Analysis of plutonium isotope ratios including Pu/Pu in individual U-Pu mixed oxide particles by means of a combination of alpha spectrometry and ICP-MS

Esaka, Fumitaka; Yasuda, Kenichiro; Suzuki, Daisuke; Miyamoto, Yutaka; Magara, Masaaki

Talanta, 165, p.122 - 127, 2017/04

https://doi.org/10.1016/j.talanta.2016.12.041

The isotope ratios of Pu/Pu, Pu/Pu, Pu/Pu, and Pu/Pu were measured for individual Pu and U-Pu mixed oxide particles by a combination of alpha spectrometry and inductively coupled plasma mass spectrometry (ICP-MS). As a consequence, we were able to determine the Pu/Pu, Pu/Pu, and Pu/Pu isotope ratios with ICP-MS after particle dissolution and chemical separation of uranium, plutonium and americium with UTEVA resins. Furthermore, Pu/Pu isotope ratios were able to be calculated by using both the Pu/(Pu+Pu) activity ratios that had been measured through alpha spectrometry and the Pu/Pu isotope ratios determined through ICP-MS. Therefore, the combined use of alpha spectrometry and ICP-MS is useful in determining plutonium isotope ratios, including Pu/Pu, in individual U-Pu mixed oxide particles.

Ionization of protoplanetary disks by galactic cosmic rays, solar protons, and supernova remnants

Kataoka, Ryuho*; Sato, Tatsuhiko

Geoscience Frontiers, 8(2), p.247 - 252, 2017/03

https://doi.org/10.1016/j.gsf.2016.06.010

Estimation of the depth-dose profile of ionization in protoplanetary disks by galactic cosmic rays (GCRs), solar protons, and by supernova remnants is of great importance in the analysis of planet formation. We therefore calculated the profile using Particle and Heavy Ion Transport code System PHITS. The attenuation length of GCR ionization is updated as 118 g cm, which is approximately 20% larger than the popular value. Hard and soft possible spectra of solar protons give 5% larger and 20% smaller attenuation lengths compared with those from standard GCR spectra, respectively. Further, all of the attenuation lengths become 10% larger in the compound gas of cosmic abundance, e.g. 128 g cm for GCRs, which can significantly affect the minimum estimate of the size of dead zones in protoplanetary disks.

Swelling pressure and leaching behaviors of synthetic bituminized waste products with various salt contents under a constant-volume condition

Irisawa, Keita; Meguro, Yoshihiro

Journal of Nuclear Science and Technology, 54(3), p.365 - 372, 2017/03

https://doi.org/10.1080/00223131.2016.1273143

Development of methods for recovering uranium from sludge-like uranium generated in decontamination of metal wastes

Ohashi, Yusuke; Tanaka, Yoshio; Tsunashima, Yasumichi; Ikeda, Yasuhisa*

Journal of Nuclear Science and Technology, 54(3), p.382 - 390, 2017/03

https://doi.org/10.1080/00223131.2016.1260065

Sludge-like uranium wastes (SUWs) have been generated with neutralization of acidic aqueous solutions used for decontamination of metal wastes containing a large amount of iron. We have examined the method for recovering uranium from such SUWs using -2-pyrrolidone (NCP) as a precipitate. As a result, it was found that precipitation ratios (PRs) of uranium in the solutions prepared by dissolving SUWs in HNO is 97.7% at [NCP]/[U(VI)] = 20, and that the PRs of iron, aluminum, fluorine, and sulfate species are less than 1%. This indicates that uranium species are precipitated selectively. The content ratios of U, Fe, Ca, F, and S in the materials after calcining precipitates obtained at [NCP]/[U(VI)] = 20 were in accordance with the conditions of uranium ore concentrate. From these results, it is expected that highly purified uranium can be efficiently recovered from SUWs by using NCP as the precipitant.

Interaction of rare earth elements and components of the Horonobe deep groundwater

Kirishima, Akira*; Kuno, Atsushi*; Amamiya, Hiroki; Kubota, Takumi*; Kimuro, Shingo*; Amano, Yuki; Miyakawa, Kazuya; Iwatsuki, Teruki; Mizuno, Takashi; Sasaki, Takayuki*; et al.

Chemosphere, 168, p.798 - 806, 2017/02

https://doi.org/10.1016/j.chemosphere.2016.10.133

For better understanding of the migration behavior of minor actinides (MA) in deep groundwater, the interaction of doped rare earth elements (REEs) and components in Horonobe deep groundwater was studied. Appx. 10 ppb of rare earth elements, i.e., Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm and Yb were doped to the sample groundwater collected from a packed sections in borehole drilled from 140 m depth experiment drift of Horonobe underground research laboratory (URL), Hokkaido, Japan. Then, that groundwater was sequentially filtrated by 0.2 micron pore filter, 10 kDa, 3 kDa and 1 kDa of nominal molecular weight limit (NMWL) ultrafilters by keeping inert condition. After that, the filtrate solutions were analyzed by ICP-MS to determine the concentrations of retained REEs at each filtration steps, while the used filters were analyzed by the neutron activation analysis (NAA) and TOF-SIMS element mapping to know the amount and chemical speciation of trapped fraction of the REEs on each filter. A remarkable relation between the retention ratios of REEs in the filtrate solutions and the ionic radius was observed, i.e., smaller rare earth element solves more in liquid phase under the Horonobe groundwater condition. NAA and TOF-SIMS analyses revealed that certain portions of REEs were trapped by 0.2 micron pore filters as rare earth phosphates which corresponded with the predicted predominant species by a chemical equilibrium calculation for the Horonobe groundwater condition, while small portions of colloidal REEs were trapped by 10 kDa and 3 kDa NMWL ultrafilters. The result suggested that phosphate anion plays an important role in the chemical behavior of REEs in saline (seawater based) groundwater, which could be referred for the prediction of migration behavior of trivalent actinide released from the repository of radioactive waste in far future.

Improvement of neutron startup source handling work by developing new transportation container for High-Temperature engineering Test Reactor (HTTR)

Shimazaki, Yosuke; Sawahata, Hiroaki; Shinohara, Masanori; Yanagida, Yoshinori; Kawamoto, Taiki; Takada, Shoji

Journal of Nuclear Science and Technology, 54(2), p.260 - 266, 2017/02

https://doi.org/10.1080/00223131.2016.1255574

The High-Temperature engineering Test Reactor (HTTR) has three neutron startup sources (NSs) in the reactor core, each of which consists of Cf with 3.7 GBq and is contained in a small capsule, installed in NS holder and subsequently in a control guide block (CR block). The NSs are exchanged at the interval of approximately 7 years. The NS holders are transported from the dealer's hot cell to the reactor facility of HTTR using a transportation container. The loading work of NS holders to the CR blocks is subsequently carried out in the fuel handling machine maintenance pit of HTTR. Technical issues, which are the reduction and prevention of radiation exposure of workers and the exclusion of falling of NS holder, were extracted from the experiences in past two exchange works of NSs to develop a safety handling procedure. Then, a new transportation container special to the NSs of HTTR was developed to solve the technical issues while keeping the cost as low as that for overhaul of conventional container. As the results, the NS handling work using the new transportation container was safely accomplished by developing the new transportation container which can reduce the risks of radiation exposure dose of workers and exclude the falling of NS holder.

Algebraic design of multi-dimensional transfer function using transfer function synthesizer

Kawamura, Takuma; Idomura, Yasuhiro; Miyamura, Hiroko; Takemiya, Hiroshi

Journal of Visualization, 20(1), p.151 - 162, 2017/02

https://doi.org/10.1007/s12650-016-0387-1

In this paper, we propose a novel transfer function design interface for multivariate volume rendering. In the conventional multivariate volume rendering, GUI based transfer function design interfaces were limited to two-dimensional variables space. In order to design higher dimensional transfer functions in an interactive and intuitive manner, a Transfer Function Synthesizer (TFS) is developed. On the TFS, multi-dimensional transfer functions are generated by algebraic synthesis of one-dimensional transfer functions, which are designed based on the conventional GUIs or algebraic expressions. The TFS enables not only multivariate volume rendering but also general visualization techniques such as surface visualization and image composition within the framework of volume rendering. The TFS is implemented on the remote visualization system PBVR, and applied to various multivariate scalar volume data generated from nuclear applications.

Sustainable and safe energy supply with seawater uranium fueled HTGR and its economy

Fukaya, Yuji; Goto, Minoru

Annals of Nuclear Energy, 99, p.19 - 27, 2017/01

AA2015-0534.pdf:0.56MB

https://doi.org/10.1016/j.anucene.2016.09.029

Sustainable and safe energy supply with seawater fueled HTGR have been investigated to sustain the nuclear energy safely by electricity generation with HTGR, the uranium resources must be inexhaustible. The seawater uranium is expected to be alternative resources to conventional resources. It is said that 4.5 billion tons of uranium is dissolved in the seawater, which corresponds to a consumption of approximately 72 thousand years. The uranium dissolved in seawater is in an equilibrium state with the uranium on surface of sea floor, which is approximately a thousand times of the amount, that is 72 million years. It can be recoverable. In other words, the uranium from seawater is almost inexhaustible natural resource. The cost of extracting uranium from seawater with current technology is still expensive compared with that of conventional uranium. However, the economy of nuclear power generation fueled by seawater uranium should be assessed for entire electricity generation cost. In the present study, the economy of electricity generation using uranium from seawater is assessed using a commercial HTGR. Compared with ordinary LWR using conventional uranium, HTGR can realize lower cost of electricity owing to small volume of simple direct gas turbine system compared with water and steam systems of LWR, rationalization by modularizing, and high thermal efficiency, even if fueled by seawater uranium. It is concluded that the HTGR fueled by seawater uranium with the current technology enables the energy sustainability to be maintained for a long term approximately 70 million years with superior inherent safety features and low cost of 7.28 yen/kWh, which is lower than the 8.80 yen/kWh cost of LWR using conventional uranium.

Inelastic and quasi-elastic neutron scattering spectrometers in J-PARC

Seto, Hideki; Ito, Shinichi; Yokoo, Tetsuya*; Endo, Hitoshi*; Nakajima, Kenji; Shibata, Kaoru; Kajimoto, Ryoichi; Kawamura, Seiko; Nakamura, Mitsutaka; Kawakita, Yukinobu; et al.

Biochimica et Biophysica Acta; General Subjects, 1861(1), p.3651 - 3660, 2017/01

https://doi.org/10.1016/j.bbagen.2016.04.025

J-PARC, Japan Proton Accelerator Research Complex provides short pulse proton beam at a repetition rate 25 Hz and the maximum power is expected to be 1 MW. Materials and Life Science Experimental Facility (MLF) has 23 neutron beam ports and 21 instruments have already been operated or under construction / commissioning. There are 6 inelastic / quasi-elastic neutron scattering spectrometers and the complementary use of these spectrometers will open new insight for life science.

Elastically-homogeneous lattice models of damage in geomaterials

Asahina, Daisuke*; Aoyagi, Kazuhei; Kim, K.*; Birkholzer, J.*; Birkholzer, J. T.*; Bolander, J. E.*

Computers and Geotechnics, 81, p.195 - 206, 2017/01

https://doi.org/10.1016/j.compgeo.2016.08.015

Hydrogeomechanical properties of excavation damaged zones along galleries in different depths of the Horonobe underground research laboratory

Aoyagi, Kazuhei; Ishii, Eiichi

Dai-14-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (Internet), 6 Pages, 2017/01

The objective of this research is to investigate the hydro-mechanical properties of excavation damaged zones (EDZs) along the galleries excavated in 250 m and 350 m depths. We conducted hydraulic tests, BTV observations and core analyses. As a result, in the 250 m gallery, the extent of the EDZ was 1.0 m into the gallery wall. The hydraulic conductivity was increased by 2 to 3 orders of magnitudes compared with that of intact rock. On the other hand, in the 350 m gallery, the extent of the EDZ was 0.4 m into the gallery wall; the hydraulic conductivity was increased by 5 orders of magnitudes compared with that of intact rock. We investaged the difference of the characteristics of the EDZs on the basis of competence factor and ductility index. As a result, it was estimated that an extent of an EDZ decreases with decrease of competence factor; a hydraulic conductivity in an EDZ increases with decrease of ductility index.

Long-term evaluation of excavation damaged zone by optical measurement in Horonobe Underground Research Laboratory

Hata, Koji*; Niunoya, Sumio*; Aoyagi, Kazuhei

Dai-14-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (Internet), 6 Pages, 2017/01

The objective of this research is to investigate the long-term hydro-mechanical behavior of rock mass around the shaft in the Horonobe Underground Research Laboratory (URL). The long-term monitoring has been carried out by optical AE sensors, optical water pressure sensors, and optical temperature sensors below 350m depth of the shaft in the Horonobe URL. From the measurement results, the extent of an excavation damaged zone was 1.5m within the shaft wall. After the excavation, it was observed that the unsaturated zone of the groundwater was spread more than 1.5m within the shaft wall.

Higher harmonic imaging of small defects in ODS steel cladding tubes and characterization of the defects with SEM

Kawashima, Koichiro*; Yano, Yasuhide; Tanno, Takashi; Kaito, Takeji

Dai-24-Kai Choompa Ni Yoru Hihakai Hyoka Shimpojiumu Koen Rombunshu (USB Flash Drive), p.99 - 104, 2017/01

no abstracts in English

Assessment of residual doses to population after decontamination in Fukushima Prefecture

Mori, Airi; Takahara, Shogo; Ishizaki, Azusa; Iijima, Masashi; Sanada, Yukihisa; Munakata, Masahiro

Journal of Environmental Radioactivity, 166(Part 1), p.74 - 82, 2017/01

https://doi.org/10.1016/j.jenvrad.2016.06.023

Large quantities of radioactive materials were released into the environment as a result of the Fukushima Daiichi Nuclear Power Station accident. Many inhabitants residing in the affected areas are now exposed to radiation in their daily lives. In an attempt to manage this radiation dose, an additional radiation dose of 1 mSv/y was adopted as a long-term dosimetric target. An activity level reading of 0.23 Sv/h was then determined as a guidance value to achieve the target by implementing decontamination measures. The objectives of this study are to assess the effects of decontamination based on this guidance value and to predict any possible future problems with the decontamination strategy. Using a probabilistic approach, we assessed the annual effective dose of indoor workers, outdoor workers, and pensioners in the Fukushima Prefecture. Our probabilistic model considers the variabilities in behavioral patterns and Cs-137 surface-activity levels. Five years after the initial contamination, the 95th percentiles of indoor workers and pensioners in 53 of the 59 municipalities were found to receive annual effective doses of below 1 mSv/y (0.026-0.73 mSv/y). However, for outdoor workers in 25 municipalities, the annual doses were over 1 mSv/y (1.0-35 mSv/y). Therefore, the guidance value is effective for indoor workers and pensioners; to determine whether additional countermeasures for outdoor workers should be implemented, a detailed assessment that uses more realistic assumptions is required.

Measurements of air dose rates in and around houses in the Fukushima Prefecture in Japan after the Fukushima accident

Matsuda, Norihiro; Mikami, Satoshi; Sato, Tetsuro*; Saito, Kimiaki

Journal of Environmental Radioactivity, 166(Part 3), p.427 - 435, 2017/01

https://doi.org/10.1016/j.jenvrad.2016.03.012

Investigation of absorption characteristics for thermal-load fluctuation using HTTR

Tochio, Daisuke; Honda, Yuki; Sato, Hiroyuki; Sekita, Kenji; Homma, Fumitaka; Sawahata, Hiroaki; Takada, Shoji; Nakagawa, Shigeaki

Journal of Nuclear Science and Technology, 54(1), p.13 - 21, 2017/01

https://doi.org/10.1080/00223131.2016.1201441

GTHTR300C is designed and developed in JAEA. The reactor system is required to continue a stable and safety operation as well as a stable power supply in the case that thermal-load is fluctuated by the occurrence of abnormal event in the heat utilization system. Then, it is necessary to demonstrate that the thermal-load fluctuation should be absorbed by the reactor system so as to continue the stable and safety operation could be continued. The thermal-load fluctuation absorption tests without nuclear heating were planned and conducted in JAEA to clarify the absorption characteristic of thermal-load fluctuation mainly by the reactor and by the IHX. As the result it was revealed that the reactor has the larger absorption capacity of thermal-load fluctuation than expected one, and the IHX can be contributed to the absorption of the thermal-load fluctuation generated in the heat utilization system in the reactor system. It was confirmed from there result that the reactor and the IHX has effective absorption capacity of the thermal-load fluctuation generated in the heat utilization system. Moreover it was confirmed that the safety estimation code based on RELAP5/MOD3 can represents the thermal-load fluctuation absorption behavior conservatively.

Applicability of polyvinylpolypyrrolidone adsorbent to treatment process of wastes containing uranium

Ohashi, Yusuke; Harada, Masayuki*; Asanuma, Noriko*; Ando, Shion; Tanaka, Yoshio; Ikeda, Yasuhisa*

Journal of Radioanalytical and Nuclear Chemistry, 311(1), p.491 - 502, 2017/01

https://doi.org/10.1007/s10967-016-5017-9

In order to assess the feasibility of method for recovering U from wastes containing uranium (scrap uranium) using polyvinylpolypyrrolidone (PVPP) adsorbent, we have examined the adsorption and desorption behavior of metal species in HCl aqueous solutions dissolving scrap uranium. It was found that the U(VI) species are selectively adsorbed onto PVPP regardless of the presence of a large amount of Na(I) and Al(III), that the adsorbed U(VI) species are desorbed from PVPP column selectively by water. Pure uranium was efficiently recovered from the eluates. From these results, the PVPP resin is expected to be used as the adsorbent in the treatment process of scrap uranium.

Variational wavefunction for the periodic Anderson model with onsite correlation factors

Kubo, Katsunori; Onishi, Hiroaki

Journal of the Physical Society of Japan, 86(1), p.013701_1 - 013701_4, 2017/01

https://doi.org/10.7566/JPSJ.86.013701

Modeling of Phosphorus Transport by Interstitial Dumbbell in -Iron Using First-Principles-Based Kinetic Monte Carlo

Ebihara, Kenichi; Suzudo, Tomoaki; Yamaguchi, Masatake

Materials Transactions, 58(1), p.26 - 32, 2017/01

https://doi.org/10.2320/matertrans.ML201602

In order to evaluate grain boundary (GB) phosphorous (P) segregation in nuclear reactor pressure vessel steels under irradiation, the rate-theory model based on first-principles calculations is developed. In this study, we evaluated the diffusion coefficient of the mixed interstitial dumbbell of a P atom and an iron(Fe) atom using a kinetic Monte Carlo (kMC) simulation based on first-principles calculations. The evaluated diffusion coefficient was almost the same with the diffusion coefficient of P atoms which migrate via octahedral interstitial sites, and was much faster than that for P transport by vacancies. Furthermore, from the simulation of the irradiation induced GB P segregation using the model which was modified to include P atoms of octahedral interstitial sites, it was found that the boundary condition at GB is not valid for P atoms of octahedral interstitial sites

Composite behavior of lath martensite steels induced by plastic strain, a new paradigm for the elastic-plastic response of martensitic steels

Ungr, T.*; Harjo, S.; Kawasaki, Takuro; Tomota, Yo*; Ribrik, G.*; Shi, Z.*

Metallurgical and Materials Transactions A, 48(1), p.159 - 167, 2017/01

AA2016-0372.pdf:2.81MB

https://doi.org/10.1007/s11661-016-3845-4

One-dimensional spinon spin currents

Hirobe, Daichi*; Sato, Masahiro*; Kawamata, Takayuki*; Shiomi, Yuki*; Uchida, Kenichi*; Iguchi, Ryo*; Koike, Yoji*; Maekawa, Sadamichi; Saito, Eiji

Nature Physics, 13(1), p.30 - 34, 2017/01

https://doi.org/10.1038/nphys3895

Development of ion exchange ligands with high separation performance and colorimetric analysis using gold nanoparticles decorated with the functional ligands

Shimojo, Kojiro

Nihon Ion Kokan Gakkai-Shi, 28(1), p.1 - 10, 2017/01

https://doi.org/10.5182/jaie.28.1

Development of metal separating reagents with high selectivity is necessary for efficient separation and recovery of valuable metals contained in industrial wastes, and removal and detection of toxic metals. We have developed novel metal separating ligands with a diglycolamic acid (DGAA) framework. The ligands have a tridentate coordination structure consisting of an amide group and a carboxy group connected by an ether chain and provide a metal separation ability superior to that of commercial ligands. Since the ligands can be synthesized simply in one step, this helps to reduce the production costs of the ligands. In the present review article, we report the extraction characteristics of DGAA-type ligand for 56 kinds of metal ions, extraction separation of rare-earth metal ions, and removal of toxic metal ions. Furthermore, a one-pot biological approach to fabricate DGAA-decorated gold nanoparticles has been developed using the DGAA-type ligand fused to the N-terminus of a gold-binding peptide. It was found that the DGAA-decorated gold nanoparticles can act as a high-sensitive colorimetric sensor for detecting toxic metal ions with color change.

Systematic measurement of double-differential neutron production cross sections for deuteron-induced reactions at an incident energy of 102 MeV

Araki, Shohei*; Watanabe, Yukinobu*; Kitajima, Mizuki*; Sadamatsu, Hiroki*; Nakano, Keita*; Kin, Tadahiro*; Iwamoto, Yosuke; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; et al.

Nuclear Instruments and Methods in Physics Research A, 842, p.62 - 70, 2017/01

https://doi.org/10.1016/j.nima.2016.10.043

Recently, deuteron incident reaction is expected to be used as a neutron source for study of radiation damage in fusion materials, boron neutron capture therapy, and so on. However, experimental data to validate the model is very few. In this work, double-differential neutron production cross sections (DDXs) for deuteron-induced reactions on Li, Be, C, Al, Cu, and Nb at 102 MeV were measured at forward angles 25 by means of a time of flight (TOF) method with NE213 liquid organic scintillators at the Research Center of Nuclear Physics (RCNP), Osaka University. The experimental DDXs and energy-integrated cross sections were compared with TENDL-2015 data and PHITS calculation. The PHITS calculation showed better agreement with the experimental results than TENDL-2015 for all target nuclei, although the shape of the broad peak around 50 MeV was not satisfactorily reproduced by the PHITS calculation.

Search for the Glueball in and decays

Jia, S.*; Tanida, Kiyoshi; Belle Collaboration*; 170 of others*

Physical Review D, 95(1), p.012001_1 - 012001_13, 2017/01

AA2016-0474.pdf:1.26MB

https://doi.org/10.1103/PhysRevD.95.012001

Classification of radioactive waste drums using random forests for their -ray spectra

Hata, Haruhi; Ishimori, Yuu

Radioisotopes, 66(1), p.1 - 10, 2017/01

https://doi.org/10.3769/radioisotopes.66.1

The feasibility of Random Forests, one of machine learning methods was examined for the classification of radioactive waste drums. It was carried out using 954 -ray spectra of drums which were already classified to natural or reprocessed uranium. After 300 spectra were selected at random to reassemble training datasets, the percentages of correct classification by Random Forests were evaluated with another 654 spectra. When the counts of spectra were reprocessed as the difference of their logarithm, Random Forests accurately classified 654 drums.

Estimation of corrosion mechanisms from the data obtained by the reproduced experiments considering the actual environments; Maritime structures and nuclear facilities

Yamamoto, Masahiro

Zairyo To Kankyo, 66(1), p.3 - 12, 2017/01

https://doi.org/10.3323/jcorr.66.3

The laboratory simulation tests which could be reproduced the corrosion reactions propagating in the actual environments were utilized to analyze the mechanism of corrosion phenomena. In this report, some results are introduced in the cases of maritime structures and nuclear facilities. Experimental apparatus was originally designed to obtain the data in high radioactive condition simulating actual plants. One is a result showing the effect of Np ion to the corrosion of stainless steel in nuclear fuel reprocessing plant. Corrosion mechanism was revealed that Np ion is reduced to Np ion by a corrosion reaction of stainless steel and then re-oxidized to Np ion in the bulk solution. And repetition of this cycle accelerated corrosion of stainless steel by a little amounts of Np addition in nitric acid solution. Another result is introduced that an effect of HO created by radiolysis of cooling water at high radioactive environment in light water reactor.

Structural engineering studies on reinforced concrete structure using neutron diffraction

Suzuki, Hiroshi; Kusunoki, Koichi*; Kanematsu, Manabu*; Mukai, Tomohisa*; Harjo, S.

Materials Research Proceedings, Vol.2, p.25 - 30, 2017/00

https://doi.org/10.21741/9781945291173-5

It has been demonstrated in our past studies that neutron diffraction can be an alternative method to conventional strain gauge for measuring the stress distribution along rebar embedded in concrete. The current study investigated the possibility of the bond stress evaluation using neutron diffraction in order to find further capability of neutron diffraction for the structural engineering study on the reinforced concrete structure. Several peaks appeared in the bond stress distribution measured by neutron diffraction, showing the inhomogeneous bond variation along the embedded rebar. This result suggests that the neutron diffraction technique with high spacial resolution makes it possible to catch local bond resistance caused by the transverse ribs. The bond stress distribution measured by the neutron diffraction technique is expected to bring detailed understanding of the bond mechanism between rebar and concrete for the reinforced concrete structure.

Determination of Pd in Pd recovered by laser-induced photoreduction with inductively coupled plasma mass spectrometry

Asai, Shiho; Yomogida, Takumi; Saeki, Morihisa*; Oba, Hironori*; Hanzawa, Yukiko; Horita, Takuma; Kitatsuji, Yoshihiro

Analytical Chemistry, 88(24), p.12227 - 12233, 2016/12

https://doi.org/10.1021/acs.analchem.6b03286

Safety evaluation of a radioactive waste repository requires credible activity estimates confirmed by actual measurements. A long-lived radionuclide, Pd, which can be found in radioactive wastes, is one of the difficult-to-measure nuclides and results in a deficit in experimentally determined contents. In this study, a precipitation-based separation method has been developed for the determination of Pd with ICP-MS. The photoreduction induced by laser irradiation at 355 nm provides short-time and one-step recovery of Pd. The proposed method was verified by applying it to a spent nuclear fuel sample. In order to efficiently recover Pd, a natural Pd standard was employed as the Pd carrier. The chemical yield of Pd was about 90% with virtually no impurities, allowing accurate quantification of Pd.

Temporal variation of dose rate distribution around the Fukushima Daiichi Nuclear Power Station using unmanned helicopter

Sanada, Yukihisa; Orita, Tadashi; Torii, Tatsuo

Applied Radiation and Isotopes, 118, p.308 - 316, 2016/12

https://doi.org/10.1016/j.apradiso.2016.09.008

An unmanned helicopter monitoring system (UHMS) was developed to survey the environmental effect of radioactive cesium scattered as a result of the Fukushima Daiichi Nuclear Power Station accident. The UHMS was mainly used to monitor the area surrounding the Fukushima Daiichi Nuclear Power Station six times from 2012 to 2015. Quantitative changes in the radioactivity distribution trend were revealed from the results of these monitorings runs.

Retention of rare earth elements, thorium and uranium in sedimentary rocks; A Case study in the Horonobe area of Hokkaido, Japan

Murakami, Takuma; Sasamoto, Hiroshi; Mizuno, Takashi

Chikyu Kagaku, 50(4), p.299 - 317, 2016/12

http://doi.org/10.14934/chikyukagaku.50.299

Development of techniques for investigating the long-term migration of elements in deep underground is important with respect to safety assessment for the geological disposal of high-level radioactive waste. As one study of the migration of elements in deep underground, the distribution of REE, Th and U in sedimentary rock of Horonobe area in Hokkaido was investigated, and discussed whether the difference of hydrogeological structure and lithofacies influences on the distributions. As the results, it was considered that REE and Th were mainly retained in minerals originating from terrigenous clastic and secondary mineral occurred in early diagenesis, and their distributions were relatively homogenous in both the Koetoi and Wakkanai formations. Uranium was indicated to be maintained in the sedimentary rock until now after depositing in deep-sea sediment. It was considered that the U deposition was occurred by adsorption on organic matter and reductive precipitation with decomposition of organic matter. In addition, it was confirmed that the distributions of these elements were not influenced by the difference of hydrogeological and lithofacies.

Chemical properties of rutherfordium (Rf) and dubnium (Db) in the aqueous phase

Nagame, Yuichiro; Kratz, J. V.*; Schdel, M.*

EPJ Web of Conferences, 131, p.07007_1 - 07007_8, 2016/12

BB2016-0022.pdf:0.96MB

https://doi.org/10.1051/epjconf/201613107007

Dating of crush zones associated with plastic deformation of biotite; Constraints by fission-track thermochronometry

Sueoka, Shigeru; Shimada, Koji; Ishimaru, Tsuneari; Niwa, Masakazu; Yasue, Kenichi; Umeda, Koji*; Danhara, Toru*; Iwano, Hideki*

Fisshion, Torakku Nyusureta, (29), p.5 - 7, 2016/12

http://ftrgj.org/FTNLs/FTNLparts/sueoka16.pdf

no abstracts in English

Report on the International Conference on Thermochronology 2016 in Maresias, Brazil

Sueoka, Shigeru; Tagami, Takahiro*

Fisshion, Torakku Nyusureta, (29), p.26 - 28, 2016/12

http://ftrgj.org/FTNLs/FTNLparts/thermo16.pdf

no abstracts in English

Measurement of atomic radii

Kaneko, Masashi

Gendai Kagaku, (549), P. 11, 2016/12

This article was made to explain the paper stating that atomic size was measured by computational method (R. Hoffmann, et al., Chem. Eur. J., 22, doi: 10.1002/chem.201602949) for student majoring chemistry. The estimation of atomic size was performed by means relativistic density functional theory. The atomic radii of noble gas and d-block elements were discussed.

Symposium on "Science of nuclear fuel cycle and backend; Research and education" with a memory of Professor Joonhong Ahn, the University of California, Berkeley

Nakayama, Shinichi; Okumura, Masahiko*; Nagasaki, Shinya*; Enokida, Yoichi*; Umeki, Hiroyuki*; Takase, Hiroyasu*; Kawasaki, Daisuke*; Hasegawa, Shuichi*; Furuta, Kazuo*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 23(2), p.131 - 148, 2016/12

http://nuce.aesj.or.jp/jnuce/vol23/Jnuce-Vol23-2-p131-148.pdf

A symposium "Science of nuclear fuel cycle and backend - Research and education -" was held at the Univer-sity of Tokyo in June 25, 2016. This aimed at developing the research on nuclear fuel cycle and backend. The time and the number of participants of the symposium were limited, but the active discussion was conducted, and the common perception for the future was shared among the experienced participants in those fields. This paper provides the discussions made in the symposium, and also, as a memory to Professor Ahn, the University of California, Berkeley, his prominent achievements in academic research and education.

Report on the Workshop "Radiation Research Based on Computer Simulation" held at the 59th Annual Meeting of the Japanese Radiation Research Society

Sato, Tatsuhiko; Hamada, Nobuyuki*

Hoshasen Seibutsu Kenkyu, 51(4), p.397 - 401, 2016/12

A workshop entitled "Radiation Research Based on Computer Simulation" was held at the 59th annual meeting of the Japanese Radiation Research Society. Approximately 50 participants attended the workshop, and six speakers gave a talk about their computational radiation biology studies. The title of the presentations are "Research on DNA damage and track structure simulation", "Study of cellular response based on stochastic model for simulating irradiated and non-irradiated cells", "Effectiveness of mathematical model for low-dose radiation effect", "Research on particle therapy based on cell surviving fraction model", "Development of model for natural induction of cataract", and "Mathematical model for carcinogenesis considering the differences of temporal and spatial doses". In the workshop, possible future collaborations were intensively discussed. This report briefly summarizes the outline of the workshop.

Simultaneous recovery and separation of rare earth elements in ferromanganese nodules by using

Fujimoto, Jun*; Tanaka, Kazuya; Watanabe, Naoko*; Takahashi, Yoshio*

Hydrometallurgy, 166, p.80 - 86, 2016/12

https://doi.org/10.1016/j.hydromet.2016.09.005

We examined recovery of REEs in Fe-Mn nodules by using (Fe-reducing bacterium). In this method, Fe-Mn nodule decomposition and REE recovery were achieved simultaneously in a single solution system. Fe-Mn nodules were reductively decomposed in NaCl solution under anaerobic conditions with daily addition of sodium lactate as an electron donor. During the decomposition of Fe-Mn nodule, REEs released from the Fe-Mn nodule were adsorbed on bacterial cells. Of the conditions studied here, the best REE adsorption rates were obtained with 0.5M NaCl solution at pH7 with daily addition of 1 mmol sodium lactate.

Contrast variation by dynamic nuclear polarization and time-of-flight small-angle neutron scattering, 1; Application to industrial multi-component nanocomposites

Noda, Yohei*; Koizumi, Satoshi*; Masui, Tomomi*; Mashita, Ryo*; Kishimoto, Hiromichi*; Yamaguchi, Daisuke; Kumada, Takayuki; Takata, Shinichi; Oishi, Kazuki*; Suzuki, Junichi*

Journal of Applied Crystallography, 49(6), p.2036 - 2045, 2016/12

https://doi.org/10.1107/S1600576716016472

The Welded joint strength reduction factors of modified 9Cr-1Mo Steel for the advanced loop-type sodium cooled fast reactor

Yamashita, Takuya; Wakai, Takashi; Onizawa, Takashi; Sato, Kenichiro*; Yamamoto, Kenji*

Journal of Pressure Vessel Technology, 138(6), p.061407_1 - 061407_6, 2016/12

https://doi.org/10.1115/1.4034017

Development of inspection and repair techniques in reactor vessel of experimental fast reactor "Joyo"; Retrieval of the bent test subassembly

Ashida, Takashi; Ito, Hideaki; Miyamoto, Kazuyuki*; Nakamura, Toshiyuki; Koga, Kazuhiro*; Ohara, Norikazu*; Ino, Hiroichi*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(4), p.210 - 222, 2016/12

https://doi.org/10.3327/taesj.J15.032

In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly of material testing rig named "MARICO-2" had been broken and bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). As the result, for Joyo restart, it was necessary to replace the damaged UCS and to retrieve the bent sub-assembly. This paper describes in-vessel repair techniques performed in the retrieval work of the obstacle inside of the reactor vessel. The devices which were prepared for this work demonstrated expected performance under the environmental conditions of an SFR such as high temperature and radiation dose, and the work was completed in 2014. The successful operation of this retrieval work of the damaged component inside of a reactor vessel will contribute to the development of in-service inspections and repair technics in an SFR.

Creep-fatigue evaluation method for weld joint of Mod.9Cr-1Mo steel, 2; Plate bending test and proposal of a simplified evaluation method

Ando, Masanori; Takaya, Shigeru

Nuclear Engineering and Design, 310, p.217 - 230, 2016/12

AA2016-0318.pdf:2.62MB

https://doi.org/10.1016/j.nucengdes.2016.10.025

In the present study, to develop an evaluation procedure and design rules for Mod.9Cr-1Mo steel weld joints, a method for creep-fatigue life evaluation of Mod.9Cr-1Mo steel weld joints was proposed based on the finite element analysis (FEA) results with a series of cyclic plate bending tests of the longitudinal and horizontal seamed plates. The strain concentration and redistribution behaviors were evaluated and failure cycles were estimated using FEA by considering the test conditions and metallurgical discontinuities in the weld joints. The elastic follow-up factors calculated from a comparison of the elastic and inelastic FEA results were determined to be less than 1.5. Based on the estimated elastic follow-up factors obtained via inelastic FEA, a simplified technique using elastic FEA was proposed for evaluating the creep-fatigue life in Mod.9Cr-1Mo steel weld joints.

Dissolution behavior of lithium compounds in ethanol

Furukawa, Tomohiro; Hirakawa, Yasushi; Kondo, Hiroo; Kanemura, Takuji

Nuclear Materials and Energy (Internet), 9, p.286 - 291, 2016/12

BB2015-1402.pdf:3.16MB

https://doi.org/10.1016/j.nme.2016.05.005

In order to exchange the components which received irradiation damage during the operation at the International Fusion Materials Irradiation Facility, the adhered lithium, which is partially converted to lithium compounds such as lithium oxide and lithium hydroxide, should be removed from the components. In this study, the dissolution experiments of lithium compounds (lithium nitride, lithium hydroxide, and lithium oxide) were performed in a candidate solvent, allowing the clarification of time and temperature dependence. Based on the results, a cleaning procedure for adhered lithium on the inner surface of the components was proposed.

Strength anisotropy of rolled 11Cr-ODS steel

Tanno, Takashi; Yano, Yasuhide; Oka, Hiroshi; Otsuka, Satoshi; Uwaba, Tomoyuki; Kaito, Takeji

Nuclear Materials and Energy (Internet), 9, p.353 - 359, 2016/12

BB2015-1727.pdf:6.74MB

https://doi.org/10.1016/j.nme.2016.02.009

Materials for core components of fusion reactors and fast reactors, such as blankets and fuel cladding tubes, must be excellent in high temperature strength and irradiation resistance because they will be exposed to high heat flux and heavy neutron irradiation. Oxide dispersion strengthened (ODS) steels have been developing as the candidate material. Japan Atomic Energy Agency (JAEA) have been developing 9 and 11 Chromium (Cr) ODS steels for advanced fast reactor cladding tubes. The JAEA 11Cr-ODS steels were rolled in order to evaluate their anisotropy. Tensile tests and creep tests of them were carried out at 700 C in longitudinal and transverse orientation. The anisotropy of tensile strength was negligible, though that of creep strength was distinct. The observation results and chemical composition analysis suggested that the cause of the anisotropy in creep strength was prior powder boundary including Ti-rich precipitates.

The Reaction mechanism of polyalcohol dehydration in hot pressurized water

Ruiz-Barragan, S.*; Ribas Ario, J.*; Shiga, Motoyuki

Physical Chemistry Chemical Physics, 18(47), p.32438 - 32447, 2016/12

https://doi.org/10.1039/C6CP05695D

The use of high-temperature liquid water (HTW) as a reaction medium is a very promising technology in the field of green chemistry. In order to fully exploit this technology, it is crucial to unravel the reaction mechanisms of the processes carried out in HTW. In this work, the reaction mechanism of 2,5-hexanediol dehydration in HTW has been studied by means of three different ab initio simulations: string method, metadynamics and molecular dynamics in real time. It is found that the whole reaction involving the protonation, bond exchange and the deprotonation occurs in a single step without a stable intermediate. The hydrogen bonded network of surrounding water has a vital role in assisting an efficient proton relay at the beginning and at the end of the reaction. It is confirmed that the reaction is energetically most favorable in the SN2 pathway with an estimated barrier of 36 kcal/mol, which explains the high stereo selectivity and the reaction rate observed in experiment.

Azimuthally anisotropic emission of low-momentum direct photons in Au+Au collisions at = 200 GeV

Adare, A.*; Hasegawa, Shoichi; Imai, Kenichi; Nagamiya, Shoji; Sako, Hiroyuki; Sato, Susumu; Tanida, Kiyoshi; PHENIX Collaboration*; 545 of others*

Physical Review C, 94(6), p.064901_1 - 064901_14, 2016/12

AA2016-0473.pdf:0.66MB

https://doi.org/10.1103/PhysRevC.94.064901

Characterization of the insoluble sludge from the dissolution of irradiated fast breeder reactor fuel

Aihara, Haruka; Arai, Yoichi; Shibata, Atsuhiro; Nomura, Kazunori; Takeuchi, Masayuki

Procedia Chemistry, 21, p.279 - 284, 2016/12

BB2015-3214.pdf:0.31MB

https://doi.org/10.1016/j.proche.2016.10.039

Uranium and plutonium extraction by -dialkylamides using multistage mixer-settler extractors

Ban, Yasutoshi; Hotoku, Shinobu; Tsutsui, Nao; Suzuki, Asuka; Tsubata, Yasuhiro; Matsumura, Tatsuro

Procedia Chemistry, 21, p.156 - 161, 2016/12

https://doi.org/10.1016/j.proche.2016.10.022

A continuous counter-current experiment was carried out to demonstrate the validity of a process using -dialkylamides for recovering U and Pu. This process consisted of two cycles, and the 1st cycle and the 2nd cycle employed -di(2-ethylhexyl)-2,2-dimethylpropanamide and -di(2-ethylhexyl)butanamide as extractants, respectively. The feed solution for the 1st cycle was 5.1 mol/dm (M) nitric acid containing 0.92 M U, 1.6 mM Pu, and 0.6 mM Np. The raffinate collected in the 1st cycle was used as the feed for the 2nd cycle. The ratios of U recovered in the U fraction and U-Pu fraction were 99.1% and 0.8%, respectively. The ratio of Pu recovered in the U-Pu fraction was 99.7%. The concentration ratio of U with respect to Pu in the U-Pu fraction was 9, and this indicated that Pu was not isolated. The decontamination factor of U with respect to Pu in the U fraction was obtained as 4.510. These results supported the validity of the proposed process.

Dynamics in condensed matter by 4SEASONS

Kajimoto, Ryoichi

Radioisotopes, 65(12), p.523 - 534, 2016/12

https://doi.org/10.3769/radioisotopes.65.523

no abstracts in English

Forest type effects on the retention of radiocesium in organic layers of forest ecosystems affected by the Fukushima nuclear accident

Koarashi, Jun; Atarashi-Andoh, Mariko; Matsunaga, Takeshi; Sanada, Yukihisa

Scientific Reports (Internet), 6, p.38591_1 - 38591_11, 2016/12

https://doi.org/10.1038/srep38591

Forest-floor organic layers play a key role in controlling the overall bioavailability of Cs in forest ecosystems; however, there is still an insufficient understanding of how forest types influence the retention capability of Cs in organic layers in Japanese forest ecosystems. Here we conducted plot-scale investigations on the retention of Cs in organic layers at two contrasting forest sites in Fukushima. In a deciduous broad-leaved forest, approximately 80% of the deposited Cs migrated to mineral soil located below the organic layers within two years after the accident, with an ecological half-life of approximately one year. Conversely, in an evergreen coniferous forest, more than half of the deposited Cs remained in the organic layers, with an ecological half-life of 2.1 years. The observed retention behavior can be well explained by the tree phenology and accumulation of Cs associated with litter materials with different degrees of degradation in the organic layers.

Efforts in the "Fugen"; The History of up to termination of operation and Efforts of decommissioning measures

Morishita, Yoshitsugu

Denki Hyoron, 101(11), p.24 - 29, 2016/11

no abstracts in English

Impact of mesoscale recirculation of the Kuroshio on asymmetric oceanic structure around Okinawa Island

Uchiyama, Yusuke*; Odani, Sachika*; Yamanishi, Takafumi*; Kamidaira, Yuki; Mitarai, Satoshi*

Doboku Gakkai Rombunshu, B2 (Kaigan Kogaku) (Internet), 72(2), p.I_481 - I_486, 2016/11

http://doi.org/10.2208/kaigan.72.I_481

no abstracts in English

Report on site tour of the Fukushima Nuclear Power Station

Suto, Toshiyuki

Gijutsushi, 28(11), p.8 - 11, 2016/11

Five years have passed since the accident of the Fukushima Daiichi Nuclear Power Station. The Nuclear and Radiation section of the Institute of Professional Engineers hosted a site tour of the plant to make themselves sure what is going on in it and to disseminate information about it. The conditions of landscape during traveling between the gathering place and the plant, each reactor, contaminated water treatment, site, and work environment improvement will be reported.

Structure determinations of graphene and silicene on metal surfaces using total-reflection high-energy positron diffraction

Fukaya, Yuki

Hyomen Kagaku, 37(11), p.547 - 552, 2016/11

https://doi.org/10.1380/jsssj.37.547

no abstracts in English

Deceleration processes of secondary electrons produced by a high-energy Auger electron in a biological context

Kai, Takeshi; Yokoya, Akinari; Ukai, Masatoshi; Fujii, Kentaro; Watanabe, Ritsuko

International Journal of Radiation Biology, 92(11), p.654 - 659, 2016/11

https://doi.org/10.1080/09553002.2016.1195933

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

https://doi.org/10.7566/JPSCP.11.050005

Development of micro-structured fluorescent plates for high-resolution imaging

Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Matsubayashi, Masahito

JPS Conference Proceedings (Internet), 11, p.020005_1 - 020005_6, 2016/11

https://doi.org/10.7566/JPSCP.11.020005

Measurement of radioactive contamination on work clothing of workers engaged in decontamination operations

Tsujimura, Norio; Yoshida, Tadayoshi; Hoshi, Katsuya

JPS Conference Proceedings (Internet), 11, p.070003_1 - 070003_7, 2016/11

https://doi.org/10.7566/JPSCP.11.070003

Year-round variations in the fluvial transport load of particulate Cs in a forested catchment affected by the Fukushima Daiichi Nuclear Power Plant accident

Matsunaga, Takeshi; Nakanishi, Takahiro; Atarashi-Andoh, Mariko; Takeuchi, Erina; Muto, Kotomi; Tsuzuki, Katsunori; Nishimura, Shusaku; Koarashi, Jun; Otosaka, Shigeyoshi; Sato, Tsutomu*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 310(2), p.679 - 693, 2016/11

AA2015-0821.pdf:3.78MB

https://doi.org/10.1007/s10967-016-4840-3

Particulate Cs in stream water was collected continuously for two years in order to assess the long-term trend of the Cs discharge from the forest environment. Sampling was conducted from December 2011 to December 2013 in a mountainous stream, which received the Cs from the Fukushima Daiichi Nuclear Power Plant accident. A seasonal increase in fluvial transport load of particulate Cs associated with suspended solids (SS) was observed in August and September when rainfall was abundant. The particulate Cs concentration decreased at a faster rate than the rate due to radioactive decay. This decrease might be resulted from redistribution of the easily eroded and polluted soil surface due to heavy rain events such as typhoons. These findings indicate that the particulate Cs load was subject to the inter-annual variations in rainfalls, and decreased gradually over a long period of time due to a decrease in Cs concentration in SS.

Assessment of radiation doses to the public and its management in the areas contaminated by a nuclear accident

Takahara, Shogo

Kankyo Eisei Kogaku Kenkyu, 30(4), p.12 - 30, 2016/11

no abstracts in English

Flux pinning properties in YBCO films with growth-controlled nano-dots and heavy-ion irradiation defects

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Uraguchi, Yusei*; Suenaga, Momotaro*; Makihara, Takahiro*; Fujiyoshi, Takanori*; Ishikawa, Norito

Physica C, 530, p.72 - 75, 2016/11

https://doi.org/10.1016/j.physc.2016.04.011

In order to clarify the influence of size and spatial distribution of three-dimensional pinning centers (3D-PCs) on hybrid flux pinning, columnar defects (CDs) were installed by using 200 MeV Xe ions along the -axis direction into quasi-multilayered films consisting of YBaCuOy layers and pseudo layers of BaSnO. The positive effect of the BaSnO doping on the hybrid flux pinning stands out for the critical current density around in high magnetic field and/or inclined magnetic field off the -axis, whereas there is little difference in the at among the same growth temperature samples for low magnetic field. In the case of the in-plane distributed BaSnO nano-dots, the Jc around is remarkably enhanced, whereas there is a detrimental effect on the Jc around . These imply that the tuning of 3D-PCs is one of the keys to improve the at all magnetic field orientations for the hybrid flux pinning.

Measurements of directed, elliptic, and triangular flow in Cu+Au collisions at =200 GeV

Adare, A.*; Hasegawa, Shoichi; Imai, Kenichi; Nagamiya, Shoji; Sako, Hiroyuki; Sato, Susumu; Tanida, Kiyoshi; PHENIX Collaboration*; 397 of others*

Physical Review C, 94(5), p.054910_1 - 054910_18, 2016/11

AA2016-0472.pdf:0.98MB

https://doi.org/10.1103/PhysRevC.94.054910

Improvement of ex-vessel molten core behavior models for the JASMINE code

Matsumoto, Toshinori; Kawabe, Ryuhei; Sugiyama, Tomoyuki; Maruyama, Yu

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 9 Pages, 2016/11

During severe accident at nuclear power stations, molten core material jet could be discharged from the reactor pressure vessel into the water pool formed at the pedestal or cavity in the containment vessel. To improve the JASMINE code, The method for determining particle diameters which follow the Rosin-Rammler distribution was implemented. The jet breakup experiments, DEFOR-A conducted by KTH (Royal Institute of Technology, Sweden) were analyzed with the code. The influence of the experimental conditions, such as water subcooling, melt jet diameter and superheat were discussed. A crust layer formation model was also implemented in the code. The analyses using the model were carried out for the melt spreading experiments, PULiMS conducted by KTH. The spreading area was overestimated. Further improvement of the melt spreading model were discussed to close the gaps by introducing additional models such as heat conduction in the substrate materials, void formed inside the melt and so on.

Analysis with CFD code for THAI test on thermal-hydraulics during PAR activation

Sato, Masatoshi; Matsumoto, Toshinori; Sugiyama, Tomoyuki; Maruyama, Yu

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 10 Pages, 2016/11

Event sequence analyses of a forest fire heat effect on a sodium-cooled fast reactor for an external hazard PRA methodology development

Okano, Yasushi; Yamano, Hidemasa

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 9 Pages, 2016/11

This paper deals with an event sequence by forest fire heat effect on a decay heat removal function of a sodium-cooled fast reactor. Related to the potential vulnerability, an event scenario was developed using conservative assumptions. An event tree was developed with an initiating event of the loss of off-site power, and the headings are related to "external diesel fuel tanks", "emergency diesel generator and its auxiliary system", "alternative cooling system and its power source", and "decay heat air cooler". A failure probability on each heading was given from a fragility curve as a function of reaction intensity or by assumptions based on conservative models. A core damage frequency, under the conditional of the loss of off-site power, was conservatively evaluated around 10/year. A key heading in the event tree with large effect on the frequency is the intactness of the external diesel fuel tanks.

Event sequence analysis of core disruptive accident in a metal-fueled sodium-cooled fast reactor

Yamano, Hidemasa; Tobita, Yoshiharu; Kubo, Shigenobu; Ueda, Nobuyuki*

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 10 Pages, 2016/11

In this study, the event sequence analysis of CDA in a large metal-fueled SFR has been performed in order to investigate reactivity progression and molten fuel relocation behavior in the metal-fueled SFR. The initiating phase analysis during the CDA initiated by unprotected loss-of-flow accidents has been conducted using the CANIS code, which showed a small power peak. Using the initial conditions based on the initiating phase analysis, the SIMMER-III code was applied to a whole-core scale analyses to clarify the event sequence including the reactivity progression and molten fuel relocation. As a result, recriticality in the whole core analysis resulted in a very mild energy release. The mild energy release in the metal-fueled core can be attributed to the small specific heat of metal fuel and the large prompt negative reactivity feedback mechanism.

In-vessel retention of unprotected accident in a fast reactor; Assessment of material-relocation and heat-removal behavior in ULOF

Sogabe, Joji; Suzuki, Toru; Wada, Yusaku; Tobita, Yoshiharu

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 7 Pages, 2016/11

Experimental database for bed formation behaviors of solid particles

Sheikh, M. A. R.*; Son, E.*; Kamiyama, Motoki*; Morioka, Toru*; Matsumoto, Tatsuya*; Morita, Koji*; Matsuba, Kenichi; Kamiyama, Kenji; Suzuki, Toru

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 10 Pages, 2016/11

During the material relocation phase of core disruptive accidents in sodium-cooled fast reactors, the sedimentation behavior of fragmented debris leading to the formation of debris beds is crucial for in-vessel retention by debris bed cooling. In this study, a series of experiments using simulant materials was performed to develop an experimental database of bed formation behavior by gravity driven discharge of solid particles from a nozzle into a quiescent cylindrical water pool. The bed height as well as the bed shape was measured. Three types of spherical and non-spherical particles, namely AlO, ZrO and stainless steel with different size were employed to study the effect of key experimental parameter on debris bed mound shape. Based on the experimental results, an empirical correlation as experimental database was proposed to predict the particle bed height. The proposed correlation reasonably reproduces the experimental trend of the bed height variation on the crucial factors. This result demonstrates a wide applicability of the proposed empirical model to predict the bed height in terms of all crucial factors with reasonable accuracy.

Production of droplets during liquid jet impingement onto a flat plate

Yi, Z.*; Oya, Naoki*; Enoki, Koji*; Okawa, Tomio*; Ohno, Shuji; Aoyagi, Mitsuhiro; Takata, Takashi

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 7 Pages, 2016/11

It is important to set the amount of sodium droplet mechanistically for appropriate numerical evaluations of sodium leak and fire behavior in a sodium-cooled fast reactor plant. In the present work, fundamental experiments were performed to measure the splash ratio during the vertical water jet impact onto a horizontal wall. It was shown that the splash ratio can be correlated well as a function of the impact Weber number, the Strouhal number and the Ohnesorge number of the droplets impinging the liquid film.

Development of air cooling performance evaluation method for fuel debris on retrieval of Fukushima Daiichi NPS by dry method, 1; Outline of research project

Yoshida, Hiroyuki; Uesawa, Shinichiro; Yamashita, Susumu; Nagase, Fumihisa

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 7 Pages, 2016/11

Development of evaluation method for hydraulic behavior in venturi scrubber for filtered venting

Horiguchi, Naoki; Yoshida, Hiroyuki; Nakao, Yasuhiro*; Kaneko, Akiko*; Abe, Yutaka*

Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 7 Pages, 2016/11

Cavity voltage variation at beam extraction in the J-PARC MR

Tamura, Fumihiko; Yoshii, Masahito*; Omori, Chihiro*; Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Hasegawa, Katsushi*; Hara, Keigo*

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.808 - 810, 2016/11

http://www.pasj.jp/web_publish/pasj2016/proceedings/PDF/TUP0/TUP001.pdf

J-PARC MR provides high intensity proton beams of 390 kW to the neutrino experiment. The proton beams are extracted by fast extraction. It has been found that the cavity voltage goes up for about 20 s just after extraction. It is because the rf feed forward system for beam loading compensation outputs compensation signals for its system delay. The MR cavity has a relatively low Q value of 22 and the cavity voltage can varies in the order of 10 s. The voltage variation of the cavity voltage increases with the beam intensity and it is a possible reason of the damage of the gap capacitors. A counter measure using the inhibit function of the summation amplifier in the LLRF system has been applied. In this presentation, we present the details of the cavity voltage variation and the results of the counter measure. Also, we present the analysis of beam loading using the voltage variation.

Current status of the kicker magnet power supply in 3-GeV RCS

Togashi, Tomohito; Takayanagi, Tomohiro; Yamamoto, Kazami; Kinsho, Michikazu

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.725 - 728, 2016/11

http://www.pasj.jp/web_publish/pasj2016/proceedings/PDF/MOP1/MOP117.pdf

The 3-GeV RCS (Rapid Cycling Synchrotron) at J-PARC (Japan Proton Accelerator Research Complex) has the pulse kicker power supply system which use the thyratron switches for beam extraction. It has passed from operation starting for more than 10 years, but an exchange of a part and check are being put into effect periodically, so a kicker power supply also keeps operation smoothly now. I spent long time and studied how to use, so thyratron could be used now for more than 10,000 hours. But long years have passed, so selection of a substitute of a discontinuance part is a pending problem. Silicon oil has also degraded, so I have to consider a way of a performance recovery and a procedure of an exchange. This report explains the current state of the kicker magnet power supply from a result of the regular inspection and conditions.

Development of a control system at a 3 MeV linac in J-PARC

Sawabe, Yuki*; Ishiyama, Tatsuya; Takahashi, Daisuke; Kato, Yuko; Suzuki, Takahiro*; Hirano, Koichiro; Takei, Hayanori; Meigo, Shinichiro; Kikuzawa, Nobuhiro; Hayashi, Naoki

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.647 - 651, 2016/11

http://www.pasj.jp/web_publish/pasj2016/proceedings/PDF/MOP0/MOP096.pdf

In the J-PARC, a 3 MeV linac has been developed for the tests of beam scraper irradiation and charge exchange by high-power laser. To accomplish tests efficiently and safely, the control system for 3 MeV was designed and developed, and this system consists of four subsystems, personal protection system, machine protection system, timing system, and remote control system using the EPICS. In this paper, the details of control system for a 3 MeV linac are presented.

In-situ visual exploration of multivariate volume data based on particle based volume rendering

Kawamura, Takuma; Noda, Tomoyuki; Idomura, Yasuhiro

Proceedings of 2nd Workshop on In Situ Infrastructures for Enabling Extreme-scale Analysis and Visualization (ISAV 2016) (Internet), p.18 - 22, 2016/11

https://doi.org/10.1109/ISAV.2016.9

A novel in-situ online visualization framework is developed based on the Particle Based Volume Rendering (PBVR), which renders multivariate volume data using view-independent particle data. Our online approach enables visualization of particle data with interactive view exploration and changes of multi-dimensional transfer functions at runtime. The runtime visualization show excellent strong scaling up to thousands of cores, and its computational cost is small. These features enable flexible in-situ data exploration for monitoring extreme scale simulations. The utility of the proposed framework is demonstrated by applying it to simulations of molten debris relocation in reactor pressure vessels using the JUPITER code.

Nuclear thermal design of high temperature gas-cooled reactor with SiC/C mixed matrix fuel compacts

Aihara, Jun; Goto, Minoru; Inaba, Yoshitomo; Ueta, Shohei; Sumita, Junya; Tachibana, Yukio

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.814 - 822, 2016/11

Japan Atomic Energy Agency (JAEA) has started R&D for apply SiC/C mixed matrix to fuel element of high temperature gas-cooled reactors (HTGRs) to improve oxidation resistance of fuel. Nuclear thermal design of HTGR with SiC/C mixed matrix fuel compacts was carried out as a part of above R&Ds. Nuclear thermal design was carried out based on a small sized HTGR for developing countries, HTR50S. Maximum enrichment of uranium is set to be 10 wt%, because coated fuel particles with 10 wt% uranium have been fabricated in Japan. Numbers of kinds of enrichment and burnable poisons (BPs) were set to be same as those of original HTR50S (3 and 2, respectively). We succeeded in nuclear thermal design of a small sized HTGR which performance was equivalent to original HTR50S, with SiC/C mixed matrix fuel compacts. Based on nuclear thermal design, intactness of coated fuel particles was evaluated to be kept on internal pressure during normal operation.

Sensitivity analysis of xenon reactivity temperature dependency for HTTR LOFC test by using RELAP5-3D code

Honda, Yuki; Fukaya, Yuji; Nakagawa, Shigeaki; Baker, R. I.*; Sato, Hiroyuki

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.704 - 713, 2016/11

A high-temperature gas-cooled reactor (HTGR) has superior safety characteristics. A loss of forced cooling (LOFC) test using a high-temperature engineering test reactor (HTTR) has been carried out to verify the inherent safety of an HTGR when forced cooling is diminished without reactor scram. In the test, an all-gas circulator was tripped with an initial reactor power of 9 MW and re-criticality was shown. This study focuses on developing a point kinetics method with RELAP5-3D code for an LOFC accident. There is a large temperature difference between the inlet and outlet of the core in an HTGR, and the temperature fluctuation range has been large in several accidents. We analyze the temperature dependency of xenon-135 reactivity and show that the temperature dependency of xenon-135 microscopic absorption cross-section affected the re-criticality time of the LOFC test.

IS process hydrogen production test for components and system made of industrial structural material, 1; Bunsen and HI concentration section

Tanaka, Nobuyuki; Takegami, Hiroaki; Noguchi, Hiroki; Kamiji, Yu; Iwatsuki, Jin; Aita, Hideki; Kasahara, Seiji; Kubo, Shinji

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.1022 - 1028, 2016/11

Japan Atomic Energy Agency (JAEA) has manufactured 100 NL/h-H-scale hydrogen test apparatus. In advance to conduct the continuous operation, we investigated performance of the components in each section of the IS process. In this paper, the results of test of Bunsen and HI concentration sections was shown. In Bunsen reaction, section, we confirmed that outlet gas flow rate included no SO gas, indicating that all the feed SO gas was absorbed to the solution in the Bunsen reactor for the Bunsen reaction. On the basis of these results, we evaluated that Bunsen reactor was workable. In HI concentration section, HI concentration was conducted by EED stack. As a result, it can concentrate HI in HIx solution as theoretically predicted on the basis of the previous paper. Based on the results added to that shown in Series II, we have conducted a trial continuous operation and succeeded it for 8 hours.

The IAEA coordinated research project on modular HTGR safety design; Status and outlook

Reitsma, F.*; Kunitomi, Kazuhiko; Ohashi, Hirofumi

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.341 - 352, 2016/11

The IAEA Coordinated Research Project (CRP) on Modular High Temperature Gas-cooled Reactor (HTGR) Safety Design started in December 2014 and is now in its second year of implementation. The project investigates and makes proposals on safety design criteria by not only considering the existing water cooled reactors safety requirements for nuclear power plant design but also making use of past and current experience of HTGR licensing in the IAEA member states including Japan. The detailed project content and a description of modular HTGRs and its safety features are given. This informs the comments made on the applicability of the existing requirements and the examples of newly proposed HTGR specific safety requirements under development.

Irradiation test about oxidation-resistant graphite in WWR-K research reactor

Shibata, Taiju; Sumita, Junya; Sakaba, Nariaki; Osaki, Takashi*; Kato, Hideki*; Izawa, Shoichi*; Muto, Takenori*; Gizatulin, S.*; Shaimerdenov, A.*; Dyussambayev, D.*; et al.

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.567 - 571, 2016/11

Graphite are used for the in-core components of HTGR, and it is desirable to enhance oxidation resistance to keep much safety margin. SiC coating is the candidate method for this purpose. JAEA and four Japanese graphite companies are studying to develop oxidation-resistant graphite. Neutron irradiation test was carried out by WWR-K reactor of INP of Kazakhstan through ISTC partner project. The total irradiation cycles of WWR-K operation was 10 cycles by 200 days. Irradiation temperature about 1473 K would be attained. The maximum fast neutron fluence (E 0.18 MeV) for the capsule irradiated at a central irradiation hole was preliminary calculated as 1.210/m, and for the capsule at a peripheral irradiation hole as 4.210/m. Dimension and weight of the irradiated specimens were measured, and outer surface of the specimens were observed by optical microscope. For the irradiated oxidation resistant graphite, out-of-pile oxidation test will be carried out at an experimental laboratory.

Conceptual design of iodine-sulfur process flowsheet with more than 50% thermal efficiency for hydrogen production

Kasahara, Seiji; Imai, Yoshiyuki; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; Yan, X.

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.491 - 500, 2016/11

A conceptual design of a practical large scale plant of the thermochemical water splitting iodine-sulfur (IS) process flowsheet was carried out as a heat application of Japan Atomic Energy Agency's commercial Gas Turbine High Temperature Reactor Cogeneration (GTHTR300C) plant design. Innovative techniques proposed by JAEA were applied for improvement of hydrogen production thermal efficiency; flash concentration of HSO using waste heat from Bunsen reaction, prevention of HSO vaporization from a distillation column by introduction of HSO solution, and I condensation heat recovery by direct contact heat exchange in the HI distillation column. A simulation of material and heat balance showed hydrogen of about 31,900 Nm/h was produced by 170 MW heat from the GTHTR300C. A process thermal efficiency of 50.2% was achievable with incorporation of the innovative techniques and several high performance components expected in future R&D.

Investigation of snow cover effects and attenuation correction of ray in aerial radiation monitoring

Ishizaki, Azusa; Sanada, Yukihisa; Mori, Airi; Imura, Mitsuo; Ishida, Mutsushi; Munakata, Masahiro

Remote Sensing, 8(11), p.892_1 - 892_12, 2016/11

https://doi.org/10.3390/rs8110892

In aerial radiation monitoring (ARM), the air dose rate cannot be appropriately estimated under snowy conditions due to attenuation of ray by the snow layer. A technique to address this issue is required for ARM to obtain enough signals for air dose rate. To develop this technique, we investigated the relationship between snow depth and ARM measurement results using ARM, laser imaging detection and ranging, and ground measurement before and after snowfall. From the measured data, the results obtained using three different correction factors were examined and compared. An appropriate correction improved the underestimation of the air dose rate. However, further improvement in the accuracy of the analysis require accurate estimation of the snow water equivalent.

Validation study in SAS4A code in simulated mild TOP condition

Kawada, Kenichi; Suzuki, Toru

Transactions of the American Nuclear Society, 115(1), p.1597 - 1598, 2016/11

Automatic Prompt Gamma-ray Analysis system; Automation of an existing large-scale analytical device

Osawa, Takahito

Automation and Control Trends, p.149 - 166, 2016/10

https://doi.org/10.5772/64650

The Prompt Gamma-ray activation Analysis system (PGA) installed in the Japan Research Reactor-3 (JRR-3) was automated between 2012 and 2013. This automation is a good example of a large-scale old analytical device automated in a nuclear facility. This automatic system has several useful functions, such as automatic sample exchange and analysis, automatic helium gas flow control and flow channel switching function, automatic neutron recording system, and fail-safe function using Machine Vision, and the Internet. The analysis system was automated using a vertical revolute joint robot, control programs, and data acquisition devices. The main control software named AutoPGA was developed using LabVIEW and the program can control all functions of the automatic system, capable of analysing up to 14 samples automatically. In the automation, the core of the PGA system was not modified and the extremely low background level of rays was maintained well; however, the efficiency of routine measurements dramatically increased.

Effect of remediation parameters on in-air ambient dose equivalent rates when remediating open sites with radiocesium-contaminated soil

Malins, A.; Kurikami, Hiroshi; Kitamura, Akihiro; Machida, Masahiko

Health Physics, 111(4), p.357 - 366, 2016/10

AA2015-0584.pdf:0.84MB

https://doi.org/10.1097/HP.0000000000000552

Impacts of C-uptake by plants on the spatial distribution of C accumulated in vegetation around a nuclear facility; Application of a sophisticated land surface C model to the Rokkasho reprocessing plant, Japan

Ota, Masakazu; Katata, Genki; Nagai, Haruyasu; Terada, Hiroaki

Journal of Environmental Radioactivity, 162-163, p.189 - 204, 2016/10

https://doi.org/10.1016/j.jenvrad.2016.05.032

Impacts of plant C uptake on (C) distributions around a nuclear facility were investigated by a land surface C model (SOLVEG-II). The simulation combined the SOLVEG-II with a mesoscale model and an dispersion model was applied to CO transfer at test operations of the Rokkasho reprocessing plant (RRP) in 2007. The calculated C-specific activities in rice grains agreed with the observations. Numerical experiment of chronic CO release from the RRP showed that C-specific activities of rice plants at harvest differed from the annual mean ones in the air, which was attributed to seasonal variations in atmospheric CO and plant growth. C accumulation in plant significantly increased when CO releases were limited during daytime, compared with the results observed during nighttime, due to extensive CO uptake by daytime photosynthesis. These results indicated that plant growth and photosynthesis should be considered in predictions of ingestion dose of C for long-term chronic and short-term diurnal releases of CO, respectively.

Remaining lives of fatigue crack growths for pipes with subsurface flaws and subsurface-to-surface flaw proximity rules

Katsumata, Genshichiro*; Li, Y.; Hasegawa, Kunio*; Lacroix, V.*

Journal of Pressure Vessel Technology, 138(5), p.051402_1 - 051402_5, 2016/10

https://doi.org/10.1115/1.4032816

If a subsurface flaw is located near a component surface, the subsurface flaw is transformed to a surface flaw in accordance with a subsurface-to-surface proximity rule. The re-characterization process from subsurface to surface flaw is adopted in all fitness-for-service (FFS) codes. However, the specific criteria of the re-characterizations are different among the FFS codes. Recently, the authors have proposed a new subsurface-to-surface flaw proximity rule based on experimental data and equivalent fatigue crack growth rate calculations. In this study, fatigue crack growth calculations were carried out for pipes with subsurface flaws, using the proximity rule provided in the current codes and the proposed subsurface-to-surface proximity rule. Different pipe sizes, flaw aspect ratios and ligament distances from subsurface flaws to inner surface of pipes were taken into account. As the results, the current proximity rule gives less conservative fatigue lives, when the aspect ratios of the subsurface flaws are small.

Performance test of automatic analysis system of strontium-90 in environmental sample

Fujita, Hiroki; Nojima, Takehiro; Nagaoka, Mika; Osawa, Takahito; Yokoyama, Hiroya; Ono, Hironobu*

KEK Proceedings 2016-8, p.168 - 172, 2016/10

https://lib-extopc.kek.jp/preprints/PDF/2016/1625/1625008.pdf

An automatic analysis system was developed to analyze Strontium-90 (Sr) radioactivity in environmental sample for 2013-2015. Various kinds of ashed environmental samples were used in performance tests of the automatic system. These tests were successful without any system trouble. However, Sr concentration had not been measured using the samples analyzed by the system. In this research, Sr concentration in seaweed sample was compared by between the system's analysis and worker's one. Moreover, the system was improved in each analysis process.

Investigation to evaluate the influence of the TEPCO's Fukushima Daiichi NPS accident for environmental monitoring about marine organisms

Nagaoka, Mika; Matsubara, Natsumi; Fujita, Hiroki; Nakano, Masanao

KEK Proceedings 2016-8, p.134 - 138, 2016/10

https://lib-extopc.kek.jp/preprints/PDF/2016/1625/1625008.pdf

no abstracts in English

A Report on the 5th ANNRI Conference

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

Kaku Deta Nyusu (Internet), (115), p.49 - 60, 2016/10

http://www.aesj.or.jp/~ndd/ndnews/pdf115/No115-10.pdf

This is a report on the 5th ANNRI conference held at Tokyo Institute of Technology in Ookayama in August 4th, 2016.

Re-structuring of the NEA Data Bank Management Committee; New Management Committee MBDAV

Suyama, Kenya

Kaku Deta Nyusu (Internet), (115), p.61 - 69, 2016/10

http://www.aesj.or.jp/~ndd/ndnews/pdf115/No115-11.pdf

In recent years, discussion on the reform of the governing body of OECD/NEA Data Bank has been carried out. This document explains its background and outline.

Level of detail control for environmental monitoring datasets

Miyamura, Hiroko; Takemiya, Hiroshi; Wu, H.-Y.*; Takahashi, Shigeo*

Kashika Joho Gakkai-Shi, 36(143), p.152 - 156, 2016/10

https://doi.org/10.3154/jvs.36.143_10

Broad survey on the distribution of the air dose rate has been performed after the accident at the Fukushima Daiichi Nuclear Power Plant continuously. The surveyed monitoring datasets are stored in a database and are made available to the public. Recently, the size of the datasets have been significantly increased as more detailed measurements in space and time are available, and effective reduction of the size of the datasets is necessary for visualizing and exploring such large scale datasets. However, if the datasets are not carefully reduced, we often miss a part of important features of the distribution data. Therefore, we develop an effective Level of Detail control (LoD) method for retaining critical features of the distribution. In the method, the global and local features of the distribution are extracted by means of differential topology analyses. Then, the simplified data is created by edge collapse operation with taking into account these features of the data.

Spontaneous decays of magneto-elastic excitations in non-collinear antiferromagnet (Y,Lu)MnO

Oh, J.*; Le, M. D.*; Nahm, H.-H.*; Sim, H.*; Jeong, J.*; Perring, T. G.*; Woo, H.*; Nakajima, Kenji; Kawamura, Seiko; Yamani, Z.*; et al.

Nature Communications (Internet), 7, p.13146_1 - 13146_6, 2016/10

https://doi.org/10.1038/ncomms13146

Magnons and phonons are fundamental quasiparticles in a solid and can be coupled together to form a hybrid quasi-particle. However, detailed experimental studies on the underlying Hamiltonian of this particle are rare for actual materials. Moreover, the anharmonicity of such magnetoelastic excitations remains largely unexplored, although it is essential for a proper understanding of their diverse thermodynamic behaviour and intrinsic zero-temperature decay. Here we show that in non-collinear antiferromagnets, a strong magnon phonon coupling can significantly enhance the anharmonicity, resulting in the creation of magnetoelastic excitations and their spontaneous decay. By measuring the spin waves over the full Brillouin zone and carrying out anharmonic spin wave calculations using a Hamiltonian with an explicit magnon phonon coupling, we have identified a hybrid magnetoelastic mode in (Y,Lu)MnO and quantified its decay rate and the exchange-striction coupling termrequired to produce it.

Comparison of stress intensity factor solutions for surface cracks with high aspect ratio

Nagai, Masaki*; Lu, K.; Kamaya, Masayuki*

Nihon Kikai Gakkai M&M 2016 Zairyo Rikigaku Kanfarensu Koen Rombunshu (Internet), p.481 - 483, 2016/10

In nuclear power plants, a number of cracks attributed to stress corrosion cracking (SCC) have been detected in welds made with nickel alloy weld metals. One of the characteristics of these cracks is that crack aspect ratio is greater than 0.5, where a is the crack depth and is the crack length. When a crack is detected in components of nuclear power plants during in-service inspection, flaw evaluation is conducted according to the requirement of codes such as JSME Rules on Fitness-for-Service for Nuclear Power Plants. Here, the stress intensity factor plays an important role for predicting crack growth behavior due to fatigue and/or SCC. Although several solutions of the stress intensity factor are already given in the JSME code, no solutions are available for the cracks with 0.5. According to the current code, surface cracks with 0.5 are characterized as semi-circular shape . To evaluate these cracks in a rational manner, several solutions have been proposed for cracks with 0.5. In this paper, comprehensive comparison was made between solutions for cracks 0.5, and benchmark analysis on SCC crack growth was performed.

Critical heat flux prediction for subcooled flow boiling in annulus

Liu, W.; Podowski, M. Z.*

Nihon Kikai Gakkai Netsu Kogaku Konfarensu 2016 Koen Rombunshu (USB Flash Drive), 2 Pages, 2016/10

Prediction of Critical Heat Flux (CHF) is important for nuclear reactor safety. However, the CHF prediction for subcooled flow boiling in complicated geometry such as fuel assembly still remains unsolved. As the first step for the CHF prediction in rod bundles, in this paper, we tried to predict the CHF in annulus, which is the most basic flow geometry simplified from a fuel bundle. We performed the CHF prediction by using liquid sublayer dryout model, combining with ANSYS CFX code to get the single phase velocity distribution inside the annulus. The results show that the CHF in annulus can be predicted in an accuracy of about 20%.

Diluted magnetic semiconductors with narrow band gaps

Gu, B.; Maekawa, Sadamichi

Physical Review B, 94(15), p.155202_1 - 155202_8, 2016/10

AA2016-0395.pdf:0.38MB

https://doi.org/10.1103/PhysRevB.94.155202

Outcome of first containment cooling experiments using CIGMA

Shibamoto, Yasuteru; Yonomoto, Taisuke; Ishigaki, Masahiro; Abe, Satoshi

Proceedings of 11th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-11) (USB Flash Drive), 10 Pages, 2016/10

Bayesian optimization analysis of containment venting operation in a BWR severe accident

Zheng, X.; Ishikawa, Jun; Sugiyama, Tomoyuki; Maruyama, Yu

Proceedings of 13th Probabilistic Safety Assessment and Management Conference (PSAM-13) (USB Flash Drive), 10 Pages, 2016/10

Estimation of rock mass stress state based on convergence measurement during gallery excavation

Aoyagi, Kazuhei; Nago, Makito*; Kamemura, Katsumi*; Sugawara, Kentaro*

Proceedings of 9th Asian Rock Mechanics Symposium (ARMS-9) (USB Flash Drive), 10 Pages, 2016/10

High flux pinning efficiency by columnar defects dispersed in three directions in YBCO thin films

Sueyoshi, Tetsuro*; Nishimura, Takahiro*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito

Superconductor Science and Technology, 29(10), p.105006_1 - 105006_7, 2016/10

https://doi.org/10.1088/0953-2048/29/10/105006

A systematic investigation of flux pinning by widely direction-dispersed columnar defects (CDs) in YBaCuOy thin films was carried out by using heavy-ion irradiation: a parallel configuration of CDs aligned along the -axis, and two trimodal splay configurations composed of crossing CDs; relative to the -axis, where the splay plane defined by the three irradiation angles is perpendicular (trimodal-A) or parallel (trimodal-B) to the transport current direction. The trimodal configurations show high pinning efficiency over a wide range of magnetic field orientations compared to the parallel one at low magnetic field. In particular, trimodal-B shows the higher critical current density of the two trimodal configurations.

Redistribution and export of contaminated sediment within eastern Fukushima Prefecture due to typhoon flooding

Kitamura, Akihiro; Kurikami, Hiroshi; Sakuma, Kazuyuki; Malins, A.; Okumura, Masahiko; Machida, Masahiko; Mori, Koji*; Tada, Kazuhiro*; Tawara, Yasuhiro*; Kobayashi, Takamaru*; et al.

Earth Surface Processes and Landforms, 41(12), p.1708 - 1726, 2016/09

https://doi.org/10.1002/esp.3944

Sediment erosion and transport processes that are considered to be important in predicting the future radioactive material distribution through sediment-sorbed form in Fukushima Prefecture are simulated. Since large portion of the sediment is considered to be supplied into the rivers, it is important to trace their migration process in terms of each river basin. We choose five river basins, namely the Odaka, the Ukedo, the Maeda, the Kuma, and the Tomioka, from north to south, because of their importance in contamination aspects and prediction studies. The results are summarized as comprehensive dataset of sediment migration for particular river basins in typical typhoon events that account for the most of annual soil erosion. Detail calculations implemented for the amount of sediment supplied in to the river, deposited on river and dam beds, and exported to the ocean.