Inspectors from the International Atomic Energy Agency have arrived in Japan to examine the atomic power plant damaged in an earthquake last month.
The plant suffered more than 50 malfunctions because of the quake
The operators of the Kashiwazaki-Kariwa power station have admitted there were leakages of radioactive material.
But the Tokyo Electric Power Company says there is no danger to the public.
The visit follows a request by the Niigata regional government. Tokyo initially said no international inspection was necessary.
Niigata officials said bringing in outside experts would help to damp down rumours that the radiation leaks had been more serious than admitted.
Unease arose when the leaks were found to have been much bigger than first estimated.
The power company has said getting the plant running again could take some time, because contaminated water needs to be cleaned up first and dozens of other problems need to be fixed.
The magnitude 6.8 earthquake struck in mid-July and caused more than 50 malfunctions at the Kashiwazaki-Kariwa plant.
The quake killed 10 people and injured hundreds.