Marine reactors

Mitenkov F., Polunihev V. — "Small nuclear heat and power cogeneration stations and water desalination complexes on the basic of marine reactor plants" Nuclear Engineering and Design, 173 (1997) 183-191,... 

ADVANCED MARINE REACTOR MRX AND ITS APPLICATION FOR ELECTRICITY AND HEAT CO-GENERATION... 

Design conditions of the MRX concerning the specific herns of a marine reactor are introduced as follows. 

PREDICTED RADIONUCLIDE RELEASE FROM MARINE REACTORS DUMPED IN THE KARA SEA IAEA, VIENNA, 1997 IAEA-TECDOC-938 ISSN 1011-4289... 

Of the discarded marine reactors, six of the 16 contained their spent nuclear fuel (SNF). In addition, approximately 60% of the SNF from one of the three icebreaker reactors was disposed of in a reinforced concrete and stainless steel (SS) shell container. The vast majority of the low and intermediate level solid radioactive waste was disposed of in containers of unknown composition. The Kara Sea disposal sites for the 16 marine reactors and low and intermediate level solid radioactive waste varied in depth from 12 to 380 m. In particular, the icebreaker reactors and part of their SNF were reportedly disposed of in Tsivolka Fjord at an estimated depth of 50 m. 

It should be noted that this document discusses only the estimates of the inventory and release of radionuclides associated with the marine reactors dumped in the Kara Sea. The low level liquid radioactive waste and low and intermediate level solid wastes discarded in the Barents and Kara Seas were not included in this study. 

Table I presents a summary of pertinent disposal information for the marine reactors dumped in the Kara Sea [1], Figure 1 shows a map of the Northeast coast of Russia with Novaya Zemlya and the approximate locations of the five disposal sites.

FIG. 1. Approximate locations of the marine reactor disposal sites in the Kara Sea on the northeast coast of Russia. 

Table II summarizes the current available information for the steam generating installations of the marine reactors dumped in the Kara Sea [3, 4, 6, 7, 8].

TABLE III. ESTIMATED 1994 RADIONUCLIDE INVENTORIES OF FISSION PRODUCTS, ACTIVATION PRODUCTS, AND ACTINIDES IN THE MARINE REACTORS DUMPED IN THE KARA SEA [3, 7, 8, 12]... 

In order for the lASAP to provide an assessment of the radiological impact of the dumped marine reactors, source terms were required for the following release scenarios ... 

The use of nuclear reactors to drive ships has been promoted particularly among nautical nations. Commercial marine reactors include the Savannah in the USA, the Otto Hahn in Germany, and the Mutsu in Japan. They experienced marine operation but unfortunately the development had been cancelled after several years. Nuclear-powered ships require fi ee access to ports in the world, but unfortunately there were no sufficient number of ports to make the marine reactor s operation feasible. Some countries had accepted to prepare the ports, but doing this would still take time. 

As for the features of nuclear-powered vessels, the Mutsu had a displacement of about 10,000 tons. Its reactor produced 35 MW of thermal power to deliver speeds of 18 knots. Meanwhile, the marine reactors were required to withstand incomparably severer load changes than land-based reactors. For example, they were required to be capable of increasing power from base load to fiill power in 30 s to avoid collision. The Mutsu was able to meet most performance requirements during operation, including experimental voyage. 

Although nuclear submarines are not the main theme of this handbook, they can keep running underwater for a long time without emitting carbon dioxide or the need for oxygen for propulsion. Several hundred nuclear submarines have been built for military use in Russia and the USA, and their performance has resulted in proof of the high safety performance of LWRs. Marine reactors had been also applied to icebreakers operated in USSR/Russia over 50 years. Nuclear-powered aircraft carriers are equipped with several nuclear reactors. 

T. Tateyama, Y. Tanaka and T. Kageyama, Advanced Marine Reactor MRX, proceedings of the Intmiational Conference on Design and Safety of Advanced Nuclear Power Plants, 1992 October 25-29, Tokyo, Japan. 

MRX is significantly smaller and lighter compared with previous marine reactors such as those of the Nuclear Ship MUTSU, OTTO HAHN and SAVANNAH. Fibres 6.4.1. and... 

The operational and safety performance of the advanced marine reactor MRX, which is based on the features such as an integral type PWR, a water filled containment vessel and a passive decay heat removal system, depends strongly on the characteristics of the hydrothermal dynamics. JAERI has a plan to study experimentally the hydrothermal characteristics of MRX under oscillating conditions by setting a synthetic hydrothermal dynamics test facility (SHTF) on board. This facility uses electric heaters and a core characteristics simulator instead of nuclear fuel. 

A marine reactor should be compact and lightweight since it has to be installed in the narrow and limited space in a ship, and also for ship economics. 

Japan Atomic Energy Research Institute "Conceptual Design of the Advanced Marine Reactor MRX", JAERI-M 91-004, (in Japanese), (1991). 

Sako, K., et al. "Advanced Marine Reactors, MRX and DRX", Trans. 11th Int. Conf on Structural Mechanics in Reactor Technology, Aug. 1991, Tokyo, p.357. 

Ishizaka, Y., et al. "Development of a Built-in Type Control Rod Drive Mechanism (CRDM) for Advanced Marine Reactor X (MRX)", ibid., p.P4.6-l. 

---