Tepco has a problem in Japan. They want to start a big nuclear plant. This plant is Kashiwazaki-Kariwa. It is the biggest in the world.
But the plant stopped on Thursday. This happened during important steps. A warning signal made them stop. The plant was closed for 14 years. This was after the Fukushima problem.
One reactor started on Wednesday. Regulators said it was okay. But the next day, it stopped. A loud alarm sounded. Tepco put control rods back. These rods stop the nuclear reaction.
The reactor is safe now. No one is in danger. They are looking for the reason. The site boss said it will take time. "It will not be fixed in one or two days," he said.
This stops Japan's energy plans. Japan wants more nuclear power. This means less fuel from other countries. It also helps with climate goals. AI computers need much energy. This plant can make a lot. It is important for the country.