The following is the radiation doses of the air measured by the monitoring posts (MP1-8) at Fukushima Daiichi Nuclear Power Station.

Monitoring post (MP1 - MP8)

Monitoring points

Monitoring points

Radiation dose

Radiation dose
  • *

    Wind direction and wind speed are measured at the same level as the top of the exhaust stack by the weather measuring device on the west side of the seismic isolation building.

  • *

    In case of heavy rain, wind direction and wind speed may not be measured accurately.

  • *

    In the case that wind speed is less than 0.5 m/s, wind direction is shown as “-“ and wind speed is shown as “CALM”

Relationship between weather and radiation

Radiation dose in the air varies depending on the weather. Generally, radiation dose increases when it rains due to natural radioactive materials falling onto the ground surface. On the other hand, radiation dose decreases in locations where puddles (due to rainfall) and accumulated snow are present as radiation from the ground is blocked by water and snow.


  • *The data taken from 00:00~23:50 will be posted on our homepage at 00:10 next day as "The past measurement results (from October 17, 2012).
  • *As of 2:00 PM, August 28,2014 the decimal place displayed for the monitoring posts, No. 1 to 8, will be changed to the 3rd place (X.XXX μSv/h) from the 1st place (X.X μSv/h).
  • *We improved the measurement conditions of monitoring post 2 to 8 for precise measurement of air dose rate. Construction works such as tree-clearing, surface soil removal, and shield wall setting were implemented from Feb 10 to Apr 18.Therefore monitoring results at these points are lower than other points in the power plant site.
  • *Data may be missing due to equipment failure, cleaning, or regular inspections.
  • *Measurement of dose rate (gamma ray) by portable monitoring post, carried out in order to make up for missing data of existing monitoring post, was discontinued at 0:00 on December 3, 2018 due to the improvement of reliability on existing monitoring posts.
  • *Neutron ray has not been detected since March 16, 2011. Past detection results are here.

to TOP

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