|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 Ōminato, 13 July 1970
|Completed:||4 September 1972 (fuel loaded)|
|Class and type:||Mutsu|
|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)|
Nuclear propulsion tests
The reactor was completed on 25 August 1972, and fuel was loaded on 4 September. When officials announced that the first test run was to be run at the pier in Ōminato, local protests forced them to reconsider. Eventually it was decided to test the ship in the open ocean, 800 kilometres (430 nmi) east of Cape Shiriya. The ship departed Ōminato on 26 August 1974, and the reactor attained criticality on 28 August.
As the crew brought the reactor up to 1.4% of capacity at 5pm on 1 September 1974, there was a minor leak of neutrons and gamma rays from the reactor shielding. Westinghouse had reviewed the design and warned of this possibility, but no changes were made to the design. 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. The government finally came to an agreement with the local government and fishermen; the Mutsu was allowed back to port on condition that it was to find a new home port, and the ship returned to Ōminato on 15 October.
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. Following an overhaul, the Mutsu was completed in February 1991. She then completed her original design objective of travelling 82,000 kilometres (51,000 mi) in testing, and was decommissioned in 1992. Over 25 years the programme had cost more than 120 billion yen (about US$ 1.2 billion).
Notes and references
- OECD Nuclear Energy Agency (2001), Investing in Trust: Nuclear Regulators and the Public : Workshop Proceedings, Paris, France, 29 November - 1 December 2000, OECD Publishing, p. 30, ISBN 978-92-64-19314-7
- Nakao, Masayuki, Radiation Leaks from Nuclear Power Ship "Mutsu" (PDF), Japan Science and Technology Agency (JST) Good overview of the construction, leak, and lessons learnt.