In Okuma, Japan, the Fukushima Daiichi nuclear power plant’s radiation levels have substantially decreased since the catastrophic meltdown occurred 14 years ago. Today, many plant areas allow workers to walk around in simple surgical masks and regular clothing.
However, different protocols apply for entering the reactor buildings, including those damaged by the 2011 earthquake and tsunami. In these high-risk areas, workers are required to use full protective gear, including facemasks with filters, multiple layers of gloves and socks, shoe covers, hooded hazmat suits, waterproof jackets, and helmets. As the cleanup tasks continue, involving the removal of melted fuel debris, workers encounter intense psychological stress alongside hazardous radiation exposure.
The monumental task of cleaning up around 880 tons of melted fuel debris involves using advanced technology. A remote-controlled robotic arm tried multiple times to remove debris but successfully retrieved a small sample from the damaged No. 2 reactor last November. This marked a significant step in the lengthy decommissioning process destined to last possibly over a century. Akira Ono, the chief decommissioning officer at Tokyo Electric Power Company Holdings, which operates the plant, emphasized the value of even the smallest samples in advancing the understanding of the fuel’s condition. Larger retrieval missions are anticipated for the 2030s to facilitate smoother debris removal.
Upcoming retrieval operations at the No. 2 reactor intend to have the extendable robot venture further into the reactor for samples closer to where the nuclear fuel overheated and collapsed. Masakatsu Takata, a utility spokesperson, identified the target area within the No. 5 reactor’s inner structure, which shares an identical design with No. 2, as he explained.
Despite significant decontamination efforts reducing radiation levels within the No. 2 reactor building, they remain dangerously high. The melted fuel debris is shielded by a substantial concrete containment wall. In August, some workers participated in 15- to 30-minute shifts to diminish radiation exposure. The robotic equipment, though remotely controlled, had to be manually handled at points.
“The high levels of radiation and time constraints made us feel both anxious and rushed,” shared Yasunobu Yokokawa, a mission team leader, describing the difficulty of their work. Wearing full-face masks impaired visibility and breathing, the waterproof layer added sweating and mobility issues, and triple-layer gloves made finger movement challenging.
To avoid unnecessary radiation exposure, they secured areas around their gloves and socks and carried personal dosimeters. Teams also rehearsed tasks to minimize exposure. Early operational delays occurred when workers found some pipes arranged incorrectly. Additionally, the robot’s camera malfunctioned due to high radioactivity and required replacement.
Radiation doses for workers varied and, although some reached a higher level, none approached the five-year safety limit of 100 millisieverts. Nevertheless, worker concerns about safety and radiation have risen, as noted by Ono via a survey among 5,500 workers. In 2023, incidents at a water treatment facility led to chemical burns and hospitalizations for a few workers, though no severe health impacts followed.
Yokokawa and his colleague, Hiroshi Ide, both active since the 2011 crisis, aim to enhance safety measures in challenging radiation environments. Preparations are underway on the No. 2 reactor’s top floor to remove spent fuel units from a cooling pool, anticipated to commence in two to three years. At the No. 1 reactor, constructing a massive roof is part of containment strategies ahead of decontamination and spent fuel removal.
Remote-controlled crane operations come into play to minimize worker exposure while erecting pre-assembled components, particularly in contaminated areas around the No. 1 reactor.
Simultaneously, treated radioactive wastewater is being removed, and emptied tanks are being dismantled to create space for new facilities focusing on research and storage of the melted fuel debris. Through preliminary robotic missions fetching samples, this phase aims to identify broader strategies for fuel removal, starting with the No. 3 reactor.
The arduous process of decommissioning is in its nascent stages, with experts acknowledging potential challenges ahead. Completion is tentatively targeted for 2051, but the melted fuel debris retrieval already trails by three years, adding layers of complexity to many undetermined issues.
Ide, whose home in Namie remains uninhabitable due to contamination, is emblematic of the citizens’ hopes. Despite the restrictions, he remains committed to overseeing the decommissioning success. “As someone from Fukushima, I aspire to see it done thoroughly, enabling safe homecomings,” he stated.
