Fuel Debris Removal Restarts: How Dangerous Is It?

Sep 12, 2024 | News On Japan

TOKYO - The removal of fuel debris, a crucial and highly challenging part of the Fukushima Daiichi Nuclear Power Plant decommissioning process, has resumed. This process, regarded as the most difficult aspect of the decommissioning effort, focuses on extracting melted and solidified nuclear fuel, known as fuel debris, from the plant's reactors.

Professor Takashi Okamoto from the University of Tokyo explained the operation, which took place on September 10 at the No. 2 reactor. Due to the extreme radiation levels inside the containment vessel, the debris can only be removed using robots.

Fuel debris is extremely hazardous due to its high radiation levels, making it impossible for humans to access the area without severe risk. In this operation, robots were deployed alongside human workers, although even the areas where people were present had relatively high radiation levels, complicating the task. The total amount of fuel debris in reactors 1 to 3 is estimated to be about 880 tons, but only a small quantity -- less than 3 grams -- was removed during this phase due to the high radiation risks.

The operation has made significant progress, with the successful insertion of the equipment into the containment vessel marking a major step forward. Tokyo Electric Power Company (TEPCO) considers this the first phase of the operation, an important milestone in the long and complex process of fuel debris removal. According to Professor Okamoto, the removal of debris is challenging because it must be done entirely by robots, given the hazardous nature of the material and the inability of humans to approach it.

There are no concerns about radioactive contamination or a potential recriticality during the operation, as the amount being removed is very small. Even if the process fails, there would be no environmental impact, and the task could be redone. The extracted fuel debris will be analyzed at a research facility in Ibaraki Prefecture to study its crystal structure, which will help develop future strategies for more extensive debris removal.

While there are 880 tons of fuel debris remaining, Professor Okamoto expressed cautious optimism that once they understand the condition of the material inside, it may be possible to remove the rest within a reasonable timeframe. The overall goal is to complete the decommissioning by 2051, with the removal and safe storage of the debris as the top priority.

Source: FNN

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