Electromagnetic fields measurement and safety consideration in magnetic confinement fusion test facilities

The environmental electromagnetic fields were measured around a magnetic confinement fusion test facility namely Large Helical Device (LHD) which is equipped with large superconducting magnet coils system and high-power plasma heating systems of Neutral Beam Injection, Electron Cyclotron resonance Heating and Ion Cyclotron Range of Frequencies (ICRF) heating. The leakage of the static magnetic field from the LHD was less than 1.2 mT, and it varied according to the coil operation. The extremely low frequency electromagnetic field was measured around power supply units for the coil system, and the magnetic field of higher than the guideline level of the International Commission on Nonionizing Radiation Protection (ICNIRP) was predicted. Leakage of high frequency electromagnetic field from the ICRF was observed in bursts according to plasma shots. The measured values were less than the occupational guideline levels. Although the electromagnetic fields were less than the regulation levels, more monitoring survey is necessary from the view point of occupational safety. (author)