JP2015028433A5

JP2015028433A5 -

Info

Publication number: JP2015028433A5
Application number: JP2013157455A
Authority: JP
Filing date: 2013-07-30
Publication date: 2016-02-25
Anticipated expiration: 2033-07-30

Description

上記した目的を達成する本発明の特徴は、冷却水に接する原子力プラントの構造部材の測定点においてその構造部材に取り付けられた保持部材に設けられてその構造部材と同じ材料で作られた一対の電極間に、冷却水が一対の電極の表面に接触している状態で、交流電圧を印加し、一対の電極間に交流電圧を印加しながら一対の電極間の第１交流インピーダンスを測定し、測定された第１交流インピーダンス、および予め求められている、電極に形成された貴金属被覆部の第２交流インピーダンスに基づいて、貴金属被覆部の面積を求め、求められた貴金属被覆部の面積に基づいて、測定点における構造部材の貴金属被覆率である電極の表面における貴金属被覆率を求めることにある。 A feature of the present invention that achieves the above-described object is that a pair of members made of the same material as the structural member provided at a holding member attached to the structural member at a measurement point of the structural member of the nuclear power plant in contact with the cooling water. While the cooling water is in contact with the surfaces of the pair of electrodes between the electrodes, an AC voltage is applied, and the first AC impedance between the pair of electrodes is measured while the AC voltage is applied between the pair of electrodes. Based on the measured first AC impedance and the second AC impedance of the noble metal coating portion formed on the electrode, which is obtained in advance, the area of the noble metal coating portion is obtained, and based on the obtained area of the noble metal coating portion. Thus, the precious metal coverage on the surface of the electrode, which is the precious metal coverage of the structural member at the measurement point, is obtained.

Claims

At a measurement point of a structural member of a nuclear power plant in contact with the cooling water, the cooling water is provided between the pair of electrodes provided on a holding member attached to the structural member and made of the same material as the structural member. Apply AC voltage in contact with the surface of
Measuring the first AC impedance between the pair of electrodes while applying the AC voltage between the pair of electrodes;
Based on the measured first AC impedance and the second AC impedance of the noble metal coating formed on the electrode, which is obtained in advance, the area of the noble metal coating is obtained,
Based on the area of the precious metal coating portion obtained, precious metal coverage monitoring method characterized by obtaining a noble metal coverage on the surface of the electrode is a noble metal coverage of the structural member in the measuring point.

Obtaining the area of the noble metal coating portion is performed based on the obtained resistance of the noble metal coating portion and the second AC impedance of the noble metal coating portion obtained using the first AC impedance. The precious metal coverage monitoring method according to claim 1.

The structural member is a pipe connected to a nuclear reactor pressure vessel of the nuclear power plant, and the holding member provided with the pair of electrodes communicates with the pipe to an electrode supporting tubular member attached to the pipe. The precious metal coverage obtained is a precious metal coverage of the pipe when the pair of electrodes are arranged in the electrode support tubular member and are in contact with the cooling water flowing through the pipe. The precious metal coverage monitoring method according to 1.

The noble metal coverage monitoring method according to claim 1, wherein the corrosion potential of the structural member at the measurement point is measured by a corrosion potential sensor arranged at the measurement point.

The structural member is a neutron detector disposed in a nuclear reactor pressure vessel of the nuclear power plant, and when the pair of electrodes provided on the holding member is disposed in the neutron detector, The precious metal coverage monitoring method according to claim 1, wherein the required precious metal coverage is a precious metal coverage of the neutron detector.

A pair of electrodes attached to the holding member so as to face each other, a potentiostat connected to each electrode by a lead wire, a frequency response analyzer connected to the potentiostat, and output from the frequency response analyzer A first arithmetic unit for determining an area of the noble metal coating portion based on a first AC impedance and a second AC impedance of the noble metal coating portion formed on the surface of the electrode stored in a storage device, and the noble metal coating A noble metal coverage monitoring apparatus, comprising: a second arithmetic unit that obtains a noble metal coverage on the surface of the electrode based on an area of the portion.

The noble metal coverage monitoring apparatus according to claim 6, wherein an interval between the pair of electrodes is in a range of 0.5 to 3.0 mm.

The noble metal coverage monitoring apparatus according to claim 6, wherein a sensor measurement unit of a corrosion potential sensor is attached to the holding member.

When the precious metal coverage obtained by the precious metal coverage monitoring method according to any one of claims 1 to 5 is less than a set precious metal coverage, precious metal is added to cooling water in a reactor pressure vessel of a nuclear power plant. Injecting and stopping the injection of the noble metal into the cooling water when the precious metal coverage is equal to or higher than the set precious metal coverage.