Japan’s tsunami and nuclear disaster sparked a $ 300 billion effort to rebuild an interior

The country expanded the reconstruction budget four times in 10 years and has allocated the equivalent of $ 2,400 for each person in Japan to revive Tohoku, the northeast region affected by the tsunami, and mitigate radiation at the nuclear plant. Even as boardwalks are being erected and houses rebuilt, many people have not returned.

Most of the money was spent rebuilding homes, building seawalls, and repairing other damaged infrastructure with the goal of bringing people back and reviving major industries like fishing, agriculture, and tourism.

The Tohoku region, home to about 7% of Japan’s population, has seen a population decline for more than a generation as young people move to larger cities. Half of the tsunami victims were 65 or older.

In the three prefectures most affected by the tsunami, Iwate, Miyagi and Fukushima, the collective population has fallen by 6% since the disaster.

Hundreds of miles of seawalls, some as high as 50 feet, have been erected along the shoreline, at a cost of about $ 13 billion. Approximately 80% of the planned 268 miles of boardwalks have been completed.

At Ishinomaki, waves of up to 33 feet traveled more than 3 miles inland, killing more than 3,000 people, including 74 of the 78 children attending Okawa Elementary School that day. The city is now protected by boardwalks up to 32 feet high.

The tsunami slammed into more than 1,000 miles of shoreline and flooded some communities as far as 6 miles inland. Some cities suffered widespread house destruction, such as Rikuzentakata in Iwate, where 99.5% of houses were damaged. In Ishinomaki, 4,000 people died or are still missing and 76.6% of all houses in the city were at least partially destroyed.

When the earthquake occurred, Fukushima Daiichi’s reactors automatically shut down. The backup diesel generators ran the cooling pumps until two tsunami waves flooded the plant and took the generators out of service. In the following days, the accumulation of hydrogen caused explosions in reactors 1, 2 and 3; at 4. Radiation levels increased to 400 millisieverts per hour (people are typically exposed to 2.4 millisieverts per year). The government declared an evacuation zone with a radius of 12.5 miles.

Now, a forest of steel tanks containing more than a million tons of water with radioactive elements grows outside the plant. Water flows through the plant every second keeping the reactors cool, which adds to the problem. The Japanese government and Tokyo Electric Power Co.

, the plant’s owner, are studying the release of radioactive tritium-containing water to the Pacific. They say it is safe and other countries do the same at their nuclear plants, but people in the fishing industry are concerned.

Authorities estimate that there are another 30 years of work left before Fukushima Daiichi is completely dismantled. The most important task, which has not yet begun, is to remove the melted fuel from reactors 1, 2 and 3. Because the internals of reactors are too radioactive for humans and often inaccessible to robots, they have not yet been fully mapped or photographed.

Remembering what is sometimes called the “triple disaster” – earthquake, tsunami, and nuclear collapse – is an annual event in Japan. On March 11 this year, the government will hold a ceremony to mark the 10th anniversary of the disaster at the Tokyo National Theater, offering a minute of silent prayer at 2:46 pm, the time the earthquake occurred. Emperor Naruhito and Empress Masako will attend.

—Alex Newman contributed to this article.