Safety requirements expected for the prototype fast breeder reactor "Monju"

Saito, Shinzo; Okamoto, Koji*; Kataoka, Isao*; Sugiyama, Kenichiro*; Muramatsu, Ken*; Ichimiya, Masakazu*; Kondo, Satoru; Yonomoto, Taisuke

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 10 Pages, 2015/05

Itinerant U 5 band states in the layered compound UFeGa observed by soft X-ray angle-resolved photoemission spectroscopy

Fujimori, Shinichi; Terai, Kota; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Muramatsu, Yasuji; Fujimori, Atsushi; Yamagami, Hiroshi*; Tokiwa, Yoshifumi*; Ikeda, Shugo; et al.

Physical Review B, 73(12), p.125109_1 - 125109_6, 2006/03

https://doi.org/10.1103/PhysRevB.73.125109

We have performed angle-resolved photoemission spectroscopy (ARPES) experiments on paramagnetic UFeGa using soft X-ray synchrotron radiation (=500 eV) and derived the bulk- and U 5-sensitive electronic structure of UFeGa. Although the agreement between the experimental band strucure and the LDA calculation treating U 5 electrons as beeing itinerant is qualitative, the morphology of the Fermi surface is well explained by the calculation. This result claims that the importance of the electron correlation effect even for the itinerant U 5 compound.

Large-scaled thermohydraulic tests using sodium for commercialization of LMFBR technology

; ; ; ; ; ;

PNC TN9410 95-265, 171 Pages, 1995/10

PNC-TN9410-95-265.pdf:8.91MB

Requirements for a large-scaled sodium test facility are examined to designate basic specifications that will answer to the needs for the development of innovative heat transport concepts of LMFBRs (Liquid Metal Fast Breeder Reactors), such as shortening of a main piping system, compact components including a reactor vessel and decay heat removal focussing on natural circulation. Four large-scaled sodium tests related to plant system dynamics, decay heat removal by natural circulation, protection of a reactor vessel wall and a steam generator are planed using an integral system model simulated a Japanese DFBR (Demonstration Fast Breeder Reactor) to study thermohydraulic characteristics of heat transport systems. In the present paper, notable points, objectives, expected results, test items and specific features of thermohydraulic tests are specified to confirm the concept of the test facility. The facility is positioned not only in responding to "demands from the utility group to the nation about large-scaled confirmation tests for DFBR", but also as an integral large-scaled sodium test facility that will be utilized over a long time from a view point of "establishing peculiar characteristic know-how of FBR" to pave the way for commercial LMFBRs.

Investigation of preventive measures of gas entrainment phenomena for large scale FBR; Investigation on Baffle ring and porous-type UIS

; ; Yamaguchi, Akira; ; ; Sugawara, Satoru

PNC TN9410 92-352, 62 Pages, 1992/11

PNC-TN9410-92-352.pdf:2.3MB

In-vessel thermohydraulic analysis with multi-dimensional code AQUA was conducted to investigate efficiency of a baffle ring and of a porous-type UIS (upper instrumentation structure) for preventation of gas entrainment to coolant from gas plenum of reactor vessel. Through the analysis using the AQUA code and the discussion based on their results, the following results have been obtained: [Baffle Ring Equipment] (1)In order to reduce maximum surface verocity, the effect with the width 40 cm of the baffle ring equipment better than the width 20 cm. (2)Maximum surface velocity is 40 cm/s using the baffle ring equipment of width 40 cm. [Porous-type UIS] (1)Effective mass flow ratio of the UIS porous to the UIS skirt is 50 % to decrease maximum surface velocity. (2)Maximum surface velocity is 52 cm/s using the porous-type UIS with the above mass flow distribution. Furthermore analysis with the AQUA code were carried out for the conbined condition of the baffle rings with 40 cm width and the porous-type UIS with the condition of the effective mass flow ratio 50 %. Maximum surface velocity 0.33 m/s closer to the MONJU condition (0.3 m/s) was obtained from the analysis.

Investigation on efficiency of outer barrel for large-scale fast breeder reactor

; ; ; Yamaguchi, Akira; ; Sugawara, Satoru

PNC TN9410 91-089, 130 Pages, 1991/03

PNC-TN9410-91-089.pdf:5.14MB

In-vessel thermohydraulic analysis with multi-dimensional code AQUA was conducted for transient simulating a pump coast down and reactor scram (manual reactor trip event) to confirm efficiency of outer barrel equipments on a large-scale fast breeder reactor. Through the analysis using the AQUA code and the discussion based on their results, the following results have been obtained: [Main Loop Temperature Transient] The transient rate with the outer barrel equipments are approximately equal to the result when an inner barrel was adopted. [Thermal stratification] Axial temperature distributions are approximately equal to the result in the case without an inner barrel. Therefore appearance of an axial temperature distribution can be neglected from a structural design. [Circumferential Temperature Distribution] Maximum temperature gradient 104C/m was confirmed. The value is equivalent to three times of that when an inner barrel was not adopted. Further investigation on a thermal stress at reactor vessel is necessary. [Sodium Surface Velocity] Maximum velocity is the same as that described for the case without an inner barrel. From the above results, it is concluded that the outer barrel considered here is an efficient equipment to relax the main loop temperature transient.