JP2017161379A - Hydrogen sensor system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen sensor system in which a hydrogen sensor is protected from environment in a case of an accident and effect of iodine in catalytic reaction of noble metal or hydrogen storage reaction of noble metal is eliminated.SOLUTION: A hydrogen sensor system 11 includes: a hydrogen sensor 111 including noble metal; a housing 112 which surrounds the hydrogen sensor 111 and in which an opening B is disposed in a part of the housing; and an iodine removal part 113 for removing iodine in gas.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to a hydrogen sensor system.

  In severe nuclear reactor accidents, hydrogen is generated by the reaction between water and high-temperature zirconium. In an environment where oxygen is present, hydrogen reacts explosively when there is an ignition source or when the temperature is high enough to autoignite. There is a concern that the explosion may damage equipment related to safety, including reactor pressure vessels and containment vessels.

  In order to measure hydrogen during severe accidents, a method of installing a hydrogen sensor in a building such as a nuclear power plant is conceivable. As a conventional hydrogen sensor, there is a thermoelectric conversion type sensor that measures a temperature change caused by an exothermic reaction using a noble metal catalyst (Pt, Pd, etc.) that promotes combustion of hydrogen and oxygen (for example, Patent Documents). 1, 2). Further, as a conventional hydrogen sensor, there is a sensor that absorbs hydrogen in a noble metal wire (Pd-Ag or the like) as a hydrogen storage alloy and measures the amount of change in resistance value (for example, Patent Document 3).

Japanese Patent No. 4430844 Japanese Patent No. 3226923 JP-B-2-24460

  Even if you try to install a conventional hydrogen sensor in a building such as a nuclear power plant, the hydrogen sensor may be affected by the airflow during a severe accident, or the hydrogen sensor may be damaged by falling objects during a severe accident. There is a risk of it.

  Moreover, since the surface of the hydrogen sensor containing a noble metal is easily covered with iodine generated in a severe accident, there is a problem that the above-described catalytic reaction and hydrogen storage reaction are easily hindered.

  The hydrogen sensor system according to the present embodiment includes a hydrogen sensor containing a noble metal, a casing that surrounds the hydrogen sensor and is provided with an opening in part, and an iodine removal unit that removes iodine in the gas. .

  According to the hydrogen sensor system according to the present embodiment, the hydrogen sensor can be protected from the environment at the time of an accident, and the influence of iodine in the noble metal catalytic reaction and hydrogen storage reaction can be removed.

Schematic which shows the environment where a hydrogen concentration measuring apparatus is installed. The figure which shows the structural example of a hydrogen sensor system. The external view which shows the structure of a hydrogen sensor. (A), (B) is a figure which shows the 1st example of the arrangement | positioning method of the sintered metal (or stainless steel lump) to an opening part. The figure which shows the 2nd example of the arrangement | positioning method of the sintered metal (or stainless steel lump) to an opening part. The figure which shows the relationship between the thickness of an iodine removal part, and iodine concentration. The figure which shows the 1st modification of a structure of a hydrogen sensor system. The figure which shows the 2nd modification of a structure of a hydrogen sensor system. The figure which shows arrangement | positioning of a hydrogen sensor and an iodine removal part. The figure which shows the 3rd modification of a structure of a hydrogen sensor system.

  The hydrogen sensor system according to the present embodiment will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing an environment in which a hydrogen concentration measuring apparatus is installed.

  FIG. 1 shows a place where hydrogen concentration is measured (monitored), for example, a reactor containment vessel 1 in a nuclear power plant, and a hydrogen concentration measuring device 10 that measures the hydrogen concentration in the reactor containment vessel 1. The main purpose of hydrogen concentration measurement is to respond to severe accidents at nuclear power plants.

  The reactor containment vessel 1 stores all the facilities of a nuclear reactor (not shown) and a primary cooling system (not shown). When an accident such as a pipe break occurs, the reactor containment vessel 1 automatically closes a pipe (not shown) that penetrates the reactor containment vessel 1.

  The hydrogen concentration measuring apparatus 10 includes a hydrogen sensor system 11, a resistor (tester) 12, and a control unit 13 according to this embodiment. The configuration of the hydrogen sensor system 11 will be described later with reference to FIG.

  The resistor 12 measures the electrical resistance value of the noble metal wire by passing a current through the noble metal wire 31 (shown in FIG. 3) of the hydrogen sensor system 11. As the resistor 12, a known one is applied. However, when a resistance measuring method other than the four-terminal method (for example, the two-terminal method, Wheatstone bridge) is adopted as the resistor 12, each measuring method is used. The one suitable for is applied.

  The control unit 13 includes a CPU (Central Processing Unit), a memory, and the like. The control unit 13 calculates the hydrogen concentration based on the electrical resistance value measured by the resistor 12. For example, the control unit 13 calculates the hydrogen concentration corresponding to the electrical resistance value measured by the resistor 12 based on the correlation equation between the hydrogen concentration and the electrical resistance value acquired in advance.

  FIG. 2 is a diagram illustrating a configuration example of the hydrogen sensor system 11.

  As shown in FIG. 2, the hydrogen sensor system 11 includes a hydrogen sensor 111, a housing 112 that surrounds the hydrogen sensor 111 and is provided with one or more openings B, and an iodine removal unit 113 that removes iodine in the gas. And comprising. In FIG. 2, the iodine removing unit 113 is disposed in the opening B of the housing 112. In the present embodiment, a case where the housing 112 of the hydrogen sensor system 11 is provided with one opening B will be described.

  The hydrogen sensor system 11 operates not only during steady operation of the nuclear reactor but also during severe accidents. The gas G outside the housing 112 reaches the hydrogen sensor 111 via the iodine removing unit 113 disposed in the opening B. The gas G outside the housing 112 passes through the opening B. For this reason, when the iodine removal part 113 is arrange | positioned in the opening part B, the contact probability with the gas G containing iodine which generate | occur | produces at the time of a severe accident, and the iodine removal part 113 becomes large, and gas G with a small amount of iodine removal part 113 It becomes possible to adsorb the iodine contained in.

  FIG. 3 is an external view showing the structure of the hydrogen sensor 111.

  As shown in FIG. 3, the hydrogen sensor 111 includes a noble metal wire 31, a fixing portion 32, and a connecting portion 33.

  The noble metal wire 31 is arranged so as to be spirally wound on the outer surface of the fixing portion 32. The noble metal wire 31 is made of a hydrogen storage alloy (Pd—Ag or the like) having a hydrogen storage ability that changes its electrical resistance value due to hydrogen storage.

  The fixing portion 32 is made of an insulating material such as ceramics or glass, and is used for fixing and insulating the noble metal wire 31. Although FIG. 3 illustrates the case where the fixing portion 32 has a cylindrical shape, the fixing portion 32 does not necessarily have a cylindrical shape. That is, it is not necessary for the entire fixing portion 32 to be made of the same material. When the fixing | fixed part 32 has a cylindrical shape, the fixing | fixed part 32 can take the structure which encloses a heater in the internal space. Moreover, when the fixing | fixed part 32 has a cylindrical shape, the fixing | fixed part 32 can take the structure which encloses an electrical wiring in the interior space.

  The connection portion 33 fixes the noble metal wire 31 to the fixing portion 32 and functions as a terminal for measuring the electric resistance value of the noble metal wire 31. 3 shows an example in which the connection portion 33 is installed on the outer surface of the side surface of the fixed portion 32, but the connection portion 33 may be installed on the inner surface of the side surface of the fixed portion 32.

  Returning to the description of FIG. 2, the housing 112 surrounds the hydrogen sensor 111. The material of the housing 112 is preferably stainless steel. The housing 112 prevents the hydrogen sensor 111 from being affected by the airflow at the time of a severe accident, and protects the hydrogen sensor 111 from falling objects at the time of a severe accident.

  Moreover, it is considered that a lot of hydrogen and a slight amount of oxygen exist in the gas at the time of a severe accident. If the entire periphery of the hydrogen sensor 111 is surrounded, the gas G cannot be exchanged between the outside and the inside of the housing 112, so that an opening B for diffusing the gas G is formed in a part of the housing 112. Provided.

  The iodine removing unit 113 is provided in the opening B of the housing 112. Here, a material suitable as the iodine removing unit 113 will be described.

It is known that stainless steel is corroded by iodine (Evaluation of inner surface corrosion behavior of ferritic stainless steel, March 1987). Iodine causes the following reaction on the surface of the stainless steel to corrode the stainless steel. That is, iodine is trapped on the surface of the stainless steel and reacts with metal atoms to become stable. For this reason, stainless steel is an excellent capturing material for iodine contained in the gas G.
M (s) + I ₂ (g) → MI ₂ (s)
M (s) + 2I (g) → MI ₂ (s)

  When the material of the iodine removing unit 113 is stainless steel, the iodine removing unit 113 is a sintered metal of stainless steel obtained by baking and hardening stainless steel powder at a temperature around the melting point. In the case of sintered metal, the size of the voids in the element can be adjusted by the size of the powder.

  Or when the material of the iodine removal part 113 is stainless steel, the iodine removal part 113 is the stainless steel lump formed with the wrinkle curled by rolling a stainless steel wire. When the iodine removing unit 113 is a sintered metal or stainless steel lump, the hydrogen sensor system 11 holds the sintered metal or stainless steel lump and holds the holding plate S1 (for fixing itself to the opening B of the housing 112 ( 4 (A), (B)) or holding container S2 (shown in FIG. 5).

  Or when the material of the iodine removal part 113 is stainless steel, it is one stainless steel wire mesh (stainless steel plain weave wire mesh or stainless twill wire mesh). Alternatively, the iodine removal unit 113 is a plurality of stainless wire meshes stacked in the normal direction of the stainless wire mesh surface. In the latter case, the iodine removing unit 113 may be a plurality of stainless wire meshes in which the positions of the openings of adjacent stainless steel wire meshes are shifted. The opening is a space between the lines constituting the stainless wire mesh.

  4A and 4B are diagrams illustrating a first example of a method for arranging a sintered metal (or stainless steel lump) in the opening B. FIG.

  FIG. 4A shows a holding plate S <b> 1 for disposing the sintered metal in the opening B of the housing 112. The holding plate S1 has a mesh-shaped portion having an opening through which gas can enter and exit. The sizes (dimensions) of the plurality of openings may be unified or may not be unified. The holding plate S1 is fixed to the inner wall of the housing 112 by screwing (FIG. 4B). Alternatively, the holding plate S1 is fixed to the inner wall of the housing 112 by adhesion or welding. In the opening B shown in FIG. 4B, a space in which the sintered metal can be arranged is formed in the upper part of the holding plate S1 fixed to the inner wall of the housing 112.

  The net of the holding plate S1 can be a stainless steel wire that serves as an iodine capturing material.

  FIG. 5 is a diagram illustrating a second example of a method for arranging the sintered metal (or stainless steel lump) in the opening B. FIG.

  FIG. 5 shows a holding container S <b> 2 for arranging the sintered metal in the opening B of the housing 112. The holding container S2 includes a bottom surface having a mesh-shaped portion having an opening through which gas can enter and exit, and forms a space in which a sintered metal can be placed. The sizes of the plurality of openings may be unified or may not be unified. The holding container S2 is fixed to the outer wall of the housing 112 by screwing. Alternatively, the holding container S2 is fixed to the inner wall of the housing 112 by adhesion or welding. A space in which the sintered metal can be placed is formed inside the holding container S2 fixed to the outer wall of the housing 112.

  In addition, the net | network of the bottom face of holding | maintenance container S2 can also be made into the stainless steel wire used as the iodine capture | acquisition material.

  Returning to the explanation of FIG. 2, zeolite and activated carbon are known as materials having a large surface area and adsorbing various materials. Therefore, zeolite or activated carbon can be used as an adsorbent for iodine contained in the gas G. When the material of the iodine removing unit 113 is zeolite or activated carbon, the hydrogen sensor system 11 holds the zeolite or activated carbon, and holds the body (FIG. 4A), The holding plate S1 shown in (B) or the holding container S2 shown in FIG. 5 is included.

Thirdly, in silver zeolite, H ⁺ and Ag ^{+ in the} vicinity of Al atoms of the zeolite are ion-exchanged, and Ag ⁺ is attached in the vicinity of Al atoms by ionic bonds. Since silver and iodine can easily cause the following reaction, silver zeolite can capture iodine contained in the gas G firmly.
2Ag (s) + I ₂ (g) → 2AgI
Ag (s) + I (g) → AgI

  When the material of the iodine removal part 113 is silver zeolite, the hydrogen sensor system 11 holds the silver zeolite, and holds the body for fixing it to the opening B of the housing 112 (FIGS. 4A and 4B). The holding plate S1 shown in FIG. 5 or the holding container S2) shown in FIG.

  In addition, the material of the iodine removal part 113 should just be comprised by at least 1 among the stainless steel, zeolite, activated carbon, and silver zeolite which were mentioned above.

  Then, the thickness of the iodine removal part 113 is demonstrated.

  The gas G containing iodine enters the inside of the housing 112 through the opening B of the housing 112. When the iodine removing unit 113 is disposed in the opening B, iodine contained in the gas G is gradually adsorbed to the iodine removing unit 113 according to the approach distance (thickness) to the iodine removing unit 113, so the iodine concentration is The distribution is as shown in FIG. 6 in relation to the thickness.

  FIG. 6 is a diagram showing the relationship between the thickness of the iodine removing unit 113 and the iodine concentration.

As shown in FIG. 6, the iodine concentration in the thickness of the iodine removing unit 113 is C, the iodine concentration contained in the gas is C0, the adsorption coefficient is a, and the thickness (distance from the outer wall of the iodine removing unit 113). Is x, the iodine concentration C is expressed by the following equation.
C = C0 exp (-ax)

Among stainless steel, zeolite, activated carbon, and silver zeolite, the adsorption coefficient a of stainless steel is the smallest, and the porosity is about 0.3 and is 2 [cm ⁻¹ ] or more. Therefore, when the adsorption coefficient a of stainless steel is 2 [cm ⁻¹ ], the iodine concentration C is 0.022 C0 when the thickness x is 1.9 [cm], and the thickness is 2.0. When it is [cm], it becomes 0.018 C0. That is, when the material of the iodine removing unit 113 is stainless steel, if the thickness x of the stainless steel is 2 [cm] or more, the iodine concentration C reaching the hydrogen sensor 111 is set to 2% outside the housing 112. The following can be reduced. Even considering the iodine concentration based on the most severe scenario expected at the time of a severe accident, it is sufficient if the iodine concentration C reaching the hydrogen sensor 111 can be reduced to 2% or less. The upper limit of the thickness x of the stainless steel may be appropriately determined from the target response time of the hydrogen sensor 111 (Response time).

  When the thickness x of the iodine removing unit 113 is 2 [cm], the thickness of the upper wall of the housing in FIG. 4B may be 2 [cm] or more. When the thickness x of the iodine removing unit 113 is set to 2 [cm], the depth of the holding container S2 may be set to 2 [cm] or more in FIG.

  In addition, although iodine will be adsorbed by the stainless steel as the iodine removal part 113 at the time of a severe accident, stainless steel cannot be exchanged for about two weeks after the occurrence of a severe accident. However, even when considering the iodine amount based on the most severe scenario expected at the time of a severe accident, if the thickness x of the stainless steel as the iodine removal unit 113 is 2 [cm] or more, the iodine removal unit 113 is sufficient. Can continue to adsorb iodine.

  In addition, the system which occludes hydrogen with the noble metal wire of the hydrogen sensor 111 was demonstrated. However, the technical idea of the present embodiment is not limited to a system that stores hydrogen by a noble metal wire. The technical idea of the present embodiment can be applied to the hydrogen sensor 111 including a noble metal. For example, the technical idea of this embodiment can be applied to a thermoelectric conversion system that measures a temperature change caused by an exothermic reaction using a noble metal catalyst (Pt, Pd, etc.) that promotes combustion of hydrogen and oxygen. is there.

  According to the hydrogen sensor system 11, the iodine contained in the gas is brought into contact with the iodine removing unit 113 to remove iodine from the gas that reaches the hydrogen sensor 111, so that iodine in the gas reaches the surface of the hydrogen sensor 111. There is almost nothing, and the oxygen-hydrogen reaction which is the surface reaction of the noble metal of the hydrogen sensor 111 and the hydrogen occlusion reaction of the noble metal are not inhibited. Therefore, according to the hydrogen sensor system 11, it is possible to remove the influence of iodine in the catalytic reaction of noble metals and the hydrogen storage reaction. Further, according to the hydrogen sensor system 11, the housing 112 can protect the hydrogen sensor from the environment at the time of the accident.

(First modification)
FIG. 7 is a diagram illustrating a first modification of the configuration of the hydrogen sensor system 11.

  As shown in FIG. 7, the hydrogen sensor system 11 includes a hydrogen sensor 111, a housing 112, an iodine removing unit 113, and iodine removing units 114 and 115 disposed inside the housing 112. The iodine removing unit 113 is not an essential configuration. Any one of the iodine removing units 114 and 115 may be provided. Hereinafter, the case where all the iodine removal parts 113-115 are provided is demonstrated.

  The iodine removing unit 114 is installed on the inner wall of the housing 112, and the iodine removing unit 115 is installed on the inner upper wall of the housing 112. The gas G outside the housing 112 reaches the hydrogen sensor 111 via the iodine removing unit 113 disposed in the opening B.

  In FIG. 7, the same components as those shown in FIG.

  If iodine contained in the gas G that has entered the housing 112 does not adhere to the hydrogen sensor 111, the function of the hydrogen sensor 111 is not impaired. Therefore, as shown in FIG. 7, iodine removing units 114 and 115 are disposed in the vicinity of the hydrogen sensor 111. As a result, part of the iodine that has entered the housing 112 is removed by the iodine removing units 114 and 115, so that iodine hardly adheres to the surface of the hydrogen sensor 111.

  According to the first modification of the hydrogen sensor system 11, the provision of the iodine removal units 114 and 115 in addition to the iodine removal unit 113 allows the catalytic reaction of the noble metal to be performed more sufficiently than in the case of the hydrogen sensor system 11 shown in FIG. The influence of iodine in the hydrogen storage reaction can be removed.

(Second modification)
FIG. 8 is a diagram illustrating a second modification of the configuration of the hydrogen sensor system 11.

  As shown in FIG. 8, the hydrogen sensor system 11 includes a hydrogen sensor 111, a housing 112, an iodine removing unit 113, and an iodine removing unit 116 disposed inside the housing 112. The iodine removing unit 113 is not an essential configuration. Hereinafter, the case where all the iodine removal parts 113 and 116 are provided is demonstrated.

  The iodine removing unit 116 is provided on the outer periphery of the hydrogen sensor 111 in a non-contact manner with the hydrogen sensor 111. The gas G outside the housing 112 reaches the hydrogen sensor 111 via the iodine removing unit 113 disposed in the opening B.

  In FIG. 8, the same components as those shown in FIG.

  FIG. 9 is a diagram showing the arrangement of the hydrogen sensor 111 and the iodine removing unit 116.

  As shown in FIG. 9, the iodine removing unit 116 is held by the holding container S <b> 3 on the outer periphery of the hydrogen sensor 111. The holding container S3 has a mesh-shaped outer side surface and inner side surface having an opening that allows gas to enter and exit. The sizes of the plurality of openings may be unified or may not be unified. The iodine removing unit 116 is sandwiched between the outer side surface and the inner side surface of the holding container S3. The hydrogen sensor 111 and the iodine removing unit 116 are supported by the housing 112 (shown in FIG. 8) by a support unit (not shown) so as not to contact each other. The net of the holding container S3 may be a stainless wire that serves as an iodine capturing material.

  Note that the iodine removing unit 116 may have a plate shape, and may be provided on the upper side or the lower side of the hydrogen sensor 111 in a non-contact manner with the hydrogen sensor 111.

  Returning to the description of FIG. 8, the iodine contained in the gas G that has entered the housing 112 does not interfere with the function of the hydrogen sensor 111 unless it adheres to the hydrogen sensor 111. Therefore, as shown in FIG. 8, an iodine removing unit 116 is disposed on the outer periphery of the hydrogen sensor 111 in a non-contact manner with the hydrogen sensor 111. Thereby, part of the iodine that has entered the housing 112 is removed by the iodine removing unit 116, so that iodine hardly adheres to the surface of the hydrogen sensor 111.

  The hydrogen sensor system 11 shown in FIG. 8 may include iodine removing units 114 and 115 shown in FIG. 7 in addition to the iodine removing units 113 and 116.

  According to the second modification of the hydrogen sensor system 11, by providing the iodine removal unit 116 in addition to the iodine removal unit 113, the catalytic reaction of the noble metal and the hydrogen occlusion are more sufficiently than in the case of the hydrogen sensor system 11 shown in FIG. The influence of iodine in the reaction can be removed.

(Third Modification)
FIG. 10 is a diagram illustrating a third modification of the configuration of the hydrogen sensor system 11.

  As shown in FIG. 10, the hydrogen sensor system 11 includes a hydrogen sensor 111, a housing 112, an iodine removing unit 113, and a heater 117 disposed inside the housing 112. The iodine removing unit 113 is not an essential configuration. Hereinafter, the case where the iodine removal part 113 and the heater 117 are provided is demonstrated.

  The heater 117 is provided in the vicinity of the hydrogen sensor 111, for example, below the hydrogen sensor 111 so as not to contact the hydrogen sensor 111. The gas G outside the housing 112 reaches the hydrogen sensor 111 via the iodine removing unit 113 disposed in the opening B.

  Iodine evaporates at high temperatures. Therefore, in order to remove iodine adhering to the surface (noble metal surface) of the hydrogen sensor 111, it is effective to make the surface of the hydrogen sensor 111 high temperature. Therefore, the heater 117 is disposed in the vicinity of the hydrogen sensor 111. The hydrogen sensor 111 is supported by the housing 112 by a support portion (not shown) so as not to contact the heater 117. Single iodine evaporates at 184.3 ° C. However, on the surface of the noble metal, the noble metal atom and the iodine atom are bonded by a weak covalent bond. Therefore, in order to remove iodine from the surface of the noble metal, it is necessary to apply a temperature exceeding the barrier to the surface of the noble metal.

  Therefore, the heater 117 is controlled by the control unit 13 (shown in FIG. 1) so that the temperature of the surface of the hydrogen sensor 111 is 300 ° C. or higher, more preferably 500 ° C. or higher. The heater 117 may be provided inside the cylindrical fixing portion 32 (shown in FIG. 3), or may be provided around the hydrogen sensor 111 so as not to contact the hydrogen sensor 111. The heater 117 may be provided on the upper side of the hydrogen sensor 111 so as not to contact the hydrogen sensor 111.

  The heater 117 is controlled by the control unit 13 (illustrated in FIG. 1) so that the temperature of the surface of the hydrogen sensor 111 becomes a predetermined value (less than 500 ° C.), and the measured hydrogen concentration becomes a scenario. The temperature of the surface of the hydrogen sensor 111 may be controlled to be 500 ° C. or higher when it is significantly lower than the predicted value based on it. In that case, the control unit 13 may notify the operator that the measured hydrogen concentration is affected by iodine.

  The hydrogen sensor system 11 illustrated in FIG. 10 may include the iodine removing units 114 and 115 illustrated in FIG. 7 and the iodine removing unit 116 illustrated in FIG. 8 in addition to the iodine removing unit 113.

  According to the third modification of the hydrogen sensor system 11, the heater 117 is provided in addition to the iodine removing unit 113, so that the catalytic reaction or hydrogen occlusion reaction of the noble metal is sufficiently performed as compared with the case of the hydrogen sensor system 11 shown in FIG. 2. The influence of iodine can be removed.

  According to the hydrogen sensor system according to at least one embodiment and its modification described above, the hydrogen sensor can be protected from the environment at the time of the accident, and the influence of iodine in the catalytic reaction or hydrogen storage reaction of the noble metal can be removed.

  Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof. For example, the hydrogen sensor of the embodiment can be installed in any nuclear facility of a BWR plant and a PWR plant. In addition, the hydrogen sensor of the embodiment can be installed in any facility other than a nuclear facility as long as it detects hydrogen and requires measurement.

DESCRIPTION OF SYMBOLS 11 ... Hydrogen sensor system, 111 ... Hydrogen sensor, 112 ... Housing | casing, 113-116 ... Iodine removal part, 117 ... Heater.

Claims (6)

A hydrogen sensor containing precious metals;
A housing surrounding the hydrogen sensor and provided with an opening in part;
An iodine removal unit for removing iodine in the gas;
Hydrogen sensor system with   2. The hydrogen sensor system according to claim 1, wherein a material of the iodine removing unit is configured by at least one of stainless steel, zeolite, activated carbon, and silver zeolite.   The hydrogen sensor system according to claim 1, wherein the iodine removing unit is disposed in the opening.   The hydrogen sensor system according to claim 1, wherein the iodine removing unit is installed on an inner wall of the casing.   The hydrogen sensor system according to any one of claims 1 to 4, wherein the iodine removing unit is disposed on an outer periphery of the hydrogen sensor in the housing.   The hydrogen sensor system according to any one of claims 1 to 5, further comprising a heater in the housing.

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