| Career (Japan) | |
|---|---|
| Name: | Mutsu |
| Namesake: | City of Mutsu, Aomori |
| Operator: | Japan Atomic Energy Research Institute |
| Builder: | Second Tokyo Factory, Ishikawajima-Harima Hvy Ind |
| Laid down: | 17 November 1968 |
| Launched: | 12 June 1970 Delivered Ohminato 13 July 1970 |
| Completed: | 4 September 1972 (fuel loaded) |
| Decommissioned: | 1992 |
| General characteristics | |
| Class and type: | Mutsu |
| Type: | Nuclear-powered freighter |
| Tonnage: | 8240 tons |
| Length: | 130 m (430 ft) |
| Beam: | 19 m (62 ft) |
| Draught: | 6.9 m (23 ft) |
| Depth: | 13.2 m (43 ft) |
| Installed power: | 36MW Mitsubishi PWR |
| Propulsion: | steam turbine 10,000 hp (7.5 MW) |
| Speed: | 32 km/h (17 kn) |
| Range: | Nuclear |
| Crew: | 80 |
Mutsu was Japan's first, and only nuclear-powered ship.[1] It was built as a nuclear merchant ship, one of four such vessels ever constructed, but never carried commercial cargo.
Contents |
The reactor was completed on 25 August 1972, and fuel was loaded on 4 September.[2] When officials announced that the first test run was to be run at the pier in Ohminato, local protests forced them to reconsider.[2] Eventually it was decided to test the ship in the open ocean, 800 kilometres (500 mi) east of Cape Shiriya.[2] The ship departed Ohminato on 26 August 1974, and the reactor attained criticality on 28 August.[2]
As the crew brought the reactor up to 1.4% of capacity at 5pm on 1 September 1974,[2] there was a minor leak of neutrons and gamma rays[1] from the reactor shielding.[2] Westinghouse had reviewed the design and warned of this possibility, but no changes were made to the design.[2] There was no significant radiation exposure, but it became a political issue, with local fisherman blocking her return to port for over fifty days.[1] The government finally came to an agreement with the local government and fishermen for Mutsu to be allowed back to port on condition that it found a new home port, and the ship returned to Ohminato on 15 October.[2]
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.[2] Following an overhaul, the Mutsu was completed in February 1991.[2] She then completed her original design objective of travelling 82,000 kilometres (51,000 mi) in testing, and was decommissioned in 1992.[2] Over 25 years, the programme had cost more than 120 billion yen (~US$1.2bn).[2]
The reactor was removed in 1995. After decontamination, the Mutsu was rebuilt as the ocean observation vessel Mirai.[1][3]