JP5358554B2 - Corrosion potential sensor and corrosion potential sensor installation structure - Google Patents

Corrosion potential sensor and corrosion potential sensor installation structure Download PDF

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JP5358554B2
JP5358554B2 JP2010282656A JP2010282656A JP5358554B2 JP 5358554 B2 JP5358554 B2 JP 5358554B2 JP 2010282656 A JP2010282656 A JP 2010282656A JP 2010282656 A JP2010282656 A JP 2010282656A JP 5358554 B2 JP5358554 B2 JP 5358554B2
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corrosion potential
electrode
casing
potential sensor
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JP2012132696A (en
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正彦 橘
陽一 和田
信之 太田
一成 石田
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Hitachi GE Nuclear Energy Ltd
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本発明は、腐食電位センサに及び腐食電位センサの設置構造に係り、特に、原子炉の冷却水が表面に接触する、炭素鋼、鉄基合金あるいはニッケル基合金等で作られた構造部材の腐食電位を測定するのに好適な腐食電位センサ及び腐食電位センサの設置構造に関する。   The present invention relates to a corrosion potential sensor and an installation structure of the corrosion potential sensor, and in particular, corrosion of structural members made of carbon steel, iron-base alloy, nickel-base alloy, or the like, in which the reactor coolant is in contact with the surface. The present invention relates to a corrosion potential sensor suitable for measuring a potential and an installation structure of the corrosion potential sensor.

原子力プラントの機器及び配管を構成する、ステンレス鋼またはニッケル基合金製の構造部材は、特定の条件の下で、応力腐食割れ(SCC)の感受性を示す。そこで、原子力プラントの健全性を維持するために、その構造部材に対してSCCの防止策が適用される。近年では、原子力プラントの設備利用率の向上及び長寿命化のような経済性向上の観点からも、SCCの予防策が原子力プラントに適用されている。   Structural members made of stainless steel or nickel-base alloys that make up nuclear plant equipment and piping exhibit stress corrosion cracking (SCC) susceptibility under certain conditions. Therefore, in order to maintain the soundness of the nuclear power plant, SCC prevention measures are applied to the structural members. In recent years, preventive measures for SCC have been applied to nuclear power plants from the viewpoint of improving the utilization factor of nuclear power plants and improving the economic efficiency such as extending the life.

SCC防止策として、材料の耐食性向上、応力改善、あるいは腐食環境の緩和を目的とした技術が適用される。沸騰水型原子炉(BWR)では、構造部材の表面に接触する原子炉冷却水(炉水)の腐食環境の改善に基づくSCC対策の一つとして、水素注入が国内外で広く行われている。この水素注入の例が、例えば、特許第2687780号公報に記載されている。炉水中には、原子炉圧力容器内(炉内)で水の放射線分解により生成し、腐食の原因となる酸素や過酸化水素が存在し、これらが腐食環境を形成している。水素注入では、給水系を通じて炉水に水素を添加し、酸素や過酸化水素と反応させて水に還元する。この結果、炉水の酸素濃度及び過酸化水素濃度が低下し、構造部材の腐食電位(ECP)が低下するために、構造部材におけるSCCの発生及びSCCの進展速度が緩和される。   As an SCC prevention measure, a technique for improving the corrosion resistance of the material, improving the stress, or relaxing the corrosive environment is applied. In boiling water reactors (BWR), hydrogen injection is widely performed at home and abroad as one of the SCC measures based on the improvement of the corrosive environment of reactor cooling water (reactor water) that contacts the surface of structural members. . An example of this hydrogen injection is described in, for example, Japanese Patent No. 2687780. In the reactor water, there are oxygen and hydrogen peroxide that are generated by radiolysis of water in the reactor pressure vessel (inside the reactor) and cause corrosion, and these form a corrosive environment. In hydrogen injection, hydrogen is added to the reactor water through a water supply system, and reacted with oxygen and hydrogen peroxide to be reduced to water. As a result, the oxygen concentration and the hydrogen peroxide concentration in the reactor water are lowered, and the corrosion potential (ECP) of the structural member is lowered. Therefore, the occurrence of SCC and the SCC progress rate in the structural member are alleviated.

さらに、水素注入時において構造部材の腐食電位の低下を促進させる技術として、例えば、特開平4−223299号公報に記載された貴金属注入の技術が知られている。この技術は、白金族貴金属元素を炉水に注入し、白金族貴金属元素が有する水素の電気化学反応への触媒作用を利用して、水素注入時において構造部材の腐食電位をより大きく低下させる。   Further, as a technique for accelerating the decrease in the corrosion potential of the structural member during hydrogen injection, for example, a noble metal injection technique described in JP-A-4-223299 is known. This technique injects a platinum group noble metal element into the reactor water and utilizes the catalytic action of the platinum group noble metal element on the electrochemical reaction of hydrogen to significantly lower the corrosion potential of the structural member at the time of hydrogen injection.

これらの腐食環境緩和技術では、構造部材の腐食電位を精度良く知る必要がある。そこで、原子炉内あるいは配管に腐食電位センサを設置し、構造部材の腐食電位を測定することが行われている。腐食電位センサは、使用条件下で、腐食電位測定の基準となる一定の電位(基準電位)を発生する。このため、腐食電位センサは、基準電極、参照電極あるいは照合電極とも呼ばれている。構造部材が、炉水の温度、酸素濃度、過酸化水素濃度及び流速の条件の下で有する電位と、腐食電位センサの有する基準電位との電位差を、電位差計を用いて測定することにより、構造材料の腐食電位を知ることができる。   In these corrosion environment mitigation techniques, it is necessary to accurately know the corrosion potential of the structural member. Therefore, a corrosion potential sensor is installed in the reactor or in the piping to measure the corrosion potential of the structural member. The corrosion potential sensor generates a constant potential (reference potential) that serves as a reference for measuring the corrosion potential under the use conditions. For this reason, the corrosion potential sensor is also called a reference electrode, a reference electrode, or a verification electrode. By measuring the potential difference between the potential of the structural member under the conditions of the temperature, oxygen concentration, hydrogen peroxide concentration and flow rate of the reactor water and the reference potential of the corrosion potential sensor using a potentiometer, It is possible to know the corrosion potential of the material.

腐食電位は、通常、どのような基準電極を基準にして得た値かを示して表示する。基準として標準水素電極電位が広く用いられ、各温度における水素の酸化還元反応を0Vとして基準としていることを意味するvs.SHE(versus Standard Hydrogen Electrode)を、電位差の単位であるVの直後に付し、Vvs.SHEのように表記する。腐食電位(ECP)を精度良く測定するためには、腐食電位センサの設置が不可欠であり、腐食電位センサは原子炉の運転条件で使用可能であることが求められる。   The corrosion potential is usually displayed by indicating what kind of reference electrode is used as a reference. A standard hydrogen electrode potential is widely used as a reference, which means that the redox reaction of hydrogen at each temperature is set to 0 V as a reference. SHE (versus Standard Hydrogen Electrode) is attached immediately after V which is a unit of potential difference, and Vvs. It is expressed as SHE. In order to accurately measure the corrosion potential (ECP), the installation of a corrosion potential sensor is indispensable, and the corrosion potential sensor is required to be usable under the operating conditions of the reactor.

腐食電位センサの従来技術が、Proceedings of International Symposium on Plant Aging and Life Prediction of Corrodible Structures, May 15-18, 1995, Sapporo Japan, p413 JSCE-NACE (1995)に記載されているほか、特開2000−65785号公報、特開2000−146891号公報及び特開2009−42111号公報にも記載されている。   The conventional technology of the corrosion potential sensor is described in Proceedings of International Symposium on Plant Aging and Life Prediction of Corrodible Structures, May 15-18, 1995, Sapporo Japan, p413 JSCE-NACE (1995). It is also described in Japanese Patent No. 65785, Japanese Patent Application Laid-Open No. 2000-146871 and Japanese Patent Application Laid-Open No. 2009-42111.

特開2000−65785号公報に記載された腐食電位センサは、電極、酸素イオン伝導体(絶縁体)及び金属ボディー(センサ筺体)を備える。酸素イオン伝導体は、酸化ジルコニウム(ジルコニア)で作られ、一端が開放されて一端が閉じられた管状の形状(試験管状の形状)を有している。酸素イオン伝導体の開放端部が、金属ボディーにロウ付けにより接合されている。腐食電位センサの基準電位を発生する電極は、触媒(白金)、酸化銀及びリード線を有する。触媒、酸化銀及びリード線は、一端が閉じられた酸素イオン伝導体内に配置され、触媒が酸素イオン伝導体の閉じられた端部に配置され、酸化銀の充填層が触媒の充填層の隣に配置される。   The corrosion potential sensor described in JP 2000-65785 A includes an electrode, an oxygen ion conductor (insulator), and a metal body (sensor housing). The oxygen ion conductor is made of zirconium oxide (zirconia) and has a tubular shape (a test tubular shape) in which one end is opened and the other end is closed. The open end of the oxygen ion conductor is joined to the metal body by brazing. The electrode that generates the reference potential of the corrosion potential sensor includes a catalyst (platinum), silver oxide, and a lead wire. The catalyst, silver oxide and lead are placed in a closed oxygen ion conductor at one end, the catalyst is placed at the closed end of the oxygen ion conductor, and the silver oxide packed bed is adjacent to the catalyst packed bed. Placed in.

特開2000−146891号公報に記載された腐食電位センサは、蓋が筒状の絶縁体の一端部に固定され、絶縁体の他端部が内部スリーブで密封され、外部スリーブが絶縁体の外面に取り付けられている。銀塩化銀電極が絶縁体内に配置され、この電極に接続されたリード線が外部スリーブの外に引き出されている。   In the corrosion potential sensor described in Japanese Patent Application Laid-Open No. 2000-146891, a lid is fixed to one end of a cylindrical insulator, the other end of the insulator is sealed with an inner sleeve, and an outer sleeve is an outer surface of the insulator. Is attached. A silver-silver chloride electrode is disposed in the insulator, and a lead wire connected to the electrode is drawn out of the outer sleeve.

特開2009−42111号公報は、腐食電位センサを記載している。この腐食電位センサは、白金製の電極、ジルコニア絶縁体、金属製のセンサ筺体及びリード線を有する。基準電位を発生する電極がロウ付けにより絶縁体の一端部に取り付けられ、センサ筺体がセンサ絶縁体の他端部に取り付けられる。   Japanese Unexamined Patent Application Publication No. 2009-42111 describes a corrosion potential sensor. This corrosion potential sensor has a platinum electrode, a zirconia insulator, a metal sensor housing, and a lead wire. An electrode for generating a reference potential is attached to one end of the insulator by brazing, and a sensor housing is attached to the other end of the sensor insulator.

また、特開2001−166082号公報に記載された腐食電位センサは、腐食電位を測定する、原子力プラントの構造部材、例えば、再循環系配管と同一材料で構成した試験片、及び基準電極を、再循環系配管内を流れる炉水に接触するように、配置している。   In addition, the corrosion potential sensor described in Japanese Patent Application Laid-Open No. 2001-166082 includes a structural member of a nuclear power plant that measures the corrosion potential, for example, a test piece made of the same material as the recirculation piping, and a reference electrode. It arrange | positions so that it may contact the reactor water which flows in recirculation system piping.

特許第2687780号公報Japanese Patent No. 2687780 特開平4−223299号公報JP-A-4-223299 特開2000−65785号公報JP 2000-65785 A 特開2000−146891号公報Japanese Patent Laid-Open No. 2000-146891 特開2009−42111号公報JP 2009-42111 A

Proceedings of International Symposium on Plant Aging and Life Prediction of Corrodible Structures, May 15-18, 1995, Sapporo Japan, p413 JSCE-NACE (1995)Proceedings of International Symposium on Plant Aging and Life Prediction of Corrodible Structures, May 15-18, 1995, Sapporo Japan, p413 JSCE-NACE (1995)

原子力プラントである沸騰水型原子力プラントの再循環系配管のような炉水の流速が速い部位での腐食電位を、その場の環境条件の下で測定しようとする場合には、腐食電位センサ(ECPセンサ)を再循環系配管に直接設置する必要がある。腐食電位センサの再循環系配管への設置は、再循環系配管に設けられた筒状の測定用座内に腐食電位センサを挿入して腐食電位センサの頭頂部が再循環系配管内を流れる炉水に接触する状態にし、腐食電位センサを測定用座に取り付けることによって行なわれる。   When measuring the corrosion potential at a site where the flow rate of reactor water is high, such as the recirculation piping of a boiling water nuclear plant, which is a nuclear power plant, under the environmental conditions of the site, the corrosion potential sensor ( ECP sensor) must be installed directly in the recirculation piping. To install the corrosion potential sensor in the recirculation system piping, insert the corrosion potential sensor into the cylindrical measurement seat provided in the recirculation system piping, and the top of the corrosion potential sensor flows in the recirculation system piping. The test is performed by contacting the reactor water and attaching the corrosion potential sensor to the measurement seat.

ところが、図3(A)に示すように、腐食電位センサの頭頂部が再循環系配管の内面よりも内側に到達する状態で、腐食電位センサを測定用座に取り付けた場合には、再循環系配管内を流れる炉水の流れが、腐食電位センサに当たって腐食電位センサの頭頂部で乱されてしまう。さらには、腐食電位センサが再循環系配管内の高流速の炉水の流れに直交した状態になっているので、腐食電位センサが流動振動によって破損するまたは腐食電位センサにおいて電極を筐体から電気的に絶縁する目的で使用されている絶縁体が腐食減肉してしまう可能性がある。   However, as shown in FIG. 3 (A), when the corrosion potential sensor is attached to the measurement seat in a state where the top of the corrosion potential sensor reaches the inner side of the inner surface of the recirculation piping, recirculation is performed. The flow of the reactor water flowing in the system piping hits the corrosion potential sensor and is disturbed at the top of the corrosion potential sensor. Furthermore, since the corrosion potential sensor is in a state orthogonal to the flow of the high flow rate reactor water in the recirculation system piping, the corrosion potential sensor is damaged by flow vibration or the electrode is electrically connected from the housing in the corrosion potential sensor. There is a possibility that the insulator used for the purpose of insulative insulation will corrode and thin.

そこで、図3(B)に示すように(特開2009−42111号公報の図3参照)、腐食電位センサの頭頂部の先端を、再循環系配管の内面の位置を揃えて配置し、腐食電位センサを測定用座に取り付けることが求められる。その頭頂部の先端を再循環系配管の内面の位置に揃えることは、炭素鋼配管の流動加速腐食(FAC)の影響を評価する場合には、より厳密に要求される。   Therefore, as shown in FIG. 3B (see FIG. 3 of Japanese Patent Laid-Open No. 2009-42111), the tip of the top of the corrosion potential sensor is arranged with the position of the inner surface of the recirculation system pipe aligned to corrode. It is required to attach the potential sensor to the measurement seat. In order to evaluate the influence of the flow accelerated corrosion (FAC) of the carbon steel pipe, it is more strictly required to align the tip of the top of the head with the position of the inner surface of the recirculation pipe.

図3(B)に示すように腐食電位センサを測定用座に取り付けた場合には、腐食電位センサと測定用座の内面の間、及び再循環系配管に形成された腐食電位センサ挿入用の挿入孔の内面の間に、環状の間隙が形成される。これらの間隙内も、再循環系配管内を流れる炉水で満たされている。腐食電位センサによる再循環系配管の腐食電位は、腐食電位センサの電位検知部と再循環系配管内面の間の電位差を測定することによって求められる。   When the corrosion potential sensor is attached to the measurement seat as shown in FIG. 3B, the corrosion potential sensor is inserted between the corrosion potential sensor and the inner surface of the measurement seat and in the recirculation piping. An annular gap is formed between the inner surfaces of the insertion holes. These gaps are also filled with reactor water flowing through the recirculation system piping. The corrosion potential of the recirculation system pipe by the corrosion potential sensor is obtained by measuring the potential difference between the potential detection part of the corrosion potential sensor and the inner surface of the recirculation system pipe.

発明者らの検討結果により、以下に示す知見を得ることができた。すなわち、腐食電位センサの頭頂部とこの頭頂部が挿入される構造部材(例えば、配管)の挿入孔の内面との間に形成される間隙の幅が十分広ければ、その頭頂部の側面と挿入孔の内面との電位差は、構造部材の流動している水と接触する表面(例えば、配管の内面)の腐食電位を示している。しかしながら、腐食電位センサの頭頂部とその挿入孔の内面との間に形成される間隙の幅が狭い場合には、その頭頂部の側面と挿入孔の内面との電位差は、構造部材の流動している水と接触する表面(例えば、配管の内面)の腐食電位ではなく、挿入孔内面の腐食電位、または挿入孔内面の腐食電位及び構造部材の流動している水と接触する表面の腐食電位が混成された腐食電位を示すことになる。その間隙の幅が狭い場合には、間隙内の水は、構造部材表面に沿って流れる水の流動の影響を受けずに停滞した状態になり、流動している水に含まれる溶存酸素及び過酸化水素が蓄積されやすい環境になる。このため、挿入孔内面の腐食電位は、構造部材の流動している水と接触する表面の腐食電位と違った値になる。   Based on the results of the study by the inventors, the following findings could be obtained. That is, if the width of the gap formed between the top of the corrosion potential sensor and the inner surface of the insertion hole of the structural member (for example, piping) into which the top is inserted is sufficiently wide, the side of the top of the head is inserted. The potential difference from the inner surface of the hole indicates the corrosion potential of the surface (for example, the inner surface of the pipe) in contact with the flowing water of the structural member. However, when the width of the gap formed between the top of the corrosion potential sensor and the inner surface of the insertion hole is narrow, the potential difference between the side of the top and the inner surface of the insertion hole causes the flow of the structural member. The corrosion potential of the inner surface of the insertion hole, or the corrosion potential of the inner surface of the insertion hole and the surface of the structural member that is in contact with flowing water, not the corrosion potential of the surface that is in contact with the water (for example, the inner surface of the pipe) Indicates a mixed corrosion potential. When the width of the gap is narrow, the water in the gap remains stagnant without being affected by the flow of water flowing along the surface of the structural member, and dissolved oxygen and excess contained in the flowing water. The environment is likely to accumulate hydrogen oxide. For this reason, the corrosion potential of the inner surface of the insertion hole is different from the corrosion potential of the surface of the structural member in contact with the flowing water.

発明者らは、腐食電位センサの頭頂部の先端を構造部材の流動する水と接触する面に揃えて配置した場合でも、この頭頂部と、構造部材に形成された腐食電位センサの挿入孔の内面との間に形成される間隙の幅が狭くなる場合に、測定された配管の腐食電位の精度が低下するとの新たな知見を見出し、この知見に基づいて、腐食電位センサの頭頂部と、構造部材に形成された腐食電位センサの挿入孔の内面との間に形成される間隙の幅にかかわらず、構造部材の腐食電位を精度良く測定する必要があるとの認識を持つに至った。   The inventors of the present invention, even when the top of the top of the corrosion potential sensor is aligned with the surface of the structural member in contact with the flowing water, the top of the top of the corrosion potential sensor and the insertion hole of the corrosion potential sensor formed in the structural member. When the width of the gap formed between the inner surface and the inner surface becomes narrower, a new finding that the accuracy of the measured corrosion potential of the piping is reduced is found, and based on this finding, the top of the corrosion potential sensor, Regardless of the width of the gap formed between the inner surface of the insertion hole of the corrosion potential sensor formed on the structural member, it has been recognized that the corrosion potential of the structural member needs to be accurately measured.

本発明の目的は、構造部材の腐食電位を精度良く測定することができる腐食電位センサ及び腐食電位センサの設置構造を提供することにある。   The objective of this invention is providing the installation structure of the corrosion potential sensor which can measure the corrosion potential of a structural member accurately, and a corrosion potential sensor.

上記した目的を達成するため本発明の特徴は、ケーシングと、ケーシング内に形成された空間内、及びケーシングの一部としてケーシングの端部、のいずれかに配置された基準電極と、基準電極に接続された第1導線と、ケーシングの外面に形成される電位検知部と、ケーシングの外面から離れた状態で電位検知部に対向して前記ケーシングの外部に配置された電極部材とを備え、
ケーシングが筒状の金属部材及び金属部材に取り付けられて少なくとも電位検知部と金属部材の間に配置された絶縁部材とを有し、電極部材が金属部材に取り付けられ、ケーシングが腐食電位測定対象物に取り付けられたときに電極部材に形成された複数の開口が腐食電位測定対象物の表面に接触する水が通るように配置され、電極部材の電位検知部に対向する部分が、腐食電位測定対象物と同じ材質で構成され、電位差計がケーシングの外部で第1導線に接続され、腐食電位測定対象物に接続される第2導線が電位差計に接続されることにある。
In order to achieve the above-described object, the present invention is characterized in that a reference electrode disposed in any of a casing, a space formed in the casing, and an end of the casing as a part of the casing, and a reference electrode A connected first conducting wire, a potential detection unit formed on the outer surface of the casing, and an electrode member disposed outside the casing facing the potential detection unit in a state of being separated from the outer surface of the casing;
The casing is attached to the cylindrical metal member and the metal member and has at least an electric potential detection unit and an insulating member disposed between the metal member, the electrode member is attached to the metal member, and the casing is an object for measuring the corrosion potential. A plurality of openings formed in the electrode member when attached to the surface of the electrode member are arranged so that water that contacts the surface of the object to be measured for corrosion potential passes, and the portion facing the potential detection part of the electrode member is the object to be measured for corrosion potential The potentiometer is connected to the first conductor outside the casing, and the second conductor connected to the corrosion potential measurement object is connected to the potentiometer .

電極部材が金属部材に取り付けられ、ケーシングが腐食電位測定対象物に取り付けられたときに電極部材に形成された複数の開口が腐食電位測定対象物の表面に接触する水が通るように配置され、電極部材の電位検知部に対向する部分が、腐食電位測定対象物と同じ材質で構成されているので、プラントの構造部材に形成された、腐食電位センサの先端部が挿入される孔部の内面と腐食電位センサのケーシングとの間に形成される間隙の幅にかかわらず、構造部材の腐食電位を精度良く測定することができる。 When the electrode member is attached to the metal member and the casing is attached to the corrosion potential measurement object, a plurality of openings formed in the electrode member are arranged so that water that contacts the surface of the corrosion potential measurement object passes through. Since the portion of the electrode member that faces the potential detection portion is made of the same material as the corrosion potential measurement object, the inner surface of the hole formed in the structural member of the plant into which the tip of the corrosion potential sensor is inserted The corrosion potential of the structural member can be accurately measured regardless of the width of the gap formed between the casing and the casing of the corrosion potential sensor.

好ましくは、電極部材が、絶縁部材の金属部材への取り付け部から絶縁部材側で、ケーシングの、電位検知部を含む先端部を覆っている捕捉電極部材であることが望ましい。   Preferably, the electrode member is a capture electrode member that covers the tip of the casing including the potential detection portion on the insulating member side from the attachment portion of the insulating member to the metal member.

上記した特徴を有する腐食電位センサが、プラントの、腐食電位測定対象物である構造部材に設置した筒状の支持座に取り付けられて支持座内に配置されており、
ケーシングの、支持座内に位置する部分の先端が、腐食電位センサの軸方向において、構造部材の水と接触する表面の位置に配置され、
ケーシングの、支持座内に位置する部分の先端部が構造部材に形成された孔部内に挿入された状態で、電極部材が、その孔部の内面よりも腐食電位センサの中心軸側に配置されることによっても、上記した目的を達成することができる。
A corrosion potential sensor having the above-described features is attached to a cylindrical support seat installed on a structural member that is an object to be measured for corrosion potential in the plant, and is disposed in the support seat.
The tip of the portion of the casing located in the support seat is arranged at the position of the surface in contact with the water of the structural member in the axial direction of the corrosion potential sensor,
The electrode member is disposed closer to the central axis side of the corrosion potential sensor than the inner surface of the hole with the tip of the portion of the casing located in the support seat being inserted into the hole formed in the structural member. By doing so, the above-described object can be achieved.

本発明によれば、プラントの構造部材に形成された、腐食電位センサの先端部が挿入される孔部の内面と腐食電位センサのケーシングとの間に形成される間隙の幅にかかわらず、構造部材の腐食電位を精度良く測定することができる。   According to the present invention, the structure is formed regardless of the width of the gap formed between the inner surface of the hole formed in the structural member of the plant and into which the tip of the corrosion potential sensor is inserted and the casing of the corrosion potential sensor. The corrosion potential of the member can be measured with high accuracy.

本発明の好適な一実施例である実施例1の腐食電位センサを沸騰水型原子力プラントの再循環系配管に設置した構造を示す縦断面図である。It is a longitudinal cross-sectional view which shows the structure which installed the corrosion potential sensor of Example 1 which is one suitable Example of this invention in the recirculation system piping of a boiling water nuclear power plant. 図1に示す捕捉電極部材を示す斜視図である。It is a perspective view which shows the capture electrode member shown in FIG. 腐食電位センサの配管への設置状態を示す説明図であり、(A)は腐食電位センサの先端を配管の内面よりも内側に配置した状態を示す説明図、(B)は腐食電位センサの先端を配管の内面の位置に配置した状態を示す説明図である。It is explanatory drawing which shows the installation state to the piping of a corrosion potential sensor, (A) is explanatory drawing which shows the state which has arrange | positioned the front-end | tip of a corrosion-potential sensor inside the inner surface of piping, (B) is the front-end | tip of a corrosion potential sensor It is explanatory drawing which shows the state which has arrange | positioned in the position of the inner surface of piping. 腐食電位センサの頭頂部と再循環系配管の間に発生する電力線を示す説明図であり、(A)は従来の腐食電位センサで発生する電力線を示す説明図、(B)は本発明の一例である腐食電位センサで発生する電力線を示す説明図である。It is explanatory drawing which shows the power line which generate | occur | produces between the top part of a corrosion potential sensor, and recirculation system piping, (A) is explanatory drawing which shows the power line which generate | occur | produces with the conventional corrosion potential sensor, (B) is an example of this invention It is explanatory drawing which shows the power line which generate | occur | produces with the corrosion potential sensor which is. 沸騰水型原子力プラントの炉水の条件下における、表面の一部に白金層を形成したステンレス鋼製の試験片表面の腐食電位の、白金層とステンレス鋼の境界からの変化を示す特性図である。A characteristic diagram showing the change in corrosion potential of the surface of a stainless steel specimen with a platinum layer formed on a part of the surface under the reactor water conditions of a boiling water nuclear power plant from the boundary between the platinum layer and stainless steel. is there. 本発明の他の実施例である実施例2の腐食電位センサを沸騰水型原子力プラントの再循環系配管に設置した構造を示す縦断面図である。It is a longitudinal cross-sectional view which shows the structure which installed the corrosion potential sensor of Example 2 which is another Example of this invention in the recirculation system piping of a boiling water nuclear power plant. 本発明の他の実施例である実施例3の腐食電位センサを沸騰水型原子力プラントの再循環系配管に設置した構造を示す縦断面図である。It is a longitudinal cross-sectional view which shows the structure which installed the corrosion potential sensor of Example 3 which is another Example of this invention in the recirculation system piping of a boiling water nuclear power plant. 図7に示す捕捉電極部材を示す斜視図である。It is a perspective view which shows the capture electrode member shown in FIG.

発明者らは、腐食電位センサを原子力プラントの構造部材に設置してこの腐食電位の先端部を構造部材に形成される孔部内に配置したとき、腐食電位センサに対向する孔部の内面における腐食電位の影響を抑制でき、構造部材の、流動する水に接触する表面の腐食電位を精度良く測定できる腐食電位センサの構成を検討した。   When the corrosion potential sensor is installed in a structural member of a nuclear power plant and the tip portion of this corrosion potential is placed in a hole formed in the structural member, the inventors corrode the inner surface of the hole facing the corrosion potential sensor. The structure of a corrosion potential sensor that can suppress the influence of the potential and can accurately measure the corrosion potential of the surface of the structural member in contact with the flowing water was examined.

特開2009−42111号公報に記載された腐食電位センサは、ジルコニア絶縁体の先端に取り付けられた電極上、すなわち、白金上での水素の電極反応を利用する。腐食電位センサの軸方向での電極(白金)の先端面、及び電極(白金)の側面が電位検知部となる。   The corrosion potential sensor described in Japanese Patent Application Laid-Open No. 2009-42111 utilizes an electrode reaction of hydrogen on an electrode attached to the tip of a zirconia insulator, that is, on platinum. The tip surface of the electrode (platinum) in the axial direction of the corrosion potential sensor and the side surface of the electrode (platinum) serve as a potential detection unit.

この腐食電位センサを、図4(A)に示すように、配管(例えば、再循環系配管)に溶接にて設置した測定用座及び配管に形成された孔部内に挿入する。腐食電位センサのセンサ筺体がアダプタを介して測定用座に取り付けられる。このとき、絶縁体に取り付けられた電極の先端が、配管の内面の位置に配置されている。この電極の先端面及び側面にそれぞれ電位検知部が形成される。配管の腐食電位の測定は、電極に接続されてジルコニア絶縁体及びセンサ筺体内に配置されたリード線と、配管に接続された配線を、例えば、エレクトロメータに接続し、エレクトロメータにて電極と配管の間の電位差を測定することによって行われる。電極と配管に形成された孔部の間の間隙の幅が小さいとき、電極の側面と孔部の内面の間の距離が最も短いため、電極側面から孔部内面に向かう電力線(図4(A)に直線で示す矢印)は、距離が長い電極の先端から配管の内面に向かう電力線(図4(A)に曲線で示す矢印)よりも多くなる。このため、測定された配管の腐食電位は、孔部の内面の腐食電位及び配管内面の腐食電位が混成された電位となり、腐食電位の測定における電極先端の寄与が電極側面による寄与よりも小さくなる。   As shown in FIG. 4A, this corrosion potential sensor is inserted into a measurement seat and a hole formed in the pipe, which are installed in a pipe (for example, a recirculation system pipe) by welding. A sensor housing of the corrosion potential sensor is attached to the measurement seat through an adapter. At this time, the tip of the electrode attached to the insulator is disposed at the position of the inner surface of the pipe. Potential detection portions are formed on the tip and side surfaces of the electrode, respectively. The corrosion potential of the pipe is measured by connecting the lead wire connected to the electrode and arranged in the zirconia insulator and sensor housing, and the wiring connected to the pipe, for example, to an electrometer and connecting the electrode with the electrometer. This is done by measuring the potential difference between the pipes. When the width of the gap between the electrode and the hole formed in the pipe is small, the distance between the side surface of the electrode and the inner surface of the hole is the shortest. ) Are more than power lines (arrows indicated by curves in FIG. 4A) from the tip of the electrode having a long distance to the inner surface of the pipe. For this reason, the measured corrosion potential of the pipe is a mixed potential of the corrosion potential of the inner surface of the hole and the corrosion potential of the inner surface of the pipe, and the contribution of the electrode tip in the measurement of the corrosion potential is smaller than the contribution of the electrode side surface. .

そこで、発明者らは、上記した電力線の発生状況を基に、図4(B)に示すように、電極の先端及び側面のそれぞれの実質的に等距離の位置になるように、この電極の先端及び側面と対向するように、他の電極を配置した。なお、便宜的に、腐食電位センサの絶縁体の先端に設けられた電極を第1電極、この第1電極に対向させて配置された電極を第2電極という。第2電極は、複数の支持棒を用いて腐食電位センサのセンサ筺体に取り付けた。第2電極の第1電極の側面に対向する部分、及び支持棒は、腐食電位センサと配管に形成された孔部の内面の間に配置される。図4(B)に示す腐食電位センサも、アダプタを介して測定用座に取り付けられる。図4(B)に示す腐食電位センサでは、第1電極に接続されてジルコニア絶縁体及びセンサ筺体内に配置されたリード線、及び配管に接続された配線がエレクトロメータ(電位測定装置)に接続される。第2電極は、支持棒、センサ筺体、アダプタ及び測定用座を介して配管に電気的に接続されている。   Therefore, the inventors based on the above power line generation situation, as shown in FIG. 4 (B), the electrode's tip and side surfaces are positioned at substantially equal distances. Other electrodes were arranged so as to face the tip and side surfaces. For convenience, the electrode provided at the tip of the insulator of the corrosion potential sensor is referred to as a first electrode, and the electrode disposed opposite to the first electrode is referred to as a second electrode. The second electrode was attached to the sensor housing of the corrosion potential sensor using a plurality of support bars. The portion of the second electrode facing the side surface of the first electrode and the support rod are disposed between the corrosion potential sensor and the inner surface of the hole formed in the pipe. The corrosion potential sensor shown in FIG. 4B is also attached to the measurement seat via an adapter. In the corrosion potential sensor shown in FIG. 4 (B), the lead wire connected to the first electrode and disposed in the zirconia insulator and the sensor housing, and the wiring connected to the pipe are connected to the electrometer (potential measuring device). Is done. The second electrode is electrically connected to the pipe via a support bar, a sensor housing, an adapter, and a measurement seat.

第2電極は腐食電位を測定する構造部材と同じ材質の金属(例えば、SUS316L)で構成され、配管内を流れている水に接触している。この第2電極を有する腐食電位センサでは、図4(B)に示すように、第1電極の先端及び側面から構造部材に向かう電力線が、構造部材に形成された孔部の内面に到達せず、第1電極に近い第2電極に到達するため、エレクトロメータが第2電極の腐食電位を測定する。この結果、図4(B)に示された腐食電位センサは、腐食電位の測定において、腐食電位センサと孔部の内面の間に形成される間隙、すなわち、炉水停滞部に接する構造部材の部分(孔部の内面)における腐食電位の影響を低減できるので、その分、水の流れに曝された構造部材の表面の腐食電位の寄与が増加する。   The second electrode is made of a metal (for example, SUS316L) made of the same material as the structural member for measuring the corrosion potential, and is in contact with water flowing in the pipe. In the corrosion potential sensor having the second electrode, as shown in FIG. 4B, the power line from the tip and side surfaces of the first electrode to the structural member does not reach the inner surface of the hole formed in the structural member. In order to reach the second electrode close to the first electrode, the electrometer measures the corrosion potential of the second electrode. As a result, in the corrosion potential sensor shown in FIG. 4B, in the measurement of the corrosion potential, the gap formed between the corrosion potential sensor and the inner surface of the hole, that is, the structural member in contact with the reactor water stagnation portion. Since the influence of the corrosion potential in the portion (inner surface of the hole) can be reduced, the contribution of the corrosion potential on the surface of the structural member exposed to the flow of water is increased accordingly.

このため、腐食電位センサの第1電極と構造部材に形成されて腐食電位センサの先端部が挿入される孔部の内面との間に形成された広い幅の間隙及び狭い幅の間隙にかかわりなく、流動する水に接触する構造部材の腐食電位を精度良く測定することができる
図4(B)に示された腐食電位センサにおいて、腐食電位センサの先端部が挿入された、構造部材の孔部の内面での腐食電位の影響を低減できるのは、導電率が低い、BWRのような炉水の環境では、電位の及ぶ範囲が極めて限定されていることに起因する。これを、図5を用いて詳細に説明する。図5に示す特性は、SUS304ステンレス鋼製の試験片の表面の一部に蒸着により白金層を形成し、この表面の残りの部分をSUS304ステンレス鋼のままにしたその試験片のその表面における腐食電位の測定結果を示している。図5に示された腐食電位分布の測定は、280℃のBWRの炉水条件を模擬した水中にその試験片を浸漬させて、腐食電位センサを、試験片の白金層を形成した表面に沿って走査しながら行った。
Therefore, regardless of the wide width gap and the narrow width gap formed between the first electrode of the corrosion potential sensor and the inner surface of the hole portion where the tip of the corrosion potential sensor is inserted. The corrosion potential of the structural member in contact with the flowing water can be accurately measured. In the corrosion potential sensor shown in FIG. 4B, the hole of the structural member into which the tip of the corrosion potential sensor is inserted. The influence of the corrosion potential on the inner surface of the steel can be reduced because the range of potential is extremely limited in the environment of reactor water such as BWR having low conductivity. This will be described in detail with reference to FIG. The characteristic shown in FIG. 5 is that the surface of the specimen of SUS304 stainless steel is formed by depositing a platinum layer by vapor deposition and the remaining part of the surface is left as SUS304 stainless steel. The measurement result of electric potential is shown. The measurement of the corrosion potential distribution shown in FIG. 5 is performed by immersing the test piece in water simulating the BWR reactor water condition at 280 ° C., and placing the corrosion potential sensor along the surface of the test piece on which the platinum layer is formed. I went while scanning.

試験片を浸漬した水の条件を、酸素に対して水素が化学量論比で2以上になるように調節したので、白金層の腐食電位は、−0.4〜−0.3Vvs.SHEの一定値を示した。表面における白金層とSUS304ステンレス鋼の境界からSUS304ステンレス鋼がむき出しになっている領域に向かって、腐食電位センサを試験片の表面に沿って移動させると、その表面の腐食電位は次第に上昇する。その表面において、上記の境界からSUS304ステンレス鋼がむき出しになっている領域に向かって12mm離れた位置では、腐食電位は完全にSUS304ステンレス鋼の腐食電位と同じ値を示した。このとき、白金層の腐食電位が影響した範囲は、上記の境界から高々5mm程度離れた位置までであった。   Since the water condition in which the test piece was immersed was adjusted so that the stoichiometric ratio of hydrogen to oxygen was 2 or more, the corrosion potential of the platinum layer was −0.4 to −0.3 Vvs. A constant value of SHE was shown. When the corrosion potential sensor is moved along the surface of the test piece from the boundary between the platinum layer and the SUS304 stainless steel on the surface toward the region where the SUS304 stainless steel is exposed, the corrosion potential of the surface gradually increases. On the surface, at a position 12 mm away from the boundary toward the region where the SUS304 stainless steel is exposed, the corrosion potential completely showed the same value as the corrosion potential of SUS304 stainless steel. At this time, the range affected by the corrosion potential of the platinum layer was up to about 5 mm away from the boundary.

SUS304ステンレス鋼がむき出しになっている領域において白金層の腐食電位と同じ値の腐食電位になる領域は、上記境界のごく近傍に存在する。この境界とこの境界から数mm離れた位置の間における、SUS304ステンレス鋼がむき出しになっている領域では、白金の腐食電位とSUS304ステンレス鋼の腐食電位が混成していることが判った。以上のことから、構造部材の、流動する水に接触する表面の腐食電位を精度良く測定するためには、腐食電位センサの第2電極は、孔部の内面よりも第1電極側に配置しなければならないことが分かった。   In the region where SUS304 stainless steel is exposed, the region having the same corrosion potential as that of the platinum layer exists in the very vicinity of the boundary. It was found that the corrosion potential of platinum and the corrosion potential of SUS304 stainless steel were mixed in the region where SUS304 stainless steel was exposed between this boundary and a position several mm away from this boundary. From the above, in order to accurately measure the corrosion potential of the surface of the structural member that is in contact with flowing water, the second electrode of the corrosion potential sensor is disposed closer to the first electrode than the inner surface of the hole. I knew I had to.

さらに、特開2000−65785号公報に記載された腐食電位センサでは、セラッミクスで作られたイオン伝導体の、内部に充填された触媒(白金)が接触する領域の外面、すなわち、イオン伝導体の、構造部材の上記した孔部内に配置される先端部の外面(曲面部の外面)が電位検知部になる。このような腐食電位センサにおいても、腐食電位センサの、酸素イオン伝導体の先端部の外面に形成された電位検知部から所定の間隔で離してこの電位検知部に対向して曲面を有する第2電極を配置し、この第2電極でその電位検知部を覆っても良い。   Furthermore, in the corrosion potential sensor described in Japanese Patent Application Laid-Open No. 2000-65785, the outer surface of the area where the catalyst (platinum) filled in the ionic conductor made of ceramics contacts, that is, the ionic conductor. The outer surface (the outer surface of the curved surface portion) of the tip portion disposed in the hole portion of the structural member becomes the potential detection portion. Also in such a corrosion potential sensor, the corrosion potential sensor has a curved surface facing the potential detection portion at a predetermined interval away from the potential detection portion formed on the outer surface of the front end portion of the oxygen ion conductor. An electrode may be disposed and the potential detection unit may be covered with the second electrode.

以上の検討結果を反映した本発明の実施例を以下に説明する。   Examples of the present invention reflecting the above examination results will be described below.

本発明の好適な一実施例である実施例1の腐食電位センサを、図1及び図2を用いて説明する。本実施例の腐食電位センサ1は、銀/塩化銀電極(基準電極)7を有する銀/塩化銀型腐食電位センサである。この腐食電位センサ1は、特開2000−146891号公報に記載された腐食電位センサの構成を有しており、ケーシング30、銀/塩化銀電極7、リード線(導線)8及び捕捉電極部材(電極部材)11を備えている。ケーシング30は、蓋(第2絶縁部材)2、絶縁体(第1絶縁部材)3、外部スリーブ(金属部材)4及びセンサボディ(金属部材)5を有する。   A corrosion potential sensor according to embodiment 1 which is a preferred embodiment of the present invention will be described with reference to FIGS. The corrosion potential sensor 1 of this embodiment is a silver / silver chloride type corrosion potential sensor having a silver / silver chloride electrode (reference electrode) 7. The corrosion potential sensor 1 has the configuration of a corrosion potential sensor described in Japanese Patent Application Laid-Open No. 2000-146871 and includes a casing 30, a silver / silver chloride electrode 7, a lead wire (conductive wire) 8, and a capture electrode member ( Electrode member) 11 is provided. The casing 30 includes a lid (second insulating member) 2, an insulator (first insulating member) 3, an external sleeve (metal member) 4, and a sensor body (metal member) 5.

ケーシング30の構成を具体的に説明する。高純度サファイヤ製の蓋2が、高純度サファイヤ製の筒状の絶縁体3の一端部に固定される。蓋2には外面に雄ネジが形成された細径部が設けられ、この細径部の雄ネジが絶縁体3の端部の内面に形成された雌ネジと噛み合って固定される。蓋2は、回り止めのために、周方向の複数個所で絶縁体3に点溶接される。ステンレス鋼製の筒状の外部スリーブの一端部が、絶縁体3の外面にロウ付け部を介して取り付けられる。外部スリーブは、絶縁体3の他端部である細径部を取り囲んでいる。ステンレス鋼製のセンサボディ5の一端部がステンレス鋼製の外部スリーブの他端部にロウ付けにより取り付けられている。センサボディ5の他端部は封鎖されている。外部スリーブ4とセンサボディ5を、金属部材として一体化しても良い。電位検知部27Aが、ケーシング30の外面において蓋2と絶縁体3の間に形成される。 The configuration of the casing 30 will be specifically described. A lid 2 made of high purity sapphire is fixed to one end of a cylindrical insulator 3 made of high purity sapphire. The lid 2 is provided with a small diameter portion having a male screw formed on the outer surface, and the male screw of the small diameter portion is engaged with and fixed to a female screw formed on the inner surface of the end portion of the insulator 3. The lid 2 is spot-welded to the insulator 3 at a plurality of locations in the circumferential direction to prevent rotation. One end of a cylindrical outer sleeve 4 made of stainless steel is attached to the outer surface of the insulator 3 via a brazing portion. The outer sleeve 4 surrounds a small diameter portion that is the other end portion of the insulator 3. One end of the stainless steel sensor body 5 is attached to the other end of the stainless steel outer sleeve 4 by brazing. The other end of the sensor body 5 is sealed. The outer sleeve 4 and the sensor body 5 may be integrated as a metal member. A potential detector 27 </ b> A is formed between the lid 2 and the insulator 3 on the outer surface of the casing 30.

内部スリーブ(封鎖部材)6が、この細径部の端部に取り付けられて絶縁体3を密封状態で封鎖している。銀/塩化銀電極7は、絶縁体3内に配置され、リード線8に接続される。リード線8が、内部スリーブ6を貫通してセンサボディ5内に配置される。リード線8と内部スリーブ6の間も、密封されている。センサボディ5に取り付けられた鉱物絶縁ケーブル17は、リード線8を含んでいる。   An inner sleeve (blocking member) 6 is attached to the end of the small diameter portion to seal the insulator 3 in a sealed state. The silver / silver chloride electrode 7 is disposed in the insulator 3 and connected to the lead wire 8. A lead wire 8 passes through the inner sleeve 6 and is disposed in the sensor body 5. The lead wire 8 and the inner sleeve 6 are also sealed. A mineral insulated cable 17 attached to the sensor body 5 includes a lead wire 8.

捕捉電極部材11は、図2に示すように、電極部10及び支持部31を有する。電極部10は、円板である電極板28及び複数の電極棒13を有する。各電極棒13が、電極板28の一面に垂直に取り付けられており、ケーシング30の周方向において所定の間隔で配置されている。電極棒13相互間の間隔は蓋2の直径よりも小さくなっている。支持部31は、複数の支持棒12及び複数の円環部材14を有する。各円環部材14が、ケーシング30の軸方向において所定の間隔を持って配置され、ケーシング30の軸方向に伸びる各支持棒12によって互いに連結される。電極部材10及び支持部31の上記した各要素部材は、全て、腐食電位センサ1に対する腐食電位測定対象物である再循環系配管18と同じ材料であるSUS316L鋼製である。   The capture electrode member 11 includes an electrode portion 10 and a support portion 31 as shown in FIG. The electrode unit 10 includes an electrode plate 28 that is a disk and a plurality of electrode rods 13. Each electrode bar 13 is vertically attached to one surface of the electrode plate 28, and is disposed at a predetermined interval in the circumferential direction of the casing 30. The distance between the electrode bars 13 is smaller than the diameter of the lid 2. The support portion 31 includes a plurality of support rods 12 and a plurality of annular members 14. The annular members 14 are arranged at a predetermined interval in the axial direction of the casing 30 and are connected to each other by the support rods 12 extending in the axial direction of the casing 30. The above-described element members of the electrode member 10 and the support portion 31 are all made of SUS316L steel, which is the same material as the recirculation pipe 18 that is a corrosion potential measurement object for the corrosion potential sensor 1.

電極部10を構成する電極板28の各電極棒13が取り付けられた一面が、ケーシング30の先端部を構成する蓋2の、平面である端面に所定の間隔で向き合って配置されている。各電極棒13が、蓋2の側面に所定の間隔で向き合って配置されており、環状の電位検知部27Aに対向している。支持部31が電極部10に取り付けられている。支持部31を構成する円環部材14のうち、電極板28に最も近い位置に配置された円環部材14が、各電極棒13の上端に溶接にて取り付けられる。各支持棒12は、外部スリーブ4の外面に溶接にて接合されている。電極板28と蓋2の端面との間の間隔、及び各電極棒13と蓋2の側面との間の間隔は、等しくなっている。   One surface to which each electrode rod 13 of the electrode plate 28 constituting the electrode portion 10 is attached is arranged facing a flat end surface of the lid 2 constituting the tip portion of the casing 30 at a predetermined interval. The electrode bars 13 are arranged on the side surface of the lid 2 so as to face each other at a predetermined interval, and face the annular potential detection unit 27A. A support portion 31 is attached to the electrode portion 10. Of the annular member 14 constituting the support portion 31, the annular member 14 disposed at a position closest to the electrode plate 28 is attached to the upper end of each electrode rod 13 by welding. Each support bar 12 is joined to the outer surface of the outer sleeve 4 by welding. The distance between the electrode plate 28 and the end surface of the lid 2 and the distance between each electrode bar 13 and the side surface of the lid 2 are equal.

各支持棒12及び各円環部材14が、絶縁体3の外面から離れた位置で絶縁体3を取り囲んでいる。電極部10が、ケーシング30の先端部である蓋2の先端面及び側面を覆っている。   Each support rod 12 and each annular member 14 surround the insulator 3 at a position away from the outer surface of the insulator 3. The electrode unit 10 covers the front end surface and the side surface of the lid 2 that is the front end portion of the casing 30.

支持部31の各支持棒12及び各円環部材14の表面には、プラズマコーティング法により、絶縁被膜であるジルコニア被膜が形成されている。ジルコニア被膜の替りに、アルミナ、サファイヤまたはダイヤモンドの被膜を形成しても良い。電極部10を構成する電極板28及び各電極棒13は金属面が露出している。   A zirconia film, which is an insulating film, is formed on the surface of each support rod 12 and each annular member 14 of the support portion 31 by a plasma coating method. Instead of the zirconia film, an alumina, sapphire or diamond film may be formed. The metal surfaces of the electrode plate 28 and each electrode rod 13 constituting the electrode unit 10 are exposed.

電極部10の金属露出面を腐食電位測定対象物である再循環系配管18の炉水と接触する内面と同じ状態にするために、その金属露出表面に、予め、沸騰水型原子力プラントの炉水を模擬した溶存酸素濃度300ppbの模擬水を500hr以上接触させる予備酸化処理を施す。この処理により、酸化皮膜が、電極部10及び支持棒12,13のそれぞれの金属露出面に予め形成される。   In order to make the exposed metal surface of the electrode part 10 the same as the inner surface of the recirculation system pipe 18 that is the object of corrosion potential measurement, which is in contact with the reactor water, the furnace surface of the boiling water nuclear power plant is previously formed on the exposed metal surface. A pre-oxidation treatment is performed in which simulated water having a dissolved oxygen concentration of 300 ppb simulating water is brought into contact with 500 hours or more. By this treatment, an oxide film is formed in advance on the exposed metal surfaces of the electrode portion 10 and the support rods 12 and 13.

原子力プラントにおける腐食電位センサ1の設置構造は以下の通りである。腐食電位センサ1は、例えば、沸騰水型原子力プラントの原子炉に接続される再循環系配管18に溶接にて取り付けられた筒状の測定用座(支持座)19に取り付けられる。腐食電位センサ1は測定用座19内に挿入されており、腐食電位センサ1のセンサボディ5が、測定用座19の一端に取り付けられたアダプタ20を貫通してこのアダプタ20に溶接にて取り付けられる。この状態で、腐食電位センサ1の蓋2の先端が、再循環系配管18の半径方向において、再循環系配管18の内面の位置に配置されている。リード線8に接続された配線(導線)16が、電位差計(電位差測定装置)15に接続される。電位差計15に接続された配線(導線)17が、再循環系配管18に接続される。   The installation structure of the corrosion potential sensor 1 in a nuclear power plant is as follows. The corrosion potential sensor 1 is attached to, for example, a cylindrical measurement seat (support seat) 19 attached by welding to a recirculation system pipe 18 connected to a nuclear reactor of a boiling water nuclear power plant. The corrosion potential sensor 1 is inserted into the measurement seat 19, and the sensor body 5 of the corrosion potential sensor 1 passes through the adapter 20 attached to one end of the measurement seat 19 and is attached to the adapter 20 by welding. It is done. In this state, the tip of the lid 2 of the corrosion potential sensor 1 is disposed on the inner surface of the recirculation system pipe 18 in the radial direction of the recirculation system pipe 18. A wiring (conductive wire) 16 connected to the lead wire 8 is connected to a potentiometer (potential difference measuring device) 15. A wiring (conductive wire) 17 connected to the potentiometer 15 is connected to the recirculation piping 18.

腐食電位センサ1が再循環系配管18に取り付けられた状態で、腐食電位センサ1の先端部(蓋2の部分)が、再循環系配管18に形成された孔部に配置される。この腐食電位センサ1と測定用座19の間、及び腐食電位センサ1の先端部と再循環系配管18に形成された孔部の間に、環状の間隙21が形成される。   With the corrosion potential sensor 1 attached to the recirculation system pipe 18, the tip of the corrosion potential sensor 1 (the portion of the lid 2) is disposed in a hole formed in the recirculation system pipe 18. An annular gap 21 is formed between the corrosion potential sensor 1 and the measurement seat 19 and between the tip of the corrosion potential sensor 1 and a hole formed in the recirculation system pipe 18.

腐食電位測定装置は、腐食電位センサ1、電位差計15、リード線8と電位差計15を接続する配線16、及び腐食電位測定対象物(例えば、再循環系配管18)と電位差計15を接続する配線17を備えている。   The corrosion potential measuring device connects the corrosion potential sensor 1, the potentiometer 15, the wiring 16 connecting the lead wire 8 and the potentiometer 15, and the corrosion potential measurement object (for example, the recirculation system pipe 18) and the potentiometer 15. Wiring 17 is provided.

再循環系配管18に設けた再循環ポンプを駆動することによって、原子炉内の炉水が、吸引されて昇圧され、原子炉内に配置されたジェットポンプに導かれて原子炉容器内の炉心に供給される。再循環系配管18内を流れる炉水は、再循環系配管18の内面に接触すると共に、電極板28の、蓋2の先端の平面に対向している電極板28の平面とは反対側の平面に接触する。さらに、この炉水は、電極板28の周方向に配置されて隣り合う各電極棒13の相互間を通って、蓋2の先端の平面とこの平面に対向する電極板28の平面の間を流れ、両方の平面に接触する。間隙21内にも炉水が存在する。隣り合う各電極棒13のそれぞれの相互間には、炉水が流れる開口が形成される。   By driving a recirculation pump provided in the recirculation system pipe 18, the reactor water in the reactor is sucked up and pressurized, and led to a jet pump arranged in the reactor and cored in the reactor vessel. To be supplied. Reactor water flowing in the recirculation system pipe 18 is in contact with the inner surface of the recirculation system pipe 18 and is opposite to the plane of the electrode plate 28 facing the plane of the tip of the lid 2 of the electrode plate 28. Touch the plane. Further, the reactor water is disposed in the circumferential direction of the electrode plate 28 and passes between adjacent electrode rods 13, and passes between the plane of the tip of the lid 2 and the plane of the electrode plate 28 facing this plane. Flow and touch both planes. Reactor water is also present in the gap 21. An opening through which reactor water flows is formed between the adjacent electrode rods 13.

腐食電位センサ1は、以下のようにして、再循環系配管18の腐食電位を測定する。腐食電位センサ1が上記したように再循環系配管18に取り付けられた状態で、沸騰水型原子力プラントが運転されているとき、再循環系配管18内を流れる炉水が、蓋2に形成された雄ネジと絶縁体3に形成された雌ネジの間の隙間を介して、絶縁体3内の銀/塩化銀電極7が配置された領域内に浸入する。このため、銀/塩化銀電極7は、絶縁体3内で炉水に浸漬される。内部スリーブ6が絶縁体3の鉱物絶縁ケーブル17側の端部を密封しているので、絶縁体3内に浸入した炉水が鉱物絶縁ケーブル17に接触することを防止できる。   The corrosion potential sensor 1 measures the corrosion potential of the recirculation piping 18 as follows. When the boiling water nuclear power plant is operated with the corrosion potential sensor 1 attached to the recirculation system pipe 18 as described above, the reactor water flowing in the recirculation system pipe 18 is formed in the lid 2. It penetrates into the area | region in which the silver / silver chloride electrode 7 in the insulator 3 is arrange | positioned through the clearance gap between the female screw and the female screw formed in the insulator 3. For this reason, the silver / silver chloride electrode 7 is immersed in the reactor water in the insulator 3. Since the inner sleeve 6 seals the end portion of the insulator 3 on the side of the mineral insulated cable 17, it is possible to prevent the reactor water that has entered the insulator 3 from coming into contact with the mineral insulated cable 17.

ケーシング30の外面に形成された電位検知部27Aが、蓋2に形成された雄ネジと絶縁体3に形成された雌ネジの間の隙間に存在する水、及び絶縁体3内の水を通して銀/塩化銀電極7に電気的に接続される。電位検知部27Aは、また、蓋2と電極部10の間を流れる炉水を通して電極部10に電気的に接続される。   The electric potential detector 27A formed on the outer surface of the casing 30 is silver through the water present in the gap between the male screw formed on the lid 2 and the female screw formed on the insulator 3, and the water in the insulator 3. / Electrically connected to the silver chloride electrode 7. The potential detection unit 27 </ b> A is also electrically connected to the electrode unit 10 through the reactor water flowing between the lid 2 and the electrode unit 10.

本実施例では、銀/塩化銀電極7が基準電極となり、電位検知部27Aと電極部10の間の電位差が電位差計15で測定される。電位差計15は、配線17、再循環系配管18、アダプタ20、センサボディ5及び支持棒12によって電極部10に電気的に接続され、さらに、配線16、リード線8、銀/塩化銀電極7、絶縁体3内に浸入した炉水、及び蓋2に形成された雄ネジと絶縁体3に形成された雌ネジの間の隙間に存在する水によって電位検知部27Aに電気的に接続される。さらに、電位検知部27Aと電極部10、具体的には、電位検知部27Aと各電極棒13が、これらの間に存在する炉水を介して電気的に導通される。このため、電位検知部27Aと電極部10との間に電力線が発生し、電位検知部27Aと材質が再循環系配管18と同じである電極部10の間の電位差が電位差計15で測定される。この測定された電位差に基づいて再循環系配管18の腐食電位が求められる。   In this embodiment, the silver / silver chloride electrode 7 serves as a reference electrode, and the potential difference between the potential detection unit 27A and the electrode unit 10 is measured by the potentiometer 15. The potentiometer 15 is electrically connected to the electrode portion 10 by a wiring 17, a recirculation pipe 18, an adapter 20, a sensor body 5 and a support rod 12, and further, a wiring 16, a lead wire 8, a silver / silver chloride electrode 7. In addition, the reactor water that has entered the insulator 3 and the water present in the gap between the male screw formed on the lid 2 and the female screw formed on the insulator 3 are electrically connected to the potential detector 27A. . Furthermore, the electric potential detection unit 27A and the electrode unit 10, specifically, the electric potential detection unit 27A and each electrode bar 13 are electrically connected through the reactor water existing between them. Therefore, a power line is generated between the potential detection unit 27A and the electrode unit 10, and the potential difference between the potential detection unit 27A and the electrode unit 10 whose material is the same as that of the recirculation pipe 18 is measured by the potentiometer 15. The Based on the measured potential difference, the corrosion potential of the recirculation pipe 18 is obtained.

本実施例の腐食電位線センサ1によれば、電位検知部27Aに最も近接した導体が再循環系配管18ではなく、再循環系配管18と同材質である電極部10となる。このため、電位差計15は、再循環系配管18に形成された、腐食電位センサ1の先端部が挿入された孔部の内面の腐食電位ではなく、その内面よりも電位検知部27Aに近い、再循環系配管18と同材質である電極部10の腐食電位を測定することになる。したがって、腐食電位センサ1は、間隙21の幅にかかわらず、すなわち、炉水が停滞する間隙の影響を低減することができ、再循環系配管18の、流動する炉水が接触する内面の腐食電位を精度良く測定することができる。特に、再循環系配管18内を流れる炉水が、前述したように、電極部10に形成された複数の開口(隣り合う電極棒13の相互間の間隙)を通して流れるので、電位検知部27Aがその流動する炉水に曝される。電位検知部27と電極部10の間に存在する炉水が、流動状態にあって停滞することがないので、再循環系配管18の腐食電位を示す電極部10の腐食電位を精度良く測定することができる。 According to the corrosion potential line sensor 1 of the present embodiment, the conductor closest to the potential detection unit 27A is not the recirculation piping 18 but the electrode portion 10 made of the same material as the recirculation piping 18. For this reason, the potentiometer 15 is not the corrosion potential of the inner surface of the hole formed in the recirculation pipe 18 and into which the tip of the corrosion potential sensor 1 is inserted, but closer to the potential detection unit 27A than the inner surface. The corrosion potential of the electrode part 10 made of the same material as that of the recirculation pipe 18 is measured. Therefore, the corrosion potential sensor 1 can reduce the influence of the gap in which the reactor water stagnate regardless of the width of the gap 21, and corrodes the inner surface of the recirculation pipe 18 that contacts the flowing reactor water. The potential can be measured with high accuracy. In particular, reactor water flowing through the recirculation pipe 18 is, as mentioned above, since the flow through the plurality of openings formed in the electrode portions 10 (the gap between the mutually adjacent electrode rod 13), potential detection Part 27A is exposed to the flowing reactor water. Since the reactor water existing between the potential detection unit 27 and the electrode unit 10 is in a flowing state and does not stagnate, the corrosion potential of the electrode unit 10 indicating the corrosion potential of the recirculation pipe 18 is accurately measured. be able to.

本実施例では、捕捉電極部材11、すなわち、電極部10が蓋2を取り囲んでいるので、何らかの原因で、蓋2が絶縁体3から脱落したとしても、脱落した蓋2を捕捉電極部材11で捕捉することができる。したがって、脱落した蓋2が、再循環系配管18内を流れる炉水の流れにのって運ばれることを防止することができる。絶縁体3が、外部スリーブ4から脱落した場合でも、脱落した外部スリーブ4を、捕捉電極部材11で捕捉することができる。   In this embodiment, since the capture electrode member 11, that is, the electrode portion 10 surrounds the lid 2, even if the lid 2 falls off the insulator 3 for some reason, the fallen lid 2 is removed by the capture electrode member 11. Can be captured. Therefore, it is possible to prevent the dropped lid 2 from being carried along the flow of the reactor water flowing in the recirculation pipe 18. Even when the insulator 3 is detached from the outer sleeve 4, the detached outer sleeve 4 can be captured by the capture electrode member 11.

本実施例は、蓋2に対向する電極部10を、脱落した蓋2を捕捉する電位検知部捕捉手段として用いているので、電極部10と電位検知部捕捉手段を別々に設ける場合に比べて、腐食電位センサ1の構成を単純化することができる。また、電位検知部捕捉手段の構成を、電位検知部27Aと電極部10の間の電位差を計測する電気回路の一部として用いているので、電極部10と電位差計15をつなぐ電気回路の構成を単純化することができる。   In this embodiment, since the electrode unit 10 facing the lid 2 is used as a potential detection unit capturing unit that captures the dropped lid 2, the electrode unit 10 and the potential detection unit capturing unit are provided separately. The configuration of the corrosion potential sensor 1 can be simplified. Further, since the configuration of the potential detection unit capturing means is used as a part of the electrical circuit for measuring the potential difference between the potential detection unit 27A and the electrode unit 10, the configuration of the electrical circuit connecting the electrode unit 10 and the potentiometer 15 Can be simplified.

捕捉電極部材11に相互間に間隙を形成するように配置した複数の電極棒13を用いているので、蓋2と電極部10の間に炉水を容易に供給することができる。また、各支持棒12及び各円環部材14のそれぞれの表面をジルコニア被膜で覆っているので、支持部31を、電極部10と電位差計15をつなぐ電気回路の一部として利用することができる。   Since the plurality of electrode rods 13 arranged so as to form a gap between the capture electrode member 11 are used, the reactor water can be easily supplied between the lid 2 and the electrode portion 10. Moreover, since each surface of each support rod 12 and each annular member 14 is covered with a zirconia film, the support portion 31 can be used as a part of an electric circuit connecting the electrode portion 10 and the potentiometer 15. .

本実施例の腐食電位センサ1の絶縁体3の端面の一部を電極板28に対向させた形状にすることによって、この絶縁体3と蓋2との間でケーシング30の外面に形成される電位検知部27Aを、電極板28に対向させることも可能である。   By forming a part of the end face of the insulator 3 of the corrosion potential sensor 1 of this embodiment so as to face the electrode plate 28, it is formed on the outer surface of the casing 30 between the insulator 3 and the lid 2. It is also possible to make the potential detector 27A face the electrode plate 28.

本実施例の腐食電位センサ1は、沸騰水型原子力プラントの他の配管(例えば、原子炉浄化系配管、原子炉の底部に接続されたドレン配管及び給水配管等)に設置して該当する配管の腐食電位の測定に用いることができる。さらに、加圧水型原子力プラント及び火力プラントにおける配管等の腐食電位の測定にも、使用することができる。   The corrosion potential sensor 1 of the present embodiment is installed in other piping of the boiling water nuclear power plant (for example, reactor purification system piping, drain piping connected to the bottom of the reactor, water supply piping, etc.) and the corresponding piping. It can be used to measure the corrosion potential. Furthermore, it can also be used for measuring the corrosion potential of pipes and the like in pressurized water nuclear plants and thermal power plants.

本発明の他の実施例である実施例2の腐食電位センサを、図6を用いて説明する。本実施例の腐食電位センサ1Aは、特開2009−42111号公報に記載された腐食電位センサの構成を有し、ケーシング30A、捕捉電極部材11及びリード線8を備えている。本実施例で用いるケーシング30Aは、電極29、絶縁体3、外部スリーブ4及びセンサボディ5を有する。ケーシング30Aは、実施例1に用いられるケーシング30において銀/塩化銀電極7を削除して蓋2をジルコニウム製の電極29に替えた構成を有する。   A corrosion potential sensor according to embodiment 2, which is another embodiment of the present invention, will be described with reference to FIG. The corrosion potential sensor 1A of the present embodiment has the configuration of a corrosion potential sensor described in Japanese Patent Application Laid-Open No. 2009-42111, and includes a casing 30A, a capture electrode member 11, and a lead wire 8. A casing 30 </ b> A used in this embodiment includes an electrode 29, an insulator 3, an external sleeve 4, and a sensor body 5. The casing 30A has a configuration in which the silver / silver chloride electrode 7 is deleted from the casing 30 used in the first embodiment and the lid 2 is replaced with an electrode 29 made of zirconium.

基準電極である電極29は、絶縁体3の端部に取り付けられ、絶縁体3を密封する。リード線8が電極29に接続される。本実施例の腐食電位センサ1Aの他の構成は、腐食電位センサ1と同じである。本実施例の腐食電位センサ1Aも、腐食電位センサ1と同様に、再循環系配管18の測定用座19に取り付けられ、測定用座19内に配置される。本実施例では、電極29の外面が電位検知部27Bになる。電極部10の電極板28が電極29の端面と所定間隔をおいて配置され、各電極棒13が電極29の側面と所定間隔をおいて配置される。電極部10の電極板28及び各電極棒13が、電位検知部27Bと対向している。   The reference electrode 29 is attached to the end of the insulator 3 and seals the insulator 3. Lead wire 8 is connected to electrode 29. Other configurations of the corrosion potential sensor 1A of the present embodiment are the same as those of the corrosion potential sensor 1. Similarly to the corrosion potential sensor 1, the corrosion potential sensor 1 </ b> A of the present embodiment is attached to the measurement seat 19 of the recirculation pipe 18 and is disposed in the measurement seat 19. In the present embodiment, the outer surface of the electrode 29 becomes the potential detection unit 27B. The electrode plate 28 of the electrode unit 10 is disposed at a predetermined interval from the end surface of the electrode 29, and each electrode bar 13 is disposed at a predetermined interval from the side surface of the electrode 29. The electrode plate 28 and each electrode bar 13 of the electrode unit 10 are opposed to the potential detection unit 27B.

本実施例も、実施例1と同様に、捕捉電極部材11を備えているので、実施例1で生じる各効果を得ることができる。捕捉電極部材11は、絶縁体3から脱落した電極29を、実施例1における脱落した蓋2と同様に、捕捉する。さらに、捕捉電極部材11は、外部スリーブ4から脱落した絶縁体3及び電極29も捕捉することができる。   Since this embodiment also includes the capture electrode member 11 as in the first embodiment, each effect produced in the first embodiment can be obtained. The capture electrode member 11 captures the electrode 29 dropped from the insulator 3 in the same manner as the lid 2 dropped in the first embodiment. Furthermore, the capture electrode member 11 can also capture the insulator 3 and the electrode 29 that have fallen from the external sleeve 4.

本発明の他の実施例である実施例3の腐食電位センサを、図7及び図8を用いて説明する。本実施例の腐食電位センサ1Bは、特開2000−65785号公報に開示された腐食電位センサの構成を有し、ケーシング30B、リード線8及び捕捉電極部材11Aを備えている。本実施例で用いるケーシング30Bは、電極、絶縁体3A及びセンサボディ5を有する。   A corrosion potential sensor according to embodiment 3, which is another embodiment of the present invention, will be described with reference to FIGS. The corrosion potential sensor 1B of the present embodiment has the configuration of a corrosion potential sensor disclosed in Japanese Patent Laid-Open No. 2000-65785, and includes a casing 30B, a lead wire 8, and a capture electrode member 11A. The casing 30 </ b> B used in this embodiment includes an electrode, an insulator 3 </ b> A, and a sensor body 5.

絶縁体3Aは、酸化ジルコニウム(ジルコニア)で作られ、一端が開放されて一端が閉じられた管状の形状(試験管状の形状)を有している。絶縁体3Aは酸素イオンに対しては固体電解質として作用し、酸素イオンを介して外部と腐食電位センサ1Bの内部は平衡が成立する。絶縁体3Aの開放端部が、センサボディ5内に挿入されてセンサボディ5にロウ付けにより接合されている。腐食電位センサ1Bの基準電位を発生する電極は、白金粉末23、銀ワイヤ24及び酸化銀粉末25を有する。白金粉末23、銀ワイヤ24及び酸化銀粉末25は、一端が閉じられた絶縁体3A内に配置され、白金粉末23が絶縁体3Aの閉じられた端部に配置され、酸化銀粉末25の充填層が白金粉末23の充填層の隣に配置される。   The insulator 3A is made of zirconium oxide (zirconia), and has a tubular shape (test tubular shape) in which one end is opened and the other end is closed. The insulator 3A acts as a solid electrolyte for oxygen ions, and an equilibrium is established between the outside and the inside of the corrosion potential sensor 1B via the oxygen ions. The open end of the insulator 3A is inserted into the sensor body 5 and joined to the sensor body 5 by brazing. The electrode that generates the reference potential of the corrosion potential sensor 1 </ b> B includes a platinum powder 23, a silver wire 24, and a silver oxide powder 25. The platinum powder 23, the silver wire 24, and the silver oxide powder 25 are disposed in the insulator 3A that is closed at one end, and the platinum powder 23 is disposed at the closed end of the insulator 3A to fill the silver oxide powder 25. A layer is placed next to the packed bed of platinum powder 23.

酸化銀粉末25は腐食電位センサ1A内で酸素分圧を一定に保つために用いられている。高温で酸化銀の一部が銀と酸素に分解する。腐食電位センサ1B内は体積が一定であるため、ある酸素分圧で銀と酸素が結合して酸化銀が形成される反応が無視できない速度となって平衡となる。この結果、酸化銀、銀及び酸素は使用温度の下で平衡となって酸素分圧が一定に保たれる。このような酸素分圧を一定にする作用は、酸化銀の他、ニッケル/酸化ニッケル、鉄/酸化鉄、水銀/酸化水銀などの金属と金属酸化物の組み合わせによっても得られる。酸素分圧の高い系が好ましいが、分解しやすいと腐食電位センサが不安定となる。   The silver oxide powder 25 is used to keep the oxygen partial pressure constant in the corrosion potential sensor 1A. Part of silver oxide decomposes into silver and oxygen at high temperatures. Since the volume in the corrosion potential sensor 1B is constant, the reaction in which silver and oxygen are combined to form silver oxide at a certain partial pressure of oxygen is balanced at a non-negligible rate. As a result, silver oxide, silver and oxygen are equilibrated at the operating temperature and the oxygen partial pressure is kept constant. Such an action of making the oxygen partial pressure constant can be obtained by a combination of a metal oxide such as nickel / nickel oxide, iron / iron oxide, mercury / mercury oxide and the like in addition to silver oxide. A system having a high oxygen partial pressure is preferable, but if it is easily decomposed, the corrosion potential sensor becomes unstable.

また、白金粉末23は絶縁体3Aを通して腐食電位センサ1A内に入ってきた酸素イオンが速やかに電子を得て酸素イオンとなる触媒作用と、酸素イオンと電子を反応させることによってその位置で電流を集める集電作用とを担っている。   In addition, the platinum powder 23 has a catalytic action in which oxygen ions that have entered the corrosion potential sensor 1A through the insulator 3A quickly obtain electrons to become oxygen ions, and react the oxygen ions and electrons to generate a current at that position. It is responsible for collecting current.

白金粉末23及び酸化銀粉末25のそれぞれの充填層は、絶縁体3Aの内面に接触している。白金粉末23の充填部が位置する絶縁体3Aの先端部の外面は、曲面を有し、半球面形状になっている。絶縁体3Aの開放端部が、絶縁体3A内に挿入されたサファイヤピストン(封鎖部材)26によって封鎖される。サファイヤピストン26は、絶縁体3Aに固定され、白金粉末23の充填層及び酸化銀粉末25の充填層を保持する。銀ワイヤ24は酸化銀粉末25の充填層内に配置される。サファイヤピストン26を貫通して酸化銀粉末25の充填層に達したリード線8は、銀ワイヤ24に接続される。実施例1と同様に、センサボディ5に取り付けられた鉱物絶縁ケーブル17は、リード線8を含んでいる。   Each filled layer of the platinum powder 23 and the silver oxide powder 25 is in contact with the inner surface of the insulator 3A. The outer surface of the distal end portion of the insulator 3A where the filling portion of the platinum powder 23 is located has a curved surface and has a hemispherical shape. The open end of the insulator 3A is sealed by a sapphire piston (blocking member) 26 inserted into the insulator 3A. The sapphire piston 26 is fixed to the insulator 3 </ b> A and holds a packed layer of platinum powder 23 and a packed layer of silver oxide powder 25. The silver wire 24 is disposed in a packed layer of silver oxide powder 25. The lead wire 8 that passes through the sapphire piston 26 and reaches the packed layer of the silver oxide powder 25 is connected to the silver wire 24. Similar to the first embodiment, the mineral insulated cable 17 attached to the sensor body 5 includes a lead wire 8.

本実施例における電位検知部27Cは、白金粉末23の充填部が接触する、絶縁体3Aの内面と相対する、絶縁体3Aの外面であり、前述の先端部の外面である半球面を含んでいる。   The potential detection unit 27C in the present embodiment is an outer surface of the insulator 3A facing the inner surface of the insulator 3A with which the filling portion of the platinum powder 23 comes into contact, and includes a hemispherical surface that is an outer surface of the tip portion described above. Yes.

捕捉電極部材11Aは、図8に示すように、電極部10A及び支持部31を有する。電極部10Aは金網状の電極22を含んでいる。支持部31は、実施例1と同様に、複数の支持棒12及び複数の円環部材14を有する。電極22、各支持棒12及び各円環部材14は、腐食電位センサ1Bに対する腐食電位測定対象物である再循環系配管18と同じ材質であるSUS316L鋼製である。金網状の電極22は、絶縁体3Aの先端部(電位検知部27C)と同様に半球面形状をしており、絶縁体3Aの先端部を覆っている。このため、絶縁体3Aの先端部の外面と電極22の間の寸法は、絶縁体3Aの先端部全体に亘って等しくなっている。   The capture electrode member 11A includes an electrode portion 10A and a support portion 31 as shown in FIG. The electrode portion 10 </ b> A includes a wire mesh electrode 22. The support portion 31 includes a plurality of support rods 12 and a plurality of annular members 14 as in the first embodiment. The electrode 22, each support rod 12, and each annular member 14 are made of SUS316L steel, which is the same material as the recirculation pipe 18 that is a corrosion potential measurement object for the corrosion potential sensor 1B. The wire mesh electrode 22 has a hemispherical shape similar to the tip of the insulator 3A (potential detector 27C), and covers the tip of the insulator 3A. For this reason, the dimension between the outer surface of the front-end | tip part of 3 A of insulators and the electrode 22 is equal over the whole front-end | tip part of 3 A of insulators.

電極22は金属面が露出している。支持部31の全表面には、プラズマコーティング法によりジルコニア被膜が形成されている。   The electrode 22 has a metal surface exposed. A zirconia film is formed on the entire surface of the support portion 31 by a plasma coating method.

電極22の金属露出面を腐食電位測定対象物である再循環系配管18の炉水と接触する内面と同じ状態にするために、それらの金属露出表面に、予め、沸騰水型原子力プラントの炉水を模擬した溶存酸素濃度300ppbの模擬水を500hr以上接触させる予備酸化処理を施す。この処理により、酸化皮膜が、電極22の金属露出面に予め形成される。   In order to make the exposed metal surface of the electrode 22 the same as the inner surface of the recirculation system pipe 18 that is the object of corrosion potential measurement that is in contact with the reactor water, the exposed metal surface is preliminarily provided with a furnace of a boiling water nuclear power plant. A pre-oxidation treatment is performed in which simulated water having a dissolved oxygen concentration of 300 ppb simulating water is brought into contact with 500 hours or more. By this treatment, an oxide film is formed in advance on the metal exposed surface of the electrode 22.

本実施例における原子力プラントでの腐食電位センサ1Bの設置構造を説明する。本実施例のその設置構造は、実施例1と同様に、腐食電位センサ1Bのセンサボディ5が、再循環系配管18に取り付けられた測定用座19にアダプタ20を介して取り付けられる。腐食電位センサ1Bは測定用座19内に挿入され、腐食電位センサ1Bの先端部、すなわち、絶縁体3Aの先端部(半球面になっている部分)が、再循環系配管18に形成された孔部内に配置されており、絶縁体3Aの先端(半球面部の頂点)が、再循環系配管18の半径方向において、再循環系配管18の内面の位置に配置される。実施例1と同様に、リード線8が配線16により電位差計15に接続され、再循環系配管18に接続された配線17も電位差計15に接続される。   The installation structure of the corrosion potential sensor 1B in the nuclear power plant in the present embodiment will be described. In the installation structure of this embodiment, the sensor body 5 of the corrosion potential sensor 1B is attached to the measurement seat 19 attached to the recirculation system pipe 18 via the adapter 20 as in the first embodiment. The corrosion potential sensor 1B is inserted into the measurement seat 19, and the tip of the corrosion potential sensor 1B, that is, the tip of the insulator 3A (portion that is a hemispherical surface) is formed in the recirculation system pipe 18. The tip of the insulator 3 </ b> A (the apex of the hemispherical surface portion) is disposed at the position of the inner surface of the recirculation system pipe 18 in the radial direction of the recirculation system pipe 18. As in the first embodiment, the lead wire 8 is connected to the potentiometer 15 by the wiring 16, and the wiring 17 connected to the recirculation system pipe 18 is also connected to the potentiometer 15.

実施例1と同様に、電極22が、電位検知部である絶縁体3Aと、再循環系配管18に形成された孔部の内面の間に形成された環状の間隙21内に配置されて、その孔部の内面よりも絶縁体3A側に配置されている。   As in the first embodiment, the electrode 22 is disposed in an annular gap 21 formed between the insulator 3A as a potential detection unit and the inner surface of the hole formed in the recirculation system pipe 18, It is arranged closer to the insulator 3A than the inner surface of the hole.

このような本実施例も、実施例1で生じる各効果を得ることができる。   Such a present Example can also obtain each effect which arises in Example 1. FIG.

実施例2及び3も、実施例1と同様に、沸騰水型原子力プラントの他の配管(例えば、原子炉浄化系配管、原子炉の底部に接続されたドレン配管及び給水配管等)に設置して該当する配管の腐食電位の測定に用いることができ、さらに、加圧水型原子力プラント及び火力プラントにおける配管等の腐食電位の測定にも、使用することができる   In the same manner as in Example 1, Examples 2 and 3 are also installed in other piping of the boiling water nuclear power plant (for example, reactor purification system piping, drain piping connected to the bottom of the reactor, water supply piping, etc.). Can be used to measure the corrosion potential of the corresponding pipes, and can also be used to measure the corrosion potential of pipes in pressurized water nuclear plants and thermal power plants.

1,1A,1B…腐食電位センサ、2…蓋、3,3A…絶縁体、4…外部スリーブ、5…センサボディ、6…内部スリーブ、7…銀/塩化銀電極、8…リード線、10,10A…電極部、11,11A…捕捉電極部材、12…支持棒、13…電極棒、14…円環部材、15…電位差計、16,17…配線、18…再循環系配管、19…測定用座、21…間隙、22,29…電極、23…白金粉末、24…銀ワイヤ、25…酸化銀粉末、27A,27B,27C…電位検出部、28…電極板、30,30A,30B…ケーシング、31…支持部。   DESCRIPTION OF SYMBOLS 1,1A, 1B ... Corrosion potential sensor, 2 ... Cover, 3, 3A ... Insulator, 4 ... External sleeve, 5 ... Sensor body, 6 ... Internal sleeve, 7 ... Silver / silver chloride electrode, 8 ... Lead wire, 10 , 10A ... electrode part, 11, 11A ... capture electrode member, 12 ... support rod, 13 ... electrode rod, 14 ... annular member, 15 ... potentiometer, 16, 17 ... wiring, 18 ... recirculation piping, 19 ... Measurement seat, 21 ... gap, 22, 29 ... electrode, 23 ... platinum powder, 24 ... silver wire, 25 ... silver oxide powder, 27A, 27B, 27C ... potential detection unit, 28 ... electrode plate, 30, 30A, 30B ... casing, 31 ... support part.

Claims (7)

ケーシングと、前記ケーシング内に形成された空間内、及び前記ケーシングの一部として前記ケーシングの端部、のいずれかに配置された基準電極と、前記基準電極に接続された第1導線と、前記ケーシングの外面に形成される電位検知部と、前記ケーシングの外面から離れた状態で前記電位検知部に対向して前記ケーシングの外部に配置された電極部材とを備え、
前記ケーシングが筒状の金属部材及び前記金属部材に取り付けられて少なくとも前記電位検知部と前記金属部材の間に配置された絶縁部材とを有し、前記電極部材が前記金属部材に取り付けられ、前記ケーシングが腐食電位測定対象物に取り付けられたときに前記電極部材に形成された複数の開口が前記腐食電位測定対象物の表面に接触する水が通るように配置され、前記電極部材の前記電位検知部に対向する部分が、前記腐食電位測定対象物と同じ材質で構成され、電位差計が前記ケーシングの外部で前記第1導線に接続され、前記腐食電位測定対象物に接続される第2導線が前記電位差計に接続されることを特徴とする腐食電位センサ。
A reference electrode disposed in one of a casing, a space formed in the casing, and an end portion of the casing as a part of the casing; a first conductor connected to the reference electrode; A potential detection unit formed on the outer surface of the casing; and an electrode member disposed outside the casing so as to face the potential detection unit in a state of being separated from the outer surface of the casing.
The casing has a cylindrical metal member and an insulating member that is attached to the metal member and disposed at least between the potential detection unit and the metal member, and the electrode member is attached to the metal member, When the casing is attached to the corrosion potential measurement object, the plurality of openings formed in the electrode member are arranged so that water that contacts the surface of the corrosion potential measurement object passes, and the potential detection of the electrode member A portion facing the portion is made of the same material as the object for measuring corrosion potential , a potentiometer is connected to the first conductor outside the casing, and a second conductor connected to the object for measuring corrosion potential is A corrosion potential sensor connected to the potentiometer .
前記電極部材が、前記絶縁部材の前記金属部材への取り付け部から前記絶縁部材側で、前記ケーシングの、前記電位検知部を含む先端部を覆っている捕捉電極部材である請求項1に記載の腐食電位センサ。   2. The capture electrode member according to claim 1, wherein the electrode member is a capture electrode member that covers a tip portion including the potential detection portion of the casing on the insulating member side from an attachment portion of the insulating member to the metal member. Corrosion potential sensor. 前記ケーシングが、前記金属部材、及び前記絶縁部材である第1絶縁部材と共に、前記第1絶縁部材の端部に取り付けられて前記第1絶縁部材との間に前記電位検知部を形成する第2絶縁部材を有しており、
基準電極が前記第1絶縁部材内に配置され、
前記基準電極が配置された前記第1絶縁部材内の領域を封鎖する封鎖部材が、前記金属部材内に配置されて前記第1絶縁部材に取り付けられ、
前記基準電極に接続された第1導線が、前記封鎖部材を通って前記金属部材の外部に達している請求項2に記載の腐食電位センサ。
The casing is attached to an end portion of the first insulating member together with the metal member and the first insulating member which is the insulating member to form the potential detecting unit between the casing and the first insulating member. Has an insulating member,
A reference electrode is disposed in the first insulating member;
A sealing member for sealing a region in the first insulating member in which the reference electrode is disposed is disposed in the metal member and attached to the first insulating member;
The corrosion potential sensor according to claim 2, wherein the first conductive wire connected to the reference electrode reaches the outside of the metal member through the sealing member.
前記ケーシングが、前記金属部材及び前記絶縁部材と共に、前記絶縁部材の端部に取り付けられて前記絶縁部材を封鎖し、外面が前記電位検知部になる基準電極を有しており、 前記基準電極に接続された第1導線が、前記絶縁部材内及び前記金属部材内に配置されて前記金属部材の外部に達している請求項2に記載の腐食電位センサ。   The casing has a reference electrode attached to an end of the insulating member together with the metal member and the insulating member to seal the insulating member, and an outer surface serving as the potential detection unit. The corrosion potential sensor according to claim 2, wherein the connected first conducting wire is disposed in the insulating member and in the metal member and reaches the outside of the metal member. 前記捕捉電極部材が、前記電位検知部を含む先端部を覆っている電極部、及び前記電極部を前記金属部材に取り付ける支持部を有し、絶縁被膜が前記支持部の表面に形成されている請求項2ないしのいずれか1項に記載の腐食電位センサ。 The capture electrode member has an electrode part covering a tip part including the potential detection part, and a support part for attaching the electrode part to the metal member, and an insulating film is formed on the surface of the support part The corrosion potential sensor according to any one of claims 2 to 4 . 前記絶縁被膜が、ジルコニア、アルミナ、サファイヤ及びダイヤモンドの中から選ばれた少なくとも1種の物質で形成される請求項に記載の腐食電位センサ。 The corrosion potential sensor according to claim 5 , wherein the insulating coating is formed of at least one material selected from zirconia, alumina, sapphire, and diamond. 請求項1ないしのいずれか1項に記載された腐食電位センサが、プラントの、前記腐食電位測定対象物である構造部材に設置した筒状の支持座に取り付けられて前記支持座内に配置されており、
前記ケーシングの、前記支持座内に位置する部分の先端が、前記腐食電位センサの軸方向において、前記構造部材の水と接触する表面の位置に配置され、
前記ケーシングの、前記支持座内に位置する部分の先端部が前記構造部材に形成された孔部内に挿入された状態で、前記電極部材が、前記孔部の内面よりも前記腐食電位センサの中心軸側に配置されることを特徴とする腐食電位センサの設置構造。
Disposed corrosion potential sensor according to any one of claims 1 to 5, of the plant, the corrosion potential measured object placed on the structural member is a cylindrical attached to the support seat and the support seat in Has been
The tip of the portion of the casing located in the support seat is disposed at a surface position in contact with water of the structural member in the axial direction of the corrosion potential sensor.
In the state where the tip portion of the casing located in the support seat is inserted into the hole formed in the structural member, the electrode member is located in the center of the corrosion potential sensor rather than the inner surface of the hole. Corrosion potential sensor installation structure characterized by being arranged on the shaft side.
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