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Tamura, Koji*; Minehara, Eisuke*; Yokoyama, Keiichi
no journal, ,
For Cs isotope separation, laser photochemical reaction based on the two-photon excitation scheme was developed with a self-injection-seeded Ti:sapphire laser. Fine particles corresponding to cesium hydrides were observed. Laser performance, reaction products, results of simulation will be reported.
Aoyama, Takafumi; Takeda, Toshikazu*; Ishikawa, Takashi; Iwata, Yoshihiro; Ito, Chikara; Morohashi, Yuko
no journal, ,
The high sensitivity FFDL technique for SFR has been developed using the RIMS method. The RIMS method was demonstrated by measuring the artificially blended xenon and krypton gas which was used for the pressurized steel capsule of in-pile creep rupture experiment in the experimental fast reactor Joyo. The measured isotopic ratio of xenon collected from the Joyo reactor cover gas by means of RIMS could successfully identify the ruptured capsule of which tag gas was contained. The RIMS was then applied for the proto type fast breeder reactor Monju. The RIMS system can also detect stable xenon nuclides and radioactive Xe-133 in the collected from the Joyo reactor cover gas during the fuel failure simulation test, implying that the RIMS can apply to assume the burn-up of the failed fuel subassembly by using the ratio of stable and radioactive xenon isotopes.
Toshimitsu, Masaaki; Saeki, Morihisa; Oba, Hironori; Thornton, B.*; Sakka, Tetsuo*
no journal, ,
A laser-induced breakdown spectroscopy (LIBS) technique for element analysis of samples submerged in water using a fiber optic light delivery set-up has been developed. The set-up delivers air to the sample surface via a tube and uses the same fiber optic for laser light delivery, and for observation of the light emitted by the micro-plasma generated for analysis. The emission spectra from metals, alloys and oxide samples such as Fe, SUS304, zircaloy-2, ZrO
can be clearly observed at wavelengths ranging from 730 nm to 870 nm.
Iwai, Hiroki; Nakamura, Yasuyuki; Sano, Kazuya
no journal, ,
FUGEN has a complicated core structure consisting 224 fuel channels with pressure tubes and calandria tank that has up to 150 mm thickness of stainless steel. And the periphery part of the core has the laminated structure of up to 150 mm thickness of carbon steel for radiation shielding. The core structure, which is highly activated, will be dismantled remotely in water. Thus, it is necessary to select the appropriate cutting method for FUGEN, considering characteristics of reactor such as core structure in advance. Some cutting tests and literature research for various cutting methods were carried out. As a result of down selection, three methods were decided, which are laser, plasma-arc and abrasive water jet. Among these methods, the laser cutting has not been used for decommissioning and recently development of laser is remarkable. Therefore, we are carrying out the laser cutting tests in air and water by using the fiber laser. And some results of these tests will be reported.
Daido, Hiroyuki
no journal, ,
no abstracts in English
Faenov, A.*; Matsubayashi, Masahito; Pikuz, T.; Fukuda, Yuji; Kando, Masaki; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Sakai, Takuro; Shiozawa, Masahiro*; et al.
no journal, ,
Yamada, Tomonori
no journal, ,
In terms of remote handing, a laser can enter into the narrow gap and the laser can shoot and cut the thick metal without reactive force. Thus, a laser has been expected as one of the useful decommissioning tools because the laser cutting minimizes radioactive materials such as sludge, chips, etc. to be generated from the reactor component cutting process. The laser cutting processes include complicated phenomena such as molten metal ejection and adhesion characteristics, an assist gas and liquid metal interaction with phase transitions, etc. However, the quantitative evaluation for these characteristics is not an easy task because the phenomena involves the interaction of thermal, mechanical and metallurgical effects, and is characterized by various scales of time and space. In this present work, we introduce experimental and numerical studies on thermohydraulic characteristics during laser cutting processes.
Akagi, Hiroshi; Kasajima, Tatsuya*; Kumada, Takayuki; Itakura, Ryuji; Yokoyama, Atsushi; Hasegawa, Hirokazu*; Oshima, Yasuhiro*
no journal, ,
Akaoka, Katsuaki; Maruyama, Yoichiro; Oba, Masaki; Miyabe, Masabumi; Otobe, Haruyoshi; Wakaida, Ikuo
no journal, ,
For the remote analysis of impurity in next generation nuclear fuel, Laser Breakdown Spectroscopy (LIBS) was applied to uranium oxide U
O
including a small amount of neodymium oxide NdO as a sample. We measured the breakdown spectra of Nd and U in the samples with different concentrations of Nd, and determined the calibration curves. This calibration curve shows good linearity R
0.995, and it was found that quantitative analysis of Nd contained in the U is possible.
Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Oba, Hironori; Tampo, Motonobu; Wakaida, Ikuo
no journal, ,
no abstracts in English
Tampo, Motonobu; Akaoka, Katsuaki; Oba, Hironori; Oba, Masaki; Maruyama, Yoichiro; Miyabe, Masabumi; Wakaida, Ikuo
no journal, ,
no abstracts in English
Wakaida, Ikuo; Akaoka, Katsuaki; Miyabe, Masabumi; Tampo, Motonobu; Oba, Hironori; Oba, Masaki; Maruyama, Yoichiro; Otobe, Haruyoshi; Kato, Masaaki
no journal, ,
In the next generation nuclear fuel cycle system, low-decontaminated nuclear fuel is required. Chemical analysis has problems of high radiation exposure and the cost. For the safeguard analysis, Non Destructive Analysis of Pu using by neutron detection can be not applicable because of the spontaneous neutron emission from TRU. In these situations, we are developing the remote analysis by the combination of laser induced breakdown spectroscopy (LIBS) and ablation resonance absorption spectroscopy. For elemental analysis, detection linearity and the sensitivity of order 100 ppm were obtained. For more high intense optical emission, simple microwave assisted LIBS was basically studied. In liquid phase sample, the use of ultra-thin film liquid flow was performed for LIBS target. For isotope analysis, frequency stabilized semiconductor tunable lasers were applied to the resonance absorption spectroscopy for the ablated uranium oxide, and 
U in natural uranium was separately observed.
Saeki, Morihisa; Toshimitsu, Masaaki; Oba, Hironori
no journal, ,
We proposed separation technique of platinum-group metals (PGMs) from a solution of high-level radioactive waste by using laser-induced particle formation, and performed its proof-of-principle experiment. The simulated solution of high-level radioactive liquid wastes (HLLW) was prepared by dissolving Pd, Rh, Ru and neodymium (Nd) into distilled water. The Nd metal was added as representative of lanthanide and minor actinide. After 40-min irradiation of an UV laser to mixture of the simulated solution of HLLW and ethanol, the Pd, Rh and Ru metals were separated from the Nd ion as particle with sub-micron size. The Pd, Rh and Ru metals were recovered with efficiency of 100%, 94-99%, 65-69%, while the Nd ion was completely kept in the sample solution. Moreover, we investigated dependence of recovery efficiency on various experimental parameters. The results suggest mutual separation of Pd and Rh by arrangement of the intensity of the irradiation laser.
Oba, Hironori; Saeki, Morihisa; Toshimitsu, Masaaki; Wakaida, Ikuo; Tanabe, Rie*; Ito, Yoshiro*
no journal, ,
We investigated the feasibility of laser-induced breakdown spectroscopy (LIBS) for the determination of elements in a liquid solution in the form of a jet flow and using nanosecond laser pulses. A comparison of LIBS sensitivity between two types of flows for liquid analysis was performed. A pipette nozzle tip was used to create a columnar flow of 520
m diameter, whereas a trapezoidal-shaped groove nozzle tip produced an ultrathin sheet flow of 5
40m thickness. The limit of detection of Na atoms was estimated to be about 14 ng/mL by use of the columnar flow, whereas 1.1 ng/mL in the case of the sheet flow.
-rays to nondestructive measurement of nuclear materialHajima, Ryoichi
no journal, ,
Terada, Takaya; Nishimura, Akihiko
no journal, ,
no abstracts in English
Ito, Fuyumi; Nishimura, Akihiko; Tomiyoshi, Kentaro; Ito, Chikara; Sugiyama, Akira
no journal, ,
An innovative probing system should be required for the case of reactor core melt down accidents. In the Fukushima Daiichi BWRs, molten debris might drop in the pedestal under the reactor pressure vessel. Due to the high radioactive situation, the probing system is going to be inserted into the pedestal by a remote controlled robotic arm. We are planning the probing system which consists of optics of Laser Induced Breakdown Spectroscopy (LIBS), a waterproof view scope, radiation resistant optical fibers, radiation dose monitor, and so on. The purpose of LIBS is to analyze the composition of the molten debris. That of the waterproof view scope is to know its position in the pedestal. The following paragraph mentions each outline which we did until now.
Ito, Chikara; Naito, Hiroyuki; Chiyatani, Keiji; Nishimura, Akihiko; Sugiyama, Akira; Oba, Hironori; Wakaida, Ikuo
no journal, ,
no abstracts in English
Iwata, Yoshihiro; Ito, Chikara; Harano, Hideki*
no journal, ,
no abstracts in English
Shimada, Yukihiro*; Nishimura, Akihiko; Suzuki, Hirokazu*
no journal, ,
no abstracts in English