Conceptual study on parasitic low-energy RI beam production with in-flight separator BigRIPS and the first stopping examination for high-energy RI beams in the parasitic gas cell

Sonoda, Tetsu*; Katayama, Ichiro*; Wada, Michiharu*; Iimura, Hideki; Sonnenschein, V.*; Iimura, Shun*; Takamine, Aiko*; Rosenbusch, M.*; Kojima, Takao*; Ahn, D. S.*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2019(11), p.113D02_1 - 113D02_12, 2019/11

AA2019-0315.pdf:1.37MB

https://doi.org/10.1093/ptep/ptz120

An in-flight separator, BigRIPS, at RIBF in RIKEN provides each experiment with specific nuclides separated from many nuclides produced by projectile fragmentation or in-flight fission. In this process, nuclides other than separated ones are discarded on the slits in BigRIPS, although they include many nuclides interested from the view point of nuclear structure. In order to extract these nuclides for parasitic experiments, we are developing a method using laser ion-source (PALIS). A test experiment with Se beam from RIBF has been performed by using a gas cell set in BigRIPS. Unstable nuclides around Se were stopped in the gas cell in accordance with a calculation using LISE code. The stopping efficiency has been estimated to be about 30%. As a next step, we will establish the technique for extracting reaction products from the gas cell.

Design and Manufacture of JOYO MK-III Heat Transport System Components; Main Dump Heat Exchangers

Kawahara, Hirotaka; Isozaki, Kazunori; Tomita, Naoki

JNC TN9410 2004-015, 129 Pages, 2004/04

JNC-TN9410-2004-015.pdf:6.53MB

The MK-III modification to improve the irradiation capability of JOYO was carried out. The increase of fast neutron flux and the enlargement of that field increase the reactor thermal rate from 100 MWt to 140 MWt. The main components in the cooling system such as intermediate heat exchangers (IHXs) and dump heat exchangers (DHXs) were replaced in MK-III modification in order to increase heat removal capability. This report describes the specific characteristic in the design and manufacturing, design data and principle of the design for the new DHX.

Over Design Load Vibration Test of Piping Support in JOYO

Isozaki, Kazunori; Tomita, Naoki

JNC TN9410 2003-005, 55 Pages, 2003/08

JNC-TN9410-2003-005.pdf:12.21MB

The mechanical and oil snubber type piping supports have been installed and used in the piping system including the primary and secondary cooling system in order to restrain the vibration caused by the earthquake in the experimental fast reactor "JOYO". The piping supports moves with pipe corresponding to slow displacement such as thermal expansion of the pipe. On the contrary, when the earthquake happens, it restrains the rapid vibration mechanically or hydraulically. Manufacture guarantees that the piping support can stand the vibration up to 150% load of design specification.The piping support in JOYO could stand the vibration in excess of design value, but the upper limit of the vibration had not been obtained. In order to grasp the upper limit, vibration tests were carried out using the same type piping support as installed in the primary and secondary cooling system. As a result of the vibration test, it was confirmed that the vibration restraint function of piping support could be maintained up to 6 times higher design value. This result will be used for reasonable review of the earthquake-proof design, evaluation of the components and piping system residual lifetime.

Air flow test of MK-III dump heat exchanger tube arrays for JOYO

Isozaki, Kazunori; Tomita, Naoki; Kawahara, Hirotaka

PNC TN9410 97-070, 98 Pages, 1997/07

PNC-TN9410-97-070.pdf:3.52MB

The reactor thermal power of JOYO MK-III is to be increased from 100MWt to 140MWt due to high performance of reactor core. So, Dump Heat Exchanger (DHX) of MK-III was designed to improve its heat removal capability by changing U type heat transport tube arrays to type tube arrays and increasing air flow. Natural frequency between support and support of MK-III DHX's tube arrays was about 15Hz, and karman vortex shedding frequency of tube arrays was about 90Hz by Y.N.Chen's report. Then, a possibility of piling up of karman vortex shedding frequency in high frequency mode was to be considered. And, air velocity of flow tube arrays is also increased compared to the MK-II DHX. Sodium leak accident of MONJU was caused by a flow-induced vibration of thermometer well. Therefore, the air flow test to tube arrays of MK-III DHX was conducted. Results of the air flow test and other test were as follows. (1)Air flow test (vortex shedding) The Strouhal number by geometry shape of MK-III DHX was 0.130.15 and 0.370.39. The Strouhal number observed from slow velocity to fast velocity was 0.130.15 and showed good agreement with the literature of Y.N.Chen. And, the lift coefficient (C) was below 0.1 even at a resonance condition with karman vortex shedding frequency. (2)Forced vibration test (measurement of damping factor) The damping factor () of tube arrays was minimum 0.4%, maximum 1.37%, and average 0.7%. These values are within 1.0% of the recomendation by the piping division II (non-insulation) of JEAG4601-1991. (3)Air flow test (fluid-elastic vibration) The critical velocity factor (K) of tube arrays was minimum 6.23 and average 7.39, and showed good agreement in critical velocity factor of triangular arrays of 30 degrees with the literature of S.S.Chen. (4)Stress concentration factor of fin joint The stress concentration factor of fin joint for tube arrays was below 2.0. And, maximum stress concentration factor of structure ...

Optimization of directional fast neutron detector based on scintillating optical fibers for deuterium experiment in LHD

Nakada, Naoki*; Takada, Eiji*; Isobe, Mitsutaka*; Ogawa, Kunihiro*; Nishitani, Takeo*; Iguchi, Tetsuo*; Tomita, Hideki*; Sato, Satoshi; Kawarabayashi, Jun*

no journal, , 

In order to measure the profile of the neutron generation in LHD at NIFS, we have developed the directional fast neutron detector based on scintillating optical fibers by using the forward direction of the probability of the recoil proton generation by the neutron and the scintillating optical fibers. We have enhanced the directional quality by optimizing the configuration of the scintillating optical fibers. In case 14 MeV neutrons were incident to the detector, we calculated the number of the energy deposition events with the energy of more than threshold value by PHITS. In case they were incident to the detector parallel, the number of the events at the rear part lessened due to the self-shielding. Even if the scintillating optical fiber was shortened, the angular dependency was not so changed. In case it was thin downed, it was found that the angular dependency was enhanced. We performed the neutron measurement experiment by using the developed detector and the DT neutron source at JAEA/FNS. The angular dependencies by the experiment were worse than those by the calculation. It is thought to be causally related to the high sensitivity to the -ray of the detector. In the future, we will redesign the detector for the neutron and -ray field in LHD.

Machine learning of ultrasonic phased-array images for flaw detection

Tomita, Naoki*; Furuya, Masahiro*; Asahi, Manabu*; Hisamochi, Rikuya*; Toyota, Kodai; Yada, Hiroki

no journal, , 

Ultrasonic phased array is a phase composite imaging technology developed in the radar field and has recently been used for nondestructive inspection of power generation equipment. However, scattered waves in the inspection target make it difficult to distinguish a flaw from scattering from the edge surface. In this study, we developed a method to discriminate flaws with high accuracy by adjusting parameters such as output voltage and receiver sensitivity to make it easier to see the flaws and by deep learning of the optimized flaw images. First, actual measurements were made using an ultrasonic phased-array flaw detector on a stainless-steel specimen. Next, a model was created to discriminate the presence or absence of flaws using transition learning, one of the machine learning methods. As a result, we found that the highest accuracy was achieved when transition learning was performed using inceptionv3 and resnet101, a convolutional neural network architecture. These results show that the method developed in this study is effective for nondestructive inspection.