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Ariyoshi, Gen; Saruta, Koichi; Kogawa, Hiroyuki; Futakawa, Masatoshi; Maeno, Koki*; Li, Y.*; Tsutsui, Kihei*
Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.1407 - 1420, 2023/08
Cavitation damage on a target vessel due to proton beam-induced pressure waves is one of the crucial issues for the pulsed neutron source using a mercury spallation target. As a mitigation technique for the damage, the helium microbubble injection into the mercury has been carried out by using a swirl bubbler in order to utilize compressibility of bubbles. Moreover, double-walled structure, which consists of an outer wall and an inner wall, has been applied as the target head structure. In this study, we aim to develop an abnormality diagnostic technology to detect the inner wall cracking, which is caused by such cavitation damage, from the outside of the target vessel. The mercury flow fields in the case with the cracking are evaluated by computational fluid dynamics analysis based on finite element method. And then, effect of the cracking on the flow field is discussed from the point of view of the flow-induced vibration and the acoustic vibration.
Maeno, Koki*; Ariyoshi, Gen; Tsutsui, Kihei*; Saruta, Koichi; Kogawa, Hiroyuki; Li, Y.*; Futakawa, Masatoshi
no journal, ,
Cavitation damage is one of the issues for the mercury spallation target, which threatens the structural integrities of the target vessel wall. To reduce such cavitation damages, Japan Atomic Energy Agency (JAEA) tried to prevent the cavitation bubble growth using the "flow effect". To arrange the environment for the use of the "flow effect", a narrow channel was newly installed by adding an inner wall to the mercury target head. Moreover, the microbubble injection technique to the mercury was also used to reduce the pressure waves which is one of the causes of the cavitation bubble formation. Consequently, the damage could be almost weakened. However, the damage on the inner wall can still be accumulated gradually during the practical target operation. Then, the inner wall might be penetrated by such damage accumulation: wall cracking might happen to the inner wall. Therefore, development of a diagnostic technology for such inner wall cracking should be important. So, the purpose of this study is to clarify the flow field in the target head with wall cracking conditions. Effect of the wall cracking on the flow field in the target head was investigated by CFD analysis. For simplicity, the flow channel near the target head was simulated as two-dimensional models. As the results, the continuous vortices shedding was recognized in the cases of any cracking conditions. And, pulsation flows in the narrow channel were observed in the cases of the cracking width larger than 4 mm.
Maeno, Koki*; Ariyoshi, Gen; Saruta, Koichi; Murata, Atsushi*; Kogawa, Hiroyuki; Tsutsui, Kihei*; Li, Y.*; Futakawa, Masatoshi
no journal, ,
no abstracts in English
Maeno, Koki*; Ariyoshi, Gen; Saruta, Koichi; Murata, Atsushi*; Kogawa, Hiroyuki; Li, Y.*; Tsutsui, Kihei*; Futakawa, Masatoshi
no journal, ,
no abstracts in English
