A method for alleviating stress corrosion of primary circuit structure materials of PWR

Abstract

The invention belongs to the technical field of reactor engineering stress corrosion, and discloses a method for alleviating stress corrosion of a pressurized-water-reactor primary-loop structure material. The method comprises adding a noble metal salt solution into a coolant of a pressurized-water-reactor primary loop, wherein the concentration scope of the noble metal salt solution in the coolant is 10-1000 mu g / Kg, the injection amount is 1-100 mu g / day, and the noble metal salt solution is a salt solution of one or a mixture of Pt and Rh. The method possesses the advantages of being capable of alleviating the electrochemical corrosion potential at the surface of the pressurized-water-reactor primary-loop structure material, improving the stress corrosion resistance of the structure material and prolonging the service life of the structure material.

Description

technical field

[0001] The invention belongs to the technical field of reactor engineering stress corrosion, and in particular relates to a method for alleviating stress corrosion of primary circuit structural materials of a pressurized water reactor. Background technique

[0002] The materials used in key components of nuclear power plant reactors mainly include nickel-based alloys, low-alloy steels, stainless steels, and zirconium alloys. However, the selected materials also vary with the reactor type. For example, the nickel-based alloy heat transfer tubes in the PWR account for about 75% of the surface area of ​​the primary circuit, while the structural materials of the key components of the BWR are mainly stainless steel and low-alloy steel. These materials will produce various forms of corrosion damage in harsh operating environments such as high temperature, high pressure, and high radiation, including stress corrosion cracking (SCC), corrosion fatigue (CF), intergran...

Examples

Embodiment 1

[0030] A method for alleviating the stress corrosion of structural materials of the primary circuit of a pressurized water reactor, the method is:

[0031] (1) Under the thermal shutdown condition of the PWR, the micro-metering pump is used to add sodium hexahydroxyplatinate (Na 2 Pt(OH) 6 ) solution, and set up electrochemical monitoring systems to monitor the electrochemical corrosion potential at the topcharging system, the core, the cold legs of the main pipeline, and the blowdown outlet of the main steam generator; The corrosion potential is greater than -300mV (standard hydrogen electrode potential), and the noble metal salt solution is continuously added again; the electrochemical test system mainly includes an electrochemical workstation, a working electrode, a Cu / CuO reference electrode and a Pt sheet auxiliary electrode, and the working electrode is the monitoring electrode. The main structural material itself.

[0032] 2) Stop injecting sodium hexahydroxyplatinate...

Embodiment 2

[0038] Different from Example 1, the noble metal salt solution is added through an independent injection system, and the noble metal salt solution is sodium hexahydroxyrhodium solution (Na 2 Rh(OH) 6 ). The concentration range of the noble metal salt solution in the coolant is 200 μg / kg, and the injection amount is 20 μg / day.

[0039] The independent injection system includes a precious metal salt solution storage tank, a micrometering pump, a circulation pump, and corresponding pipelines and valves.

Embodiment 3

[0041] The difference from Example 1 is that the noble metal salt solution added is a mixed solution of sodium hexahydroxyrhodate solution and sodium hexahydroxyplatinate solution in a ratio of 1:1. The concentration range of the noble metal salt solution in the coolant is 500 μg / kg, and the injection amount is 50 μg / day.

technical field

[0001] The invention belongs to the technical field of reactor engineering stress corrosion, and in particular relates to a method for alleviating stress corrosion of primary circuit structural materials of a pressurized water reactor. Background technique

[0002] The materials used in key components of nuclear power plant reactors mainly include nickel-based alloys, low-alloy steels, stainless steels, and zirconium alloys. However, the selected materials also vary with the reactor type. For example, the nickel-based alloy heat transfer tubes in the PWR account for about 75% of the surface area of ​​the primary circuit, while the structural materials of the key components of the BWR are mainly stainless steel and low-alloy steel. These materials will produce various forms of corrosion damage in harsh operating environments such as high temperature, high pressure, and high radiation, including stress corrosion cracking (SCC), corrosion fatigue (CF), intergran...

Examples

Embodiment 1

[0030] A method for alleviating the stress corrosion of structural materials of the primary circuit of a pressurized water reactor, the method is:

[0031] (1) Under the thermal shutdown condition of the PWR, the micro-metering pump is used to add sodium hexahydroxyplatinate (Na 2 Pt(OH) 6 ) solution, and set up electrochemical monitoring systems to monitor the electrochemical corrosion potential at the topcharging system, the core, the cold legs of the main pipeline, and the blowdown outlet of the main steam generator; The corrosion potential is greater than -300mV (standard hydrogen electrode potential), and the noble metal salt solution is continuously added again; the electrochemical test system mainly includes an electrochemical workstation, a working electrode, a Cu / CuO reference electrode and a Pt sheet auxiliary electrode, and the working electrode is the monitoring electrode. The main structural material itself.

[0032] 2) Stop injecting sodium hexahydroxyplatinate...

Embodiment 2

[0038] Different from Example 1, the noble metal salt solution is added through an independent injection system, and the noble metal salt solution is sodium hexahydroxyrhodium solution (Na 2 Rh(OH) 6 ). The concentration range of the noble metal salt solution in the coolant is 200 μg / kg, and the injection amount is 20 μg / day.

[0039] The independent injection system includes a precious metal salt solution storage tank, a micrometering pump, a circulation pump, and corresponding pipelines and valves.

Embodiment 3

[0041] The difference from Example 1 is that the noble metal salt solution added is a mixed solution of sodium hexahydroxyrhodate solution and sodium hexahydroxyplatinate solution in a ratio of 1:1. The concentration range of the noble metal salt solution in the coolant is 500 μg / kg, and the injection amount is 50 μg / day.