Tepco begins removing 587 spent fuel assemblies from Fukushima Daiichi Unit 2

en.Wedoany.com Reported - Tokyo Electric Power Company Holdings (Tepco) has begun extracting highly radioactive spent nuclear fuel from the fuel pool of Unit 2 at the Fukushima Daiichi nuclear power plant. The pool holds 587 spent fuel assemblies, of which seven have been transferred so far. In July, all 28 unused fuel assemblies with relatively lower radiation risk were removed.

The company plans to complete the transfer of all remaining assemblies by the end of fiscal year 2028. Since radiation levels inside the Unit 2 reactor building remain too high for personnel to enter, Tepco employs a specialized engineering approach: operators in a completely separate, distant building on the plant site control an underwater remote-controlled crane to lift the four-meter-long highly radioactive assemblies one by one and place them into heavy metal protective containers (casks) within the pool.

Once filled, the casks are lifted out and lowered onto trailers for transport to a safer shared storage pool on site for long-term cooling. In October, extraction work will be temporarily suspended to allow for facility and equipment inspections and to clear sufficient space in the shared pool. Currently, the storage pools for Units 3 and 4 have been completely emptied. Meanwhile, debris removal at Unit 1 is underway, with fuel removal scheduled to begin in fiscal year 2027 or 2028.

The spent fuel pool in the upper section of the Unit 2 reactor building contains fuel rod assemblies that were used to generate electricity before the 2011 earthquake and tsunami triggered the accident. The accident caused core meltdowns in Units 1 through 3 (Units 4 through 6 were shut down at the time, with Unit 4 sustaining partial damage). Hydrogen explosions occurred in Units 1, 3, and 4, while Unit 2 avoided an explosion because hydrogen escaped through partially collapsed walls of the reactor building. Tepco states that it is "steadily and safely advancing the fuel removal work."

To prepare for fuel removal from the Unit 2 fuel pool, a room—the anteroom—was constructed on the west side of the reactor building, and an opening in the exterior wall on the west side was completed in June 2018. Before conducting studies on measures to suppress the spread of radioactive materials during the dismantling of the upper section of the reactor building, workers surveyed the interior of the operating floor.

After studies based on multiple risk scenarios, and given the declining air dose rate trend on the operating floor, Tepco decided to revise the plan for dismantling the upper section of the reactor building. Under the revised plan, a fuel handling facility (access gantry plus anteroom) was built on the south side to transport fuel rod assemblies out of the building.

After the anteroom was connected to the building, in May 2025, fuel handling equipment was hoisted by crane onto the fuel removal work platform and secured to previously installed rail beams. Trial operation of the fuel handling equipment, which began in December 2025, was completed in March, followed by the removal of unused fuel starting in June. Since this method does not involve dismantling the upper section of the building, work can proceed while controlling dust, including radioactive materials.

At Unit 1, which experienced a hydrogen explosion, a large shield cover was completed in January 2026 to suppress dust dispersion, create a work environment during debris removal, and prevent rainwater inflow. After installing an overhead crane and related equipment, including dust monitors and air conditioning systems, full-scale debris removal began in June.