Tepco has a big problem. They want to start a big plant in Japan. It is a nuclear plant.
The plant stopped on Thursday. This was a big surprise. A loud alarm made them stop.
The plant was closed for 14 years. This was after a past problem. One part started on Wednesday. But it stopped the next day.
Now, the plant is safe. No one is in danger. They are looking for the reason. It will take time to fix.
This stops Japan's energy plans. Japan wants more power. This plant is important for them.