The following is the radiation doses of the exhaust air released from the exhaust stacks measured by the exhaust stack monitors on the premises of Fukushima Daiichi Nuclear Power Station.

Monitoring points

Monitoring point

Radiation dose

Radiation dose
  • *There are some cases that wind direction and speed at the exhaust stacks cannot be measured properly due to storm


  • *On March 30, 2021, archives were updated. Please click “Past measurement results (on and after March 25, 2021) are found here” for additional archives.
  • *The monitoring equipments on the Unit 1 to 4 exhaust stacks are currently out of use due to the accident.
  • *Data may be missing due to regular inspection or cleanup work.

Exhaust stack

An exhaust stack is a facility to release the air inside the building at the power station and the exhaust gas enerated by vacuuming the condenser. Unlike a regular chimney, the air used inside the building is released from the exhaust stack. As the released air contains a small amount of radioactive materials, an activated carbon type noble gas hold-up device and filters are used to mitigate its impact on the environment.

Exhaust stack monitor

An exhaust stack monitor is an equipment to measure the radiation dose of the air released from the power station to the environment.

Measurement unit: cps (count per second)

1 cps represents that 1 radiation ray was measured in 1 second by a radiation counter.

to TOP

  1. HOME
  2. Our Responsibilities to Fukushima
  3. Fukushima Daiichi decommissioning project
  4. Data
  5. Monitoring
  6. Radiation Dose measured at exhaust stack monitor of Fukushima Daiichi Nuclear Power Station