Development of fuel temperature calculation code for HTGRs

Inaba, Yoshitomo; Nishihara, Tetsuo

Annals of Nuclear Energy, 101, p.383 - 389, 2017/03

https://doi.org/10.1016/j.anucene.2016.11.006

In order to ensure the thermal integrity of fuel in High Temperature Gas-cooled Reactors (HTGRs), it is necessary that the maximum fuel temperature in normal operation is to be lower than a thermal design target. In the core thermal-hydraulic design of block-type HTGRs, the maximum fuel temperature should be evaluated considering data such as thermal power, core geometry, power density and neutron fluence distributions, and core coolant flow distribution. The fuel temperature calculation code used in the design stage of the High Temperature engineering Test Reactor (HTTR) presupposes to run on UNIX systems, and its operation and execution procedure are complicated and are not user-friendly. Therefore, a new fuel temperature calculation code named FTCC which has a user-friendly system such as a simple and easy operation and execution procedure, was developed. This paper describes calculation objects and models, basic equations, improvement points from the HTTR design code in FTCC, and the result of a validation calculation with FTCC. The calculation result obtained by FTCC provides good agreement with that of the HTTR design code, and then FTCC will be used as one of the design codes for HTGRs. In addition, the effect of cooling forms on the maximum fuel temperature is investigated by using FTCC. As a result, it was found that the effect of center hole cooling for hollow fuel compacts and gapless cooling with monolithic type fuel rods on reducing the temperature is very high.

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.

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.

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

Spectrum-dose conversion operator of NaI(Tl) and CsI(Tl) scintillation detectors for air dose rate measurement in contaminated environments

Tsuda, Shuichi; Saito, Kimiaki

Journal of Environmental Radioactivity, 166(Part 3), p.419 - 426, 2017/01

https://doi.org/10.1016/j.jenvrad.2016.02.008

Air dose rate monitoring in the environment has been performed since the Fukushima Dai-ichi Nuclear Power Plant accident happened. In the measurement, NaI(Tl) and CsI(Tl) scintillation detectors are used, which are usually used in nuclear power plants and calibrated in a uniform irradiation condition in a radiation calibration field. In general, however, the detector responses are dependent on incident direction and in reality, the incident direction of the photons is not uniform in the environment. In this study, to evaluate the dependence of dose on the photon incident direction, the spectrum - dose conversion operator (G(E) function) for air kerma in a semi-infinite radiation field were obtained using the PHITS code for commonly used NaI(Tl) and CsI(Tl) scintillation detectors. The results indicate that the commonly used scintillation detectors overestimate the doses by a maximum of 40% for mono-energetic photons but under the real environment, one could obtain the dose in the semi-infinite radiation field within 20%.

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.

Reduced-shifted conjugate-gradient method for a Green's function; Efficient numerical approach in a nano-structured superconductor

Nagai, Yuki; Shinohara, Yasushi*; Futamura, Yasunori*; Sakurai, Tetsuya*

Journal of the Physical Society of Japan, 86(1), p.014708_1 - 014708_9, 2017/01

https://doi.org/10.7566/JPSJ.86.014708

no abstracts in English

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

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 spin-wave-like dispersive excitations below the pseudogap temperature in the high-temperature superconductor LaSrCuO

Matsuura, Masato*; Kawamura, Sho*; Fujita, Masaki*; Kajimoto, Ryoichi; Yamada, Kazuyoshi*

Physical Review B, 95(2), p.024504_1 - 024504_6, 2017/01

https://doi.org/10.1103/PhysRevB.95.024504

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.

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.

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.

Thermochronological contribution to the Crustal Dynamics Project

Tagami, Takahiro*; Sueoka, Shigeru; Kohn, B. P.*; Fukuda, Shoma*

Fisshion, Torakku Nyusureta, (29), p.1 - 2, 2016/12

http://ftrgj.org/FTNLs/FTNLparts/tagami16.pdf

no abstracts in English

Report on 40th Annual Meeting of Fission Track Research Group in Japan

Sueoka, Shigeru

Fisshion, Torakku Nyusureta, (29), p.29 - 34, 2016/12

http://ftrgj.org/FTNLs/FTNLparts/sueokakiji16.pdf

no abstracts in English

Additional information to report on site tour of the Fukushima Daiichi Nuclear Power Station

Suto, Toshiyuki

Genshiryoku, hoshasen Bukaiho (Internet), (19), P. 15, 2016/12

The Tritiated Water Task Force under METI's Committee on Countermeasures for Contaminated Water Treatment for Fukushima Daiichi Nuclear Power Plant (1F) reported that the option of post-dilution offshore release could dispose the tritiated water at a smallest cost in the shortest amount of time. The amount of tritium in the contaminated water at 1F was compared with ones released from nuclear power plants and reprocessing plants as some help for grasping its level of magnitude.

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.

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

Effect of seawater on heat transfer without boiling in internally heated annulus

Uesawa, Shinichiro; Liu, W.; Jiao, L.; Nagatake, Taku; Takase, Kazuyuki; Shibata, Mitsuhiko; Yoshida, Hiroyuki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(4), p.183 - 191, 2016/12

https://doi.org/10.3327/taesj.J15.024

no abstracts in English

Effect of thermo-mechanical treatments on nano-structure of 9Cr-ODS steel

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

Nuclear Materials and Energy (Internet), 9, p.346 - 352, 2016/12

https://doi.org/10.1016/j.nme.2016.10.007

Tensile properties and hardness of two types of 11Cr-ferritic/martensitic steel after aging up to 45,000 h

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

Nuclear Materials and Energy (Internet), 9, p.324 - 330, 2016/12

BB2015-1728.pdf:1.04MB

https://doi.org/10.1016/j.nme.2016.08.007

Overview and outcomes of the OECD/NEA benchmark study of the accident at the Fukushima Daiichi Nuclear Power Station

Nagase, Fumihisa; Gauntt, R. O.*; Naito, Masanori*

Nuclear Technology, 196(3), p.499 - 510, 2016/12

https://doi.org/10.13182/NT16-10

The OECD/NEA Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Station (BSAF) project was established in November 2012. The primary objectives of this benchmark study are to estimate accident progression and status inside the nuclear reactors, including fuel debris distribution, and consequently to contribute to the decommissioning activity at the Fukushima Daiichi Nuclear Power Plant. Fifteen organizations of eight countries calculated thermo-hydraulic behavior inside the three reactors for the time span of about six days from the occurrence of the earthquake with their severe accident integral codes. The submitted results were compared on coolant level change, hydrogen generation, initiation and progression of melt in fuel bundle and control blade, failure of reactor pressure vessel, distribution and composition of molten and solidified materials, and progression of molten core concrete interaction. This issue summarizes the results of the comparison and discussion with still remaining uncertainties and data needs as the output from the project.

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

C ages and calendar years of Japanese swords measured with accelerator mass spectrometry

Nagata, Kazahiro*; Matsubara, Akihiro*; Kokubu, Yoko; Nakamura, Toshio*

Tetsu To Hagane, 102(12), p.736 - 741, 2016/12

https://doi.org/10.2355/tetsutohagane.TETSU-2016-036

Steel of Japanese swords has been produced with Tatara process from iron sand and charcoal. Carbon dissolved in steel was absorbed from wooden charcoal fuel at the production of the steel. From the decay of C activity in the steel, the C age of Japanese sword can be determined. The C ages of 4 Japanese swords were calibrated to a few calendar years. There are several generations of the same names of sword masters. The year of production of each sword was determined from the calendar year and the sword master's name cut in the grip of his sword after taking the age of charcoal into account. The oldest calendar year with high probability agreed with the age of sword master.

Development of a prediction system for radionuclide dispersion in Fukushima coast

Kamidaira, Yuki; Kawamura, Hideyuki; Kobayashi, Takuya; Uchiyama, Yusuke*

Doboku Gakkai Rombunshu, B2 (Kaigan Kogaku) (Internet), 72(2), p.I_451 - I_456, 2016/11

http://doi.org/10.2208/kaigan.72.I_451

no abstracts in English

Experiments EAGLE project for fast reactor safety; A Joint-research program with the Republic of Kazakhstan (NNC/RK)

Kamiyama, Kenji; Sato, Ikken; Kubo, Shigenobu

Enerugi Rebyu, 36(11), p.46 - 49, 2016/11

no abstracts in English

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

Performance of Panasonic ZP-1460 electronic personal dosemeter under exposure conditions likely to be found at Fukushima Daiichi Nuclear Power Plant

Tsujimura, Norio; Yoshida, Tadayoshi; Hoshi, Katsuya; Momose, Takumaro

JPS Conference Proceedings (Internet), 11, p.070008_1 - 070008_6, 2016/11

https://doi.org/10.7566/JPSCP.11.070008

The Evaluation of the 0.07 mm and 3 mm dose equivalent with a portable beta spectrometer

Hoshi, Katsuya; Yoshida, Tadayoshi; Tsujimura, Norio; Okada, Kazuhiko

JPS Conference Proceedings (Internet), 11, p.070009_1 - 070009_6, 2016/11

https://doi.org/10.7566/JPSCP.11.070009

Beta spectra of various nuclide species were measured by commercially available compact spectrometer. The shape of spectra obtained from the spectrometer approximately agreed with that of theoretical spectra. The beta dose equivalent at any depths has been able to be obtained as a product of measured pulse height spectra and appropriate conversion coefficients of ICRP Publ. 74. The dose rates evaluated from the spectra were comparable to the reference dose rates of standard beta calibration sources. And, we were able to determine the dose equivalent with relative error of indication of 10% without the complicated correction.

Nanoscopic structural investigation of physically cross-linked nanogels formed from self-associating polymers

Sekine, Yurina; Endo, Hitoshi*; Iwase, Hiroki*; Takeda, Shigeo*; Mukai, Sadaatsu*; Fukazawa, Hiroshi; Littrell, K. C.*; Sasaki, Yoshihiro*; Akiyoshi, Kazunari*

Journal of Physical Chemistry B, 120(46), p.11996 - 12002, 2016/11

https://doi.org/10.1021/acs.jpcb.6b06795

The detailed structure of a nanogel formed by self-association of cholesterol-bearing pullulans (CHP) was determined by contrast variation small-angle neutron scattering. The decomposition of scattering intensities into partial scattering functions of each CHP nanogel component, i.e., pullulan, cholesterol, and the cross-term between the pullulan and the cholesterol allows us to investigate the internal structure of the nanogel. The effective spherical radius of the skeleton formed by pullulan chains was found to be about 8.1 nm. In the CHP nanogel, there are about 19 cross-linking points where a cross-linking point is formed by aggregation of trimer cholesterol molecules with the spatially inhomogeneous distribution of the mass fractal dimension of 2.6. The average radius of the partial chains can also be determined to be 1.7 nm. As the result, the complex structure of the nanogels is coherently revealed at the nanoscopical level.

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

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

Development of air cooling performance evaluation method for fuel debris on retrieval of Fukushima Daiichi NPS by dry method, 2; Outline of numerical method and preliminary analysis of free convection around fuel debris

Yamashita, Susumu; Uesawa, Shinichiro; Yoshida, Hiroyuki

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

In fuel debris retrieval in decommissioning of the Fukushima Daiichi NPS, dry method is under consideration. Investigation of the cooling performance of fuel debris in the dry method will be very important problem to realize the method. However, there are uncertainties in the shape and surface temperature of fuel debris. In order to evaluate the cooling performance, the investigation of the cooling performance by free convection is required. We have been developing the numerical simulation method, which can evaluate the cooling performance of the fuel debris by free convection, using the JUPITER code in JAEA. In this paper, we show the evaluation result of the thermal conductivity by the free convection from fuel debris to the atmosphere in the simplified system.

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.

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.

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.

Local structure analysis of NaNbO and AgNbO modified by Li substitution

Yoneda, Yasuhiro; Aoyagi, Rintaro*; Fu, D.*

Japanese Journal of Applied Physics, 55(10S), p.10TC04_1 - 10TC04_5, 2016/10

https://doi.org/10.7567/JJAP.55.10TC04

We analyzed the local structures of NaNbO and NaLiNbO by combining the X-ray absorption fine structure (XAFS) and atomic pair-distribution function (PDF) techniques. NaNbO is known to be an antiferroelectric material at room temperature. It also undergoes a diffuse phase transition, in which an orthorhombic and a rhombohedral phases coexist over a wide temperature range. We identified a rhombohedral ground state structure of NaNbO and assumed an order-disorder-type phase. We also found a disorder feature in the nearest-neighbor bond distance corresponding to the Nb-O bonds. The disordered bond distribution disappeared when Na was substituted for Li. A similar disorder feature was found in AgNbO.

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.

Distribution of Cs on surfaces of buildings and building lots

Yoshimura, Kazuya; Fujiwara, Kenso; Saito, Kimiaki

KEK Proceedings 2016-8, p.67 - 71, 2016/10

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

This study evaluated the Cs inventory (Bq m) on urban surfaces for eleven buildings and building lots in evacuation zone, and relative Cs inventory was obtained by dividing with the initial inventory on plane permeable field around the studied building. The relative Cs inventory was highest at plane permeable field (0.92), followed by paved ground (0.28) on January 13, 2015. Other surfaces such as roof, wall and window showed obviously small values less than 0.1, indicating that the contamination level of buildings was limited four years after the Fukushima Dai-ichi Nuclear Power Plant accident. Roof and paved ground showed different relative Cs inventories from those in the case of Europe after the Chernobyl Nuclear Power Plant accident, suggesting the importance of local parameterization considering the factors affects to the variation of relative Cs inventory.

Summary report on the joint session entitled by "Decommissioning of reactor and accelerator facilities and present status of activation nuclear data libraries"

Nakamura, Shoji

Kaku Deta Nyusu (Internet), (115), p.18 - 23, 2016/10

http://www.aesj.or.jp/~ndd/ndnews/pdf115/No115-05.pdf

This is a summary report on the planning joint session entitled by "Decommissioning of reactor and accelerator facilities and present status of activation nuclear data libraries".

Re-structuring of the scientific program of the NEA (No.41, p.37 (1992))

Suyama, Kenya

Kaku Deta Nyusu (Internet), (115), p.70 - 79, 2016/10

http://www.aesj.or.jp/~ndd/ndnews/pdf115/No115-12.pdf

In 1992, Dr. Yasuyuki Kikuchi, the general manager of the Nuclear Data Center of JAERI, presented his article "Re-structuring of the Scientific Program of NEA" in the Nuclear Data News volume 41. This is the English translation version of it.

Cataractogenesis following high-LET radiation exposure

Hamada, Nobuyuki*; Sato, Tatsuhiko

Mutation Research; Reviews in Mutation Research, 770(Part B), p.262 - 291, 2016/10

https://doi.org/10.1016/j.mrrev.2016.08.005

From the radiation protection viewpoint, the ocular lens is among the most radiosensitive tissues in the body, and cataract is classified as tissue reactions with a threshold below which no effect would occur. After 2011, the International Commission on Radiological Protection (ICRP) has recommended an equivalent dose limit for the lens to 20 mSv/year. Although such reduction of the threshold was based on findings from low-LET radiation, the dose limit was recommended in Sv. This review is thus designed to provide an update on the current knowledge as to high-LET radiation cataractogenesis. To this end, changes in ICRP recommendations on lenticular radiation protection, epidemiological and biological findings on high-LET cataractogenesis are reviewed, and future research needs are then discussed.

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%.

Measurement of void fraction distribution in air-water two-phase flow in a 44 rod bundle

Liu, W.; Jiao, L.; Nagatake, Taku; Shibata, Mitsuhiko; Komatsu, Masao*; Takase, Kazuyuki*; Yoshida, Hiroyuki

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

To contribute the clarification of the Fukushima Daiichi Accident, Japan Atomic Energy Agency (JAEA) has been performed experiments to obtain void fraction distribution data, including detailed bubble information such as bubble velocity and size, in steam-water two-phase flow in rod bundle geometry under high pressure and high temperature condition, focusing on low flow rate at the core natural circulation flow condition after the reactor scram. In this research, experimental apparatus for measuring void fraction distribution in the 44 rod bundle was constructed. To measure the void fraction distribution under high pressure and high temperature condition (up to 2.8 MPa, 232 C), two wire mesh sensors (WMSs) were installed. To confirm the applicability of the installed WMSs and the measuring system for two-phase flow in rod bundle, experiments in air-water two-phase flow under atmospheric pressure and room temperature were performed. As a result, it was confirmed that the installed WMSs can be applicable to the two-phase flow in rod bundle. Measured results, such as instantaneous and time-averaged void fraction distribution in the rod bundle, average void fraction across the cross section of the flow channel, bubble length and velocity, were also reported.

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

In situ X-ray diffraction study of the oxide formed on alloy 600 in borated and lithiated high-temperature water

Watanabe, Masashi*; Yonezawa, Toshio*; Shobu, Takahisa; Shiro, Ayumi; Shoji, Tetsuo*

Corrosion, 72(9), p.1155 - 1169, 2016/09

https://doi.org/10.5006/1994

Detection of molecular oxygen adsorbate during room-temperature oxidation of Si(100)21 surface; In situ synchrotron radiation photoemission study

Yoshigoe, Akitaka; Yamada, Yoichi*; Taga, Ryo*; Ogawa, Shuichi*; Takakuwa, Yuji*

Japanese Journal of Applied Physics, 55(10), p.100307_1 - 100307_4, 2016/09

https://doi.org/10.7567/JJAP.55.100307

Synchrotron radiation photoelectron spectroscopy during the oxidation of the Si(100)21 surface at room temperature revealed the existence of the molecularly adsorbed oxygen, which was considered to be absent. The O 1s spectra was found to be similar to that of the oxidation of Si(111)77 surfaces. Also the molecular oxygen was appeared after the initial surface oxides, indicating that this was not a precursor for dissociation oxygen adsorption onto the clean surface. We have proposed presumable structural models for atomic configurations, where the molecular oxygen was resided on the oxidized silicon with two oxygen atoms at the backbonds.

Study of excited states decaying into and baryons

Yelton, J.*; Tanida, Kiyoshi; Belle Collaboration*; 155 of others*

Physical Review D, 94(5), p.052011_1 - 052011_14, 2016/09

AA2016-0394.pdf:0.69MB

https://doi.org/10.1103/PhysRevD.94.052011

Post-grouting with colloidal silica at great depth of the Mizunami Underground Research Laboratory, Japan

Tsuji, Masakuni*; Kobayashi, Shinji*; Sato, Toshinori; Mikake, Shinichiro; Matsui, Hiroya

Proceedings of 8th Nordic Grouting Symposium, p.171 - 185, 2016/09

This paper presents the application of a durable liquid-type colloidal silica grout (CSG), to the great depth of the Mizunami Underground Research Laboratory (MIU). The CSG had been invented decades ago in Japan for the purpose of the ground improvement. A post-grouting experiment with the CSG carried out in 300 m depth of MIU confirmed its applicability and good durability at a great depth more than 3 years. Furthermore, a comparison study of applying the CSG between this experiment and a Swedish project indicated good applicability of the Swedish theoretical design to MIU. The CSG with the Swedish design were applied to the post-grouting campaign in a gallery at 500 m depth for further reducing water ingress and for developing the latest grouting methodology. The grouting was successful in reducing the abundant inflow from the rock with many fractures. The conductivity of the grouted rock mass of the latter fans is estimated to be lower than 10 m/s.

Development of a drift-kinetic simulation code for estimating collisional transport affected by RMPs and radial electric field

Kanno, Ryutaro*; Nunami, Masanori*; Satake, Shinsuke*; Matsuoka, Seikichi; Takamaru, Hisanori*

Contributions to Plasma Physics, 56(6-8), p.592 - 597, 2016/08

https://doi.org/10.1002/ctpp.201610044

A drift-kinetic simulation code is developed for estimating collisional transport in quasi-steady state of toroidal plasma affected by resonant magnetic perturbations and radial electric field. In this paper, validity of the code is confirmed through several test calculations. It is found that radial electron flux is reduced by positive radial-electric field, although radial diffusion of electron is strongly affected by chaotic field-lines under an assumption of zero electric field.

Studies of charmed strange baryons in the final state at Belle

Kato, Yuji*; Tanida, Kiyoshi; Belle Collaboration*; 175 of others*

Physical Review D, 94(3), p.032002_1 - 032002_10, 2016/08

AA2016-0393.pdf:0.32MB

https://doi.org/10.1103/PhysRevD.94.032002

Belle II SVD ladder assembly procedure and electrical qualification

Adamczyk, K.*; Tanida, Kiyoshi; 94 of others*

Nuclear Instruments and Methods in Physics Research A, 824, p.381 - 383, 2016/07

https://doi.org/10.1016/j.nima.2015.08.067

Belle-II VXD radiation monitoring and beam abort with sCVD diamond sensors

Adamczyk, K.*; Tanida, Kiyoshi; 94 of others*

Nuclear Instruments and Methods in Physics Research A, 824, p.480 - 482, 2016/07

https://doi.org/10.1016/j.nima.2015.09.007

Failure probability analysis of aged piping using probabilistic fracture mechanics methodology considering seismic loads

Yamaguchi, Yoshihito; Katsuyama, Jinya; Li, Y.

Proceedings of 2016 ASME Pressure Vessels and Piping Conference (PVP 2016) (Internet), 10 Pages, 2016/07

https://doi.org/10.1115/PVP2016-63801

Characterization of interaction between elliptical subsurface flaws

Azuma, Kisaburo*; Li, Y.; Hasegawa, Kunio

Proceedings of 2016 ASME Pressure Vessels and Piping Conference (PVP 2016) (Internet), 8 Pages, 2016/07

https://doi.org/10.1115/PVP2016-63429

Fatigue lives of multiple flaws in accordance with combination rule

Lu, K.; Li, Y.; Hasegawa, Kunio; Lacroix, V.*

Proceedings of 2016 ASME Pressure Vessels and Piping Conference (PVP 2016) (Internet), 7 Pages, 2016/07

https://doi.org/10.1115/PVP2016-63483

Computations of stress intensity factors for semi-elliptical cracks with high aspect ratios by using the tetrahedral finite element; Fully automated parametric study

Okada, Hiroshi*; Koya, Hirohito*; Kawai, Hiroshi*; Li, Y.; Osakabe, Kazuya*

Engineering Fracture Mechanics, 158, p.144 - 166, 2016/06

https://doi.org/10.1016/j.engfracmech.2016.02.049

The stress intensity factor (SIF) solutions of semi-elliptical cracks with high aspect ratios in plate and thick wall cylinder have been investigated under various assumed stress distributions. The authors have developed an automated analysis procedure to perform parametric studies on crack shapes and loading conditions. It consists of programs to perform automatic mesh generation, analysis execution including assignments of boundary conditions and SIF evaluations by virtual crack closure integral method. It was also found that SIF solutions for the thick wall cylinder and for the complex structure could be estimated by those for the flat plate.

Presence of -martensite as an intermediate phase during the strain-induced transformation of SUS304 stainless steel

Hatano, Masaharu*; Kubota, Yoshiki*; Shobu, Takahisa; Mori, Shigeo*

Philosophical Magazine Letters, 96(6), p.220 - 227, 2016/06

https://doi.org/10.1080/09500839.2016.1190876

We have investigated the formation process of '-martensite from the -phase induced by external strain using synchrotron diffraction experiments, combined with Lorentz transmission electron microscopy (TEM) and high-resolution TEM observations. It is clearly demonstrated that -martensite with hexagonal symmetry appears as an intermediate structure during the plastic deformation of SUS304 stainless steel. In addition to stacking faults and dislocations, interfaces between the twin structures presumably play a key role in the formation of -martensite.

First observation of and search for exotic baryons in systems

Shen, C. P.*; Tanida, Kiyoshi; Belle Collaboration*; 177 of others*

Physical Review D, 93(11), p.112017_1 - 112017_9, 2016/06

AA2016-0387.pdf:0.89MB

https://doi.org/10.1103/PhysRevD.93.112017

Local structure analysis of BiNaTiO, BiNaLiTiO, and 0.95BiNaTiO 0.05BaMnVO

Yoneda, Yasuhiro; Nagamoto, Takeru*; Nakai, Tomoaki*; Kobune, Masafumi*

Transactions of the Materials Research Society of Japan, 41(2), p.197 - 200, 2016/06

http://doi.org/10.14723/tmrsj.41.197

BiNaTiO (BNT) has been investigated as a lead-free piezoelectric material. We have already performed structure analysis of BNT. The average structure of BNT with low-temperature synthesis is a rhombohedral structure and it becomes a monoclinic structure as the synthesized temperature increases. Our local structure analysis indicated that the -site atoms of Bi and Na displaced toward different position depending on the lattice expansion and construction. We synthesized BNT crystals with various substitution and performed local structure analysis to examine the hypothesis. The local structure analysis revealed that the substitution effect on BNT can be explained by our hypothesis.

Effects of OH activity and temperature on the dissolution rate of compacted montmorillonite under highly alkaline conditions

Sawaguchi, Takuma; Tsukada, Manabu; Yamaguchi, Tetsuji; Mukai, Masayuki

Clay Minerals, 51(2), p.267 - 278, 2016/05

https://doi.org/10.1180/claymin.2016.051.2.12

The dependences of the dissolution rate of compacted montmorillonite on activity of OH (a-) and temperature (T) were investigated. The dissolution rate of montmorillonite () in compacted pure montmorillonite, which was formulized as = 10 (a-) e, was higher than that in the compacted sand-bentonite mixtures: = 3500 (a-) e. The difference can be explained by considering the decrease in a- in the mixtures accompanied by dissolution of accessory minerals such as quartz and chalcedony. The dissolution rate model developed for pure montmorillonite is expected to be applied to bentonite mixtures if quantification of the decrease in a- is achieved somehow.

Structure near the threshold in the in-flight He reaction

Sada, Yuta*; Tanida, Kiyoshi; J-PARC E15 Collaboration*; 69 of others*

Progress of Theoretical and Experimental Physics (Internet), 2016(5), p.051D01_1 - 051D01_11, 2016/05

AA2016-0392.pdf:1.05MB

https://doi.org/10.1093/ptep/ptw040

Validation of Pb nuclear data by Monte Carlo analyses of sample reactivity experiments at Kyoto University Critical Assembly

Pyeon, C. H.*; Fujimoto, Atsushi*; Sugawara, Takanori; Yagi, Takahiro*; Iwamoto, Hiroki; Nishihara, Kenji; Takahashi, Yoshiyuki*; Nakajima, Ken*; Tsujimoto, Kazufumi

Journal of Nuclear Science and Technology, 53(4), p.602 - 612, 2016/04

https://doi.org/10.1080/00223131.2015.1068716

Sample reactivity experiments on the uncertainty analyses of Pb nuclear data are carried out by substituting Al plates for Pb ones at the Kyoto University Critical Assembly, as part of basic research on Pb-Bi for the coolant. Numerical simulations of sample reactivity experiments are performed with the Monte Carlo calculation code MCNP6.1 together with four nuclear data libraries JENDL-3.3, JENDL-4.0, ENDF/B-VII.0 and JEFF-3.1, to examine the accuracy of cross-section uncertainties of Pb isotopes by comparing measured and calculated sample reactivities. A library update from JENDL-3.3 to JENDL-4.0 is demonstrated by the fact that the difference between Pb isotopes of the two JENDL libraries is dominant in the comparative study, through the experimental analyses of sample reactivity by the MCNP approach. In addition, JENDL-4.0 reveals a slight difference from ENDF/B-VII.0 in all Pb isotopes and Al, and from JEFF-3.1 in U and Al.

Radially local approximation of the drift kinetic equation

Sugama, Hideo*; Matsuoka, Seikichi; Satake, Shinsuke*; Kanno, Ryutaro*

Physics of Plasmas, 23(4), p.042502_1 - 042502_11, 2016/04

https://doi.org/10.1063/1.4945618

A novel radially local approximation of the drift kinetic equation is presented. The new drift kinetic equation that includes both and tangential magnetic drift terms is written in the conservative form and it has favorable properties for numerical simulation that any additional terms for particle and energy sources are unnecessary for obtaining stationary solutions under the radially local approximation. These solutions satisfy the intrinsic ambipolarity condition for neoclassical particle fluxes in the presence of quasisymmetry of the magnetic field strength. Also, another radially local drift kinetic equation is presented, from which the positive definiteness of entropy production due to neoclassical transport and Onsager symmetry of neoclassical transport coefficients are derived while it sacrifices the ambipolarity condition for neoclassical particle fluxes in axisymmetric and quasi-symmetric systems.

The Martian surface radiation environment; A Comparison of models and MSL/RAD measurements

Matthi, D.*; Ehresmann, B.*; Lohf, H.*; Khler, J.*; Zeitlin, C.*; Appel, J.*; Sato, Tatsuhiko; Slaba, T. C.*; Martin, C.*; Berger, T.*; et al.

Journal of Space Weather and Space Climate (Internet), 6, p.A13_1 - A13_17, 2016/03

https://doi.org/10.1051/swsc/2016008

The Radiation Assessment Detector (RAD) on the Mars Science Laboratory (MSL) has been measuring the radiation environment on the surface of Mars since August 6th 2012. In this work, several models such as GEANT4, PHITS, and HZETRN/OLTARIS are used to predict the radiation environment caused by galactic cosmic rays on Mars in order to compare and validate them with the experimental results. Although good agreement is found in many cases for GEANT4, PHITS and HZETRN/OLTARIS, some models still show large, sometimes order of magnitude, discrepancies in certain particle spectra. We have found that RAD data is helping make better choices of input parameters and physical models. These results help to predict dose rates for future manned missions as well as to perform shield optimization studies.

Technical basis for application of collapse moments for locally thinned pipes subjected to torsion and bending proposed for ASME Section XI

Hasegawa, Kunio; Li, Y.; Bezensek, B.*; Hoang, P. H.*; Rathbun, H. J.*

Journal of Pressure Vessel Technology, 138(1), p.011101_1 - 011101_8, 2016/02

https://doi.org/10.1115/1.4031505

Piping components in power plants may experience combined bending and torsion moments during operation. There is a lack of guidance for pipe evaluation for pipes with local wall thinning under the combined bending and torsion moments. ASME Code Section XI Working Group is currently developing fully plastic bending pipe evaluation procedures for pressurized piping components containing local wall thinning subjected to combined torsion and bending moments. Using elastic fully plastic finite element analyses, plastic collapse bending moments under torsion were obtained for 114.3 mm to 609.6 mm diameter pipes with various local wall thinning flaw sizes. The objective of this paper is to introduce an equivalent moment, which combines torsion and bending moments by a vector summation, and to establish the applicable range of wall thinning lengths, angles and depths, where the equivalent moments are equal to pure bending moments.

EMC studies for the vertex detector of the Belle II experiment

Thalmeier, R.*; Tanida, Kiyoshi; 102 of others*

Journal of Instrumentation (Internet), 11(1), p.C01044_1 - C01044_10, 2016/01

https://doi.org/10.1088/1748-0221/11/01/C01044

Precise observation of growth of surface oxide layer for Pd and Cu nanoparticles during oxidative/reductive gases cyclic flow studied by real-time-resolved XAFS spectroscopy

Matsumura, Daiju; Nishihata, Yasuo; Okajima, Yuka*

e-Journal of Surface Science and Nanotechnology (Internet), 14, p.48 - 52, 2016/00

https://doi.org/10.1380/ejssnt.2016.48

Experience gained from the Fukushima-Daiichi accident as input for developing a technical knowledge base including remediation technologies

Miyahara, Kaname; Iijima, Kazuki; Saito, Kimiaki

Jiban Kogakkai-Shi, 63(11/12), p.62 - 69, 2015/11

AA2015-0380.pdf:1.64MB

http://ci.nii.ac.jp/naid/110010010291

This review provides a concise overview of knowledge and experience gained from the activities for environmental remediation after the Fukushima Dai-ichi accident as input for developing a technical knowledge base including remediation technologies which is translated into actions that enable the rapid return of evacuees. It is reflecting JAEA's key role in the research associated with both remediation of contaminated areas and the natural processes influencing contamination migration in non-remediated areas, working together with a number of Japanese and international organisations and research institutes. This review also provides a perspective on the future actions required to remediate areas outside the Fukushima Dai-ichi site.

Study on probabilistic fracture mechanics analysis methodology in JAEA

Li, Y.

Nihon Kikai Gakkai M&M 2015 Zairyo Rikigaku Kanfarensu Koen Rombunshu (Internet), 2 Pages, 2015/11

http://ci.nii.ac.jp/naid/110010053732

no abstracts in English

Reaction path and product analysis of sodium-water chemical reactions using laser diagnostics

Deguchi, Yoshihiro*; Muranaka, Ryota*; Kamimoto, Takahiro*; Takagi, Taku*; Kikuchi, Shin; Kurihara, Akikazu

Proceedings of 3rd International Workshop on Heat Transfer Advances for Energy Conservation and Pollution Control (IWHT 2015) (CD-ROM), 6 Pages, 2015/10

The purpose of this study aims to clarify the gas phase sodium-water reaction path and reaction products quantitatively. The counter-flow diffusion experiment device was employed to analyze the reaction path and reaction products using laser diagnostics. The main product of sodium-water reaction was determined to be NaOH and the sodium oxide was not notably measured compared with NaOH.

Development of single-sided silicon detectors in the emulsion-hybrid system at J-PARC

Lee, J. Y.*; Ekawa, Hiroyuki; Hasegawa, Shoichi; Hayakawa, Shuhei; Hosomi, Kenji; Imai, Kenichi; Sako, Hiroyuki; Sato, Susumu; Sugimura, Hitoshi; Tanida, Kiyoshi; et al.

JPS Conference Proceedings (Internet), 8, p.021008_1 - 021008_6, 2015/09

https://doi.org/10.7566/JPSCP.8.021008

RANS analyses on erosion behavior of density stratification consisted of helium-air mixture gas by a low momentum vertical buoyant jet in the PANDA test facility, the third international benchmark exercise (IBE-3)

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

Nuclear Engineering and Design, 289, p.231 - 239, 2015/08

https://doi.org/10.1016/j.nucengdes.2015.04.002

Improvement of J-PARC klystron high voltage power supply

Chishiro, Etsuji; Kawamura, Masato*; Sagawa, Ryu*; Ogawa, Shinichi*

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1091 - 1093, 2014/10

http://www.pasj.jp/web_publish/pasj2014/proceedings/PDF/SUP0/SUP048.pdf

In J-PARC linac, six units of high voltage power supplies for 324 MHz klystrons have operated since 2006, and those running time exceed 35,000 hours. In addition, six units of power supplies for the 972 MHz klystrons have been operation since 2013. In the power supply, various troubles occur under the operation. In some anode modulators, arc discharge in the transformer oil had occurred due to the deterioration of the auxiliary solid insulator. In three modules combining a step-up transformer and a rectifier, the high voltage diode was breakdown because an unexpected overvoltage was applied. And by improving the voltage dividing resistor of the module, high stability cathode voltage was achieved. In this report, we describe the trouble and the improvement that occurred in the equipment.

Research and development on waste management for the Fukushima Daiichi NPS by JAEA

Koma, Yoshikazu; Ashida, Takashi; Meguro, Yoshihiro; Miyamoto, Yasuaki; Sasaki, Toshiki; Yamagishi, Isao; Kameo, Yutaka; Terada, Atsuhiko; Hiyama, Toshiaki; Koyama, Tomozo; et al.

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.736 - 743, 2013/09

Fukushima Daiichi Nuclear Power Station (F1NPS), TEPCO, was severely damaged with the hydrogen explosions caused by losing their cooling functions due to the earthquake and the tsunami occurred on March 11, 2011. Radioactive wastes generated from the current FINPS and future their decommission and demolition are greater huge amount than those from general reactors and nuclear fuel facilities. Toward accomplishing safe and reasonable management of the wastes, great effort of R&Ds has been strongly required and performed in bringing together the knowledge and experience of all of Japan. This report outlines the current status of the R&Ds performed in JAEA.

Investigation on evaluation method based on J integral for retardation of crack growth due to excessive loading beyond small scale yielding condition

Yamaguchi, Yoshihito; Katsuyama, Jinya; Onizawa, Kunio; Sugino, Hideharu*; Li, Y.*

Proceedings of 2010 ASME Pressure Vessels and Piping Conference (PVP 2010) (CD-ROM), 8 Pages, 2010/07

https://doi.org/10.1115/PVP2010-25563

Niigata-ken Chuetsu-Oki earthquake occurred, whose magnitude was beyond the assumed one provided in seismic design. Therefore it becomes an important issue to evaluate the effect of such an excessive loading. Fatigue crack growth is usually evaluated by Paris's law using the range of stress intensity factor, K. However, since K is inappropriate in a loading condition beyond the small scale yielding, the evaluation method for such a loading condition should be established. In this study, the crack growth behaviors were investigated using austenitic stainless steel and carbon steel. Instead of K, the range of J-integral, J, has been used for the interpretation of experimental data. Applicability of J into the Wheeler model, which express the retardation effect on the crack growth, has been proposed to evaluate the retardation effect. It was indicated that the J-Wheeler model could be applied to predict the crack growth after an excessive loading beyond small scale yielding.