Japan has reportedly completed the construction of a sea tunnel for the release of radioactive water from the crippled Fukushima nuclear power plant into the sea.

According to Fukushima Central Television(FCT) on Monday, a vessel equipped with a large-sized crane recovered an excavator used to dig the tunnel from the ocean earlier in the day.

All water release preparations will be completed once authorities cover the drainage outlets.

Japan's Nuclear Regulation Authority is set to begin final inspections of the facilities on Wednesday.

The discharge is expected to begin as early as this summer, as long as the International Atomic Energy Agency does not take particular issue with the plan in its report soon set to be released.