Removing the molten nuclear fuel from Fukushima will be more difficult than releasing the plant’s wastewater

OKUMA, Japan –

In a small area of ​​the central control room of the Fukushima Daiichi Nuclear Power Plant, the switch for the transmission of treated water is turned on. A graph on a nearby computer monitor shows a steady decline in water levels as treated radioactive waste water is diluted and discharged into the Pacific Ocean.

In the coastal area of ​​the facility, two seawater pumps operate, gushing seawater in torrents through sky-blue pipes into the large collection tank, where the treated water, coming down from the tanks on the hill through a much thinner black pipe, is diluted a hundred times before release.

The sound of treated and diluted radioactive water flowing into an underground secondary pond could be heard underground as media outlets including The Associated Press toured the facility in northeastern Japan for the first time since the water release began.

“The best way to clean up the contaminated water is to remove the molten fuel residue,” said Kenichi Takahara, spokesman for Tokyo Electric Power Company Holdings, who accompanied Sunday's media tour for foreign media.

However, Takahara said the lack of information from inside the nuclear reactors makes planning and developing the necessary robotic technology and a molten fuel removal facility extremely difficult.

“When it comes to removing the molten fuel residue, we can't just pull it out and be done,” he said.

The planned decades-long release of treated water has been fiercely opposed by fishing associations and criticized by neighboring countries. In response, China immediately banned imports of seafood from Japan. Thousands of South Koreans rallied in Seoul over the weekend to condemn the release and urged Japan to keep it in tanks.

The Japanese Ministry of Foreign Affairs issued a travel warning to Japanese citizens on Sunday, urging them to exercise extra caution when visiting China. It said the harassment, including massive phone calls, was aimed at the Japanese embassy, ​​consulate and schools in China, and called on the Japanese in China to stay away from those locations and the water release protests and not talking loudly in Japanese to avoid attention.

Since the facility was destroyed by a major earthquake and tsunami on March 11, 2011, managing the ever-increasing amounts of radioactive waste water in more than 1,000 tanks has been a safety hazard and a burden. The tanks are already 98% full 1, 37 million tons capacity.

The discharge of the water into the sea is a milestone in the plant's decommissioning, which is expected to take decades. But it's only the beginning of the challenges ahead, such as removing the deadly radioactive molten fuel residue left in the three damaged reactors – a daunting task if it is ever to be accomplished.

The plant's operator, Tokyo Electric Power Company Holdings, began releasing the first batch of 7,800 tons from ten Group B tanks, which are among the plant's least radioactive waters.

They say the water has been treated and diluted to levels safer than international standards, and so far tests by TEPCO and government agencies have found no detectable radioactivity in the seawater and fish samples taken after the release.

The Japanese government and TEPCO say releasing the water is an inevitable step in the plant's decommissioning.

Since the earthquake and tsunami destroyed the power plant's cooling systems and melted three reactors, highly contaminated cooling water from the damaged reactors continuously leaked into the basements of the buildings and mixed with the groundwater. Part of the water is recycled to cool the nuclear fuel, the rest is stored in the tanks.

Release started at a daily rate of 460 tons and is progressing slowly. TEPCO plans to release 31,200 tons of treated water by the end of March 2024, which would empty only 10 tanks, as the site will continue to produce radioactive water.

The pace will later accelerate and about a third of the tanks will be removed over the next decade to make room for the plant to be decommissioned, said TEPCO Managing Director Junichi Matsumoto, who is responsible for releasing the treated water. The water will be released over a 30-year period, but as things stand, cooling water will be required as long as the molten fuel remains in the reactors.

About 880 tons of radioactively melted nuclear fuel remain in the reactors. Robotic probes have provided some information, but the condition of the molten debris remains largely unknown and the amount could be even larger, says Takahara, the TEPCO spokesman.

Experimental removal of the molten debris from Block 2 using a giant remote-controlled robotic arm is scheduled to begin later this year, but the amount will be very small, Takahara said.

Spent fuel removal from the reactor block 1 cooling pool is scheduled to start in 2027. The reactor top is still covered in debris from the blast 12 years ago and needs cleaning after a protective cover was put in place to contain radioactive dust.

In Unit 1, the hardest hit, most of the reactor core melted and fell to the floor of the primary containment chamber and possibly further into the concrete basement. A robotic probe sent into Unit 1's primary containment chamber found that its pedestal – the main support structure just below its core – was badly damaged.

Most of the thick concrete exterior was missing, exposing the inner steel rebar, prompting regulators to hire TEPCO to conduct a risk assessment.

The government is sticking to its original 30- to 40-year target for completing the decommissioning without defining what that means. Rushing to the schedule could result in increased radiation exposure for workers and greater environmental damage. Some experts say it will be impossible to remove all of the molten fuel residue by 2051 and that it would take 50 to 100 years, if that.