A look back at the decontamination efforts at Fukushima.

(Baonghean) - Four years have passed since the tsunami of March 11, 2011, struck the Tohoku region in northeastern Honshu Island and destroyed the Fukushima-Daiichi nuclear power plant, but the decontamination efforts in the area are still ongoing.

The Japanese government's efforts to "clean up" Fukushima after the radioactive leak at the nuclear power plant are being highly praised by the international community. Japan has mobilized more than 6,000 workers to dismantle the remaining parts of the plant. Due to the high levels of radiation, the work teams will rotate. It is estimated that the dismantling of the plant will be completed within 30 to 40 years.

A view of the wastewater treatment area at the Fukushima Nuclear Power Plant. Photo: Arnaud Vaulerin

In mid-February, experts from the International Atomic Energy Agency (IAEA) concluded that “Japan has made remarkable progress. The situation in the contaminated areas has improved, although remediation in these areas is very complex.” The Institute for Radiation Protection and Nuclear Safety (IRSN) also assessed that “A massive amount of work has been done at enormous cost. However, the contaminated area remains extensive, and much work remains to be done.”

Currently, managing contaminated water is a challenge for Tepco, the company operating the Fukushima nuclear power plant. Every day, approximately 350 cubic meters of fresh water must be pumped into the plant area to cool three of the six reactors that have been operating since the disaster. The storage tanks of these three reactors were damaged after the tsunami, and they must be cooled to temperatures between 20 and 50°C to prevent further explosions.

It is estimated that approximately 650 tons of radioactive water are pumped and treated daily before being returned to cool the reactors. The remainder is stored in underground or above-ground tanks. Over time, the amount of radioactive water has increased, and currently there are about 600,000 tons in the tanks. Tepco plans to expand the storage capacity of these tanks to 800,000 tons.

To address the plant's wastewater volume, Tepco began installing additional decontamination systems. After several failed attempts, these systems can now completely treat 2,000 cubic meters of radioactive water per day. From there, Tepco hopes to soon treat all the wastewater at Fukushima. However, earlier this year, Tepco announced that this goal would take longer than expected, but the current treatment rate will be maintained.

Recently, leaks of radioactive waste have been detected repeatedly. In late February, sensors attached to rainwater and groundwater pipes detected radiation levels up to 70 times higher than normal. Immediately afterward, the Japanese Nuclear Regulatory Authority severely reprimanded Tepco. A few days later, a 20-meter pipe containing contaminated water was discovered beneath the reactor's turbine building.

According to Tepco, the removal of the cores of the three reactors that melted down after the 2011 earthquake and tsunami has not yet been possible. This is considered the most difficult part of the remediation process at the Fukushima nuclear power plant. Tepco does not expect to resolve this issue before 2020 or 2025. The IAEA has assessed Tepco's work as "a very large long-term challenge" and unprecedented anywhere.

Chu Thanh(According to LeMonde, March 11)