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Journal Articles

Selection of borosilicate glass composition for neutron irradiation test

Nagai, Takayuki; Uehara, Akihiro*; Fujii, Toshiyuki*

KURRI Progress Report 2017, P. 128, 2018/08

In this study, to understand the structural change of a borosilicate glass by a neutron irradiation in detail, the neutron irradiation test was carried out for 50 min in the Pn-2 of the Kyoto University Research Reactor (KUR). The structural change of glass sample after the irradiation will be estimated in 2018FY. Before the irradiation test, the glass composition was selected to estimate a structural change accurately by Raman spectrometry and 2 kinds of Li free borosilicate glass for the irradiation test samples were prepared.

Journal Articles

Evaluation of neutron response of criticality accident alarm system detector to quasi-monoenergetic 24 keV neutrons

Tsujimura, Norio; Yoshida, Tadayoshi; Yashima, Hiroshi*

JPS Conference Proceedings (Internet), 11, p.050005_1 - 050005_6, 2016/11

Journal Articles

Neutron irradiation effect of high-density MoO$$_{3}$$ pellets for Mo-99 production, 3

Ishida, Takuya; Suzuki, Yoshitaka; Nishikata, Kaori; Yonekawa, Minoru; Kato, Yoshiaki; Shibata, Akira; Kimura, Akihiro; Matsui, Yoshinori; Tsuchiya, Kunihiko; Sano, Tadafumi*; et al.

KURRI Progress Report 2015, P. 64, 2016/08

no abstracts in English

Journal Articles

$$^{61}$$Ni synchrotron radiation-based M$"o$ssbauer spectroscopy of nickel-based nanoparticles with hexagonal structure

Masuda, Ryo*; Kobayashi, Yasuhiro*; Kitao, Shinji*; Kurokuzu, Masayuki*; Saito, Makina*; Yoda, Yoshitaka*; Mitsui, Takaya; Hosoi, Kohei*; Kobayashi, Hirokazu*; Kitagawa, Hiroshi*; et al.

Scientific Reports (Internet), 6, p.20861_1 - 20861_8, 2016/02

 Times Cited Count:6 Percentile:62.41(Multidisciplinary Sciences)

Journal Articles

Influence of borosilicate glass by neutron irradiation

Nagai, Takayuki; Kobayashi, Hidekazu; Okamoto, Yoshihiro; Uehara, Akihiro*; Fujii, Toshiyuki*

Photon Factory Activity Report 2015, Part B, 2 Pages, 2016/00

To investigate the characterization damage of a borosilicate glass by a neutron irradiation, the glass sample after neutron irradiation was estimated by using the Raman spectrophotometry and the synchrotron XAFS measurement. As a result, we confirmed that the Si-O bridge structure of a borosilicate glass and the containing element valence in the glass were changed by the neutron irradiation.

JAEA Reports

Establishment of experimental system for $$^{99}$$Mo/$$^{99m}$$Tc production by neutron activation method

Ishida, Takuya; Shiina, Takayuki*; Ota, Akio*; Kimura, Akihiro; Nishikata, Kaori; Shibata, Akira; Tanase, Masakazu*; Kobayashi, Masaaki*; Sano, Tadafumi*; Fujihara, Yasuyuki*; et al.

JAEA-Technology 2015-030, 42 Pages, 2015/11

JAEA-Technology-2015-030.pdf:4.82MB

The research and development (R&D) on the production of $$^{99}$$Mo/$$^{99m}$$Tc by neutron activation method ((n, $$gamma$$) method) using JMTR has been carried out in the Neutron Irradiation and Testing Reactor Center. The specific radioactivity of $$^{99}$$Mo by (n, $$gamma$$) method is extremely low compared with that by fission method ((n,f) method), and as a result, the radioactive concentration of the obtained $$^{99m}$$Tc solution is also lowered. To solve the problem, we propose the solvent extraction with methyl ethyl ketone (MEK) for recovery of $$^{99m}$$Tc from $$^{99}$$Mo produced by (n, $$gamma$$) method. We have developed the $$^{99}$$Mo/$$^{99m}$$Tc separation/extraction/concentration devices and have carried out the performance tests for recovery of $$^{99m}$$Tc from $$^{99}$$Mo produced by (n, $$gamma$$) method. In this paper, in order to establish an experimental system for $$^{99}$$Mo/$$^{99m}$$Tc production, the R&D results of the system are summarized on the improvement of the devices for high-recovery rate of $$^{99m}$$Tc, on the dissolution of the pellets, which is the high-density molybdenum trioxide (MoO$$_{3}$$) pellets irradiated in Kyoto University Research Reactor (KUR), on the production of $$^{99m}$$Tc, and on the inspection of the recovered $$^{99m}$$Tc solutions.

Journal Articles

A Report on the 4th ANNRI Conference

Nakamura, Shoji; Toh, Yosuke; Kimura, Atsushi; Katabuchi, Tatsuya*

Kaku Deta Nyusu (Internet), (112), p.7 - 19, 2015/10

This is a report on the 4th ANNRI Conference held in August 4th, 2015 at Research Laboratory for Nuclear Reactors of Tokyo Institute of Technology.

Journal Articles

Redox equilibrium of the UO$$_2^{2+}$$/UO$$_2^{+}$$ couple in Li$$_{2}$$MoO$$_{4}$$-Na$$_{2}$$MoO$$_{4}$$ eutectic melt at 550$$^{circ}$$C

Nagai, Takayuki; Uehara, Akihiro*; Fujii, Toshiyuki*; Sato, Nobuaki*; Kofuji, Hirohide; Myochin, Munetaka; Yamana, Hajimu*

Journal of Nuclear Materials, 454(1-3), p.159 - 163, 2014/11

 Times Cited Count:0 Percentile:100(Materials Science, Multidisciplinary)

The redox equilibrium of UO$$_2^{2+}$$/UO$$_2^{+}$$ couple was measured in Li$$_{2}$$MoO$$_{4}$$-Na$$_{2}$$MoO$$_{4}$$ eutectic melt at 550$$^{circ}$$C by cyclic voltammetry and absorption spectrophotometry. The standard redox potential of UO$$_2^{2+}$$/UO$$_2^{+}$$ couple was approximately evaluated by cyclic voltammetry. Further, the absorption spectrum and equilibrium potential were measured, repeatedly adding UO$$_2^{2+}$$ source material into the melt containing UO$$_2^{+}$$. From the correlation between the equilibrium potential of the melt and the concentration ratio [UO$$_2^{2+}$$]/[UO$$_2^{+}$$] spectrophotometrically evaluated, the standard redox potential of UO$$_2^{2+}$$/UO$$_2^{+}$$ couple was determined to be -0.847$$pm$$0.010 V vs. O$$_{2}$$/O$$^{2-}$$.

Journal Articles

Development of in-reactor observation system using Cherenkov light, 5

Otsuka, Noriaki; Takeuchi, Tomoaki; Yamamoto, Keiichi; Shibata, Akira; Kimura, Nobuaki; Takemoto, Noriyuki; Tanimoto, Masataka; Tsuchiya, Kunihiko; Sano, Tadafumi*; Unesaki, Hironobu*; et al.

KURRI Progress Report 2013, P. 215, 2014/10

Investigation of a relation between reactor power and brightness of Cherenkov light at Kyoto University Research reactor (KUR) by a CCD camera was performed due to a development of a real-time in-core measurement technique using Cherenkov light. Analyzing the brightness value of individual RGB color component at each pixel, some of the G and B brightness values reached the maximum value of 8-bit binary number, i.e. 255, above about 2-3 MW. Therefore, we corrected the G and B brightness values by the R signals whose brightness value did not saturate even at 5 MW, the maximum reactor power of KUR. Then, the total brightness value was in proportion to the reactor power after the correction. These results indicate the reactor power can be estimated by the observation of Cherenkov light.

Journal Articles

Neutron irradiation effect of high-density MoO$$_{3}$$ pellets for Mo-99 production

Nishikata, Kaori; Ishida, Takuya; Yonekawa, Minoru; Kato, Yoshiaki; Kurosawa, Makoto; Kimura, Akihiro; Matsui, Yoshinori; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; et al.

KURRI Progress Report 2013, P. 242, 2014/10

As one of effective applications of the Japan Materials Testing Reactor (JMTR), JAEA has a plan to produce Mo-99 ($$^{99}$$Mo) by (n,$$gamma$$) method ((n,$$gamma$$)$$^{99}$$Mo production), a parent nuclide of $$^{99m}$$Tc. In this study, preliminary irradiation tests were carried out with the high-density MoO$$_{3}$$ pellets in the KUR and the $$^{99}$$Mo production amount was evaluated between the calculation results and measurement results.

Journal Articles

Measurements of capture $$gamma$$ rays from the neutron resonances of $$^{74}$$Se and $$^{77}$$Se at the J-PARC/MLF/ANNRI

Hori, Junichi*; Yashima, Hiroshi*; Nakamura, Shoji; Furutaka, Kazuyoshi; Hara, Kaoru; Harada, Hideo; Hirose, Kentaro; Kimura, Atsushi; Kitatani, Fumito; Koizumi, Mitsuo; et al.

Nuclear Data Sheets, 119, p.128 - 131, 2014/05

 Times Cited Count:3 Percentile:67.8(Physics, Nuclear)

In this work, we measured the capture $$gamma$$ rays from the neutron resonances of $$^{74}$$Se and $$^{77}$$Se. A neutron time-of-flight method was adopted for the measurements with a 4$$pi$$ Ge spectrometer installed at the Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) in the J-PARC Material and Life science experimental Facility (MLF). The $$gamma$$-ray pulse-height spectra corresponding to the 27-eV resonance of $$^{74}$$Se and the 113-, 212-, 291-, 342-, 690- and 864-eV resonances of $$^{77}$$Se were obtained by gating on the TOF regions, respectively. The relative intensities of those primary transitions were derived and compared with the previous experimental data. For the 27-eV resonance of $$^{74}$$Se, a strong primary transition to the 293-keV state was observed. As for $$^{77}$$Se, the quite differences of the decay pattern were found between the resonances.

Journal Articles

Study on neutron response of criticality accident alarm system detector to quasi-monoenergetic 24 keV neutrons

Tsujimura, Norio; Yoshida, Tadayoshi; Yashima, Hiroshi*

KURRI Progress Report 2012, P. 289, 2013/10

The latest model of the criticality accident alarm system (CAAS), recently developed and installed at the Tokai Reprocessing Plant of the Japan Atomic Energy Agency, consists of a plastic scintillator combined with a cadmium-lined polyethylene moderator and responds both to $$gamma$$ rays and neutrons. To evaluate the neutron absorbed dose rate response of the CAAS detector, a 24 keV quasi-monoenergetic neutron irradiation experiment was performed at the B-1 facility of Kyoto University Research Reactor. The B-1 facility consists of 45-cm-thick iron and 35-cm-thick aluminum filters built into a radial beam tube of the reactor and provides an intense beam of 24 keV neutrons transmitted through "resonance window" in the cross-sections of iron and aluminum. The CAAS detector was mounted on a wooden platform horizontally scanning across the collimated neutron beam extracted from the beam column. A neutron rem counter and an energy-compensated GM counter were also placed on the platform to measure the reference absorbed dose rates of neutrons and $$gamma$$ rays, respectively. The neutron response of the CAAS detector was derived by dividing the neutron-induced net reading, deduced by subtraction of the estimated $$gamma$$-ray fractional reading based on the GM reading, by the reference neutron dose rate. The evaluated neutron response of the detector was confirmed to be in reasonably good agreement with the prior computer-predicted response.

Journal Articles

Reduction behavior of UO$$_{2}$$$$^{2+}$$ in molten LiCl-RbCl and LiCl-KCl eutectics by using tungsten

Nagai, Takayuki; Uehara, Akihiro*; Fujii, Toshiyuki*; Yamana, Hajimu*

Journal of Nuclear Materials, 439(1-3), p.1 - 6, 2013/08

 Times Cited Count:2 Percentile:77.1(Materials Science, Multidisciplinary)JP, 2011-035573   Licensable Patent Information Database   Patent publication (In Japanese)

The reduction of uranium from UO$$_{2}$$$$^{2+}$$ to UO$$_{2}$$$$^{+}$$ or U$$^{4+}$$ in molten LiCl-RbCl and LiCl-KCl eutectics was examined by using tungsten and chlorine gas. Spectrophotometric technique was adopted to determine the concentration of uranium species. When tungsten was immersed into the LiCl-RbCl eutectic melt at 400$$^{circ}$$C without supplying chlorine gas, 36% of the total weight of the hexavalent of UO$$_{2}$$$$^{2+}$$ was reduced to the pentavalent of UO$$_{2}$$$$^{+}$$. Under purging chlorine gas into the melt, 96% of UO$$_{2}$$$$^{2+}$$ was reduced to the tetravalent of U$$^{4+}$$. Tungsten oxy-chloride of WOCl$$_{4}$$ was produced via the reductions of UO$$_{2}$$$$^{2+}$$, which was volatized from the melt and adsorbed on the upper part of experimental cell. On the other hand, 84% of UO$$_{2}$$$$^{2+}$$ in the LiCl-KCl eutectic melt at 500$$^{circ}$$C was reduced to U$$^{4+}$$ by using tungsten and chlorine gas.

Journal Articles

Development of in-reactor observation system using Cherenkov light, 3

Kimura, Nobuaki; Takemoto, Noriyuki; Nagata, Hiroshi; Kimura, Akihiro; Naka, Michihiro; Nishikata, Kaori; Tanimoto, Masataka; Tsuchiya, Kunihiko; Sano, Tadafumi*; Unesaki, Hironobu*; et al.

KURRI Progress Report 2011, P. 219, 2012/10

In research reactors, a CCD camera is used to observe reactor core for reactor operation management, e.g. to prevent debris falling. In order to measure the reactor power and fuel burnup exactly by means of observation of Cherenkov light and $$gamma$$ ray information, the development of the on-line measurement device has been started since 2009. In this study, as a part of development of in-reactor surveillance, wavelength and absolute irradiance of Cherenkov light were measured by spectroscopy, and Cherenkov light was observed by the CCD camera. The neutral density filters (ND-filters) were used to investigate the transmittance of Cherenkov light in these measurements.

Journal Articles

Absorption spectra and cyclic voltammograms of uranium species in molten lithium molybdate-sodium molybdate eutectic at 550 $$^{circ}$$C

Nagai, Takayuki; Uehara, Akihiro*; Fukushima, Mineo; Myochin, Munetaka; Fujii, Toshiyuki*; Sato, Nobuaki*; Yamana, Hajimu*

Proceedings in Radiochemistry, 1(1), p.151 - 155, 2011/09

Absorption spectra of dissolved uranium species in molten Li$$_{2}$$MoO$$_{4}$$-Na$$_{2}$$MoO$$_{4}$$ eutectic at 550 $$^{circ}$$C were measured by spectrophotometry, and their redox reactions were also investigated by cyclic voltammetry. Observed absorption spectra of uranium species were similar to those of UO$$_{2}$$$$^{+}$$ in molten chlorides. After purging oxygen into the melt, the absorption peaks of UO$$_{2}$$$$^{+}$$ decreased and UO$$_{2}$$$$^{+}$$ was thought to be oxidized to UO$$_{2}$$$$^{2+}$$. When the uranium species were not contained in the melt, we confirmed that alkali metals deposited at -0.7 V and a small reduction of this melt was observed at -0.3 V. When UO$$_{2}$$ was dissolved into the melt, the reduction of the uranium species was observed at -0.2 V. It was suggested that the dissolved uranium species are recovered as mixed uranium-molybdenum oxides by electrolysis.

Journal Articles

Electrochemical behavior and electronic absorption spectra of uranium trivalent ions in molten LiCl-CsCl mixtures

Nagai, Takayuki; Uehara, Akihiro*; Fujii, Toshiyuki*; Sato, Nobuaki*; Yamana, Hajimu*

Journal of Nuclear Materials, 414(2), p.226 - 231, 2011/07

 Times Cited Count:6 Percentile:48.94(Materials Science, Multidisciplinary)

Journal Articles

Redox equilibria of the U$$^{4+}$$/U$$^{3+}$$ and U$$^{3+}$$/U couples in molten LiCl-RbCl eutectic

Nagai, Takayuki; Uehara, Akihiro*; Fujii, Toshiyuki*; Shirai, Osamu*; Sato, Nobuaki*; Yamana, Hajimu*

Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 77(8), p.614 - 616, 2009/08

 Times Cited Count:11 Percentile:71.26(Electrochemistry)

Formal redox potentials of the U$$^{4+}$$/U$$^{3+}$$ and U$$^{3+}$$/U couples in molten LiCl-RbCl eutectic were determined by cyclic voltammetry. These redox potentials were more negative than those in the LiCl-KCl eutectic but positive comparing to those in the NaCl-CsCl eutectic. This relation would be correlated with the averaged alkali cation radius.

Journal Articles

Redox equilibria of Pu$$^{4+}$$/Pu$$^{3+}$$ and PuO$$_{2}$$$$^{2+}$$/Pu$$^{4+}$$ couples in molten NaCl-CsCl eutectic as measured by absorption spectrophotometry

Nagai, Takayuki; Uehara, Akihiro*; Fujii, Toshiyuki*; Shirai, Osamu*; Myochin, Munetaka; Yamana, Hajimu*

Radiochimica Acta, 97(4-5), p.209 - 212, 2009/05

 Times Cited Count:3 Percentile:72.57(Chemistry, Inorganic & Nuclear)

Redox behavior of uranium and plutonium in molten salts is the essential information for establishing an effective reprocessing process with spent MOX fuel. In an oxide electro-winning reprocessing process, the spent nuclear fuel is dissolved into the molten NaCl-CsCl eutectic, and the dissolved U(VI) and Pu(VI) species are reduced to be dioxides by electrolysis. In the present study, formal redox potentials of the Pu$$^{4+}$$/Pu$$^{3+}$$ and PuO$$_{2}$$$$^{2+}$$/Pu$$^{4+}$$ couples in the molten NaCl-CsCl eutectic at 923 K were determined. The fractions of Pu$$^{3+}$$, Pu$$^{4+}$$, and PuO$$_{2}$$$$^{2+}$$ were determined by UV/Vis/NIR absorption spectrophotometry. PuO$$_{2}$$ was dissolved into the molten NaCl-CsCl eutectic by Cl$$_{2}$$$$_{2}$$ gas purging. Valences of plutonium (Pu$$^{0}$$, Pu$$^{3+}$$, Pu$$^{4+}$$, and PuO$$_{2}$$$$^{2+}$$) were controlled by changing the flow rates of Cl$$_{2}$$, O$$_{2}$$, and Ar gases.

Journal Articles

Positron annihilation lifetime measurements of vanadium alloy and F82H irradiated with fission and fusion neutrons

Sato, Koichi*; Inoue, Kazuya*; Yoshiie, Toshimasa*; Xu, Q.*; Wakai, Eiichi; Kutsukake, Chuzo; Ochiai, Kentaro

Journal of Nuclear Materials, 386-388, p.203 - 205, 2009/04

 Times Cited Count:2 Percentile:80.08(Materials Science, Multidisciplinary)

V-4Cr-4Ti F82H, Ni and Cu were irradiated with fission and fusion neutrons at room temperature and 473 K. Defect structures were analyzed and compared using positron annihilation lifetime measurement, and microstructural evolution was discussed. The mean lifetime of positrons (the total amount of residual defects) increased with the irradiation dose. The effect of cascade impact was detected in Ni at room temperature. The size and the number of vacancy clusters were not affected by the displacement rate in the fission neutron irradiation at 473 K for the metals studied. The vacancy clusters were not formed in V Cr Ti irradiated at 473 K in the range of 10$$^{-6}$$-10$$^{-3}$$ dpa. In F82H irradiated at 473 K, the defect evolution was prevented by pre-existing defects. The mean lifetime of positrons in fission neutron irradiation was longer than that in fusion neutron irradiation in V Cr Ti at 473 K. It was interpreted that more closely situated subcascades were formed in the fusion neutron irradiation and subcascades interacted with each other, and consequently the vacancy clusters did not grow larger.

Journal Articles

Redox equilibria of the U$$^{4+}$$/U$$^{3+}$$ and U$$^{3+}$$/U couples in molten LiCl-RbCl eutectic

Nagai, Takayuki; Uehara, Akihiro*; Fujii, Toshiyuki*; Shirai, Osamu*; Sato, Nobuaki*; Yamana, Hajimu*

Proceedings of 2008 Joint Symposium on Molten Salts (USB Flash Drive), p.927 - 932, 2008/10

Formal redox potentials of the U$$^{4+}$$/U$$^{3+}$$ and U$$^{3+}$$/U couples in molten LiCl-RbCl eutectic were determined by cyclic voltammetry. These redox potentials were more negative than those in the LiCl-KCl eutectic but approximately similar to those in the NaCl-CsCl eutectic. These redox potentials in molten alkali chlorides would be correlated with the averaged alkali cationic radius of the melt.

75 (Records 1-20 displayed on this page)