JP2008122419A - Prevention system of accumulated combustion of noncondensable gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system which beforehand and reliably prevents accumulated combustion of noncondensable gases in the area where gases can be accumulated, and which secures the soundness of the equipment and piping in a nuclear power plant and increases the reliability. <P>SOLUTION: The prevention system 52G for the accumulated combustion of noncondensable gases has the area 50 where gases can be accumulated in a dead-end branch pipe 45 which branches and protrudes from a main pipe 44 through which steam flows, incorporates a communicating pipe 71 which connects the branch pipe to the main pipe, and keeps the communicating pipe 71 open into the main pipe 44. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for handling non-condensable gas generated in a nuclear power plant, and more particularly to a non-condensable gas accumulation combustion prevention system applied to a gas accumulation-possible region where non-condensable gas may accumulate. .

  A nuclear reactor power plant contains a reactor pressure vessel (hereinafter referred to as RPV). The reactor cooling water in the RPV is a part of the cooling water by neutron irradiation accompanying the nuclear reaction in the core. Is decomposed to produce hydrogen gas and oxygen gas, and in some cases, there is a non-condensable gas such as a small amount of radioactive noble gas such as Kr, Xe leaking from the fuel rod. For this reason, the nuclear power plant is provided with a gas waste treatment system in order to treat the generated non-condensable gas.

  In a nuclear power plant, steam generated in a reactor pressure vessel becomes main steam and is sent to a steam turbine through a main steam system, and the generator is driven by working in the steam turbine. In addition, the main steam pipe constituting the main steam system is branched with a dead branch pipe (branch pipe) that does not flow, and there are hundreds of such dead branch pipes per one nuclear power plant. Furthermore, from the top of the reactor pressure vessel, a reactor pressure vessel top vent such as a reactor pressure vessel vent system (hereinafter referred to as RPV vent system) or a reactor pressure vessel head spray system (hereinafter referred to as RPV head spray system). Facilities are provided.

  On the other hand, the reactor main steam contains a combustible non-condensable gas generated by radioactive decomposition, and this non-condensable gas flows together with the main steam flowing through the main steam system. Piping and containers that contain the reactor main steam, if there is a stagnant portion such as a rising branch pipe or rising branch portion, this stagnant portion becomes a place where non-condensable gas can accumulate, Accumulate. An example of rapid combustion by igniting the accumulated non-condensable gas for some reason has been reported.

  FIG. 22 explains the mechanism of non-condensable gas accumulation. In general, there is a possibility that noncondensable gas is accumulated in a space isolated by a stop valve 3 provided in a pipe (mother pipe) containing main steam and a container 1 and a rising branch pipe 2 branched therefrom. high. The main steam flows through the mother pipe (pipe) 1 and the branch pipe 2 is a dead end, so that the inflowed steam is condensed by heat radiation. Non-condensable gas that does not condense is left in the branch pipe 2, and non-condensable gas having a specific gravity lighter than that of steam is sequentially accumulated in the branch pipe rising portion.

  In the nuclear power plant, the non-condensable gas 5 stagnates in the gas accumulating location 4 such as the rising branch pipe out of the pipe containing the reactor main steam and the branch pipe 2 branched from the vessel 1. The stagnant non-condensable gas may ignite and burn for some reason.

  In order to prevent ignition and combustion of non-condensable gas, the generation of non-condensable gas is prevented, the accumulation of non-condensable gas is prevented, and the location where gas can be accumulated is determined by the combustion environment conditions. It is necessary to construct a condition that does not.

  The present invention has been made in consideration of the above-described circumstances, and prevents accumulated combustion of non-condensable gas in advance and reliably, ensures the soundness of equipment and piping in nuclear power plants, and improves reliability. Another object of the present invention is to provide a system for preventing accumulated combustion of noncondensable gases.

  In order to solve the above-mentioned problems, the non-condensable gas accumulation combustion prevention system according to the present invention accumulates gas in a dead-end branch pipe that rises by branching from a main pipe through which steam flows, as described in claim 1. A communication pipe that connects the branch pipe and the mother pipe is provided to form a possible portion, and this communication pipe is opened in the mother pipe.

  Further, in order to solve the above-described problem, the non-condensable gas accumulation combustion prevention system according to the present invention has the communication pipe protruding into the mother pipe and opening, as described in claim 2, and the opening Is opened to at least one of the upstream side and the downstream side in the mother pipe.

  Furthermore, in order to solve the above-described problems, the non-condensable gas accumulation combustion prevention system according to the present invention is provided with the communication pipe at least in the branch pipe along the axial direction. It is a thin tube.

  On the other hand, in order to solve the above-described problems, the non-condensable gas accumulation combustion prevention system according to the present invention is housed in a well or a narrow tube at the top of a branch pipe branched from a mother pipe as described in claim 4. An electric heater is provided, and a portion where gas can be accumulated in the branch pipe is energized and heated by the electric heater every predetermined time, and a small amount of non-condensable gas hydrogen or oxygen is ignited and recombined by a combustion reaction. It is characterized by that.

  Moreover, in order to solve the above-described problem, the non-condensable gas accumulation combustion prevention system according to the present invention has a non-combustion gas at the top of a branch pipe that branches off from the mother pipe and rises as described in claim 5. An injection system is provided, and the non-combustion gas injection system is equipped with a timer-injected valve that is opened every predetermined time to inject non-combustible gas into the top of the branch pipe, and the non-combustible gas accumulates gas in the branch pipe. The non-condensable gas that can stay in the possible portion is purged to the mother pipe side.

  Furthermore, in order to solve the above-described problem, the non-condensable gas accumulation combustion prevention system according to the present invention has a gas accumulation-possible location where the non-condensable gas may stay as described in claim 6. Is provided with a heating facility or a cooling facility, and a portion where gas can be accumulated by the heating facility or the cooling facility is maintained at a predetermined temperature so as not to approach the non-condensable gas combustion temperature.

  In the non-condensable gas accumulation combustion prevention system according to the present invention, it is possible to suppress the generation of the non-condensable gas amount in the gas accumulation location, and to discharge the generated non-condensable gas out of the system in the gas accumulation location, Or, it is possible to set the environmental conditions so that the generated non-condensable gas is not combusted, so it is possible to prevent the non-condensable gas from accumulating and burning in advance and to maintain the soundness of the equipment and piping in the nuclear power plant And reliability can be improved.

  Embodiments of a non-condensable gas accumulation combustion prevention system according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a schematic system diagram of a boiling water nuclear power plant (BWR plant) 10 equipped with a non-condensable gas accumulation combustion prevention system according to the present invention.

  The BWR plant 10 stores a reactor pressure vessel (RPV) 12 in a reactor containment vessel (PCV) 11, and the reactor pressure vessel 12 is defined as a dry well 13 around the reactor containment vessel 11. The A reactor core 14 is stored in the reactor pressure vessel 12, and the reactor core 14 is immersed in the reactor cooling water 15. A liquid phase part storing the reactor cooling water 15 is formed at the lower part of the reactor pressure vessel 12, while a gas phase part 16 is formed above the liquid phase part.

  The reactor coolant 15 in the reactor pressure vessel 12 is heated and vaporized by the heat generated by the nuclear reaction when passing through the core 14. The generated steam is separated into steam and water in the reactor pressure vessel 12, dried, then sent to the steam turbine 18 through the main steam system 17, where the steam turbine 18 performs work, and a generator (not shown). Drive. Main steam isolation valves 19a and 19b are provided on the main steam pipe 17a constituting the main steam system 17 on the upstream side and the downstream side of the PCV 11, respectively. The expanded steam that has worked in the steam turbine 18 is condensed in a condenser (not shown), and then returned to the RPV 12 through the reactor condensate / feed water system.

  The reactor pressure vessel (RPV) 12 of the BWR plant 10 is provided with a reactor pressure vessel top vent facility 20, which comprises a reactor pressure vessel (RPV) vent system 21 and a reactor pressure. A branch vent system 23 branched from a container head spray system (hereinafter referred to as an RPV head spray system) 22.

  The RPV vent system 21 has a reactor pressure vessel (RPV) vent pipe 25 connected to the top of the reactor pressure vessel (RPV) 12. The RPV vent pipe 25 is connected to an RPV head vent nozzle 26 formed at the top of the RPV 12, and an electric valve 27 that is remotely operated as an on-off valve is provided on the way. The downstream side of the electric valve 27 is connected to the main steam pipe 17a on the upstream side of the main steam isolation valve 19a in the reactor containment vessel 11.

  Further, the branch vent system 23 includes a vent branch pipe 31 branched from a check valve of the reactor pressure vessel (RPV) head spray pipe 28 or a downstream side of the injection valve 30. The vent branch pipe 31 is provided with a motor operated valve (open / close valve) 33 as a remote control valve, and the downstream side of the motor operated valve 33 is connected to the RPV vent pipe 25 of the RPV vent system 21 on the upstream side of the motor operated valve 27. . The branch part of the vent branch pipe 31 is provided at the top position of the RPV head spray pipe 28 so as to rise from the downstream side of the check valve 30. The branch portion of the vent branch pipe 31 is provided at a position as close as possible to the check valve 30.

  Further, the RPV head spray system 22 is connected to a reactor pressure vessel head spray nozzle (hereinafter referred to as an RPV head spray nozzle) 35 having an RPV head spray pipe 28 provided at the top of the RPV 12. The RPV head spray pipe 28 of the RPV head spray system 22 may also serve as a cooling water injection pipe of a reactor isolation cooling facility (hereinafter referred to as RCIC) 38. The RCIC 38 is a facility that cools the gas phase portion 16 of the RPV 12 by using cooling water of the cooling system at the time of shutdown in order to lower the residual pressure of the upper dome of the RPV 12 when the boiling water reactor is stopped.

  On the other hand, the RPV head spray pipe 28 of the RPV head spray system 22 is provided with a check valve (injection valve) 30 and a reactor containment isolation valve (PCV isolation valve) 39a, 39b in the middle. The PCV isolation valves 39a and 39b are respectively installed inside and outside through the reactor containment vessel 11, and are normally closed during the operation of the reactor.

  By the way, the RPV vent system 21 constituting the reactor pressure vessel top vent facility 20 and the branch vent system 23 using the RPV head spray system 22 cooperate to operate a non-condensable gas around the reactor pressure vessel 12. A non-condensable gas is led out from the accumulable portion 40 and discharged to the main steam pipe 17a.

  An RPV vent system 21 and a branch vent system 23 using an RPV head spray system 22 are provided on the top of the reactor pressure vessel (RPV) 12 and cooperate with each other, so that the inside of the RPV 12 The non-condensable gas such as oxygen gas, hydrogen gas and Kr, Xe radioactive noble gas at the location 40 that may accumulate near the top of the gas can be smoothly and smoothly discharged to the main steam pipe 17a side. This prevents the non-condensable gas from accumulating around the top of the tube.

  In FIG. 1, the vent branch pipe 31 of the branch vent system 23 may be directly connected to the main steam pipe 17 a, or an orifice may be provided instead of the motor-operated valve 33, or on the upstream side of the motor-operated valve 33. An orifice may be provided.

  By the way, in the main steam system 17 for guiding the main steam generated in the reactor pressure vessel 12 to the steam turbine 18, a number of branch pipes 43 are branched from the main steam pipe 17a. For example, a reactor isolation cooling system, an emergency safety valve system, a turbine bypass system, and the like are branched. The branch pipe 43 exists in addition to the main steam system 17, and there are hundreds of lines per one nuclear power plant.

  In the branch pipe 43, as shown in FIG. 2, there is a dead end branch pipe (branch pipe) 45 that branches off from the main pipe 44 such as a main steam pipe. The branch pipe 45 is provided with an open / close valve 46 as a gate valve or a stop valve, and the open / close valve 46 isolates the mother pipe 44 and the branch pipe 45 from the surroundings.

  In the dead end branch pipe 45 that branches off from the mother pipe 44 and rises, a gas accumulation capable location 50 where the non-condensable gas 47 may accumulate is formed. A heat insulating material 51 excellent in heat insulating performance is attached to the branch pipe 45 of the gas accumulating location 50, and a non-condensable gas accumulation combustion preventing system 52 is configured. The heat insulating material 51 insulates the gas accumulating portion 50 from the surroundings and keeps the heat, and a material excellent in heat insulating performance is used.

  Next, processing of the non-condensable gas generated in the BWR plant 10 will be described.

  By the operation of the BWR plant 10, non-condensable gases such as hydrogen gas and oxygen gas generated by neutron irradiation in the reactor pressure vessel 12 and decomposition of the cooling water pass through the main steam system 17 together with the reactor main steam. To the steam turbine 18. The main steam sent to the steam turbine 18 works here to drive a generator (not shown), while the non-condensable gas sent to the steam turbine 18 along with the main steam continues to guide the condenser. Then, this condenser is sent to a gas waste treatment system (not shown) for processing.

  During operation of the BWR plant 10, main steam flows also in the mother pipe 44 such as the main steam pipe shown in FIG. 2. In the pipe connection structure of FIG. 2, since the dead end branch pipe 45 rising from the mother pipe 44 is connected, part of the main steam also flows into the branch pipe 45 branched from the mother pipe 44. The steam flowing into the branch pipe 45 is cooled and tends to condense.

  However, in the pipe connection structure shown in FIG. 2, the heat insulating material 51 is attached to the rising branch pipe 45 branched from the mother pipe 44, and the gas storage location 50 of the branch pipe 45 is covered with the heat insulating material 51. For this reason, the gas accumulation | storable location 50 is heat-retained and it is rare to produce a temperature fall.

  Therefore, since the steam flowing into the gas accumulable location 50 is not condensed and liquefied, the amount of vapor condensation at the gas accumulable location 50 can be greatly reduced, and the amount of non-condensable gas generated is relatively Can be suppressed. For this reason, it is possible to effectively and effectively prevent non-condensable gas from accumulating in the gas accumulating location 50, and to reliably prevent the occurrence of combustion due to gas accumulation of non-condensable gas. A highly accumulative non-condensable gas accumulation combustion prevention system can be provided.

  FIG. 3 is a diagram showing a second embodiment of the non-condensable gas accumulation combustion prevention system.

  The non-condensable gas accumulation combustion prevention system 52A shown in this embodiment is obtained by improving an on-off valve 55 provided in a branch pipe 45 as a branch pipe.

  In the non-condensable gas accumulation combustion prevention system 52A, an open / close valve 46 is provided in a dead-end branch pipe 45 that branches off from the main pipe 44, and a gas upstream of the open / close valve 46 can accumulate non-condensable gas. It is configured as an accumulable location 50.

  The on-off valve 46 includes a valve body 57 accommodated in a valve casing 56, and the valve body 57 is opened and closed by a valve operating portion 58 via a valve rod 59.

  A vent hole 60 is provided in the valve body 57 of the on-off valve 46, and the valve upstream side and the valve downstream side can be communicated with each other even when the valve is fully closed. That is, even when the valve is fully closed, the non-condensable gas 47 on the side where the gas can be accumulated 50 can be constantly ventilated in the space 11 opposite to the on-off valve 46. The vent hole 60 is provided on the top side of the valve body 57 on the top side of the gas accumulating portion 50 because the gas is highly likely to be accumulated upward.

  In the pipe connection structure shown in FIG. 3, since the vent hole 60 is provided in the valve body 57 of the on-off valve 46 provided in the branch pipe 45, the non-condensable gas is accumulated in the gas accumulation location 50. It can be prevented without fail. By providing the vent hole 60 in the valve body 57, the non-condensable gas can be constantly ventilated through the vent hole 60 and into the space 61 on the downstream side of the valve where the flow is.

  Therefore, the combustible non-condensable gas 47 does not accumulate in the gas accumulation possible portion 50 of the dead end branch pipe 45, and accumulated combustion due to the non-condensable gas can be prevented in advance and surely. A condensable gas accumulation combustion prevention system 52A can be provided. Accumulated combustion due to non-condensable gas can be reliably prevented, and the soundness of equipment and piping in the nuclear power plant can be ensured.

  In this case, the branch pipe (branch pipe) 45 branched from the mother pipe 44 may be covered with the heat insulating material 51 shown in FIG.

  FIG. 4 shows a third embodiment of a non-condensable gas accumulation combustion prevention system.

  In the non-condensable gas accumulation combustion prevention system 52B shown in this embodiment, a vent line 63 is connected to a gas accumulation possible location 50 of a dead end branch pipe 45 that branches off from the main pipe 44 and rises. The vent line 63 is provided on the top side of the gas accumulating location 50 because the gas is highly likely to accumulate in the upper part.

  The non-condensable gas accumulation combustion prevention system 52B shown in FIG. 4 connects a vent line 63 to a gas accumulation potential point 50 where the non-condensable gas may stay. The non-condensable gas 47 generated in the gas accumulation location 50 can be constantly scavenged by connecting the side to a pressure device or piping lower than the stagnation part, for example, a condenser or a suppression chamber.

  By constantly scavenging the non-condensable gas 47 that can be accumulated in the gas accumulating location 50, combustion due to gas accumulation of the non-condensable gas 47 can be prevented in advance. Therefore, the soundness of the equipment and piping in the nuclear power plant can be ensured.

  FIG. 5 shows a fourth embodiment of a non-condensable gas accumulation combustion prevention system.

  The non-condensable gas accumulation combustion prevention system 52C shown in this embodiment is provided with an orifice 64 in the vent line 63 of the accumulation combustion prevention system 52B shown in FIG. Since the other configuration is not different from the non-condensable gas accumulation combustion prevention system 52B shown in FIG. 4, the same components are denoted by the same reference numerals and description thereof is omitted.

  Also in the non-condensable gas accumulation combustion prevention system 52 </ b> C shown in FIG. 5, the non-condensable gas 47 that can stay in the gas accumulation location 50 is constantly scavenged by the vent line 63.

  However, it may be necessary to flow a fluid other than steam through the mother pipe 44. Also in this case, the fluid flows out through the vent line 63, but the flow rate of the fluid flowing out through the vent line 63 can be limited by providing the orifice 64.

  FIG. 6 shows a fifth embodiment of the non-condensable gas accumulation combustion preventing system according to the present invention.

  The non-condensable gas accumulation combustion prevention system 52 </ b> D shown in this embodiment is configured to keep the gas accumulation potential portion 50 where the non-condensable gas may stay at a constant temperature by the heating facility or the cooling facility 65. It is a thing.

  The accumulated combustion prevention system 52D for non-condensable gas shown in FIG. 6 is provided with a heating equipment or a cooling equipment 65 in place of the heat insulating material 51 of the accumulated combustion prevention system 52 shown in FIG. The other configurations and functions are not different from the accumulated combustion prevention system 52 shown in FIG.

  The non-condensable gas accumulation combustion prevention system 52D shown in FIG. 6 is a system in which a gas accumulation capable location 50 is heated or cooled by a heating facility or a cooling facility 65 and maintained at a constant temperature.

  As a result, by keeping the pipe temperature of the gas accumulable location 50 constant, even if non-condensable gas accumulates in the gas accumulatable location 50, the temperature is adjusted and controlled so as not to approach the combustion temperature of the non-condensable gas. it can.

  By adjusting and controlling the temperature of the gas storage location 50 to a predetermined temperature that does not approach the combustion temperature of the non-condensable gas, combustion due to the non-condensable gas can be prevented, and the soundness of the equipment and piping in the nuclear power plant is maintained. be able to.

  FIG. 7 shows a sixth embodiment of the non-condensable gas accumulation combustion prevention system.

  In the non-condensable gas accumulation combustion prevention system 52E shown in this embodiment, a thermometer 66 and a pressure gauge 67 are provided at a gas accumulation potential point 50 where the non-condensable gas 47 may stay. A temperature 66 and a pressure gauge 67 can constantly monitor the temperature and pressure of the gas storage location 50.

  In this accumulated combustion prevention system 52E, an on-off valve 46 having a drive unit 68 is provided in a branch pipe 45 that branches off from a main pipe 44 that is a fluid pipe, and this on-off valve 46 is detected by a thermometer 66 and a pressure gauge 67. The on-off valve 46 can be automatically opened depending on the temperature and pressure.

  The non-condensable gas accumulation combustion prevention system 52E shown in FIG. 7 is configured to set the environmental conditions of the gas accumulating location 50 by the gas accumulating location 50 and eventually the thermometer 66 and the pressure gauge 67 installed in the branch pipe 45. When the environmental condition of the gas accumulating point 50 is monitored and approaches the non-condensable gas combustion condition, the on-off valve 46 is automatically opened, and the combustible non-condensable deposited in the gas accumulating point 50 The gas can be automatically purged.

  When the scavenging of the non-condensable gas is completed and the environmental condition of the gas accumulating point 50 is away from the combustion condition of the non-condensable gas 47, the gas is set to be automatically closed.

  Also in this non-condensable gas accumulation combustion prevention system 52E, the accumulation of the non-condensable gas 47 exceeding the required amount can be reliably prevented in the gas accumulation location 50, and the accumulation combustion by the non-condensable gas 47 can be prevented. In addition, it is possible to reliably prevent and improve reliability. It is possible to maintain the soundness of equipment and piping in nuclear power plants.

  FIG. 8 shows a seventh embodiment of the non-condensable gas accumulation combustion prevention system.

  The non-condensable gas accumulation combustion prevention system 52F shown in this embodiment shows an example in which a bimetal trap 69 is attached to a gas accumulation possible location 50 where non-condensable gas may accumulate, Except for installing a bimetallic trap 69 at the inlet of the vent line 63 of the gas accumulation location 50, the same configuration is denoted by the same reference numeral because it is not different from the non-condensable gas accumulation prevention system 52C shown in FIG. The description is omitted.

  In the non-condensable gas accumulation combustion prevention system 52F shown in FIG. 8, a bimetal trap 69 is installed at the inlet portion of the vent line 63 of the gas accumulation potential 50 where the non-condensable gas 47 may accumulate. When the temperature of the mounting portion of the bimetal trap 69 approaches the combustion temperature of the non-condensable gas 47, the bimetal trap 69 is automatically opened so that the non-condensable gas 47 can be scavenged through the vent line 63. It is a thing.

  When the scavenging of the non-condensable gas through the vent line 63 is completed and the temperature of the bimetallic trap 69 attachment portion of the gas accumulating location 50 is separated from the combustion temperature of the non-condensable gas, the bimetallic trap 69 is vented. Is automatically blocked.

  Also in this case, it is possible to effectively and beforehand prevent a predetermined amount of non-condensable gas from accumulating in the gas accumulating location 50 in the branch pipe (branch pipe) 45 branched from the mother pipe 44. Accumulated combustion due to condensable gas can be reliably prevented. Therefore, the soundness of the equipment and piping in the nuclear power plant can be maintained.

  FIG. 9 shows an eighth embodiment of the non-condensable gas accumulation combustion preventing system according to the present invention.

  The non-condensable gas accumulation combustion prevention system 52G shown in this embodiment is branched from the main pipe 44 so that a branch pipe (branch pipe) 45 rises, and the tip of the branched branch pipe 45 is branched. Are connected by a thin tube 71 as a communication tube.

  By connecting the distal end portion of the branch pipe 45 branched from the mother pipe 44 to the mother pipe 44 by the narrow pipe 71, a flow is generated in the narrow pipe 71, and the non-condensable gas flows into the gas accumulation possible location 50 in the branch pipe 45. It is possible to effectively prevent stagnation. The narrow tube 71 as the communication tube may be connected to the upstream side of the branch 45 branching portion as shown in FIG. 9 or may be connected to the downstream side. A plurality of thin tubes 71 may be provided and connected to the mother tube 44 as shown in FIG.

  In the non-condensable gas accumulation combustion prevention system 52G shown in FIG. 9 and FIG. 10, the leading end of the dead end branch pipe 45 branched from the mother pipe 44 is connected to the mother pipe 44 by the narrow pipe 71. 71, the non-condensable gas connected to the gas accumulating point 50 is discharged using the flow in 71, or the vapor flow is generated in the branch pipe 45 to prevent the accumulation of non-condensable gas in advance. can do.

  Also in this case, the non-condensable gas accumulation combustion prevention system 52G can prevent the non-condensable gas from accumulating in the dead-end branch pipe 45 branched from the main pipe 44 in advance and reliably. It is possible to prevent gas accumulation and combustion due to sexual gas in advance.

  FIG. 11 shows a ninth embodiment of a non-condensable gas accumulation combustion prevention system.

  In the non-condensable gas accumulation combustion prevention system 52H shown in this embodiment, a narrow pipe 71 as a communication pipe connected to the distal end portion of the dead end branch pipe 45 is protruded into the main pipe 44 so that the inside of the main pipe 44 The distal end opening of the thin tube 44 inserted in is directed to the upstream side. The tip opening of the thin tube 44 may be directed downstream. Since the other configuration is not different from the accumulated combustion prevention system 52G shown in FIG. 8, the same reference numerals are given and description thereof is omitted.

  In the non-condensable gas accumulation combustion prevention system 52H shown in FIG. 11, the tip opening of the narrow tube 71 inserted into the mother tube 44 is directed upstream (or downstream), so that Since the steam flow can be positively and forcibly guided, a fluid flow can be generated in the dead end branch 45. Therefore, the flow of fluid can be caused in the gas accumulation possible place 50 formed in the dead end branch pipe 45, and the non-condensable gas is moored or stagnated in the gas accumulation possible place 50 in the branch pipe 45. Can be effectively and reliably prevented.

  Therefore, combustion due to gas accumulation of non-condensable gas can be surely prevented in advance at the gas detachable portion 50, and the soundness of the equipment and piping in the nuclear power plant can be maintained.

  FIG. 12 shows a tenth embodiment of a non-condensable gas accumulation combustion prevention system according to the present invention.

  The non-condensable gas accumulation combustion prevention system 52I shown in this embodiment is an example in which a narrow pipe 71 as a communication pipe is provided in a dead end branch pipe (branch pipe) 45 that branches off from the main pipe 44 and rises. . One end of the narrow tube 71 enters the mother tube 44 and opens toward the upstream side, while the other end opens near the tip of the branch tube 45.

  The accumulation combustion prevention principle of the non-condensable gas by the non-condensable gas accumulation combustion prevention system 52I shown in FIG. 12 is the same as that of the accumulation combustion prevention system 52G shown in FIG. Since it does not differ except for the installation mode of 71, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the non-condensable gas accumulation combustion prevention system 52I shown in the tenth embodiment, by providing the narrow tube 71 in the dead-end branch tube 45, the thin tube 71 itself does not constitute a pressure boundary, so that the thickness is reduced. Can do.

  FIG. 13 shows an eleventh embodiment of a non-condensable gas accumulation combustion preventing system according to the present invention.

  In the non-condensable gas accumulation combustion prevention system 52J shown in this embodiment, the branch pipe 45 is branched from the mother pipe 44A which is an elbow type or L-shaped fluid pipe, and the branch portion as a whole is T-shaped. Or the example which makes Y shape is shown. In the branch pipe 45, a narrow pipe 71 as a communication pipe is provided. The narrow tube 71 is inserted into the mother tube 44, and the tip thereof opens toward the upstream side, while the other end of the narrow tube opens near the tip of the branch tube 45. Other configurations and operations are not different in principle from the accumulated combustion prevention system 52H shown in FIG. 11, and are the same.

  The non-condensable gas accumulation combustion prevention system 52J of the eleventh embodiment is not different in principle except for the flow of the main vapor flow and the accumulation combustion prevention system 52H and the gas accumulation combustion prevention system 52G shown in FIG. In this case as well, combustion due to accumulation of non-condensable gas at the gas accumulation possible place 50 in the branch pipe 45 can be prevented in advance.

  FIG. 14 shows a twelfth embodiment of a non-condensable gas accumulation combustion prevention system.

  The non-condensable gas accumulation combustion prevention system 52K shown in this embodiment is provided with an open / close valve 72 that also serves as a safety valve in an inverted U-shaped branch pipe 45 that branches off from a main pipe 44 and This is an example in which a plurality of ventilation holes 73 are provided in the downstream branch pipe 45.

  By providing a plurality of fine ventilation holes 73 at the gas accumulation possible location 50 on the downstream side of the on-off valve 72, the generated non-condensable gas can be discharged to the outside.

  In the non-condensable gas accumulation combustion prevention system 52K shown in FIG. 14, when steam flows into the branched branch pipe 45, steam may leak from the ventilation hole 73. Applicable when steam leak is acceptable.

  FIG. 15 shows a thirteenth embodiment of a non-condensable gas accumulation combustion prevention system.

  The non-condensable gas accumulation combustion prevention system 75 shown in this embodiment has two stages in series at the end of a branch pipe 77 that branches off from a mother pipe 76 such as a fluid pipe of a residual heat removal facility (RHR). Stop valves 78a and 78b are provided, a vent line 79 of a thin tube forming an exhaust vent system is connected between the stop valves 78a and 78b, and a vent valve 80 is provided in the vent line 79 to provide a condenser or a nuclear reactor. It is configured to be connected to the building exhaust system 81.

  A temperature / pressure gauge 82 and a radiation measuring device 83 are installed upstream of the vent valve 80 in the vent line 79. The branch pipe 77 constitutes a gas accumulation-possible portion 85 capable of accumulating noncondensable gas.

  In this non-condensable gas accumulation combustion prevention system 75, two stop valves 78 a and 78 b are provided in a branch pipe 77 branched from a mother pipe 76, and fluid leaked from the stop valves 78 a and 78 b is vented to a vent line 79. The leaked fluid passing through the vent line 79 is exhausted to the reactor building, the condenser or the suppression chamber while gas sampling is performed by the radiation measuring device 83, and the two series stop valves 78a and 78b are used. A seat leak exhaust system is configured.

  By performing sampling gas sampling on the leaked fluid vented in the vent line 79, the presence or absence of gas accumulation of non-condensable gas in the branch pipe 77 is determined. For example, in the RHR system piping, if the vent valve 80 closed by the valve is opened intermittently by the timer 84 and vented, it is effective that non-condensable gas accumulates in the gas accumulation location 85 in the branch pipe 77. Can be prevented.

  Also in this non-condensable gas accumulation combustion prevention system 75, it is possible to effectively prevent the accumulation of combustible non-condensable gas in the gas accumulation location in the branch pipe 77, so Accumulated combustion can be prevented without fail. Therefore, the soundness of the equipment and piping in the nuclear power plant can be maintained.

  FIG. 16 shows a fourteenth embodiment of a non-condensable gas accumulation combustion prevention system according to the present invention.

  The non-condensable gas accumulation combustion prevention system 90 shown in this embodiment periodically ignites the combustible non-condensable gas to prevent accumulation combustion of the non-condensable gas. It is a combustion prevention system.

  This accumulative combustion prevention system 90 is provided with a stop valve 93 as an on-off valve in a branch pipe (branch pipe) 92 that branches off from a main pipe 91 and an electric heater 95 in a well or a narrow pipe 94 at the top of the branch pipe 92. Storing. The electric heater 95 is energized and heated every predetermined time, for example, every day, by a heater power source 97 set by a timer 96.

  The non-condensable gas accumulation combustion prevention system 90 shown in this embodiment is energized and heated every predetermined time from the heater power source 97, and the non-condensable gas accumulated in a small amount in the gas accumulation location 98 in the branch pipe 92. (Hydrogen / oxygen) is ignited, and hydrogen / oxygen is recombined by a combustion reaction. The non-condensable gas accumulated in a small amount in the gas accumulating portion 98 of the branch pipe 92 is ignited by the electric heater 95 and periodically burned, whereby a predetermined amount or more of the non-condensable gas accumulates in the gas accumulating portion 98. Can be surely prevented.

  Therefore, it is possible to reliably prevent the non-condensable gas from accumulating in the gas accumulable portion 98 and to exceed the required amount, and it is possible to effectively and reliably prevent the accumulated combustion due to the accumulated non-condensable gas.

  FIG. 17 shows a fifteenth embodiment of a non-condensable gas accumulation combustion prevention system.

  The non-condensable gas accumulation combustion prevention system 100 shown in this embodiment is provided with a stop valve 103 as an on-off valve on the end side of a branch pipe 102 that branches off from a main pipe 101 and rises. A vent line 105 is connected to the top via a vent hole 104, this vent line 105 is connected to a condenser or a reactor building exhaust system 81, and the vent line 105 is opened and closed by a temperature pressure gauge 106 and a timer 107. A vent valve 108 is provided to constitute an intermittent vent system for non-condensable gas.

  In this non-condensable gas accumulation combustion prevention system 100, a vent hole 104 and a vent valve 108 are provided at the top of a branch pipe 102 branched from a mother pipe 101, and a branch is made by venting a timer 107 for a predetermined time, for example, every day. The non-condensable gas stored in the gas storage location 109 in the pipe 102 is discharged into a condenser or a reactor building.

  By venting the vent valve 108 every predetermined time and opening and closing it, it is possible to reliably prevent a predetermined amount or more of non-condensable gas from accumulating in the gas accumulation location 109 of the branch pipe 102. Therefore, it is possible to prevent the accumulated combustion of the non-condensable gas in the gas accumulating portion 109 in advance and reliably.

  FIG. 18 shows a sixteenth embodiment of the non-condensable gas accumulation combustion prevention system.

  The non-condensable gas accumulation combustion prevention system 110 shown in this embodiment is provided with a stop valve 113 as an on-off valve on the end side of a branch pipe 112 that branches off from a mother pipe 111 and A vent line 114 constituting an exhaust vent system is provided at the top. The vent line 114 is connected to a condenser or reactor building exhaust system, which is a low-pressure side pipe or vessel 117, provided with a vent valve 116 that is driven to open and close at a predetermined time by a timer 115.

  A temperature / pressure gauge 118 and a radiation measuring device 119 are provided upstream of the vent valve 116 in the vent line 114, while a catalytic recombiner 120 is provided downstream of the vent valve 115.

  This non-condensable gas accumulation combustion prevention system 110 vents the gas accumulation location 121 in the branch pipe 112 every predetermined time, for example, every day, by opening the vent valve 116 with the timer 115, and the gas accumulation possible location. The non-condensable gas staying at 121 is guided to the low-pressure side container or pipe 117 through the vent line 114. At that time, gas sampling is performed by the radiation measuring device 118 provided in the vent line 114, while the catalytic recombiner 120 receives a catalyst heating action, and the hydrogen / oxygen of the non-condensable gas undergoes a combustion reaction to recombine (steam). )).

  Therefore, the gas accumulation possible location 121 in the branch pipe 112 is vented every predetermined time, and the staying non-condensable gas is discharged through the vent line 114 to the low-pressure side container or the pipe 117 to be stored in the gas accumulation possible location 121. Therefore, it is possible to prevent non-condensable gas from being accumulated, and to effectively and reliably prevent gas accumulation combustion.

  FIG. 19 shows a seventeenth embodiment of a non-condensable gas accumulation combustion prevention system.

  The non-condensable gas accumulation combustion prevention system 125 shown in this embodiment is applied to, for example, a reactor pressure vessel head spray system 22. The accumulated combustion prevention system 125 is connected to a head spray pipe 28 that rises from the upper mirror 12 a of the reactor pressure vessel (RPV) 12, and an injection valve 126 is provided in the pipe 28.

  A gas accumulation location 127 is formed on the downstream side of the injection valve 126 of the head spray pipe 28, and a vent line 128 constituting an exhaust vent system is connected to the top of the pipe 28. The vent line 128 is provided with a vent valve 130 with a timer 129 in the middle, and is connected to a condenser or reactor building exhaust system 131 which is a low-pressure side vessel or pipe. A vent hole 133 or an orifice is provided on the inlet side of the vent line 128, and a temperature / pressure gauge 134 is provided on the downstream side of the vent hole 133.

  A non-condensable gas accumulation combustion prevention system 125 shown in FIG. 19 has a vent line 128 connected to a gas accumulation possible location 127 where the non-condensable gas may stay, and a timer provided in the vent line 128. A vent valve 130 with a 129 vents every predetermined time, for example, every day, vents the non-condensable gas staying in the gas accumulation location 127, and exhausts the condenser or reactor building as a low-pressure side vessel / pipe. The system 131 is discharged. For this reason, the non-condensable gas does not accumulate in the gas accumulable portion 127, and the accumulated combustion of the non-condensable gas can be effectively and reliably prevented.

  FIG. 19 shows an example in which the non-condensable gas accumulated combustion prevention system 125 is applied to the RPV head spray system 22. When this system is applied to the RPV head spray system 22, a vent line is generated when the RPV head spray system 22 is operated. The vent valve 130 provided at 128 is closed. Further, the accumulated combustion prevention system 125 is not limited to the RPV head spray system 22 but can be applied to a piping system connected to a container that handles a flammable non-condensable gas.

  FIG. 20 shows an eighteenth embodiment of the non-condensable gas accumulation combustion prevention system.

  In the non-condensable gas accumulation combustion prevention system 135 shown in this embodiment, a nozzle 137 is set up on a main pipe 136 that is a fluid pipe through which steam flows, a safety valve 138 is provided on the nozzle 137, and a downstream side of the safety valve 138 is provided. Is connected to a low pressure side exhaust pipe 139 or a container, and an exhaust vent system 140 is provided at the inlet nozzle 138a of the safety valve 138 or at the top of the pipe base.

  The exhaust connection vent system 140 has a vent line 141 connected to the inlet nozzle 138a of the safety valve 138 or the top of the nozzle. This vent line 141 is provided with a vent valve 144 with a timer 143 on the way, and is connected to the low pressure side exhaust pipe 139. The vent line 141 is provided with a vent hole 145 or an orifice on the inlet side, and has a temperature / pressure gauge 146 on the downstream side thereof and on the upstream side of the vent valve 144.

  In the non-condensable gas accumulation combustion prevention system 135, the inside of the nozzle 137 of the safety valve 138 is configured as a gas accumulation possible location 148 where the non-condensable gas may stay.

  Therefore, the accumulated combustion prevention system 135 is provided with a safety valve 138 on a nozzle 137 standing on a mother pipe 136, and an exhaust vent system 140 is provided on the inlet nozzle 138a of the safety valve 138 or on the top of the nozzle. The vent valve 144 with a timer provided in the 140 vent line 141 is opened every required time, for example, every day, and vented, and the non-condensable gas staying in the gas storage location 148 in the nozzle 137 is reduced in pressure. Since it has been discharged to a side pipe or container, such as a condenser or a suppression pool, it is possible to reliably and surely prevent accumulation of noncondensable gas in the nozzle 137.

  Therefore, the soundness of the listening pipe in the nuclear power plant can be sufficiently maintained.

  FIG. 21 shows a nineteenth embodiment of the non-condensable gas accumulation combustion preventing system according to the present invention.

  A non-condensable gas accumulation combustion prevention system 150 shown in this embodiment includes a stop valve 153 as an on-off valve at the end of a branch pipe (branch pipe) 152 that branches off from a main pipe 151 and rises. A non-combustion gas injection system 155 is provided on the top side of the tube 152.

  The non-combustion gas injection system 155 includes a non-combustion gas cylinder 156 as a non-combustion gas supply source, and the gas cylinder 156 is connected to the top of the branch pipe 152 via a non-combustion gas supply line 157. In the non-combustion gas cylinder 156, an inert gas such as nitrogen or helium or a non-combustible gas such as water vapor is retained. The branch pipe 152 is formed with a gas accumulation-possible portion 158 in which the non-condensable gas may stay.

  The non-combustion gas supply line 157 is provided with a pressure regulator 160 for adjusting the gas pressure of the non-combustible gas, a vent valve 162 as a gas injection valve with a timer 161, and a temperature / pressure gauge 163. The non-combustion gas supply line 157 is opened every predetermined time, for example, every day by the vent valve 162 with the timer 161, and the non-combustible gas is supplied to the gas accumulation location 158 in the branch pipe 152 and flows into the branch pipe 152. Thus, the non-condensable gas at the portion 158 where gas can be accumulated is purged to the mother pipe 151 side.

  This non-condensable gas accumulation combustion prevention system 150 operates the non-combustion gas injection system 155 periodically at every required time, so that the non-condensable gas stays in the gas accumulation possible place 158 in the branch pipe 152. Is purged with the non-combustible gas and discharged to the side of the mother pipe 151, so that it is possible to prevent the combustible non-condensable gas from accumulating in the gas accumulation location 158.

  Therefore, accumulated combustion of non-condensable gas can be reliably prevented and the soundness of the equipment and piping in the nuclear power plant can be sufficiently maintained.

  In the embodiment of the present invention, an example in which the non-condensable gas accumulation combustion prevention system is applied to a BWR plant has been described. However, the present invention is not limited to a BWR plant, and branches of piping and containers of a pressurized water nuclear power plant. The present invention can be applied to a gas accumulating portion formed at the rising portion.

  In the embodiment of the present invention, the generation of the non-condensable gas amount at the gas accumulable location is suppressed, and the generated non-condensable gas can be discharged out of the system at the gas accumulable location, or the generated non-condensable gas is discharged. Since it can be set to environmental conditions that do not cause combustion, accumulation and combustion of non-condensable gas can be prevented without fail, and the integrity of the equipment and piping in the nuclear power plant can be sufficiently maintained, improving reliability. Can do.

The system diagram which shows roughly the BWR plant provided with the accumulation combustion prevention system of noncondensable gas. The figure which shows 1st Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 2nd Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 3rd Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 4th Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 5th Embodiment of the accumulation combustion prevention system of the non-condensable gas which concerns on this invention. The figure which shows 6th Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 7th Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 8th Embodiment of the accumulation combustion prevention system of the noncondensable gas which concerns on this invention. The figure which shows the modification of the accumulation | storage combustion prevention system of the noncondensable gas shown by FIG. The figure which shows 9th Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 10th Embodiment of the accumulation | storage combustion prevention system of the noncondensable gas which concerns on this invention. The figure which shows 11th Embodiment of the accumulation | storage combustion prevention system of the noncondensable gas which concerns on this invention. The figure which shows 12th Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 13th Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 14th Embodiment of the accumulation | storage combustion prevention system of the noncondensable gas which concerns on this invention. The figure which shows 15th Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 16th Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 17th Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 18th Embodiment of the accumulation | storage combustion prevention system of noncondensable gas. The figure which shows 19th Embodiment of the accumulation combustion prevention system of the noncondensable gas which concerns on this invention. The figure which shows the piping connection structure which branches off from the conventional mother pipe and stands up.

Explanation of symbols

10 BWR plant 11 Reactor containment vessel (PCV)
12 Reactor pressure vessel (RPV)
13 Drywell 14 Core 15 Reactor cooling water (liquid phase part)
16 Gas phase section 17 Main steam system 17a Main steam pipe 18 Steam turbine 19a, 19b Main steam isolation valve 20 Reactor pressure vessel (RPV) vent equipment 21 Reactor pressure vessel (RPV) vent system 22 Reactor pressure vessel (RPV) Head spray system 23 Branch vent system 25 RPV vent piping 27, 33 Electric valve (remote control valve)
28 RPV head spray piping 30 check valve 31 vent branch piping 38 reactor isolation cooling equipment 39a, 39b PCV isolation valve 40 gas accumulation location 43 branch pipe 44 main pipe 45 branch pipe 46 on-off valve 47 non-condensable gas 50 gas Storage location 51 Insulating material 52, 52A to 52K Accumulated combustion prevention system 56 of non-condensable gas 56 Valve casing 57 Valve body 58 Valve operating portion 59 Valve rod 60 Vent hole 63 Vent line 64 Orifice 65 Heating equipment or cooling equipment 66 Temperature Total 67 Pressure gauge 68 Drive unit 69 Bimetal trap 71 Narrow tube (communication tube)
72 On-off valve 73 Ventilation hole 75 Non-condensable gas accumulation combustion prevention system 76 Mother pipe 77 Branch pipes 78a and 78b Stop valve (on-off valve)
79 Vent line 80 Vent valve 81 Condenser or reactor building exhaust system 82 Temperature / pressure gauge 83 Radiation measuring device 85 Gas accumulation location 90 Non-condensable gas accumulation combustion prevention system 91 Mother pipe 92 Branch pipe (branch pipe)
93 Stop valve (open / close valve)
94 Well or narrow tube 95 Electric heater 96 Timer 97 Heater power supply 98 Gas accumulation location 100 Non-condensable gas accumulation combustion prevention system 101 Mother tube 102 Branch tube 103 Stop valve (open / close valve)
104 Vent hole 105 Vent line 106 Temperature / pressure gauge 107 Timer 108 Vent valve 109 Gas accumulating point 110 Non-condensable gas accumulation combustion prevention system 111 Mother pipe 112 Branch pipe 113 Stop valve (open / close valve)
114 Vent line 115 Timer 116 Vent valve 117 Low-pressure side pipe or container 118 Temperature / pressure gauge 119 Radiation measuring device 120 Catalytic recombiner 121 Gas accumulator location 125 Non-combustion gas accumulation combustion prevention system 126 Injection valve 128 Vent line 129 Timer 130 Vent valve 131 Condenser or reactor building exhaust system 133 Vent hole 134 Temperature / pressure gauge 135 Non-condensable gas accumulation combustion prevention system 136 Mother pipe 137 Safety valve 139 Low pressure side exhaust pipe or vessel 140 Exhaust vent System 141 Vent line 143 Timer 144 Vent valve 145 Vent hole 146 Temperature / pressure gauge 148 Gas accumulation location 150 Non-condensable gas accumulation combustion prevention system 151 Main pipe 152 Branch pipe 153 Stop valve 155 Non-combustion gas injection system 156 Non-combustion gas Cylinder (non-combustion gas supply source)
157 Non-combustion gas supply line 158 Gas accumulation location 160 Pressure regulator 161 Timer 162 Vent valve 163 Temperature / pressure gauge

Claims (6)

A location where gas can be accumulated is formed in a dead-end branch pipe that branches off from the main pipe through which steam flows, a communication pipe that connects the branch pipe and the main pipe is provided, and the communication pipe is opened in the mother pipe Accumulated combustion prevention system for non-condensable gas. 2. The non-condensable gas accumulation combustion prevention system according to claim 1, wherein the communication pipe protrudes into the mother pipe and opens, and the opening opens at least one of the upstream side and the downstream side in the mother pipe. 3. The non-condensable gas accumulation combustion prevention system according to claim 1, wherein the communication pipe is a narrow pipe provided at least in the branch pipe along the axial direction. An electric heater housed in a well or narrow tube is provided at the top of the branch pipe branched from the mother pipe, and a portion of the branch pipe where the gas can be accumulated is energized and heated every predetermined time, thereby a non-condensable gas accumulated in a small amount A system for preventing the accumulation and combustion of non-condensable gas, characterized in that hydrogen or oxygen is ignited and recombined in a combustion reaction. A non-combustion gas injection system is provided at the top of the branch pipe that branches off from the main pipe, and the non-combustible injection valve with a timer provided in the non-combustion gas injection system is opened every predetermined time to make it non-combustible at the top of the branch pipe. A non-condensable gas accumulation combustion prevention system characterized by injecting gas and purging non-condensable gas that can stay in a gas accumulation location in the branch pipe to the mother pipe side with non-combustible gas. Heating or cooling equipment is installed at a location where non-condensable gas can stay, and a heating or cooling facility is provided, and the location where gas can be accumulated with this heating or cooling equipment is kept at a predetermined temperature so as not to approach the non-condensable gas combustion temperature. A non-condensable gas accumulation combustion prevention system characterized in that it is retained.

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