[7] Eventually it was decided to test the ship in the open ocean, 800 kilometres (430 nmi) east of Cape Shiriya.

[7] There was no significant radiation exposure, but it became a political issue, with local fisherman blocking her return to port for more than 50 days.

[7] In Sasebo, between 1978 and 1982, various modifications were made to the reactor shield of the Mutsu, and its home port was moved to Sekinehama in 1983.

[7] She then completed her original design objective of travelling 82,000 kilometres (51,000 mi) in testing, and was decommissioned in 1992.

The nuclear material from the ship is stored across the street from the museum at a facility operated by the Japan Atomic Energy Agency.