Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Takada, Hiroshi; Haga, Katsuhiro; Meigo, Shinichiro; Tatsumoto, Hideki; Kasugai, Yoshimi; Futakawa, Masatoshi
Proceedings of 11th International Topical Meeting on Nuclear Applications of Accelerators (AccApp '13), p.154 - 158, 2014/05
Remarkable progresses were achieved at a pulsed spallation neutron source in J-PARC. One is to mitigate high-pressure waves which are generated in a mercury target and a source of serious damage on the wall of target vessel by injecting gas micro-bubbles into mercury. It was confirmed with a novel in-situ diagnostic system using a laser Doppler vibrometer that the pressure waves were certainly attenuated with the gas micro-bubbles. Secondly, the supercritical cryogenic hydrogen system has been improved to remove impurity remained in the helium circulation loop by installing a purification system. As a result, the pressure drop at the heat exchanger was suppressed successfully down to several kPa even after operating for 95 days. Furthermore, we have succeeded in sampling hydrogen gas from the cryogenic hydrogen loop during operation and verified with a Raman spectroscopy that the para-hydrogen fraction was 100%, proving the neutronic performance at the moderator is kept unchanged.
Takei, Hayanori; Obayashi, Hironari; Iwamoto, Hiroki; Kogawa, Hiroyuki; Sasa, Toshinobu
Proceedings of 11th International Topical Meeting on Nuclear Applications of Accelerators (AccApp '13), p.311 - 316, 2014/05
The objective of this study is to evaluate the feasibility of a designed beam window of TEF target by the numerical analysis with a 3D model. The analysis was performed by considering (1) the peak current density and shape of the incident beam, (2) the thermal-fluid behaviour of LBE around the beam window as a function of the flow rate and inlet temperature, (3) the material and the thickness of the beam window, (4) the structural strength of the beam window. In the reference case, the peak current density and the profile of the proton beam were 20 
A/cm
and a Gaussian shape, respectively. The flow rate of LBE and temperature at the inlet were 1 
and 350 
C. The material of a beam window was type SUS316 stainless steel with the 2 mm thick. In this reference case, the maximum velocity of LBE and the maximum temperature located at the top of the beam window were about 1.2 m/sec and 477 C. By increasing the flow rate of LBE up to 4 , the maximum temperature of a beam window was reduced around 420 C. The maximum tresca stress was 190 MPa, which was observed at the center on the outside surface of a beam window. The analyzed stress in the reference case was lower than the tolerance level of the stress strength of the material, and hence the feasibility of a designed beam window was confirmed.