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Shibamoto, Yasuteru; Nakamura, Hideo; Anoda, Yoshinari
Nuclear Technology, 133(1), p.119 - 132, 2001/01
Times Cited Count：7 Percentile：48.68(Nuclear Science & Technology)no abstracts in English
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JNC TN9400 2000-066, 52 Pages, 2000/06
JNC-TN9400-2000-066.pdf:1.82MB
Phase I of feasibility studies on commercialized fast reactor system is being peformed for two years from Japanese Fiscal Year 1999. In this report, results of the study on fluid fuel reactors (especialiy a molten salt fast breeder reactor concept) are described from the viewpoint of technical and economical concerns of the plant system design. ln JFY1999, we have started to investigate the fluid fuel reactors as alternative concepts of sodium cooled FBR systems with MOX fuel, and selected the unique concept of a molten chloride fast, breeder reactor, whose U-Pu fuel cycle can be related to both light water reactors and fast breeder reactors on the basis of present technical data and design experiences. We selected a preliminary composition of molten fuel and conceptual plant design through evaluation of technical and economical issues essential for the molten salt reactors and then compared them with reference design concepts of sodium cooled FBR systems under limited information on the molten chloride fast breeder reactors. The following results were obtained. (1)The molten chloride fast breeder reactors have inherent safety features in the core and plant performances, ad the fluid fuel is quite promising for cost reduction of the fuel fabrication and reprocessing. (2)On the other hand, the inventory of the molten chloride fuel becomes high and thermal conductivity of the coolant is inferior compared to those of sodium cooled FBR systems, then, the size of main components such as lHX's becomes larger and the amount of construction materials is seems to be increased. (3)Furthermore economical vessel and piping materials which contact with the molten chloride salts are required to be developed. From the results, it is concluded that further steps to investigate the molten chloride fast breeder reactor concepts are too early to be conducted.
Koshizuka, Seiichi*
JNC TJ9400 2000-011, 102 Pages, 2000/03
JNC-TJ9400-2000-011.pdf:2.71MB
In order to evaluate the possibility to achieve high electric power by a fast reactor with supercritical light water, the design study was carried out on a large fast reactor core with high coolant outlet temperature (SCFR-H). Since the reactor coolant circuit uses once-through direct cycle where all feedwater flows through the core to the turbine at supercritical pressure, it is possible to design much simpler and more compact reactor systems and to achieve higher thermal efficiency than those of current light water reactors. The once-through direct cycle system is employed in current fossil-fired power plants. In the present study, three types of core were designed. The first is SCFR-H with blankets cooled by ascending flow, the second is SCFR-H with blankets cooled by descending flow and the third is SCFR-H with high thermal power. Every core was designed to achieve the thermal efficiency over 43%, positive coolant density reactivity coefficient and electric power over 1600MW. Core characteristics of SCFR-Hs were compared with those of SCLWR-H (electric power: 1212MW), which is a thermal neutron spectrum reactor cooled and moderated by supercritical light water, with the same diameter of the reactor pressure vessel. It was shown that SCFR-H could increase the electric power about l.7 times maximally. From the standpoint of the increase of a reactor thermal power, a fast reactor has advantages as compared with a thermal neutron reactor, because it can increase the power density by adopting tight fuel lattices and eliminating the moderator region. Thus, it was concluded that a reactor cooled by supercritical light water could further improve the cost competitiveness by using a fast neutron spectrum and achieving a higher thermal power.
Gao Ming Quing*
PNC TN9410 97-016, 42 Pages, 1997/02
There is a free surface at the upper plenum in a reactor vessel of LMFBR.The free surface has spatial gradient caused by the internal coolant flow.This is a disadvantageous factor to engineering from the view point of gas entrainment into coolant. To eliminate the free surface gradients,ring plates about 20cm wide are fitted at about 1 meter under the free surface. They interfere fluid flow,and decrease the component velocity in vertical direction.To investigate the efficiency ofthe ringplates, analyses with the AQUA-VOF code were carried out.For contrast, three conditions were given:Case-1:Without ring plates.Case-2:Ring plates,fitted at 1.125m under the free surface.Case-3:Ring plates,fitted at 1.5m under the free surface. The results shown that the ring plateshave a sufficiently high potential to elminate the free surface gradients due to disperse the momentum along reactor vessel axis to radial direction.In the calculations with ring plate (Case-2 and -3),the maximum free surface heig
