JPH1037709A - Steam generator at nuclear fuel facility - Google Patents

Abstract

(57) [Abstract] [Problem] To supply clean steam using radioactive steam as a heating source to equipment using clean steam, reduce the fuel cost and electricity cost of the boiler in the plant, and circulate compared to the flash tank method Reduce the capacity of the pump to reduce equipment and power costs. SOLUTION: Steam from a steam turbine 15 is guided to a thin tube 17 inside a primary steam generator 16, and primary steam obtained by heating and evaporating water 18 in a body is sent to a thin tube 20 inside a secondary steam generator 19. The water 21 in the body is heated and evaporated. The secondary steam is supplied to the clean steam-using device 23 and the radioactive device 24. According to the present invention, the primary steam generator 16
When the leakage occurs in the small pipe 17 of the above, the radioactive mixing range is up to the small pipe 20 of the secondary steam generator 19 and not to the generated steam pipe 22, so that the generated steam of the secondary steam generator 19 is always in a clean state. Become. Therefore, in a nuclear fuel facility such as a nuclear power plant, clean steam can always be supplied to the clean steam using equipment 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam generator, and more particularly, to a plant for producing clean steam generated by using steam extracted from steam equipment in a nuclear power plant or nuclear fuel reprocessing facility as a heating source. TECHNICAL FIELD The present invention relates to a steam generator in a nuclear fuel using facility suitable for a system for supplying steam using equipment in a facility.

[0002]

2. Description of the Related Art In a technical standard for nuclear facilities issued by Electric Power Shinposha, a single steam generator for supplying steam for sealing a shaft of a steam turbine is described. FIG. 7 is a schematic diagram showing a nuclear power plant system including a general single-type steam generator. As shown in FIG.
The steam generated by the steam generator 2 using the steam taken out from the heating source as a heating source is used to supply the steam to the equipment 3 which does not interfere with the presence of radioactivity in the steam among all the steam-using equipment, The steam from the in-house boiler 5 is supplied to other devices 4 that use clean steam.

[0003] Referring to FIG. 8 as another system,
A reference example using a flash tank type steam generator will be described. As shown in FIG. 8, a circulating water heater 72 that uses steam extracted from a steam turbine 70 as a heating source and heats hot water pressurized by a circulating pump 73 as a device for generating clean steam. The hot water heated by the circulating water heater 72 is reduced in pressure to a predetermined pressure by a pressure control valve 74, and separated into steam and drain in a flash tank 75. The steam generated in the flash tank 75 is supplied to a device 76 that uses clean steam and a device 77 that does not interfere with the presence of radioactivity in the steam. Reference numeral 71 denotes a pressure regulating valve, 78 denotes a drain tank, 79 denotes a water supply pump, 80 denotes hot water flowing into a flash tank, and 81 denotes steam generated by a flash tank.

[0004]

The above conventional system has the following problems. 9 and 10 are schematic diagrams showing a single steam generator. FIG. 9 shows the radioactivity range during normal operation. FIG. 10 shows the radiation when a crack is generated in the thin tube of the single steam generator. It is a figure which shows a function existence range. The shadows in these figures indicate radioactivity. Since the steam from the steam turbine 10 has radioactivity brought in from the nuclear reactor, if a leak occurs in the narrow tube 12 through which the heated steam in the steam generator 11 passes, the steam generator 11
The radioactivity is mixed into the steam pipe 13 generated, and the radioactivity is also mixed into the steam supply destination device 14. Therefore,
The devices that supply the steam generated by the steam generator 11 are limited to devices that do not interfere with the presence of radioactivity in the steam.

In the case of the flash tank system shown in FIG. 8, the circulating water heater 72 is connected to the circulating pump 7.
Since the pressure is increased in step 3, the heating steam pressure becomes lower than the hot water pressure. Thus, when the tubing of the circulating water heater 72 leaks, radioactive contamination of the high-pressure side hot water is prevented, and steam is supplied to equipment using clean steam. However, since the steam generated in the flash tank 75 is steam in which a part of the heating water is flashed,
In order to obtain a predetermined amount of steam with a low steam generation rate, a large amount of heated water is required, and the capacity of the circulation pump 73 needs to be increased, resulting in a problem that equipment costs and power costs increase.

[0006] An object of the present invention is to supply steam generated as a heating source using radioactive steam taken out of a steam turbine to equipment using clean steam that does not contain radioactivity, thereby enabling the boiler of an in-house boiler to be supplied. An object of the present invention is to reduce the fuel cost or the electricity cost, and to reduce the facility cost and power cost of a circulation pump which has been increased in a flash tank type steam generator.

[0007]

The above object is achieved by the following invention. The steam generator in the nuclear fuel using facility according to claim 1 supplies steam having a possibility of containing radioactivity extracted from the steam facility in the plant to a steam using device such as a nuclear power plant or a nuclear fuel reprocessing facility. A primary steam generator that generates primary steam as a heating source,
A secondary steam generator comprising a secondary steam generator for generating secondary steam using the primary steam as a heating source, wherein the secondary steam is supplied to equipment using steam. According to such a configuration, even if the radioactivity contained in the steam taken out from the steam facility in the plant leaks into the primary steam due to, for example, a crack in a pipe in the primary steam generator, the secondary Since radioactivity does not leak to the secondary steam generated by the steam generator, clean secondary steam can be supplied to the steam-using equipment in the facility. Therefore, it is possible to reduce the operation cost of the steam generating means such as the in-house boiler. Further, the invention according to claim 2 is characterized in that the primary steam generator and the secondary steam generator have the same structure, so that the production is easy and the cost is low. Further, the invention according to claim 3 is characterized in that the equipment using steam provided on the downstream side of the secondary steam generator is an equipment that does not interfere with the presence of radioactivity in the steam or an equipment that uses clean steam. It is characterized in that any of them may be used, so that the degree of freedom of arrangement of steam-using equipment and plant design can be obtained. Also,
The invention according to claim 4 is characterized in that a device that does not interfere with the presence of radioactivity in the steam is provided between the primary steam generator and the secondary steam generator. Thus, the degree of freedom in the arrangement of equipment using steam and the design of the plant can be obtained.
Further, in the invention according to claim 5, in a nuclear fuel-using facility such as a nuclear power plant or a nuclear fuel reprocessing facility, the above-described dual steam generator is installed in the facility, thereby taking out from the steam facility in the plant. Even if the radioactivity contained in the leaked steam leaks into the primary steam, clean secondary steam can be supplied to the equipment using steam in the facility without using steam generating means such as an on-site boiler, and running costs are reduced. Also decrease. In addition, the dual-type steam generator, which is easy to manufacture and inexpensive, can be used to arrange equipment that uses steam, such as equipment that does not interfere with the presence of radioactivity in the steam, equipment that uses clean steam, and plant design. The degree of freedom is obtained. In addition, since the capacity of the circulation pump is smaller than that of the flash tank system, equipment costs and power costs are reduced. Claim 6
The described invention uses contaminated vapor containing radioactivity as a heat source,
In a steam generator in a nuclear fuel-using facility that generates clean steam that does not include the radioactivity, a primary steam generator that generates primary steam using the contaminated steam as a heat source, and generates the clean steam using the primary steam as a heat source And a secondary steam generator. According to such a configuration, even if the contaminated steam leaks into the primary steam due to a crack in the piping in the primary steam generator, etc., the clean steam generated by the secondary steam generator is not contaminated. The secondary steam can be effectively used for steam-using equipment inside and outside the facility. Further, the invention according to claim 7 is a steam generator in a nuclear fuel using facility that generates clean steam not containing the radioactivity by using the polluted steam containing the radioactivity as a heat source, wherein a primary thin tube through which the contaminated steam flows,
A primary steam generator having a primary body in which the primary capillary is provided and storing primary water, a generated steam pipe connected to the primary body, a secondary capillary connected to the generated steam pipe, and the secondary A secondary steam generator having a thin tube therein and a secondary body for storing secondary water. According to such a configuration, the contaminated steam does not normally leak from the primary tubule to the secondary tubule, but even if the contaminated steam leaks due to a crack in the primary tubule, the secondary steam generator is activated. Clean steam that is not contaminated can be generated. Therefore, clean steam can be safely supplied to the steam-using equipment inside and outside the laying.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. First, referring to FIGS. 1 and 2,
An outline of an embodiment of the present invention will be described. FIG. 1 shows the range of radioactivity existing during normal operation of the double steam generator of the present embodiment, and FIG. 2 shows the radioactivity when radioactivity leaks from a thin tube in the double steam generator. It is a figure showing an existence range. The shaded portion in the figure is the radioactivity existence range.

As shown in FIG. 1, the steam extracted from the steam turbine 15 is guided to a thin tube 17 inside a first-stage steam generator 16, and heats and evaporates water 18 in a body. The steam generated by the first-stage steam generator 16 is guided to a thin tube 20 inside the second-stage steam generator 19, and heats and evaporates water 21 in the body. The steam generated by the second-stage steam generator 19 passes through a generated steam pipe 22 and is supplied to a device 23 that uses clean steam and a device 24 that does not interfere with the presence of radioactivity in the steam.

Then, as shown in FIG. 2, in a configuration similar to FIG. 1, if a leak occurs in the thin tube 31 of the first-stage steam generator 30, the generated steam pipe 25 of the first-stage steam generator 30 Is mixed with radioactivity from the heated steam pipe 26, but the range of mixed radioactivity is up to the narrow pipe 27 of the second-stage steam generator 32 and up to the generated steam pipe 33 of the second-stage steam generator 32. , The second stage steam generator 32
The generated steam is always in a clean state. Therefore, as shown in FIG. 2, according to the double steam generator of the present embodiment, even if a leak occurs in the thin tube 31 of the first-stage steam generator 30, the generation of the second-stage steam generator 32 occurs. Since radioactivity is not mixed into the steam pipe 33, the steam generated by the steam generator can be supplied to equipment that requires clean steam.

FIG. 3 is a configuration diagram for explaining an embodiment of the present invention in further detail. As shown in the figure, steam extracted from the high-pressure turbine 40 is supplied to a pressure control valve 41.
The pressure is reduced to a predetermined pressure in the first stage steam generator 42.
Flows into the capillary inside. The steam flowing into the narrow tube of the first-stage steam generator 42 heats and evaporates water 43 of the body of the first-stage steam generator 42, and the steam generated by the first-stage steam generator 42 is supplied to a pressure control valve 45. The pressure is reduced to a predetermined pressure at
It flows into a narrow tube in the stage steam generator 46. The steam flowing into the narrow tube in the second-stage steam generator 46 is supplied to the second-stage steam generator 46.
The water 47 in the fuselage is heated and evaporated, and the second-stage steam generator 46 is heated.
Is supplied to a device 59 that uses clean steam and a device 58 that does not interfere with the presence of radioactivity in the steam. In addition, the device 58 which does not hinder the presence of radioactivity in the steam may be provided between the first-stage steam generator 42 and the second-stage steam generator 46.

The steam used in the steam-using devices 58 and 59 is condensed and collected in a drain tank 49. The drain stored in the drain tank 49 is extracted by the water supply pump 50, heated by the drain cooler 51, and supplied to the second steam generator 46. The steam that has contributed to the heating in the second-stage steam generator 46 is condensed, pressurized by the circulation pump 52 and supplied to the first-stage steam generator 42. The steam that has contributed to the heating in the first-stage steam generator 42 is condensed and collected in the feedwater heater 53. The water level control valve 54 adjusts the valve opening degree by a signal of a water level gauge 56 installed on the body of the first-stage steam generator 42 so that the body water level of the first-stage steam generator 42 becomes constant. The water level control valve 55 adjusts the valve opening by a signal from a water level gauge 57 installed on the body of the second steam generator 46 so that the water level of the body of the second steam generator 46 becomes constant. Has become.

When a leak occurs in the narrow tube in the first-stage steam generator 42 and radioactivity flows into the body of the first-stage steam generator 42, the radioactivity is detected by the sampling pipe 62 and the steam is generated. The operation of the device is stopped, and the steam from the boiler in the plant is supplied to the steam-using equipment. Thereby, the first stage steam generator 42
Even in the case where a leak occurs in the inner thin tube, the range in which the radioactivity mixed from the turbine steam is mixed depends on the first-stage steam generator 42.
, And there is no radioactivity flowing into the generated steam pipe 48 of the second-stage steam generator 46.

As described above, the generated steam in the present embodiment has no limitation on the steam supply equipment, and can supply steam to all the steam-using equipment in the plant. Can be reduced. In this case, equipment that does not interfere with the presence of radioactivity in steam refers to equipment that is also present inside equipment that uses steam to be supplied with steam, and equipment that requires clean steam refers to equipment that requires steam. Refers to equipment that does not have radioactivity inside the equipment used. Furthermore, since the generated steam in the present embodiment does not contain radioactivity, it can be supplied not only to the inside of the power plant but also to a general area outside the power plant. That is, it can be used for district heating and the like.

In this embodiment, as shown in FIG. 4, the structures of the first-stage steam generator and the second-stage steam generator are the same, a body portion 90 for storing makeup water, and a thin tube for passing heated steam. And a drain tank 92 for collecting heated steam condensed by heat exchange. Therefore, the system configuration is simple and the equipment cost is low.

Next, referring to FIGS. 5 and 6, the conditions of the steam generated by the second-stage steam generator in the double steam generator of the present invention and the conditions of the flash tank of the conventional flash tank system are made the same. The state value in the case will be described. As shown in FIG. 5, in the dual steam generator of the present invention,
The generated steam conditions of the second-stage steam generator 112 are as follows: the second-stage steam generator generated steam amount 107 (= 19000 kg / h), the second-stage steam generator generated steam pressure 108 (= 0.93 MPa).
[Abs]), second stage steam generator generated steam temperature 109
(= 176.8 ° C.) and the second-stage steam generator generated steam enthalpy 110 (= 2773.3 kJ / kg),
The heating steam conditions of the second-stage steam generator 112 and the heating steam of the first-stage steam generator 111 are as follows: the second-stage steam generator heating steam amount 104 (= 20900 kg / h), the second-stage steam generator heating steam Pressure 105 (= 1.32 MPa [ab]
s]), the second-stage steam generator heated steam enthalpy 106
(= 2786.3 kJ / kg), first stage steam generator heating steam amount 100 (= 28480 kg / h), first stage steam generator heating steam pressure 101 (= 2.31 MPa [ab]
s]), the first-stage steam generator heated steam enthalpy 103
(= 2629.3 kJ / kg).

On the other hand, as shown in FIG. 6, in the flash tank type steam generator, the conditions of the generated steam in the flash tank 132 are as follows: the flash tank generated steam flow rate 127 (= 19000 kg / h), the flash tank generated steam pressure 128 (= 0.93 MPa [abs]),
Flash tank generated steam temperature 129 (= 176.8)
° C), flash tank generated steam enthalpy 130 (=
In the case of 2773.3 kJ / kg, the condition of the hot water flowing into the flash tank 132 and the heating steam of the circulating water heater 131 are as follows.
570590 kg / h), flush tank inflow hot water pressure 125 (= 0.93 MPa [abs]), flash tank inflow hot water enthalpy 126 (= 816.4 kJ /
kg), circulating water heater heating steam flow rate 120 (= 2700)
0 kg / h), circulating water heater heating steam pressure 121 (=
2.31 MPa [abs]) and enthalpy 123 of the circulating water heater heating steam (= 2629.3 kJ / kg).

According to this, the double steam generator according to the present invention has a circulating pump treatment water amount of 113 (= 20900 kg /
h), the flash tank type steam generator has a circulation pump treated water amount of 133 (= 570590 kg).
/ H), it is clear that the processing capacity of the circulating pump can be significantly reduced in the dual steam generator, and the power cost can be reduced. In the above embodiment, the steam generator is doubled, but if the steam generator is triple, quadruple, or ‥‥‥, it is possible to further generate clean steam that is less likely to be contaminated by radioactivity. .

[0019]

According to the present invention, in a nuclear power plant or a nuclear fuel reprocessing facility, etc., a primary steam generator using steam taken out from steam facilities in the plant as a heating source, and a primary steam generator using the generated steam as a heating source. By providing a dual steam generator with a secondary steam generator that generates steam,
Even if a leak occurs in the narrow tube of the second stage steam generator, the area contaminated with radioactivity is up to the narrow tube of the second stage steam generator,
Since the radioactivity is not mixed into the generated steam pipe of the second-stage steam generator, the steam of the steam generator can be supplied to equipment that requires clean steam having no radioactivity. This eliminates the need for the boiler in the office to operate, and can significantly reduce fuel costs or electricity costs.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention and showing a radioactivity range during normal operation.

FIG. 2 is a schematic diagram showing an embodiment of the present invention and showing a radiation leakage range.

FIG. 3 is a configuration diagram showing details of a double steam generator according to the present invention.

FIG. 4 is a structural diagram of a first-stage and a second-stage steam generator in the dual steam generator of the present invention.

FIG. 5 is an explanatory diagram for explaining state values in the double steam generator according to the present invention.

FIG. 6 is an explanatory diagram for explaining state values in a conventional flash tank method.

FIG. 7 is a schematic view showing a nuclear power plant system provided with a conventional single steam generator.

FIG. 8 is a configuration diagram showing a reference example using a conventional flash tank type steam generator.

FIG. 9 is a schematic diagram showing a conventional single-type steam generator and showing a radioactivity existing range during normal operation.

FIG. 10 is a schematic diagram showing a conventional single-type steam generator and showing a radiation leakage range.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steam turbine 2 Steam generator 3 Equipment which does not interfere even if radioactivity exists in steam 4 Equipment using clean steam 5 In-house boiler 10 Steam turbine 11 Steam generator 12 Thin tube 13 Generated steam pipe 14 Steam supply destination Equipment 15 Steam turbine 16 First stage steam generator 17 Thin tube 18 Body water 19 Second stage steam generator 20 Thin tube 21 Body water 22 Generated steam piping 23 Equipment using clean steam 24 Radioactivity in steam Equipment that does not interfere even if present 25 Generated steam pipe 26 Heated steam pipe 27 Thin tube 30 First-stage steam generator 31 Thin tube 32 Second-stage steam generator 33 Generated steam pipe 40 High-pressure turbine 41 Pressure control valve 42 First-stage steam generation Vessel 43 water in the body 44 generated steam pipe 45 pressure regulating valve 46 second stage steam generator 47 water in the body 48 generated steam pipe 49 drain Tank 50 feed water pump 51 drain cooler 52 circulation pump 53 feed water heater 54, 55 water level control valve 56, 57 water level gauge 58 equipment that does not interfere with the presence of radioactivity in the steam 59 equipment that uses clean steam 60 Boiler 61 Supply water pipe 62 Sampling pipe 70 Steam turbine 71 Pressure control valve 72 Circulating water heater 73 Circulation pump 74 Pressure control valve 75 Flash tank 76 Equipment that does not hinder even if radioactivity exists in steam 77 Clean steam Equipment used 78 Drain tank 79 Water supply pump 80 Flash tank inflowing hot water 81 Flash tank generated steam 90 Body 91 Narrow tube portion 92 Drain tank 100 First stage steam generator heating steam flow 101 First stage steam generator heating steam pressure 103 1st stage steam generator heating steam enthalpy 104 2nd stage Steam generator heating steam flow rate 105 Second stage steam generator heating steam pressure 106 Second stage steam generator heating steam enthalpy 107 Second stage steam generator generated steam amount 108 Second stage steam generator generated steam pressure 109 Second stage Steam generator generated steam temperature 110 Second stage steam generator generated steam enthalpy 111 First stage steam generator 112 Second stage steam generator 113 Circulating pump treatment water volume 120 Circulating water heater heating steam flow rate 121 Circulating water heater heating steam Pressure 123 Circulating water heater heating steam enthalpy 124 Flash tank inflow hot water flow 125 Flash tank inflow hot water pressure 126 Flash tank inflow hot water enthalpy 127 Flash tank generated steam flow 128 Flash tank generated steam pressure 129 Flash tank generated steam temperature 130 Flash tank generated steam D Enthalpy 131 circulating water heater 132 flash tank 133 circulating pump treatment water

Claims (7)

[Claims] 1. A primary steam generator for a nuclear power plant, a nuclear fuel reprocessing facility, or the like, using a steam having a possibility of containing radioactivity extracted from a steam facility in the plant as a heating source to generate a primary steam. A steam generator, comprising a dual steam generator comprising a secondary steam generator that generates secondary steam using the primary steam as a heating source, wherein the secondary steam is supplied to a steam-using device. Steam generator in a nuclear fuel facility. 2. The steam generator according to claim 1, wherein the primary steam generator and the secondary steam generator have the same structure. 3. The steam generator according to claim 1, wherein the steam-using device provided downstream of the secondary steam generator has no problem even if radioactivity is present in the steam.
Or a steam generator in a facility using nuclear fuel, which may be any device using clean steam. 4. The steam generator according to claim 1, wherein a device is provided between the primary steam generator and the secondary steam generator, which does not interfere with the presence of radioactivity in the steam. A steam generator in a facility using nuclear fuel. 5. A nuclear fuel-using facility, such as a nuclear power plant or a nuclear fuel reprocessing facility, wherein the steam generator according to claim 1 is installed in the facility. 6. A steam generator in a nuclear fuel-using facility that generates clean steam not containing radioactivity by using contaminated steam containing radioactivity as a heat source, wherein the primary steam generates primary steam using the contaminated steam as a heat source. A generator,
And a secondary steam generator for generating the clean steam using the primary steam as a heat source. 7. A steam generator in a nuclear fuel-using facility that generates clean steam not containing radioactivity by using contaminated steam containing radioactivity as a heat source. A primary steam generator having a primary body for storing and storing primary water, a generated steam pipe connected to the primary body, a secondary thin tube connected to the generated steam pipe, and the secondary thin pipe provided therein. And a secondary steam generator having a secondary body for storing secondary water.