gas turbine cycle of a furnace, the operating pressure is 6 MPa and the pressure difference between the primary side and the secondary side is several MP
When it reaches a, the stress generated in the heat exchanger becomes excessive. Moreover, since the compact plate heat exchanger has a complicated structure, it is almost impossible to completely inspect the welded and brazed parts, and it is not reliable enough to be used for the reactor equipment and should not be used.

In the present invention, an indirect cycle is used, and a helical tube type intermediate heat exchanger is installed between the primary circuit and the secondary circuit. This intermediate heat exchanger has high heat transfer performance using solid radiant heat and also has sufficient safety. A similar helical tube heat exchanger will be used for the regenerative heat exchanger of the gas turbine power generation system. That is, in the present invention, the intermediate heat exchanger and the regenerative heat exchanger are compact and
Instead of using a plate heat exchanger, a helical tube heat exchanger equipped with a heat transfer accelerator is adopted to emphasize safety and take a solution with excellent heat transfer characteristics.

In light water reactors, fluid leakage has been reported due to shaft seals of rotating bodies, etc., but in the high temperature gas reactor, since the coolant is helium, the primary circuit and the secondary circuit may contain radioactive substances in the fluid. There is almost no sex. Furthermore, since the circulator of the primary circuit requires only a pressure increase of 0.3 MPa or less, it is possible to use a magnetic fluid seal and a magnetic bearing, and leakage of the helium coolant is unlikely. Further, by selecting a sealing mechanism having excellent performance for the rotating body of the secondary circuit such as a helium turbine or a compressor, it is possible to solve the problem that helium in the secondary circuit does not leak.

In the conventional high temperature gas reactor, the temperature of the turbine working fluid is low because power is generated by the steam turbine, and therefore the power generation efficiency is as low as 40% or less. It is necessary to raise the operating temperature in order to increase power generation efficiency. In the high temperature gas reactor of the present invention, a power generation efficiency of 45% is achieved by using a helium turbine having an inlet temperature of 900 ° C. Conventionally, the helium turbine high temperature gas reactor was not realized because there was no suitable blade material for the helium turbine, but in the present invention, by using a heat-resistant alloy recently developed by the Japan Atomic Energy Research Institute. Think feasible.

In the conventional helium turbine high temperature gas reactor, a turbine system is provided in the primary circuit in order to improve power generation efficiency, and in calculating efficiency, technically unreasonable adiabatic efficiency of the turbine and the compressor is used (for example, both of them are used). The same 92% value is used, and an unreasonable temperature is adopted for the helium temperature at the inlet of the compressor (a low temperature of 30 ° C is assumed to be 15 ° C higher than the annual average temperature of the coolant). Have been). In the present invention, the adiabatic efficiency of the turbine and the compressor has been thoroughly examined, and technically reasonable numerical values are used. In addition, in order to lower the compressor inlet temperature and increase power generation efficiency, it is possible to operate at a temperature of 15 ° C from the sea at a depth of approximately 150 meters.
It draws out seawater and uses it as cooling water.

In order to increase the heat generation efficiency of the gas turbine cycle, it is necessary to raise the helium temperature at the reactor inlet and outlet. Considering the results of research and development so far and the HTTR test reactor plan, etc., it is possible that the outlet temperature can reach 950 ° C. However, if the same reactor vessel structure as the conventional reactor is adopted, the inlet temperature will be 4
It is considered difficult to raise the temperature to 00 ° C or higher. In the present invention, a heat insulating layer having a corrugated metal sheet structure is attached to the inner surface of the reactor vessel to separate the two functions of the conventional reactor vessel wall, that is, the pressure-proof boundary and the heat-resistant boundary.
That is, the pressure-resistant boundary is provided on the reactor vessel wall as before, and the heat-resistant boundary is provided on the heat insulating layer having a corrugated structure of a thin metal plate, so that the helium temperature at the reactor entrance is kept at 450 while ensuring the integrity of the reactor vessel. Raise the temperature to ℃.
Increasing the reactor inlet temperature increases the flow rate of helium coolant, which can increase the thermal efficiency of the gas turbine cycle.

The spent fuel of the light water reactor contains residual uranium and plutonium produced during operation. Currently, in Japan, in order to burn fissionable plutonium contained in the spent fuel of a light water reactor, an attempt to produce a MOX fuel composed of a mixture of uranium oxide and plutonium oxide and burn it in a light water reactor has been started. However, such so-called plu-thermal cannot burn a large amount of MOX fuel, and a large amount of surplus plutonium will be present in Japan in the near future. In order to solve the problem of plutonium oversupply, in the high temperature gas reactor of the present invention, uranium and plutonium extracted from the spent fuel of the light water reactor by reprocessing are used as fuels, and fissionable plutonium is almost completely burned and consumed. Let At this time, plutonium is burned and uranium 23
In the present invention, two types of fuel pellets, a uranium oxide fuel pellet and a plutonium oxide fuel pellet, are produced in order not to newly produce plutonium from No. 8, and a fuel rod in which these pellets are alternately inserted one by one is produced. And burn it in the furnace, or manufacture a fuel rod in which only uranium fuel pellets are inserted and a fuel rod in which only plutonium fuel pellets are inserted, and appropriately arrange these in the reactor to burn them. To do.

[0018]

SUMMARY OF THE INVENTION The present invention includes a high temperature gas reactor using helium as a coolant, which includes a nuclear reactor so as to prevent radioactive materials from leaking to the atmosphere in the event of an accident, in addition to its inherent safety characteristics. An intermediate heat exchanger separates the primary circuit from the secondary circuit including a heat exchanger that supplies the turbine system and the seawater desalination device with the necessary amount of heat. And
A helical tube type heat exchanger is adopted for this intermediate heat exchanger to enhance its safety. Next, in order to increase the power generation efficiency of the helium turbine system, the helium temperature at the reactor outlet is set to 950 ° C, and the inlet temperature is set to 400 ° C to 450 ° C, which has been conventionally proposed. At this time, in order to ensure the integrity of the reactor vessel due to the rise in the inlet temperature, an internal heat insulating layer of a corrugated metal sheet is attached inside the reactor vessel to separate the temperature boundary from the pressure vessel temperature. Try to lower.

Further, by using a metal material suitable for the moving blade of the helium turbine, and simultaneously determining the moving blade airfoil type that minimizes the blade tip loss by three-dimensional calculation, and optimizing the turbine system, about 45% Obtain heat generation efficiency. Also, with the generation of thermal energy from the nuclear reactor,
In order to increase the total thermal efficiency of the nuclear reactor plant to approximately 90% by using it for the civilian and agricultural industries in the location area, the secondary circuit will be equipped with a helium turbine power generation system and a flash seawater desalination system.

Furthermore, since plutonium produced in the spent fuel of the light water reactor is burned and consumed almost completely in the high temperature gas reactor according to the present invention and no new plutonium is produced, uranium and plutonium contained in the spent fuel are removed. They are chemically separated and burned in the reactor as separate oxide fuels. In this way, the uranium cycle that almost completely burns and extinguishes the fissile plutonium produced in the fuel of the light water reactor is closed, and plutonium that can be converted to nuclear fuel is not stored in Japan.

[0021]

The principle of the present invention will be described with reference to FIGS. 1, 2 and 3. In the high temperature gas reactor of the present invention, a primary circuit including the reactor body 1 and a secondary circuit including a utilization system are separated in order to enhance safety. In this secondary circuit, power is generated by the helium gas turbine power generation system 2 having a thermal efficiency of about 45%, and the amount of heat transferred from the exhaust heat of the turbine 10 to the seawater in the precooler 15 after passing through the regenerative heat exchanger 14. Seawater is heated and flashed in the flasher 11 by Q1 and the amount of heat Q2 transferred to the seawater by the intercooler 16 provided between the high-pressure compressor 11 and the low-pressure compressor 12, to produce fresh water. The sum of the amounts of heat used for gas turbine power generation and seawater desalination is about 90% of the reactor heat output, and the high temperature gas reactor of the present invention is a system having a very high total thermal efficiency.

Is uranium and plutonium oxide obtained by separating from spent fuel of a light water reactor manufactured into a fuel compact of the same shape and size and manufacturing fuel rods in which these compacts are alternately inserted one by one? Or, manufacture a uranium fuel rod consisting only of uranium compact and a plutonium fuel rod consisting only of plutonium compact,
By appropriately arranging and burning these fuel rods in the core, the fissionable plutonium produced in the spent fuel of the light water reactor is almost completely burned and consumed, and the uranium fuel cycle is almost closed. To reduce the amount of fissile plutonium in Japan as much as possible.

As a concrete proposal for increasing the thermal efficiency of the gas turbine cycle in the present invention, the helium temperature T1 at the reactor inlet is set to 450 ° C., which is higher than that of the high temperature gas reactor conventionally constructed and operated. that time,
In order to ensure the safety of the reactor vessel 4, a metal thin plate corrugated heat insulating layer 5 as shown in FIG. Maintaining a low temperature of ℃ or below gives sufficient strength margin. This pressure boundary or pressure-resistant boundary refers to the pressure-resistant portion, and here refers to the reactor vessel, and the temperature boundary or heat-resistant boundary refers to the protective portion that prevents high-pressure helium from contacting the pressure-resistant portion. Means the heat insulation layer attached inside the reactor vessel. By separating the pressure boundary and the temperature boundary, it is possible to use a cheap material in order to reduce the operating temperature of the pressure resistant portion.

Further, using the intermediate heat exchanger 9 installed between the primary circuit and the secondary circuit, the reactor outlet temperature (T
2) The helium in the secondary circuit is heated by helium in the primary circuit at 950 ° C. and introduced into the turbine 10. The temperature (T3) of the secondary circuit helium toward the turbine inlet is set to 9
In order to heat up to 00 ° C, a thin plate-shaped cylinder is installed between the helical coils provided in this intermediate heat exchanger, and a heat transfer enhancement method utilizing solid radiation radiated from this cylinder is used to Next circuit Heat helium. This turbine 1
0 means high pressure compressor 11, low pressure compressor 12 and generator 1
3 is driven. By the way, in order to reduce the driving power of the low-pressure compressor and the high-pressure compressor to increase the power generation efficiency, the inlet helium temperature of these compressors is cooled to 35 ° C. In this cooling, the inlet helium temperature of the low pressure compressor is lowered to 35 ° C. by the regenerative heat exchanger 14 and the precooler 15 cooled by the cold seawater pumped from a water depth of about 150 m. Moreover, in order to cool the inlet helium temperature of the high-pressure compressor to 35 ° C., an intermediate cooler 16 is provided between the low-pressure compressor and the high-pressure compressor, and a water depth of about 150 m is provided as secondary side cooling water of this intermediate cooler. Uses cold seawater drawn from.

Further, a metal material having heat resistance up to 900 ° C. is used for the moving blades of the turbine 10, and the blades of the moving blades are manufactured by using the latest industrial turbine design technology for the turbine moving blades and the compressor moving blades. A turbine adiabatic efficiency of 92% and a compressor adiabatic efficiency of 88% are achieved by adopting a blade having a shape with minimum end loss. Further, the turbine expansion ratio that maximizes the thermal efficiency of the gas turbine cycle is used. In this way, a turbine power generation system having a thermal efficiency of about 45% is achieved. The cold seawater heated by the precooler and the intercooler is desalinated in the flasher 16 by the flash method.

Increasing the thermal efficiency of the gas turbine cycle requires increasing the helium temperature at the reactor inlet and outlet. The outlet temperature should be carefully determined by the results of many R & Ds, but with reference to the previous research at the Japan Atomic Energy Research Institute and the specifications of the outlet temperature of the test reactor of 950 ° C currently under construction, It is considered that the reactor outlet helium temperature of 950 ° C. according to the present invention can be actually achieved. In order to secure the safety by keeping the temperature of the reactor vessel low while achieving the helium temperature of 450 ° C. at the reactor inlet, in the present invention, the inner heat insulation layer 5 having a corrugated metal thin plate is provided on the inner surface of the reactor pressure vessel 4. The pressure-resistant boundary and heat-resistant boundary of the pressure vessel are separated. With such a structure, even if the helium temperature at the reactor inlet is increased to 450 ° C., the temperature of the pressure vessel can be kept as low as 300 ° C. or lower and the safety of the reactor vessel can be ensured.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention employs a system configuration that enhances safety and thermal efficiency as shown in FIG. In addition, by using the residual uranium contained in the spent fuel of the light water reactor and the plutonium produced during use as fuel, the fissionable plutonium is burned and consumed, and the uranium cycle is almost closed by using it together with the light water reactor. And Helium temperature T1 at the reactor inlet is 4
It is 50 ° C. and the outlet temperature T2 is 950 ° C. The heat output of this nuclear reactor is transmitted to helium, which is the working fluid of the secondary circuit, in the intermediate heat exchanger 9, and high-efficiency power generation is performed by the helium turbine 10 of the power generation system 2, and flash type fresh water is produced by using exhaust heat of the turbine. Fresh water is produced from seawater by the chemical system 3. The generated power is used by the general public, fresh water is drinking water for the people living in the area,
It is used for air conditioning, irrigation in the agricultural industry, and air conditioning for greenhouses. Light water reactor is about 35% using steam cycle
In contrast to performing only power generation with low thermal efficiency, the high temperature gas reactor system of the present invention effectively generates about 90% of the reactor output by power generation by the gas turbine system and utilization of turbine exhaust heat by the flash seawater desalination system 3. It is a system with high total thermal efficiency to be used.

Furthermore, the present invention is excellent in safety and uses fissionable plutonium produced in a light water reactor as a part of fuel to burn and consume it, thereby minimizing the amount of surplus plutonium in Japan. In addition, it has the feature that it does not cause global environmental problems such as carbon dioxide problems. The fuel of the HTGR of the present invention is TRIS.
Fuel particles coated with an O layer are used. The safety of this fuel has been assured by previous experiments.

Helium, which is chemically completely inert, is used as the coolant. The helium circulator 6 of the primary circuit has a magnetic bearing and a magnetic fluid seal. Helium in the primary circuit is heated to T2 = 950 ° C. in the nuclear reactor, its thermal energy is excellent in pressure resistance, and the helical tube type intermediate heat exchanger 9 equipped with a special heat transfer promotion method allows the helium in the secondary circuit to reach 6.1 MPa. Heat is transferred to the helium of T3 = 90
Heat to 0 ° C. Therefore, even if the radioactive material leaks from the fuel particles into the primary circuit helium at 6.0 MPa, 2
It has a structure that does not leak to the next circuit or outside the system.

Further, an internal heat insulating layer is provided on the inner surface of the reactor vessel 4, and the pressure-resistant boundary and the heat-resistant boundary are separated, so that the temperature of the reactor vessel is kept at a low temperature of 300 ° C. or lower to enhance safety. . Furthermore, unlike primary reactors such as light water reactors, helium in the primary circuit contains almost no radioactive substances, and even if a pipe breakage accident occurs, a large amount of air will enter the reactor and cause corrosion of internal reactor structures. Takes a lot of time, and it is possible to perform appropriate treatment during this time, and it has higher safety than light water reactors.

In the helical tube type intermediate heat exchanger 9, a large number of helical tubes having different diameters are arranged in parallel. This heat exchanger has its axis installed vertically, and primary helium flows outside the helical tube. A thin metal cylinder is mounted between each row of helical tubes. When this cylinder is heated by the high temperature primary circuit helium, solid radiation occurs and the helical tube is heated, so that a heat transfer promoting effect is produced.

FIG. 4 shows an example of the heat transfer experiment result of the intermediate heat exchanger having the heat transfer promoting cylinder. The cylinder has almost the same temperature as the primary circuit helium, and the temperature resistance outside the tube is about 25.
℃, the temperature resistance inside the tube is about 25 ℃, which has excellent heat transfer performance. Moreover, this metal cylinder also has the effect of suppressing the vibration generation of the helical tube due to the Karman vortex. In addition, the helical tube has excellent safety characteristics such as being capable of absorbing thermal expansion of the tube without causing a decrease in strength due to a slight increase in the radius of curvature.

FIG. 5 shows the relationship between the thermal efficiency of the high temperature gas furnace and the expansion ratio of the turbine in the present invention. In the present invention, a standard high temperature gas reactor having a heat output of 400 MW is considered. As shown in FIG. 3, the reactor inlet temperature T1 is 450 ° C. and the outlet temperature T2 is 950 ° C. The reactor inlet temperature T1 is set higher in the conventional high temperature gas reactor and the turbine flow rate is increased to increase the thermal efficiency of the gas turbine system. Some of the gas turbine systems that have been reported so far are said to have a thermal efficiency of about 50%, but in these reports, there is no rational basis for compressor adiabatic efficiency, turbine adiabatic efficiency, or compressor adiabatic efficiency. Calculations are made using the inlet temperature, etc., and the results are not reliable. In the calculation example of FIG. 5, the turbine adiabatic efficiency is 92%, the compressor adiabatic efficiency is 88%, and the cooling water for the precooler 15 and the intercooler 16 has a depth of 150.
Calculated using the compressor inlet temperature T7 = 35 ° C. obtained by calculation using 15 ° C. seawater pumped from the place of m,
It reveals that the thermal efficiency of the gas turbine system will be 45%. The amount of heat required for desalination of seawater is given by heating seawater with a precooler and an intercooler. FIG. 3 shows temperature / flow rate conditions under conditions of turbine expansion ratio = 3.9 and turbine thermal efficiency = 45%.
In the embodiment of the present invention, the total amount of heat used for power generation and seawater desalination is about 90% of the reactor output, and the plant has a very high total thermal efficiency.

The recent light water reactor has a thermal efficiency of about 35% and an electric output of about 1300 MWe, and the output tends to be further increased. However, on the other hand, the necessity and performance improvement of small and medium-sized nuclear power plants are being considered. The high temperature gas reactor of the embodiment of the present invention has a heat output of 400 MW.
It has an electric power output of 180 MWe and an electric output of 180 MWe, and is optimal as a small-to-medium-scale nuclear power plant with future demand. Furthermore,
In addition to power generation, exhaust heat from the turbine system is also used for desalination, and the produced fresh water is used for drinking water, commercial use such as air conditioning and heating, and agricultural industry such as irrigation and greenhouse heating and cooling. The main examples are power generation in small and medium scale and contribution to the location area.

The high temperature gas reactor of the embodiment of the present invention uses, as fuel, residual uranium and fissionable plutonium taken out from the spent fuel of the light water reactor, and one of the major measures is to almost completely burn and extinguish these fissionable substances. Characterize. That is, after the uranium and plutonium are chemically separated from the spent fuel by reprocessing, separate fuel pellets (for example, diameter 26
mm, length 39 mm) to produce fuel rods in which uranium pellets and plutonium pellets are alternately inserted, or to produce fuel rods consisting only of uranium pellets and plutonium pellets, Almost all the fissionable plutonium will be burned and extinguished within a few years by appropriately arranging the fuel rods of the above in the reactor and burning them. Thus, the high temperature gas reactor of the embodiment of the present invention burns the fissile plutonium produced in the light water reactor.
Consume and eliminate excess plutonium possession in Japan and close the uranium cycle. Such fuel and its use are one of the major features of the embodiment of the present invention.

[0036]

INDUSTRIAL APPLICABILITY According to the present invention, in a high temperature gas reactor using helium as a coolant, a utilization system such as a helium turbine power generation system and a seawater desalination device is installed in a secondary circuit to separate it from a primary circuit including a nuclear reactor. In addition, the system configuration is designed to emphasize safety everywhere, such as by installing a heat insulating layer on the inner surface of the reactor vessel. Furthermore, the helium gas turbine generates electricity with a high power generation efficiency of 45%, and the turbine exhaust heat is used for seawater desalination to produce freshwater that can be used for civilian and agricultural purposes in the area. Achieve the total thermal efficiency of the system. Furthermore, the fuel used is uranium and plutonium separated and extracted from the spent fuel of the light water reactor by reprocessing, and the fuel structure is a structure that burns and extinguishes fissile plutonium by burning for several years in the reactor. I am trying. Moreover, the output scale is about 180 MWe, which is medium to small scale. That is, the HTGR plant according to the present invention is safe, environmentally friendly,
A great effect can be expected as a small and medium-sized energy source with high thermal efficiency.

[Brief description of drawings]

FIG. 1 is a basic cycle diagram of a high-efficiency indirect cycle helium-cooled high temperature gas reactor.

FIG. 2 is a cross-sectional view of a reactor vessel with a pressure boundary and a temperature boundary separated.

FIG. 3 is a diagram showing the temperature / pressure / flow rate of a system and main parts of a helium-cooled high temperature gas reactor for power generation and seawater desalination.

FIG. 4 is a diagram showing a temperature distribution of each part of a helical coil type intermediate heat exchanger connecting a primary circuit and a secondary circuit.

FIG. 5 is a diagram showing the relationship between the thermal efficiency of a helium turbine and the expansion ratio of the turbine.

[Explanation of symbols]

 T1 Reactor inlet temperature T2 Reactor outlet temperature T3 Turbine inlet temperature T4 Intermediate heat exchanger secondary circuit helium inlet temperature T5 Turbine outlet temperature T6 Turbine exhaust side regeneration heat exchanger outlet temperature T7 Compressor inlet temperature T8 Compressor outlet temperature T9 Cold seawater temperature T10 Cold seawater intercooler outlet temperature P1 Reactor outlet helium pressure P2 Turbine inlet temperature P3 Compressor inlet pressure P4 Compressor outlet pressure G1 Primary circuit helium flow rate G2 Secondary circuit helium flow rate G3 Freshwater flow rate G4 Hot seawater flow rate 1 Reactor Main Body 2 Power Generation System 3 Flash Fresh Water System 4 Pressure Vessel 5 Insulation Layer 6 Circulator 9 Intermediate Heat Exchanger 10 Turbine 11 High Pressure Compressor 12 Low Pressure Compressor 13 Generator 14 Regenerative Heat Exchanger 15 Precooler 16 Intermediate Cooling Device 17 exhaust pump 18 flasher

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[Procedure amendment]

[Submission date] June 22, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

Claims (6)

[Claims] 1. A gas-cooled furnace using helium as a coolant, which is very unlikely to cause a serious accident because helium is chemically inert, and has inherent safety and excellent passive characteristics even during an accident. The primary helium circuit including the reactor has cooling characteristics and the secondary helium circuit for the heat utilization system is separated and installed so that there is no leakage of radioactive materials, and safety is improved to improve the heat output of the furnace. It has a high total thermal efficiency of using about 90% and does not emit carbon dioxide gas at all from the entire circuit, so it is an excellent resource for the environment and the global environment, and it is not a power generation facility like light water reactors.・ Helium-cooled high-temperature gas characterized by multipurpose use. 2. The helium in the primary circuit is heated to an outlet temperature of 950 ° C. in the reactor, but in order to improve the heat generation efficiency of the gas turbine cycle, the reactor inlet temperature of 350 ° C. to 400 ° C. is set to 450 ° C. To increase the flow rate of helium as a coolant by increasing the temperature to ℃, in order to maintain the temperature of the reactor vessel at a low temperature and ensure safety, the inside of the steel sheet metal corrugated structure inside the reactor vessel is made of steel. A heat insulation layer is attached to separate the pressure boundary and temperature boundary of the reactor vessel, helium enters from the lower part of the reactor, flows in the annular space between the core and the inner heat insulation layer, and helium at 450 ° C directly contacts the reactor vessel. The temperature of the reactor vessel will be reduced to about 30
By maintaining the temperature below 0 ° C to ensure safety, and simultaneously increasing the reactor inlet temperature of helium coolant to 450 ° C, the helium flow rate in the primary and secondary circuits is increased,
As a result, a reactor vessel structure that improves the thermal efficiency of the gas turbine cycle. 3. The helium gas turbine installed in the secondary circuit can generate power with a thermal efficiency of about 45% under the condition of the optimum expansion ratio, and further, in the precooler and the intercooler, the power from the turbine exhaust gas is exhausted. Seawater is desalinated by heating and flushing it with high-temperature helium and high-temperature helium from the outlet of the high-pressure compressor, and this freshwater is used for the civilian and agricultural industries in the location area to generate heat from the reactor and generate desalination of seawater. A high-temperature gas furnace with a very high total thermal efficiency that can be used for multiple purposes and can use about 90% of the heat output. 4. The electric power generated by the helium gas turbine is mainly transmitted to an electric power grid for social use, but a part of the electric power or surplus electric power at night is used to replace the ion semipermeable membrane exchange fresh water. Desalination can be used for the civilian / agricultural industry in the location area or used for water storage, while exhaust heat from the turbine can be used for seawater desalination, chemical industry, etc. High temperature gas furnace characterized by having properties. 5. A uranium fuel compact and a plutonium fuel compact are produced by chemically separating the residual uranium contained in the spent fuel of the light water reactor from the plutonium produced during operation, and producing separate oxide fuel compacts. These fuel rods are made by burning fuel rods that are inserted axially one by one alternately in the furnace, or by manufacturing fuel rods that consist of uranium fuel compact only and fuel rods that consist only of plutonium fuel compact. Is appropriately placed in the core and burned to burn the fissionable plutonium almost completely so as to eliminate plutonium that can be converted into nuclear weapons produced in a light water reactor. Alternatively, the high temperature gas reactor according to claim 3 or 4. 6. A light water reactor is being developed and constructed mainly for a large output scale of about 1000 MW of electric output, but the high temperature gas reactor of the present invention is centered on an electric output of 180 MW, and is a medium or small size up to about 3 times this. A high-temperature gas-cooled reactor having a feature of scale and having the features of claim 1 or claim 2 or claim 3 or claim 4 or claim 5.