What Remains of the Fukushima Daiichi Nuclear Reactors After a Devastating Accident

Fukushima Daiichi Nuclear Power Plant, a disabled nuclear power plant, suffered significant damage from the historic 2011 earthquake and tsunami. Here, we explore the nuclear reactors and their fate after one of the worst nuclear disasters in history.

The Fukushima Daiichi Nuclear Power Plant: A Brief Overview

The Fukushima Daiichi Nuclear Power Plant, also known as Fukushima Daiichi Genshiryoku Hatsudensho, is located on a 3.5-square-kilometre (860-acre) site in the towns of ōkuma and Futaba, in Fukushima Prefecture, Japan. The plant comprises five GE Mk1 containments and one GE Mk2 containment unit. It has a nameplate output of around 5.5 gigawatts electric.

Design and Operation of Nuclear Reactors at Fukushima Daiichi

The reactors at Fukushima Daiichi were designed and operated in conjunction with General Electric and Tokyo Electric Power Company (TEPCO). They were all Boiling Water Reactors (BWRs), with the BWR-3 design for units 1 and 2-5, and the BWR-5 design for unit 6. BWRs are known for their simplicity and relatively low cost compared to other types of reactors.

The Devastating Accident: March 11, 2011

The 2011 earthquake and subsequent tsunami, with a magnitude of 9.1, hit Japan on March 11, 2011, causing extensive damage to the Fukushima Daiichi Nuclear Power Plant. The earthquake and tsunami led to a failure of low-lying equipment, resulting in a loss of plant cooling, radiation leaks, and permanent damage to several reactors, making them impossible to restart.

The Impact on Reactors

During the event:

Units 1, 2, and 3 experienced level 5 failures and suffered meltdowns. Unit 4 suffered a level 3 failure and significant damage. Units 5 and 6 were not seriously damaged as the diesel generators for unit 6 were not flooded, enabling the circulation of cooling water in both cores and the spent fuel pools.

Unit 4 did not melt down during the event because it was undergoing regular maintenance at the time, potentially preventing the reactor from reaching a critical safety threshold.

The Current Status of the Reactors

Since the disaster, the reactors at Fukushima Daiichi have not been restarted. The meltdowns and severe damage to units 1, 2, and 3 have left them in an unrecoverable state. Units 4, 5, and 6, however, remain intact and are still under ongoing decommissioning processes. The primary focus is now on securing and stabilizing the reactors to prevent further leaks and radioactive material dispersion.

Conclusion

The Fukushima Daiichi nuclear reactors, once a symbol of Japan's energy independence, now stand as a stark reminder of the potential catastrophic consequences of natural disasters and nuclear accidents. The reactors' current state underscores the importance of robust safety measures and comprehensive disaster preparedness in the nuclear industry.