[en] Japan Atomic Energy Research Institute carried out the docking and inspection of the nuclear-powered ship 'Mutsu' at Sekinehama Port, Mutsu City, Aomori Prefecture, from the middle of June to late in July, 1989. In this inspection, the Mutsu was mounted on a floating dock off the coast, the dock was towed by tugboats into the port and moored at the pier, and after completing the works in the dock, the dock was towed to the outside of the port, and the Mutsu was launched. The Mutsu was built as a nuclear power experiment ship, and length 130 m, breadth 19 m, depth 13.2 m, design draft at full load 6.9 m, 8242 GT. One PWR of 36 MWt and one steam turbine of 10000 ps are installed, and velocity is 16.5 knots. In September, 1974, after the first criticality, the leak of radioactivity occurred. The repair of shield and general inspection on safety were carried out in Sasebo Shipyard from August, 1980 to August, 1982. Thereafter, the Mutsu stayed in Ominato, but in January, 1988, after the completion of Sekinehama Port, the Mutsu was brought there. The Sekinehama Port, the test and inspection of the Mutsu carried out so far and the plan of hereafter are reported. (K.I.)

No abstract available

[en] After signing in 1968 an agreement between the Netherlands and the Federal Republic of Germany, regarding the visit of the German nuclear ship 'Otto Hahn' to Dutch territorial watersand ports, discussions started between the operator of the ship, local port authorities and representatives of different ministries concerned to work out in addition to the port entry plan of the operator, special arrangements for visits to the harbours of Rotterdam and Vlaardingen. At the same time the legal procedures to obtain a licence, according to the Nuclear Energy Act started. After consultation with the National Health Council a safety review group and the port authorities, a licence was granted with some specific requirements and the arrangement for visits to the harbours of Rotterdam and Vlaardingen was established. In the years 1971 to 1977 several visits to the above mentioned ports took place, the procedures being more or less routine nowadays. In the years 1974 - 1975, based on the request of the operator, the possibility of visits to other Dutch ports was investigated. A model was developed to compare, with respect to population distribution, the different harbours together with the routes to an emergency berth or the open sea. The results of this study, where all nautical aspects were disregarded, are given

[en] During the period September 1974-February 1975, a detailed investigation was undertaken on the neutron streaming from reactor shielding observed on board the N.S. MUTSU. Tests were carried out with the reactor at partial power (83 kWth = 0.23%) of full rating, under which condition the radiation distribution was measured in the space outside the primary and secondary shields, for the purpose of determining the cause of the abnormal radiation observed during the preceding low-power tests. The results derived from these measurements, as well as analytical calculations, indicated that the abnormal radiation resulted from neutrons leaking out through the gap that existed between the pressure vessel and the primary shield. Based on the foregoing results, a plan has been adopted for modifying the shielding arrangement, by adding new shielding to close the gap referred to above and further supplementing and modifying both the upper and lower parts of the reactor shielding structure. (orig.)

[en] This paper covers a span of time commencing before the launching of the N.S. Savannah in 1959 until completion of layup in 1971, which includes the total operation period of the ship. Capt. McMichael's association with the program included the launching, completion of the ship, tests and trials, port entry regulations, and the entire demonstration phase of operation. Mr. Cain's experience covers the whole of the experimental commercial phase of operation as a berthline cargo ship. The paper attempts, from a somewhat different viewpoint of the two authors to identify some of the problems encountered and lessons learned from this unique operation on the basis of active participation in many phases of the entire program

No abstract available

[en] The abnormal radiation level observed on the upper deck of N.S. Mutsu was caused by neutrons streaming through an annular air gap between the reactor pressure vessel and the primary shield. In order to lower this level, a modification of shielding has been planned, for which a shielding mock-up experiment was carried. The foregoing modifications brought some change to the expected behavior of the reactor plant under ship accident situations, and studies were performed to verify plant safety, such as calculations to determine containment vessel integrity and decay heat removal after sinking, and calculations supported by experiment to ascertain the structural strength of the double bottom upon stranding of the ship

[en] Japan Nuclear Ship Development Agency had made previously application for the permission of the alteration of the reactor installation in the nuclear ship Mutsu (the first of this kind in Japan), based on the overall safety investigation of the ship made by JNDA. Taking the opportunity of the governmental safety examination concerning the permission, the correspondence of the safety aspects of the n.s. Mutsu to the existing guidelines for the safety of nuclear reactor facilities was examined. These results to further enhance the safety of the n.s. Mutsu are described concerning the following matters: the safety design examination guideline for power-generating LWR facilities (58 items); the safety evaluation guideline for power-generating LWR facilities (the analysis of abnormal transients during operation and accidents); the safety countermeasures to be adopted in the reactor plant of the n.s. Mutsu from the situation of the TMI nuclear accident in U.S. (7 in design and 10 in operation management); the analysis simulating the TMI accident. (J.P.N.)

[en] Using methods of forced vibration analysis, calculations of impact accelerations were carried out in way of the reactor space of a 600,000 ton nuclear tanker when struck by another ship in the area of the collision barrier. The General Bending Response Program was used by representing the ship as an elastically coupled non-uniform beam-spring model subject to a Fourier series representation of the transient force of impact. Sectional properties were developed for the ship in both ballast and full load conditions in order to describe the model. Sensitivity calculations were made for variations in loading conditions, ship-hull damping, impact duration and impact magnitude for the lateral mode of vibration. An additional calculation was made for the combined torsional-horizontal bending mode of vibration

[en] There are about 250 nuclear propelled ships, only 2 of them are merchant ships: the US freighter Savannah and the bulk carrier Otto Hahn of the Federal Republic of Germany. This paper is restricted to the experience with both of these ships, showing partly similar and partly different procedures for port entry. They have called at 107 ports in 40 countries. The Savannah was operated in the periods from 1962 - 1971 and the Otto Hahn is still in operation. The endeavours of the OECD and IMCO to review and to harmonize international rules for nuclear merchant ships should be supported and continued