The International Atomic Energy Agency inspection was part of a four-day visit to Japan that started on Tuesday, its second since the water discharge began last August despite strong protests from fishing groups and neighbouring China, which has banned Japanese seafood.
The Japanese government and the plant operator, Tokyo Electric Power Company Holdings, or TEPCO, say the discharges are diluted to better than international standards, and agency chief Rafael Mariano Grossi said in March they were being carried out safely.
During the site visit on Wednesday, the plant suffered a temporary blackout when some underground digging apparently damaged an electrical cable in an area separate from the water discharge.
The blackout halted the water discharges for several hours but the IAEA was nonetheless able to complete its inspection.
One excavation worker suffered burns and had to be treated in hospital, but the plant's cooling systems were unaffected and the water discharge resumed safely on Wednesday evening.
The IAEA did not immediately comment on the blackout.
A 2011 earthquake and tsunami damaged the Fukushima plant's power supply and reactor cooling functions, triggering meltdowns of three reactors and causing large amounts of radioactive wastewater to accumulate.
After more than a decade of clean-up work, the plant began discharging the water after treating it and diluting it with seawater on August 24, starting a process that is expected to take decades.
After Wednesday's plant visit, the IAEA team members are expected to have more discussion in Tokyo through Friday.
Data and samples collected from the Fukushima plant will be corroborated at IAEA labs and independent third-party labs from China, South Korea, Switzerland and the United States, and will be released in a report.
The team includes independent international experts from 10 countries - Argentina, Australia, Britain, Canada, China, France, Russia, South Korea, the United States and Vietnam.
