High performance engine oils with improved quality have been developed as one of the solution of the problem, but based on the data of the company to which the author belongs, it is confirmed that the fuel additive is useful to solve the problem in a short time. Furthermore, as one of the recent trends in the USA and Europe, some ship owners use full synthetic or semi-synthetic lubricating oil for high-speed diesel engines, to save overall running cost. The use of the semi-synthetic lubricating oil will be further evaluated from the viewpoint of the cost and resource savings.
References
1) F. Hirata, H. Watanuma, Y. Shima, H. Miyano Journal of M.E.S.J. Vol. 33, No. 6 (1998)
2) O. Hanashima, N. Kagiwata, N. Kitamura Journal of M.E.S.J. Vol. 33, No. 6 (1998)
[Shigehisa YURA]
10. Nuclear Ships
10.1 Research and Development by Japan Atomic Energy Research Institute (JAERI)1)
10.1.1 Nuclear-powered Ship Mutsu
The nuclear-powered ship Mutsu completed its planned experiments in 1995 and was then overhauled in the Sekinehama mooring port, in accordance with the Basic Plan for Studies Necessary for Research and Development of Nuclear Ships by JAERI, approved by the prime minister and the minister of transport on 31 March 1985. After the overhaul, the Mutsu's hull was reborn as the world's largest oceanographic observation ship, the Mirai, under the Japan Marine Science and Technology Center (JAMSTEC). Sekinehama, the port used for the Mutsu, is also the home port of the Mirai. A maintenance station to service the oceanographic observation buoys to be mounted on board the Mirai and a building for processing and analysis of observation data have been constructed there.
10.1.2 Studies for Improvement of Marine Reactors
Together with research and development using the Mutsu, JAERI has performed advanced research and development for improved marine reactors, aimed at realization of future marine reactors. Marine reactor requirements for output, load conditions, and automated operation differ depending on the kind on ship on which the reactor is to be used. Research and development has been performed for two kinds of improved marine reactors: a large marine reactor, designated MRX (Marine Reactor X), and a deep-sea reactor, designated DRX (Deep-sea Reactor X). These reactors are intended for installation onboard an ice-breaking observation ship and a deep-sea scientific research ship, respectively, which are both expected to be constructed soon. Conceptual designs have already been established for MRX and DRX, and development is proceeding in parallel for element technology, such as fundamental testing of passive safety technology, and element equipment, such as a control rod drive device to be built into the reactor containment. Consideration has been given to how to advance design and studies on the engineering level, including demonstrations to establish the concept, acquisition of the thermal hydrostatic data necessary for developing a detailed design, and demonstration of the reliability of new concepts and of reactor operational and maintenance performance.
In parallel with design studies, it is necessary to solve technical problems related to practical application. Efforts in that direction have included development of a control rod drive device to be built into the reactor containment, basic studies of passive safety technology, a study of water immersion technology for marine reactors, development of integral reactor components, a study of sophisticated shielding design technology, development of a sophisticated automation system for the marine reactor plant, and development of a highburnup core.
As described later, examination of the concept of the marine reactor called SCR (Submersible Compact Reactor) began in 1998, based on the conceptual design of the DRX. The SCR will be installed on an undersea-navigating observation ship in the 600-meter class, which will be most useful and realistic for current ocean research. The DRX was designed for a deep-sea stationary research ship of the 6000-meter class, which would move only vertically. No investigation has been conducted on the problems of three-dimensional operation and of the possibility of collision in the sea. The following design policies have thus been added to the design concepts employed in the DRX, such as an integrated PWR, reactor vessel with internal control drive unit, water-filled containment, and decay heat removal system by natural circulation:
1) Employment of a decay heat removal system that can remove heat in any direction of the hull when submerged, and
2) Separate housing of the secondary system, such as a turbogenerator.
The SCR is composed of a primary cooling system, Emergency Decay-heat Removal System (EDRS), Pressure Reduction and Make-up System (PRMS), power generation equipment, steam equipment, and feed water and condensing water equipment.
