Progress Status and Future Challenges of the Mid-and-Long-Term Roadmap
toward Decommissioning of TEPCO Holdings' Fukushima Daiichi Nuclear Power Station Units 1-4 (Outline)

Progress status

The temperatures of the Reactor Pressure Vessel (RPV) and the Primary Containment Vessel (PCV) of Units 1-3 have been maintained within the range of approx. 15-25°C*1 for the past month. There was no significant change in the density of radioactive materials newly released from Reactor Buildings in the air*2. It was evaluated that the comprehensive cold shutdown condition had been maintained.

*1 The values varied somewhat depending on the unit and location of the thermometer.
*2 In January 2017, the radiation exposure dose due to the release of radioactive materials from the Unit 1-4 Reactor Buildings was evaluated as less than 0.00029 mSv/year at the site boundary.The annual radiation dose by natural radiation is approx. 2.1 mSv/year (average in Japan).

Completion of dismantling of the Unit 1 R/B cover wall panels

Status of the land-side impermeable walls

Freezing scope of the land-side impermeable walls

Reduction of water injection volume to the reactor

Toward investigation inside the Unit 1 PCV

Results of investigation inside the Unit 2 PCV

Installation progress of a cover for Unit 3 fuel removal

Completion of marine soil coverage inside the port

Results of the questionnaire survey for workers to improve the work environment

* Data of Monitoring Posts (MP1-MP8.)
Data (10-minute value) of Monitoring Posts (MPs) measuring airborne radiation rate around site boundaries show 0.503 - 2.100 ホシSv/h January 25 - February 21, 2017).
We improved the measurement conditions of monitoring posts 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 Feburary 10 to April 18, 2012.
Therefore monitoring results at these points are lower than elsewhere in the power plant site.
The radiation shielding panel around monitoring post No. 6, which is one of the instruments used to measure the radiation dose of the power station site boundary, were taken off from July 10-11, 2013, since the surrounding radiation dose has largely declined due to further deforestation, etc.