JP2014013175A - Hydrogen processing system for nuclear power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen processing system for a nuclear power plant which can reduce the risk that hydrogen gas permeating a hydrogen permeable membrane leaks outside.SOLUTION: A hydrogen processing system comprises an iodine processing catalyst layer 1, a hydrogen permeable membrane 2, and a hydrogen recombination catalyst layer 3. The hydrogen recombination catalyst layer 3 is arranged in contact with the downstream side surface of the hydrogen permeable membrane 2, and the iodine processing catalyst layer 1 is arrange in contact with the upstream side surface of the hydrogen permeable membrane 2. When hydrogen gas is generated by a reaction between zirconium and water vapor in a loss-of-coolant accident, iodine compound gas existing in the gas in a reactor containment vessel containing hydrogen gas is removed by the iodine processing catalyst layer 1. Hydrogen gas permeates the hydrogen permeable membrane 2 and reaches the hydrogen recombination catalyst layer 3 to which oxygen gas is supplied, and is combined with the oxygen to be converted to water vapor. Because the hydrogen recombination catalyst layer 3 is in contact with the hydrogen permeable membrane 2, the risk of leakage of hydrogen gas permeating the hydrogen permeable membrane 2 to the outside is eliminated.

Description

  The present invention relates to a hydrogen treatment system for a nuclear power plant, and more particularly to a hydrogen treatment system for a nuclear power plant suitable for application to a boiling water nuclear power plant.

  In a nuclear power plant, when piping connected to the reactor pressure vessel breaks, the pressure at which steam containing radioactive material released from the broken portion of the piping into the reactor containment vessel is provided in the reactor containment vessel It is assumed that hydrogen gas and oxygen gas are generated by flowing into the cooling water of the pressure suppression pool in the suppression chamber and radiolysis of the cooling water. Such an event is called a coolant loss accident. In the event of a loss of coolant, if the water level in the reactor pressure vessel drops and the temperature of the nuclear fuel material in the fuel rods contained in the fuel assemblies loaded in the reactor core in the reactor pressure vessel rises, Hydrogen gas is generated by the reaction of zirconium and water vapor contained in the cladding tube enclosing the nuclear fuel material of the fuel rod. This hydrogen gas is released from the reactor pressure vessel into the reactor containment vessel.

  In a boiling water nuclear power plant that uses a containment vessel with a pressure suppression chamber as a countermeasure against the loss of coolant, boiling water is used to prevent combustion even if hydrogen gas is generated in the containment vessel. During operation of a nuclear power plant, the atmosphere in the reactor containment vessel is replaced with nitrogen gas. Furthermore, the boiling water nuclear power plant has a heating-type hydrogen treatment facility connected to a reactor containment vessel by piping. When a coolant loss accident occurs, the blower is driven to supply gas containing hydrogen and oxygen in the reactor containment vessel to the heated hydrogen treatment facility, and hydrogen and oxygen are heated by the electric heater of the heated hydrogen treatment facility. It is recombined and converted to water vapor.

  In recent years, catalytic hydroprocessing equipment that has excellent passive safety and does not require external power has been developed. An example of this catalytic hydrogen treatment facility is described in JP-A-10-227885. The catalytic hydrogen treatment facility has a catalyst for reacting hydrogen and oxygen, and a chimney that houses the catalyst, and is disposed in a dry well and a pressure suppression chamber in the reactor containment vessel. Japanese Patent Application Laid-Open No. 2009-69122 discloses an example in which a catalytic hydrogen treatment facility is disposed outside a reactor containment vessel and inside a reactor building.

  In a loss of coolant accident, hydrogen gas is used as a method of reducing the hydrogen concentration in the containment vessel, bringing the gas in the containment vessel into contact with the hydrogen permeable membrane, and storing the hydrogen gas that has permeated the hydrogen permeable membrane in the reactor. Japanese Unexamined Patent Publication No. 11-30694 discloses a method of discharging the vessel outside the vessel and reducing the hydrogen concentration in the reactor containment vessel. The hydrogen gas separated from the reactor containment vessel by the hydrogen permeable membrane is exhausted as a gas to the outside of the hydrogen treatment facility. In Japanese Patent Application Laid-Open No. 11-30694, the surface of the hydrogen permeable membrane facing the reactor containment vessel is coated with a catalyst that promotes the reaction between hydrogen gas and oxygen gas. When hydrogen gas and oxygen gas are present in the reactor containment vessel, the hydrogen gas and oxygen gas are combined into water by the action of the catalyst.

  Japanese Patent Application Laid-Open No. 11-166996 describes a method of reducing the hydrogen gas concentration in the reactor containment vessel by reacting the hydrogen gas and nitrogen gas in the reactor containment vessel with an ammonia synthesis catalyst and converting them to ammonia. Has been.

  Japanese Patent Application Laid-Open No. 2010-190869 discloses that hydrogen gas in a nuclear reactor containment vessel is guided to a hydrogen gas storage device having a hydrogen storage alloy through an iodine filter and a hydrogen permeable membrane and absorbed by the hydrogen storage alloy. Describes a method for reducing the hydrogen gas concentration in the reactor containment vessel.

Japanese Patent Laid-Open No. 10-227885 JP 2009-69122 A Japanese Patent Laid-Open No. 11-30694 Japanese Patent Laid-Open No. 11-166996 JP 2010-190869 A

  Even if a large amount of hydrogen gas is generated in the reactor containment vessel, the atmosphere in the reactor containment vessel is replaced with nitrogen gas during normal operation as described above. Low. However, it is not preferable to leave potentially flammable hydrogen gas in the reactor containment vessel.

  In the conventional method for reducing the hydrogen gas concentration using the heated hydrogen treatment facility and the catalytic hydrogen treatment facility, a predetermined amount or more of oxygen gas is required to treat the hydrogen gas. Therefore, the hydrogen gas in the nitrogen gas atmosphere in the reactor containment vessel cannot be processed efficiently.

  In the hydrogen gas processing method using the ammonia synthesis catalyst described in JP-A-11-166996, the hydrogen gas in the reactor containment vessel is reacted with nitrogen gas to process the hydrogen gas. Oxygen gas is not required, but a large amount of strongly alkaline and toxic ammonia is generated in the reactor containment vessel in the state of gas or liquid with the treatment of hydrogen gas. For this reason, it becomes a big obstacle for the recovery work of the nuclear power plant after that.

  In the hydrogen gas processing facility described in Japanese Patent Application Laid-Open No. 11-30694, the hydrogen gas in the reactor containment vessel passes through the hydrogen permeable membrane and is discharged out of the reactor containment vessel through the hydrogen discharge pipe in the event of a coolant loss accident. ing. The hydrogen gas processing facility disclosed in Japanese Patent Application Laid-Open No. 11-30694 can reduce the hydrogen concentration in the reactor containment vessel without using oxygen gas. However, it is necessary to discharge the combustible hydrogen gas through the hydrogen discharge pipe after the hydrogen permeable membrane. A hydrogen recombination catalyst is coated on the surface of the hydrogen permeable membrane on the reactor containment vessel side, and the hydrogen gas can be treated using the oxygen gas present in the reactor containment vessel. In the unlikely event of a loss of coolant, the amount of hydrogen gas generated when the aforementioned reaction between zirconium and water vapor occurs is much greater than the amount of oxygen generated by radiolysis of the cooling water. The hydrogen gas treated by the action of the hydrogen recombination catalyst coated on the surface of the reactor containment vessel becomes a part of the hydrogen gas existing in the reactor containment vessel. Most of the hydrogen gas generated by the reaction between zirconium and water vapor passes through the hydrogen permeable membrane and is discharged out of the reactor containment vessel.

  In the hydrogen processing apparatus described in Japanese Patent Application Laid-Open No. 2010-190869, the hydrogen storage alloy in the hydrogen gas storage device absorbs the hydrogen gas that has permeated through the hydrogen permeable film provided in the pipe connected to the reactor containment vessel. The hydrogen gas in the reactor containment vessel is processed. If all the hydrogen gas generated by the reaction between zirconium and water vapor is absorbed by the hydrogen storage alloy, a large amount of hydrogen storage alloy is required, and it is necessary to make the hydrogen gas storage device very large or to install a large number of hydrogen storage devices.

  As disclosed in Japanese Patent Application Laid-Open No. 2010-190869, hydrogen gas that has permeated through a hydrogen permeable membrane is led to a hydrogen gas storage device by piping. If the piping breaks, hydrogen gas leaks and hydrogen explodes. There is a risk of occurrence.

  An object of the present invention is to provide a hydrogen treatment system for a nuclear power plant that can reduce the risk of hydrogen gas permeating through a hydrogen permeable membrane leaking to the outside.

  A feature of the present invention that achieves the above-described object is that a hydrogen permeable membrane that separates and permeates hydrogen gas from the gas in the reactor containment vessel, and a hydrogen permeable membrane that is disposed in contact with the downstream surface of the hydrogen permeable membrane. A hydrogen recombination catalyst layer for recombining oxygen gas with hydrogen gas that permeates the membrane, wherein the hydrogen recombination catalyst layer is in contact with a region containing oxygen on a surface other than the surface in contact with the hydrogen permeable membrane. There is in being.

  Since the hydrogen recombination catalyst layer is disposed in contact with the downstream surface of the hydrogen permeable membrane, the hydrogen gas that has permeated through the hydrogen permeable membrane is led to the hydrogen recombination catalyst layer without using a pipe, and is reconstituted with oxygen gas. The hydrogen gas which permeate | transmitted the hydrogen permeable membrane can be combined, and the danger that the gas leaks outside can be reduced.

  Preferably, the hydrogen permeable membrane and the hydrogen recombination catalyst layer are formed in a cylindrical shape, the hydrogen recombination catalyst layer is disposed inside the hydrogen permeable membrane, and the outer surface of the hydrogen recombination catalyst layer is located on the downstream side of the hydrogen permeable membrane. It is desirable to connect the oxygen supply device to a region surrounded by the cylindrical hydrogen recombination catalyst layer. Thus, by making the hydrogen permeable membrane and the hydrogen recombination catalyst layer into a cylindrical shape, the space inside the cylindrical hydrogen recombination catalyst layer can be used as a passage through which gas flows, and oxygen can be contained in the passage. A simple operation method of supplying gas can be realized.

  Preferably, the hydrogen permeable membrane and the hydrogen recombination catalyst layer are formed in a cylindrical shape, the hydrogen recombination catalyst layer is disposed outside the hydrogen permeable membrane, and the inner surface of the hydrogen recombination catalyst layer is located on the downstream side of the hydrogen permeable membrane. It is desirable to contact the outer surface of the hydrogen recombination catalyst layer with oxygen gas. Thus, by making the hydrogen permeable membrane and the hydrogen recombination catalyst layer into a cylindrical shape, the space inside the cylindrical hydrogen permeable membrane can be used as a passage through which hydrogen gas flows, and the hydrogen gas is contained in this passage. It is possible to realize a simple driving method of supplying

  ADVANTAGE OF THE INVENTION According to this invention, the danger that the hydrogen gas which permeate | transmitted the hydrogen permeable film will leak outside can be reduced.

It is explanatory drawing which shows the principle of the process of hydrogen gas in this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the hydrogen treatment system of the nuclear power plant applied to the nuclear reactor containment vessel of the boiling water nuclear power plant of Example 1 which is one suitable Example of this invention. It is a detailed longitudinal cross-sectional view of the hydrogen treatment part of the hydrogen treatment system shown in FIG. It is a cross-sectional view of the hydrogen treatment part of the hydrogen treatment system shown in FIG. It is a block diagram of the hydrogen treatment system of the nuclear power plant applied to the reactor containment vessel of the boiling water nuclear power plant of Example 2 which is another Example of this invention. It is a detailed longitudinal cross-sectional view of the hydrogen treatment part of the hydrogen treatment system shown in FIG. It is a cross-sectional view of the hydrogen treatment part of the hydrogen treatment system shown in FIG.

  The inventors examined a hydrogen treatment system for a nuclear power plant that solves the above-described problems. And the inventors thought that potentially flammable hydrogen gas should be converted to a chemical form that does not have flammable properties when extracted or transferred from within the reactor containment. . As a result, the inventors used a hydrogen permeable membrane, placed a hydrogen recombination catalyst layer in contact with the surface of the hydrogen permeable membrane located downstream of the hydrogen permeable membrane, and recombined oxygen gas with the hydrogen recombination. We found a measure to supply to the catalyst layer.

  The principle of the hydrogen treatment system created by the inventors will be described with reference to FIG. The basic concept of this hydrogen treatment system includes an iodine treatment catalyst layer 1, a hydrogen permeable membrane 2, and a hydrogen recombination catalyst layer 3. The hydrogen recombination catalyst layer 3 is disposed in contact with the surface located on the downstream side of the hydrogen permeable membrane 2. The iodine treatment catalyst layer 1 is filled with, for example, a spherical iodine treatment catalyst in which silver is supported on alumina. The iodine treatment catalyst layer 1 is constituted by, for example, a cartridge filled with a number of spherical iodine treatment catalysts. The hydrogen permeable film 2 is an organic polymer film or a metal film. Examples of metal films that transmit hydrogen include palladium films, alloy films obtained by adding silver, copper, gold, yttrium, and gadolinium to palladium, alloy films obtained by adding titanium and nickel to niobium, and alloy films obtained by adding nickel to vanadium. . The hydrogen recombination catalyst layer 3 is composed of, for example, a cartridge filled with a catalyst that reacts hydrogen with oxygen to convert it into water. The catalyst used for the hydrogen recombination catalyst layer 3 is made, for example, by supporting platinum or palladium on alumina, cerium oxide, a mixed oxide of cerium oxide and zirconium oxide, or the like.

  When hydrogen gas generated by the reaction of zirconium and water vapor in the accident of loss of coolant is released into the reactor containment vessel, the gas present in the reactor containment vessel is mainly hydrogen gas, nitrogen gas, water vapor, oxygen Contains gas and iodine compound gas. When the gas in the reactor containment vessel passes through the iodine treatment catalyst layer 1, the iodine compound gas contained in the gas is removed by the iodine treatment catalyst in the iodine treatment catalyst layer 1. The gas from which the iodine compound gas has been removed through the iodine treatment catalyst layer 1 comes into contact with the hydrogen permeable membrane 2. At that time, only hydrogen gas contained in the gas permeates the hydrogen permeable membrane 2 and reaches the hydrogen recombination catalyst layer 3. Oxygen gas is supplied to the hydrogen recombination catalyst layer 3, and the hydrogen gas that has reached the hydrogen recombination catalyst layer 3 is combined with oxygen gas by the action of the hydrogen recombination catalyst in the hydrogen recombination catalyst layer 3, and immediately the water vapor Converted to Since the hydrogen gas that has passed through the hydrogen permeable membrane 2 can be recombined with the oxygen gas in the hydrogen recombination catalyst layer 3 that contacts the hydrogen permeable membrane 2, piping that connects the hydrogen permeable membrane 2 and the hydrogen recombination catalyst layer 3. Is eliminated, and the risk of leakage of hydrogen gas that has passed through the hydrogen permeable membrane 2 to the outside is eliminated.

  Embodiments of the present invention to which the above-described hydrogen treatment gas treatment principle is applied will be described below.

  A hydrogen treatment system for a nuclear power plant applied to a reactor containment vessel of a boiling water nuclear power plant according to embodiment 1, which is a preferred embodiment of the present invention, will be described with reference to FIGS. .

  The hydrogen treatment system 7 of this embodiment includes a hydrogen treatment unit 11, an oxygen supply pipe 8, and an offgas transfer pipe 9. The boiling water nuclear power plant has a reactor pressure vessel 6 and surrounds the reactor pressure vessel 6 with a reactor containment vessel 5. The reactor pressure vessel 6 is arranged in a dry well in the reactor containment vessel 5. As shown in FIGS. 3 and 4, the cylindrical hydrogen treatment unit 11 disposed in the dry well in the reactor containment vessel 5 includes an iodine treatment catalyst layer 1, a hydrogen permeable membrane 2, and a hydrogen recombination catalyst layer. 3. Each of the iodine treatment catalyst layer 1, the hydrogen permeable membrane 2, and the hydrogen recombination catalyst layer 3 has a cylindrical shape, for example, a cylindrical shape, and is arranged concentrically. The hydrogen recombination catalyst layer 3 is disposed on the innermost side, the hydrogen permeable membrane 2 surrounds the hydrogen recombination catalyst layer 3, and the inner surface of the hydrogen permeable membrane 2 is in contact with the outer surface of the hydrogen recombination catalyst layer 3. The iodine treatment catalyst layer 1 surrounds the hydrogen permeable membrane 2, and the inner surface of the iodine treatment catalyst layer 1 is in contact with the outer surface of the hydrogen permeable membrane 2. The iodine treatment catalyst layer 1 communicates with the dry well in the reactor containment vessel 5. A passage 10 is formed in the cylindrical hydrogen recombination catalyst layer 3 and is surrounded by the hydrogen recombination catalyst layer 3.

  The iodine treatment catalyst layer 1 is configured by, for example, filling a large number of iodine treatment catalysts in which silver is supported on particulate alumina. The hydrogen permeable membrane 2 is made of palladium, for example. The hydrogen recombination catalyst layer 3 is filled with a large number of hydrogen recombination catalysts in which platinum is supported on particulate alumina.

  An oxygen supply pipe 8 passes through the reactor containment vessel 5 and is arranged from the outside of the reactor containment vessel 5 toward the inside of the reactor containment vessel 5, and is connected to the hydrogen treatment unit 11. The oxygen supply pipe 8 communicates with a passage 10 formed in the hydrogen recombination catalyst layer 3 in the hydrogen treatment unit 11. The off-gas transfer pipe 9 connected to the hydrogen treatment unit 11 and connected to the passage 10 passes through the reactor containment vessel 5 and reaches the outside of the reactor containment vessel 5. The oxygen supply pipe 8 and the off-gas transfer pipe 9 are connected to the hydrogen treatment unit 11 so that oxygen gas does not enter the reactor containment vessel 5. The oxygen supply pipe 8 and the off gas transfer pipe 9 are open to the external environment. A blower (not shown) for supplying air is provided in the oxygen supply pipe 8. A heater is attached to the hydrogen treatment unit 11 and the off-gas transfer pipe 9.

  A pipe (not shown) connected to the reactor pressure vessel 6 breaks in the reactor containment vessel 5 and a coolant loss accident occurs. Further, in the core (not shown) in the reactor pressure vessel 6 It is assumed that hydrogen gas is generated by the reaction between zirconium and water vapor contained in the cladding tube that encloses the nuclear fuel material of the fuel rod.

  High-temperature steam, hydrogen gas, iodine compound gas and fission product gas discharged from the breakage point of the pipe connected to the reactor pressure vessel 6 to the dry well in the reactor containment vessel 5, and the reactor containment vessel 5 The filled nitrogen gas flows into the iodine treatment catalyst layer 1 of the hydrogen treatment unit 11. The iodine treatment catalyst in the iodine treatment catalyst layer 1 removes iodine compound gas from the inflowing gas. The hydrogen gas passes through the iodine treatment catalyst layer 1, further passes through the hydrogen permeable membrane 2, and reaches the hydrogen recombination catalyst layer 3. By driving the blower, air containing oxygen is supplied from the external environment into the passage 10 through the oxygen gas supply pipe 8. The air reaching the passage 10 flows from the inner surface of the hydrogen recombination catalyst layer 3 into the particulate hydrogen recombination catalyst tube in the hydrogen recombination catalyst layer 3. The hydrogen gas that has permeated through the hydrogen permeable membrane 2 is recombined with oxygen contained in the air flowing into the hydrogen recombination catalyst layer 3 by the action of the hydrogen recombination catalyst in the hydrogen recombination catalyst layer 3 to become water vapor. . Water vapor generated by recombination of hydrogen gas and oxygen and air supplied from the oxygen supply pipe 8 (water vapor and air are referred to as off-gas) are discharged from the passage 10 to the off-gas transfer pipe 9 to be contained in the reactor containment vessel 5. Transported outside and released to the outside environment. The hydrogen permeable membrane 2 does not transmit water vapor other than hydrogen gas, iodine compound gas, fission product gas and nitrogen gas.

  Since the hydrogen treatment unit 11 and the off-gas transfer pipe 9 are heated by the heater, the water vapor generated in the hydrogen recombination catalyst layer 3 is prevented from being condensed in the hydrogen treatment unit 11 and the off-gas transfer pipe 9.

  The hydrogen permeable membrane 2 in contact with the hydrogen recombination catalyst layer 3 is warmed by the reaction heat generated by the recombination of hydrogen gas and oxygen in the hydrogen recombination catalyst layer 3. In this embodiment, since a palladium film, which is a metal film, is used as the hydrogen permeable film 2, the hydrogen permeable film 2 is warmed by the reaction heat to improve the hydrogen permeation performance, and the amount of hydrogen gas that forms the hydrogen permeable film 2 Will increase.

  Further, when the power supply cannot be used when a coolant loss accident occurs, the blower provided in the oxygen supply pipe 8 and the heater attached to the hydrogen treatment unit 11 and the off-gas transfer pipe 9 cannot be used. . In this case, the hydrogen gas that has permeated through the hydrogen permeable membrane 2 is recombined with oxygen existing in advance in the passage 10 in the hydrogen recombination catalyst layer 3. Ascending airflow is generated by the heat generated by the recombination reaction, and air is newly supplied from the external environment through the oxygen supply pipe 8 into the passage 10 surrounded by the hydrogen recombination catalyst layer 3, and as described above. Since the hydrogen permeable membrane 2 is warmed by the heat generated by the recombination reaction and the hydrogen permeation performance of the hydrogen permeable membrane 2 is improved, the hydrogen recombination reaction in the hydrogen recombination catalyst layer 3 is promoted.

  According to the present embodiment, the hydrogen recombination catalyst layer 3 is disposed in contact with the downstream surface of the hydrogen permeable membrane 2 in the cylindrical hydrogen treatment unit 11, and oxygen is supplied to the hydrogen recombination catalyst layer 3. Therefore, even when a coolant loss accident occurs and the oxygen concentration in the reactor containment vessel 5 is very low compared to the hydrogen concentration, hydrogen gas is allowed to pass through the hydrogen permeable membrane 2 and downstream of the hydrogen permeable membrane 2. In the hydrogen recombination catalyst layer 3 located at, it can be efficiently recombined with oxygen gas.

  If a coolant loss accident occurs and, in the unlikely event, a reaction between zirconium and water vapor contained in the fuel rod cladding tube in the core occurs, iodine compound gas is transferred from the reactor pressure vessel 6 to the reactor containment vessel 5. Discharged into the dry well. When this iodine compound gas comes into contact with the hydrogen permeable membrane 2, there is a concern that the hydrogen permeable membrane 2 is poisoned by the iodine compound gas and deteriorates the hydrogen permeation performance. In this embodiment, since the iodine treatment catalyst layer 1 is disposed upstream of the hydrogen permeable membrane 2, the iodine compound gas can be removed by the iodine treatment catalyst layer 1, and the hydrogen permeable membrane 2 is covered with the iodine compound gas. Can prevent poison.

  In this embodiment, since the iodine treatment catalyst layer 1 is disposed in contact with the outer surface of the hydrogen permeable membrane 2 and the hydrogen recombination catalyst layer 3 is disposed in contact with the inner surface of the hydrogen permeable membrane 2, the iodine treatment catalyst layer 1. A pipe connecting the hydrogen permeable membrane 2 and the hydrogen recombination catalyst layer 3 is not required, and the configuration of the hydrogen treatment system 7 is simplified.

  Since the hydrogen recombination catalyst layer 3 is disposed in contact with the surface (inner surface) located on the downstream side of the hydrogen permeable membrane 2, piping for connecting the hydrogen permeable membrane 2 and the hydrogen recombination catalyst layer 3 becomes unnecessary. Therefore, the risk of leakage of hydrogen gas that has permeated through the hydrogen permeable membrane 2 to the outside due to the breakage of the pipe can be reduced. For this reason, the safety | security of the hydrogen treatment system 7 in a present Example improves. Furthermore, since the iodine treatment catalyst layer 1 is arranged in contact with the upstream surface of the hydrogen permeable membrane 2, a pipe connecting the iodine treatment catalyst layer 1 and the hydrogen permeable membrane 2 is not necessary. The risk of leakage of hydrogen gas that has passed through the iodine treatment catalyst layer 1 to the outside due to breakage can be reduced. For this reason, the safety | security of the hydrogen treatment system 7 in a present Example further improves.

  In this embodiment, since the hydrogen permeable membrane 2 and the hydrogen recombination catalyst layer 3 are cylindrical and the hydrogen recombination catalyst layer 3 is disposed inside the hydrogen permeable membrane 2, the cylindrical hydrogen recombination catalyst layer 3 is arranged. A simple operation method of supplying oxygen gas into the passage 10 through the oxygen supply pipe 8 can be realized.

  Further, as a hydrogen recombination catalyst filled in the hydrogen recombination catalyst layer 3 of the hydrogen treatment unit 11, cerium oxide or a mixed oxide of cerium oxide and zirconium oxide is used as a carrier, and palladium (or platinum) is attached to the surface of the carrier. In the case of using the catalyst, oxygen necessary for recombining the hydrogen gas that has permeated through the hydrogen permeable membrane 2 is supplied from the cerium oxide even in an environment in which no oxygen gas exists, and the hydrogen recombination catalyst layer 3 The hydrogen gas can be recombined by the action of palladium (or platinum). A hydrogen recombination catalyst containing cerium oxide and palladium exerts both the supply of oxygen and the recombination reaction of hydrogen and oxygen.

  By filling the hydrogen recombination catalyst layer 3 of the hydrogen treatment unit 11 with the above-described hydrogen recombination catalyst containing cerium oxide and palladium (or platinum), a gas not containing oxygen gas, such as nitrogen gas, is supplied from the oxygen supply pipe 8. Even when supplied into the passage 10, the hydrogen gas that has permeated through the hydrogen permeable membrane 2 is supplied from the cerium oxide in the hydrogen recombination catalyst layer 3 by the action of the hydrogen recombination catalyst containing cerium oxide and palladium (or platinum). Can be recombined with oxygen. In this case, although the amount of oxygen that can be supplied from cerium oxide per unit mass is limited, cerium oxide can reabsorb oxygen by contacting cerium oxide with oxygen gas. Therefore, when oxygen is no longer released from the cerium oxide in the hydrogen recombination catalyst layer 3, oxygen can be stored in the cerium oxide by supplying oxygen gas into the passage 10 from the oxygen supply pipe 8. .

  When using a mixed oxide of cerium oxide and zirconium oxide and using a mixed oxide having a cerium oxide ratio of 30 mol% as a support and palladium on the surface of this simple substance, an oxygen gas is not present. The hydrogen recombination reaction rapidly progressed at about 45 ° C. or higher. On the other hand, when a catalyst in which palladium was impregnated on the surface of this simple substance using cerium oxide as a support was used, the hydrogen recombination reaction proceeded rapidly at about 160 ° C. or higher in an environment where no oxygen gas was present. By making the support of the catalyst used for the hydrogen recombination catalyst layer 3 a mixed oxide of cerium oxide and zirconium oxide, the hydrogen recombination reaction can proceed more efficiently at a lower temperature than when the support is made of cerium oxide. it can.

  A nuclear power plant hydrogen treatment system applied to a reactor containment vessel of a boiling water nuclear power plant according to embodiment 2, which is another embodiment of the present invention, will be described with reference to FIGS.

  The hydrogen treatment system 7A of the present embodiment has a configuration in which, in the hydrogen treatment system 7 of the first embodiment, the hydrogen treatment section 11 is replaced with the hydrogen treatment section 11A, and an iodine treatment catalyst tower 1A and a dehumidifying device 12 are provided. The processing unit 11A is disposed outside the reactor containment vessel 5. The other configuration of the hydrogen treatment system 7A is the same as that of the hydrogen treatment system 7.

  The cylindrical hydrogen treatment unit 11A includes a hydrogen permeable membrane 2 and a hydrogen recombination catalyst layer 3 as shown in FIGS. Each of the hydrogen permeable membrane 2 and the hydrogen recombination catalyst layer 3 has a cylindrical shape, for example, a cylindrical shape, and is arranged concentrically. The hydrogen treatment unit 11A differs from the hydrogen treatment unit 11 in that the cylindrical hydrogen recombination catalyst layer 3 surrounds the cylindrical hydrogen permeable membrane 2, and the downstream surface of the hydrogen permeable membrane 2, that is, the hydrogen permeable membrane. 2 is arranged in contact with the outer surface. The hydrogen treatment unit 11A is provided with a heater (not shown). The reactor containment vessel 5 is installed in a reactor building (not shown). The hydrogen treatment unit 11A is disposed outside a reactor containment vessel 5 in a vessel (not shown) installed in a room in the reactor building, and an air supply pipe (not shown) connected to the vessel. And the steam discharge pipe (not shown) reach the outside environment outside the reactor building.

  The hydrogen processing unit 11A has a passage 10A surrounded by the hydrogen permeable membrane 2 inside. A gas supply pipe 13 connected to the reactor containment vessel 5 and connected to the dry well in the reactor containment vessel 5 is connected to the hydrogen treatment unit 11A and communicated with the passage 10A. A dehumidifying device 12 and an iodine treatment catalyst tower 1 </ b> A are provided in the gas supply pipe 13. Further, the gas supply pipe 13 is provided with a blower. An off-gas transfer pipe 9 connected to the hydrogen treatment unit 11A and connected to the passage 10A is connected to the reactor containment vessel 5 and connected to the dry well.

  As in the first embodiment, a pipe (not shown) connected to the reactor pressure vessel 6 breaks in the reactor containment vessel 5 and a coolant loss accident occurs. Further, in the reactor pressure vessel 6 It is assumed that hydrogen gas is generated by the reaction of zirconium and water vapor contained in the cladding tube enclosing the nuclear fuel material of the fuel rod in the core (not shown).

  High-temperature steam, hydrogen gas, iodine compound gas and fission product gas discharged from the breakage point of the pipe connected to the reactor pressure vessel 6 to the dry well in the reactor containment vessel 5, and the reactor containment vessel 5 The gas containing nitrogen gas filled in drives the blower provided in the gas supply pipe 13, so that the dehumidifier 12 and the iodine treatment catalyst tower 1 </ b> A pass through the gas supply pipe 13 from the dry well in the reactor containment vessel 5. And sequentially supplied to the hydrogen treatment unit 11A. The water vapor contained in the supplied gas is removed by the dehumidifying device 12, and the iodine compound gas is removed by the iodine treatment catalyst tower 1A. The gas from which the water vapor and iodine compound gas have been removed reaches the passage 10A of the hydrogen treatment unit 11A and contacts the inner surface of the hydrogen permeable membrane 2. The hydrogen gas contained in the gas passes through the hydrogen permeable membrane 2 and reaches the downstream surface of the hydrogen permeable membrane 2, that is, the hydrogen recombination catalyst layer 3 in contact with the outer surface of the hydrogen permeable membrane 2. .

  Air supplied through an air supply pipe into a vessel arranged in the reactor building and containing the hydrogen treatment unit 11 </ b> A is particulated in the hydrogen recombination catalyst layer 3 from the outer surface of the hydrogen recombination catalyst layer 3. It flows between the hydrogen recombination catalysts. The hydrogen gas that has reached the hydrogen recombination catalyst layer 3 is recombined by the action of the hydrogen recombination catalyst of the hydrogen recombination catalyst layer 3 and oxygen contained in the air flowing into the hydrogen recombination catalyst layer 3 into water vapor. Become. This water vapor is discharged to the external environment through a vapor discharge pipe connected to a container housing the hydrogen treatment unit 11A. The remaining gas that has not permeated the hydrogen permeable membrane 2 in the hydrogen treatment unit 11A, that is, the fission product gas and the nitrogen gas, is discharged from the passage 10A to the off-gas transfer pipe 9, and the dry well in the reactor containment vessel 5 is discharged. Returned to

  The recombination reaction between hydrogen gas and oxygen generated in the hydrogen recombination catalyst layer 3 is an exothermic reaction, and the heat generated by the reaction warms the hydrogen permeable membrane 2 which is a metal film. Transmission performance is improved. Since the hydrogen treatment unit 11A is heated by the heater, the water vapor generated in the hydrogen recombination catalyst layer 3 is prevented from being condensed in the hydrogen treatment unit 11A.

  The hydrogen recombination catalyst layer 3 is in contact with the downstream surface of the hydrogen permeable membrane 2, that is, the outer surface of the hydrogen permeable membrane 2, and the iodine treatment catalyst tower 1A communicates with the hydrogen permeable membrane 2 through the gas supply pipe 12. The example can obtain each effect produced in Example 1 except the effect that the leakage of hydrogen gas from between the iodine treatment catalyst layer 1 and the hydrogen permeable membrane 2 can be prevented.

  In the present embodiment, the hydrogen permeable membrane 2 and the hydrogen recombination catalyst layer 3 are formed in a cylindrical shape, and the hydrogen permeable membrane 2 is disposed inside the hydrogen recombination catalyst layer 3, so that the inner side of the cylindrical hydrogen permeable membrane 2 is arranged. It can be used as a passage 10A through which hydrogen gas is circulated, and a simple operation method of supplying hydrogen gas into the passage 10A through the gas supply pipe 13 can be realized.

  Also in this example, as a hydrogen recombination catalyst for filling the hydrogen recombination catalyst layer 3, cerium oxide or a mixed oxide of cerium oxide and zirconium oxide was used as a carrier, and palladium (or platinum) was attached to the surface of the carrier. A catalyst may be used.

  Each of the hydrogen treatment systems of Embodiments 1 and 2 may be applied to the treatment of hydrogen gas in a reactor containment vessel in a pressurized water nuclear plant.

  DESCRIPTION OF SYMBOLS 1 ... Iodine treatment catalyst layer, 1A ... Iodine treatment catalyst tower, 2 ... Hydrogen permeable membrane, 3 ... Hydrogen recombination catalyst layer, 5 ... Reactor containment vessel, 6 ... Reactor pressure vessel, 7, 7A ... Hydrogen treatment system, 8 ... oxygen supply pipe, 9 ... off-gas transfer pipe, 10, 10A ... passage, 11, 11A ... hydrogen treatment section, 13 ... gas supply pipe.

Claims (11)

  A hydrogen permeable membrane that separates and permeates hydrogen gas from the gas in the reactor containment vessel, and the hydrogen gas and oxygen gas that are disposed in contact with the downstream surface of the hydrogen permeable membrane and pass through the hydrogen permeable membrane A hydrogen recombination catalyst layer that recombines the hydrogen recombination catalyst layer, wherein the hydrogen recombination catalyst layer is in contact with a region containing oxygen at a surface other than the surface in contact with the hydrogen permeable membrane. Plant hydrogen treatment system.   2. The hydrogen treatment system for a nuclear power plant according to claim 1, wherein an iodine treatment catalyst layer for removing iodine contained in the gas in the reactor containment vessel is disposed in contact with an upstream surface of the hydrogen permeable membrane.   3. The hydrogen treatment system for a nuclear power plant according to claim 1, wherein an oxygen supply device that supplies the oxygen gas communicates with a region containing oxygen. 4.   A cylindrical hydrogen permeable membrane that separates and permeates hydrogen gas from the gas in the reactor containment vessel, and an outer surface that is surrounded by the hydrogen permeable membrane and is in contact with an inner surface that is located downstream of the hydrogen permeable membrane. A cylindrical hydrogen recombination catalyst layer that recombines the hydrogen gas and oxygen gas that permeate the hydrogen permeable membrane, and an oxygen supply that supplies the oxygen gas to an internal space surrounded by the hydrogen recombination catalyst layer And a hydrogen treatment system for a nuclear power plant.   The hydrogen permeable membrane and the hydrogen recombination catalyst layer are disposed in the nuclear reactor containment vessel, the oxygen supply device is provided through the nuclear reactor containment vessel, and a gas exhaust pipe connected to the internal space is provided. The hydrogen treatment system for a nuclear power plant according to claim 4, which penetrates the reactor containment vessel.   A cylindrical iodine treatment catalyst layer for removing iodine contained in the gas in the nuclear reactor containment vessel is disposed so as to surround the hydrogen permeable membrane in the nuclear reactor containment vessel, and an inner surface of the iodine treatment catalyst layer is arranged. The hydrogen treatment system for a nuclear power plant according to claim 4 or 5, wherein the hydrogen treatment system is in contact with an outer surface located upstream of the hydrogen permeable membrane.   A cylindrical hydrogen permeable membrane that separates and permeates hydrogen gas from the gas in the reactor containment vessel, and an inner surface that surrounds the hydrogen permeable membrane and is in contact with an outer surface located downstream of the hydrogen permeable membrane. A cylindrical hydrogen recombination catalyst layer for recombining the hydrogen gas and oxygen gas that permeate the hydrogen permeable membrane, wherein an outer surface of the hydrogen recombination catalyst layer is in contact with a region containing oxygen. A hydrogen treatment system for nuclear power plants. The hydrogen permeable membrane and the hydrogen recombination catalyst layer are disposed outside the reactor containment vessel, and a gas supply pipe connected to the reactor containment vessel and guiding the gas in the reactor containment vessel is provided with the hydrogen Connected to the internal space surrounded by the permeable membrane,
The hydrogen treatment system for a nuclear power plant according to claim 7, wherein a gas transfer pipe connected to the internal space is connected to the reactor containment vessel.   The hydrogen treatment system for a nuclear power plant according to claim 8, wherein an iodine treatment catalyst device for removing iodine contained in the gas in the reactor containment vessel is provided in the gas supply pipe.   The hydrogen treatment system for a nuclear power plant according to claim 8 or 9, wherein a dehumidifying device is provided in the gas supply pipe.   2. The hydrogen recombination catalyst filled in the hydrogen recombination catalyst layer is a catalyst in which palladium is impregnated on a support made of cerium oxide and a mixed oxide of cerium oxide and zirconium oxide. 11. A hydrogen treatment system for a nuclear power plant according to any one of items 1 to 10.

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