The detection of radioactivity risks of tungsten electrodes is mainly for thorium tungsten electrodes (WT series), because the radioactive element thorium (ThO₂) is added to this type of electrode, which has a certain α radioactivity. Other doped electrodes such as lanthanum tungsten, cerium tungsten, and zirconium tungsten usually do not contain radioactive elements or only trace amounts, which can be ignored.
The following are the methods for detecting and assessing the radioactivity risk of tungsten electrodes:
- Determine The Type Of Electrode (first Step)
First confirm whether it is a thorium tungsten electrode:
The model number is WT10, WT20 (i.e. contains 1% and 2% thorium);
The appearance is mostly a red logo ring (international standard);
From regular manufacturers, the packaging is usually marked with “containing thorium”.
If it is not a thorium tungsten electrode (such as WL, WC, WZ series), the radioactivity risk is extremely low.
- Physical Detection Methods
- Geiger Counter
It can directly detect whether there is α, β or γ rays on the electrode surface;
Suitable for initial screening, portable and fast;
Thorium tungsten electrodes can measure high count values at close range.
- Scintillation counter or NaI detector
Higher sensitivity, which can quantitatively detect the γ radiation dose of the electrode;
It can be used in conjunction with energy spectrometers to identify radionuclide species (such as ²³²Th);
Suitable for use in laboratories or security inspection departments.
- α or γ spectrum analyzer
Laboratory-grade analytical equipment can accurately determine the concentration of radionuclides;
It can be used to determine whether it meets international safety limits (e.g., ISO, IAEA standards).
- Chemical Analysis (professional Laboratory Required)
The content of radioactive elements can be analyzed by dissolving the sample;
For example, ICP-MS (inductively coupled plasma mass spectrometry) is used for the quantitative detection of Th content;
Used to calibrate the relationship between material composition and radioactive strength.
- Reference Standards And Limits
IAEA standards stipulate:
If the activity concentration of thorium-containing materials exceeds 1 Bq/g, it should be classified as a controlled radioactive source.
The EU REACH regulation has strict restrictions on thorium-containing products;
ISO 6848 standard (materials for welding tungsten electrodes):
Clearly mark the thorium tungsten electrode as a radioactive material, and pay attention to ventilation and waste management.
- Risk Protection Suggestions
If confirmed to be a thorium tungsten electrode:
Wear gloves and maintain good ventilation when using;
To avoid inhaling dust during the grinding process, the grinding should be carried out in a closed dust collection device;
Waste thorium and tungsten should be managed as radioactive solid waste;
If exposure to large amounts or long-term use is possible, the operator’s radiation dose should be evaluated periodically.
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