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Yoshida, Kazuo; Abe, Hitoshi
JAEA-Research 2014-001, 22 Pages, 2014/03
JAEA-Research-2014-001.pdf:2.97MB
Boiling accidents of reprocessed liquid wastes at fuel reprocessing facilities are postulated to occur by the loss of cooling function for waste storage tanks due to a long-term total loss of AC power. Some amounts of radioactive materials could be released from facilities by vapor flow from a boiling liquid waste storage tank. The amount of water and nitric acid vapor, which is one of key parameters to estimate the duration time of evaporation to dryness and the amounts of radioactive materials transferring from liquid to vapor phase, is calculated based on the liquid/vapor equilibrium data of liquid wastes. This report discusses on the relationship between degrees of boiling point, nitrate salt mole fraction, and the liquid/vapor equilibrium of single component non-volatile nitrate solution. A estimation method is proposed of liquid/vapor equilibrium of multicomponent nitrate solution simulating reprocessed liquid wastes.
2012 FYOchiai, Shoji; Asamori, Koichi; Tokiwa, Tetsuya; Nohara, Tsuyoshi; Matsuoka, Toshiyuki
JAEA-Research 2014-002, 69 Pages, 2014/03
JAEA-Research-2014-002.pdf:7.39MB
The purpose of this study is to examine the analysis techniques and observation techniques required to obtain the seismic data on long-term stability of the geological environment. Through the earthquake observation of about 9 years and the development of seismic network as a case study of Horonobe, we confirmed the observation techniques, such as the effectiveness of the seismograph installation using the pit for a snowy cold environment. The performance of the observation points in a relatively soft ground was about 1 mGal acceleration that can distinguish earthquake from background noise. For analysis technology, we confirmed the valid range of observational data for hypocenter determination. Also, the analysis conditions for improving the hypocenter accuracy by applying the Double-Difference Method (DD method) and Multiplet-clustaring method were confirmed. It was estimated that applicability of these methods is high in the condition that the hypocenters concentrated. The reliability of DD method has been improved by using many data including the observation points near the hypocenter. Analyzed focal mechanisms showed reverse fault of east-west compression. This is consistend with the geological structure and the regional stress field.
Furuta, Takuya; Takahashi, Fumiaki
JAEA-Research 2014-003, 100 Pages, 2014/03
JAEA-Research-2014-003.pdf:5.04MB
Precise dose assessment requires the factors for each building. In addition, the data were based on researches for foreign buildings, which may be different from Japanese buildings. We therefore surveyed building trends in Fukushima and selected representative houses and buildings. 3-D models of the buildings were constructed and the radiation doses inside the buildings were calculated by PHITS to derive the effects of shielding and dose reduction by the buildings. The results provide us useful knowledge for dose assessment of residents in Fukushima area.
Hasegawa, Ken; Yamada, Nobuto; Koide, Kaoru
JAEA-Research 2014-004, 177 Pages, 2014/06
JAEA-Research-2014-004.pdf:36.19MB
Tono Geoscience Center conducted CSMT and MT surveys in the region of the Toki granite from 1997 to 1999, as a part of the Regional Hydrogeological Study. After these surveys were performed, applicability of MT method to prospecting of the deeper part of the granite was evaluated. As a result, several problems of CSMT and MT surveys were pointed out. Accordingly, we checked the quality of data obtained through the surveys and found out that the interpretation results of the underground resistivity distribution are deficient in reliability because almost all data contain large artificial electromagnetic noise. Major reason behind its poor results is adoption of the high-frequency tensor CSMT system. Because of its ease of data acquisition, it was adopted without investigation of electromagnetic noises around the survey area. This fact indicated that we must investigate details of the noise around survey area in advance and select optimum equipment and survey specifications, which can distinguish a signal from data containing such large noise.
Sanada, Yukihisa; Takamura, Yoshihide; Urabe, Yoshimi; Tsuchida, Kiyofumi; Nishizawa, Yukiyasu; Yamada, Tsutomu; Sato, Yoshiharu; Hirayama, Hirokatsu; Nishihara, Katsuya; Imura, Mitsuo; et al.
JAEA-Research 2014-005, 67 Pages, 2014/05
JAEA-Research-2014-005.pdf:52.68MB
Distribution of radiocesium existing on the waterbed such as lake or pond was concerned about at the present that passed for two years by an accident. Here, the direct measurement technique of the radiocesium concentration (in-situ measurement technique) was developed. This method was used an plastic scintillation detector (p-Scanner). This detector carried out quick measurement of a large area. In addition, the count-rate of p-Scanner was converted to the radiocesium concentration (Ba/kg-wet) by comparative measurement of 
-ray spectrometer. We applied the technique to the agricultural pond in Fukushima and made a map of distribution of radiocesium concentration.
Sanada, Hiroyuki; Sato, Toshinori; Tanno, Takeo*; Hikima, Ryoichi*; Tada, Hiroyuki*; Kumasaka, Hiroo*; Ishii, Takashi*; Sakurai, Hideyuki*
JAEA-Research 2014-006, 124 Pages, 2014/06
JAEA-Research-2014-006.pdf:11.26MB
Japan Atomic Energy Agency has been implementing the Mizunami Underground Research Laboratory (MIU) Project in order to develop the comprehensive investigation techniques for the geological environment and the engineering techniques to construct a deep underground laboratory in crystalline rock. In the rock mechanical study in the MIU Project, the development of the evaluation method for the excavation damaged zone due to excavation of shafts and research galleries is one of the important issues. In this report, crack tensor was calculated using the tunnel wall mapping and rock mechanical test results in the shaft and research galleries in the MIU. Two dimension excavation analysis was conducted at the Ventilation Shaft and GL -500 m Sub Stage using the calculated crack tensor at GL -500 m. Based on calculated crack tensor at GL 500 m, validation of the crack tensor at GL -500 m estimated during Phase I was verified. Relative error of crack tensor was calculated in order to examine variation of relative error to the scale of observation areas.
Fukushima Project Team, Oarai Research and Development Center; Fukushima Fuels and Materials Department, Oarai Research and Development Center
JAEA-Research 2014-007, 32 Pages, 2014/06
JAEA-Research-2014-007.pdf:9.33MB
Primary containment vessel (PCV), reactor pressure vessel and pedestal in Fukushima Daiichi Nuclear Power Station units 1 through 3 have been exposed to severe thermal, chemical and mechanical conditions due to core meltdown events and seawater injections for emergent core cooling. These components will be immersed in diluted seawater with dissolved fission products under irradiation until the end of debris removal. Fresh water injected into the cores contacts with debris to cool, dissolutes or erodes their constituents, mixed with retained water, and becomes "accumulated water" with radioactive nuclides. We have focused the leaching of fission products into the accumulated water under lower temperature (323 K). FUGEN spent oxide fuel segments were immersed to determine the leaching factor of fission product and actinide elements. Since PCV made from carbon steel is one of the most important boundaries to prevent from fission products release, corrosion behavior has been paid attention to evaluate their integrity. Carbon steel specimens were immersion- and electrochemical-tested in diluted seawater with simulants of the accumulated water at 323 K. in order to evaluate the effect of fission products in particular cesium and radiation.
Sasaki, Yuji; Tsubata, Yasuhiro; Kitatsuji, Yoshihiro; Sugo, Yumi; Shirasu, Noriko; Ikeda, Yasuhisa*; Kawasaki, Takeshi*; Suzuki, Tomoya*; Mimura, Hitoshi*; Usuda, Shigekazu*; et al.
JAEA-Research 2014-008, 220 Pages, 2014/06
JAEA-Research-2014-008.pdf:41.81MB
The researches on Development of mutual separation technology of minor actinides by the novel hydrophilic and lipophilic diamide compounds, entrusted to Japan Atomic Energy Agency by the Ministry of Education, Culture, Sports, Science and Technology of Japan, from 2010 to 2012 are summarized. This project was composed of three themes, those are (1) Development of total recovery of MA+Ln: basic researches for new extractant, DOODA, (2) Development of mutual separation of Am/Cm/Ln: basic researches of Ln-complex, solvent extraction, and extraction chromatography, and (3) Evaluation of separation technique: process simulation. For topic (1), we summarized the information on characteristic of DOODA extractant. For topic (2), we summarized the information on structures of Ln-complexes, solvent extraction and chromatography. For topic (3), we summarized the information on conditions of mixer-settler and evaluation of each fraction separated.
Kimura, Nobuyuki; Kobayashi, Jun; Kameyama, Yuri*; Nagasawa, Kazuyoshi*; Ezure, Toshiki; Ono, Ayako; Kamide, Hideki
JAEA-Research 2014-009, 104 Pages, 2014/07
JAEA-Research-2014-009.pdf:15.23MBJAEA-Research-2014-009-appendix(CD-ROM).pdf:17.88MB
In this study, water experiments (WATLON) were carried out to clarify the unsteady behavior of heat transfer under wall jet condition in the mixing tee. In experiments, heat transfer coefficients between fluid and wall in the mixing region were obtained from temperature measurements using thermocouples (movable tree type in fluid and embedded type in wall). To clarify the relation between the local velocity and the wall temperature, those were measured simultaneously by the Particle Image Velocimetry (PIV) and the thermocouple measurement, respectively. Sampling time of the velocity by the PIV and the temperature by the thermocouple were synchronized in the measurement. The experimental results showed that the heat transfer coefficient was from 2 - 6 time larger than the reference value predicted by the Dittus-Boelter correlation in straight pipes and was increased as the local velocity near the wall.
Onoe, Hironori; Maemura, Tsuneyuki*; Kimura, Hitoshi*; Hishiya, Tomoyuki*; Mizuno, Takashi; Takeuchi, Ryuji; Iwatsuki, Teruki
JAEA-Research 2014-010, 35 Pages, 2014/06
JAEA-Research-2014-010.pdf:59.86MB
In this study, groundwater flow modeling based on the hydrogeological conceptual model was carried out using data of hydraulic responses and groundwater chemistry changes until 500m depth of MIU excavation. As a result of this study, trend of inflow rate into the MIU facilities and hydraulic and geochemical impacts around the MIU Construction Site caused by the MIU construction were reproduced in groundwater flow simulation. In addition, validation of the hydrogeological conceptual model was confirmed.
Kojima, Keiji*; Onishi, Yuzo*; Aoki, Kenji*; Tochiyama, Osamu*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Yoshida, Hidekazu*; Ogata, Nobuhisa
JAEA-Research 2014-011, 43 Pages, 2014/09
JAEA-Research-2014-011.pdf:56.68MB
This report is concerned with research to reconstruct more realistic near-field (NF) concept for the geological disposal. In previous year, we examined the realistic concept for near-field, including rock mass around the tunnel, particularly based on the nuclide migration scenario. The time-series change of the field was divided into five stages of 0 to IV through the process of geological disposal (Excavation, Operation and Post-closure). Then at each respective stage, post-closure stage in particular; we examined interaction between environmental factors and exhaustive extraction of those factors affecting the near-field, focusing on each scale-time cross-section. In the reconstruction of realistic near-field concept, it is necessary to analyze security matters are unacceptable by society, regarding geological disposal. We also exchanged views on those matters and presented the future direction of research and development for geological disposal.
Sanada, Yukihisa; Nishizawa, Yukiyasu; Urabe, Yoshimi; Yamada, Tsutomu; Ishida, Mutsushi; Sato, Yoshiharu; Hirayama, Hirokatsu; Takamura, Yoshihide; Nishihara, Katsuya; Imura, Mitsuo; et al.
JAEA-Research 2014-012, 110 Pages, 2014/08
JAEA-Research-2014-012.pdf:169.17MBJAEA-Research-2014-012(errata).pdf:0.27MB
By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (NPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPP. This document was summarized in the results of the aerial radiation monitoring using the manned helicopter in the fiscal 2013.
Omori, Kazuaki; Munemoto, Takashi; Hasegawa, Takashi; Shingu, Shinya*; Hagiwara, Hiroki; Iwatsuki, Teruki
JAEA-Research 2014-013, 29 Pages, 2014/08
JAEA-Research-2014-013.pdf:48.04MB
We summarized investigation method of colloid in groundwater. We examined the ultrafiltration of groundwater by using in-situ water monitoring system and batch type airtight container. Additionally, we examined the cross flow filtration method replaced by ultrafiltration. The knowledge of investigating methods is obtained.
Hagiwara, Hiroyuki; Kimura, Nobuyuki*; Onojima, Takamitsu; Nagasawa, Kazuyoshi*; Kamide, Hideki; Tanaka, Masaaki
JAEA-Research 2014-014, 178 Pages, 2014/09
JAEA-Research-2014-014.pdf:53.12MB
Thermal stratification in the upper plenum is one of the most important issues of a reactor vessel in sodium cooled fast reactor. The steep temperature gradient across the stratification interface may cause the thermal load against the reactor vessel wall. In this study, the water experiment was carried out using the 1/11 scale upper plenum model of the Japan sodium-cooled fast reactor (JSFR) in order to evaluate the thermal stratification under the natural circulation condition and a direct heat exchanger (DHX) operation condition. The temperature gradient under the natural circulation condition was approximately 1/3 times smaller than that under the forced circulation condition. In the DHX operation case, the steep temperature gradient occurred in the lower region of upper plenum due to the cold fluid from the outlet of DHX.
turbine system, 1; Sodium/CO heat exchangerKisohara, Naoyuki; Sakamoto, Yoshihiko; Kotake, Shoji*
JAEA-Research 2014-015, 33 Pages, 2014/09
JAEA-Research-2014-015.pdf:27.33MB
JAEA has performed a design study of an S-CO gas turbine system applied to the JSFR. In this study, the S-CO cycle turbine system was directly connected to the primary sodium system of the JSFR to eliminate the secondary sodium circuit, aiming for further economical improvement. The Na/CO heat exchanger is one of the key components, and this report describes its structure and the safety in case of CO leak. A Printed Circuit Heat Exchanger (PCHE) is employed to the heat exchanger. A SiC/SiC ceramic composite material is used for the PCHE to prevent crack growth and to reduce thermal stress. The Na/CO heat exchanger has been designed in such a way that a number of small heat transfer modules are combined in the vessel in consideration of manufacture and repair. CO leak events in the heat exchanger have been also evaluated, and it revealed that no significant effect has arisen on the core or the primary sodium boundary.
turbine system, 2; Turbine system and plant sizeKisohara, Naoyuki; Sakamoto, Yoshihiko; Kotake, Shoji*
JAEA-Research 2014-016, 60 Pages, 2014/09
JAEA-Research-2014-016.pdf:22.38MB
JAEA has performed a design study of an S-CO gas turbine system applied to the JSFR. In this study, the S-CO cycle turbine system was directly connected to the primary sodium system of the JSFR to eliminate the secondary sodium circuit, aiming for further economical improvement. This report describes the system configuration, heat/mass balance, and main components of the S-CO turbine system, based on the JSFR specifications. The layout of components and piping in the reactor and turbine buildings were examined and the dimensions of the buildings were estimated. The study has revealed that the reactor and turbine buildings could be reduced by 7% and 40%, respectively, in comparison with those in the existing JSFR design with the secondary sodium circuit employing the steam turbine. The cycle thermal was also calculated as 41.9-42.3%, which is nearly the same as that of the JSFR with the water/steam system.
Satoh, Daiki; Furuta, Takuya; Takahashi, Fumiaki; Endo, Akira; Lee, C.*; Bolch, W. E.*
JAEA-Research 2014-017, 25 Pages, 2014/08
JAEA-Research-2014-017.pdf:15.8MB
In order to estimate effective dose for the public for external exposure to radioactive cesium distributed in a soil due to the accident of the Fukushima Daiichi Nuclear Power Station, dose conversion coefficients (DCC) have been calculated by using a three-dimensional radiation transport code PHITS. The DCC were evaluated for different ages constituting the public, that is 6-day-old babies, 1-, 5-, 10-, and 15-year-old children, and adults, under the condition which the radioactive cesiums, Cs-134 and Cs-137, are distributed uniformly in the soil with a specific depth of 0.0 g/cm
, 0.5 g/cm, 2.5 g/cm, 5.0 g/cm, and 10.0 g/cm. In addition, we evaluate the DCC for cumulative effective dose for external exposure by remaining on ground with radioactive cesium for a period of concern, that is 1 month, 1 year, and 50 years. As a result of the calculation, it was found that the effective dose for any age does not exceed the value of ambient dose equivalent H
(10), while the effective dose increases with decreasing the age, and the difference of dosimetry system between the ICRP 1990 and 2007 Recommendations does not make a significant difference for the external dose calculation on contaminated ground. We also developed a method to evaluate the DCC for volume source with an arbitrary distribution in a soil, and derived an equation to be applicable to dose estimation in contaminated areas around Fukushima Daiichi Nuclear Power Station considering initial condition of radioactivity of Cs-134 and Cs-137.
Muramatsu, Toshiharu; Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Nguyen, P. L.; Matsunaga, Yukihiro
JAEA-Research 2014-018, 41 Pages, 2014/09
JAEA-Research-2014-018.pdf:42.21MB
In decommissioning works of the Fukushima Daiichi Nuclear Power Plants, it is required that fuel debris solidifying mixed materials of fuels and in-vessel structures should be removed. The fuel debris is considered to have characteristics, such as indefinite shapes, porous bodies, multi-compositions, higher hardness, etc. from the knowledge in the U.S. and the Three Mile Island nuclear power plant. Laser lights are characterized by higher power density, local processability, remote controllabilitiy, etc. and can be performed thermal cutting and crushing-up for various materials which does not depend on fracture toughness. This report describes a research program and research activities in FY2013 aiming at developing removal system of fuel debris by the use of laser lights.
Tanaka, Masaru*; Gofuku, Akio*; Ishizaka, Kaoru*; Sato, Kazuhiko; Nagahama, Yoji
JAEA-Research 2014-019, 103 Pages, 2014/12
JAEA-Research-2014-019.pdf:12.1MB
We had been conducting a research on risk perception and confidence-building among stakeholders regarding environmental remediation of Uranium mine site and disposal of industrial waste from FY 2007. FY 2011, we study how the Great East Japan Earthquake and Fukushima nuclear accident affects public risk perception. Therefore, a questionnaire survey on public risk perception of environmental remediation of Uranium mine site and disposal of the industrial waste in Okayama prefecture had been carried out. Another questionnaire survey on public risk perception of the disposal of disaster waste for residents in Okayama prefecture has been carried out. Following are some of the results: (1) For risk perception regarding environmental remediation of Uranium mine site, "knowledge of radiation" and "Concern about radioactive material" and "Information literacy" did not change significantly. Conversely trust in "Public administration" and "facility owner" and "Science and technology" was decreased significantly. (2) For risk perception regarding disaster waste, many people recognize the need for wide area disposal of disaster waste. Conversely, many residents are concerned about radioactive materials.
Fukui, Katsunori*; Hashiba, Kimihiro*; Sato, Toshinori; Sanada, Hiroyuki; Kuwabara, Kazumichi
JAEA-Research 2014-020, 50 Pages, 2014/11
JAEA-Research-2014-020.pdf:2.8MB
On the radioactive waste disposal, the long-term mechanical stability of shafts and galleries excavated in rock is required. Therefore, it is very important to understand the time-dependent behavior of rock mass for evaluating long-term mechanical stability. The purpose of this study is determining the mechanisms of time-dependent behavior of rock mass by precise testing, observation and measurement in order to develop methods for evaluating long-term mechanical stability of a rock mass. This report describes the results of the activities in fiscal year 2013. In Chapter 1, we described the overview and background of this study. In Chapter 2, the results of a long-term creep test on Tage tuff, started in fiscal year 1997 are described. In Chapter 3, the result of organization and analysis for time-dependent behavior of crystalline rock was described. In Chapter 4, for the drafting of in-situ test plan, examination of the numerical analysis technique of rock mass was carried out.
Kawamoto, Koji; Kuboshima, Koji*; Murakami, Hiroaki; Ishibashi, Masayuki; Sasao, Eiji
JAEA-Research 2014-021, 30 Pages, 2014/11
JAEA-Research-2014-021.pdf:6.79MB
The MIU (Mizunami Underground Research Laboratory) Project has three overlapping phases, Surface-based investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). Currently, the project is under Phase II and Phase III. One of Phase II goals is set up to develop and revise models of the geological environment using the investigation results obtained during excavation, and to determine and assess changes in the geological environment in response to excavation. This report aims at compiling results of study on geology and geological structure at the -500m Stage in the MIU construction site, investigated in the Phase II and provides the fundamental information on the geology and geological structure for future study and modeling of geological environment.
Abe, Hitoshi; Masaki, Tomoo; Amano, Yuki; Uchiyama, Gunzo
JAEA-Research 2014-022, 12 Pages, 2014/11
JAEA-Research-2014-022.pdf:1.03MB
To contribute safety evaluation of boiling and drying accident of high active liquid waste (HALW) in fuel reprocessing plant, release behavior of Ru, which was considered as an important nuclide for evaluating public dose from the volatile viewpoint, has been investigated. It has been reported that release of Ru becomes conspicuously after HALW is dried up. In this work, to grasp the release behavior of Ru, release ratio of Ru with thermal decomposition of Ru nitrate, which would be in the dried HALW, was measured and release rate constant of Ru from the nitrate was estimated. It was found that the calculation result of release rate of Ru from the nitrate with rise of temperature by using the constant could well simulate the result acquired from the beaker-scale experiment.
Ito, Kei; Tanaka, Masaaki; Ohno, Shuji; Ohshima, Hiroyuki
JAEA-Research 2014-023, 34 Pages, 2014/11
JAEA-Research-2014-023.pdf:4.48MB
In a sodium-cooled fast reactor, inert gas (bubbles or dissolved gas) exists in the primary coolant system. Such inert gas may cause disturbance in reactivity and/or degradation of IHX performance, and therefore, the inert gas behaviors have to be investigated to ensure the stable operation of a fast reactor. The authors have developed a plant dynamics code SYRENA to simulate the concentration distributions of the dissolved gas and the bubbles in a fast reactor. In this study, the models in SYRENA code are improved to achieve accurate simulations. Moreover, new models are introduced to simulate the various bubble behaviors in liquid metal flows. To validate the improved models and the newly developed models, the inert gas behaviors in the large-scale sodium-cooled reactor are simulated. As a result, it is confirmed that the complicated bubble dynamics in each component can be simulated appropriately by SYRENA code.
Takahara, Shogo; Iijima, Masashi; Shimada, Kazumasa; Kushida, Teruo; Shiratori, Yoshitake
JAEA-Research 2014-024, 57 Pages, 2015/01
JAEA-Research-2014-024.pdf:5.49MB
In order to assess the doses to representative person using deterministic approach, we measured radiation dose rates and surveyed on behavioral patterns in the areas contaminated by the Fukushima Daiichi Nuclear Power Station Accident. Statistical analyzes were also performed to identify the characteristics of individual doses from external exposures, as well as radiation dose rates and behavioral patterns. Radiation dose rates measured in living areas distribute with lognormal form. Behavioral patterns of the populations were different corresponding to their occupation. Time spent outdoors of indoor workers were distributed in lognormal form and those of outdoor workers had the normal distribution. Multi-regression analyses were made to explore a significant relationship between individual doses and relevant contributors. These results indicated that the significant differences were given in individual doses due to the spatial differences of radiation dose rates as well as the interindividual differences of behavioral patterns. Based on the results of analyses of relevant contributors to the external exposures, deterministic dose assessment model was developed. The validity of this model was confirmed because the assessed values were higher than those measured.
Shinozaki, Takashi; Mihara, Takeshi; Udagawa, Yutaka; Sugiyama, Tomoyuki; Amaya, Masaki
JAEA-Research 2014-025, 34 Pages, 2014/12
JAEA-Research-2014-025.pdf:6.05MB
EDC test is a test method on the mechanical property of fuel cladding tube, and it focuses on the stress condition generated by PCMI under a RIA. We conducted EDC tests which simulate the mechanical conditions during a RIA by using the unirradiated cladding tubes which simulate hydride rim. Circumferential residual strains observed in post-test specimens tended to decrease with increasing the hydrogen concentration in the test cladding tubes and the thickness of the hydride rim. We also prepared RAG tube and performed EDC tests on it. It was observed that circumferential total strains at failure tended to decrease with increasing pre-crack depth on the outer surface of RAG tube specimen. We conducted biaxial stress tests by applying longitudinal tensile load onto RAG tube specimens. It was observed that circumferential total strains at failure under biaxial stress conditions tended to decrease compared to the results under uniaxial tensile condition.
Yamada, Tomonori; Muramatsu, Toshiharu
JAEA-Research 2014-026, 28 Pages, 2015/02
JAEA-Research-2014-026.pdf:18.03MB
In this study the response of hardened cement pastes, which is a major component of concrete, to laser irradiation was investigated under various experimental conditions aiming at the future application to "laser-processing" of concrete. (1) Evaluation of water-cement ratio for laser irradiation. It was found that hardened cement paste subjected to laser irradiation explodes very easily to be hollowed in all the experimental conditions; this response is applicable to "laser-drilling" of a hardened cement paste. (2) Evaluation of the kind of mortar for laser irradiation. Totally 75 laser irradiation tests for fixed mortar blocks were performed with combinations of following experimental conditions: fine aggregate in the mortar blocks was either of quartz, limestone, or Nachiguro-ishi. Although it was found that all kinds of the mortar fuse under laser irradiation after all, difference in the response to laser irradiation among the mortars was also found.
Ichikawa, Yasuaki*; Kimoto, Kazushi*; Sato, Toshinori; Sanada, Hiroyuki; Kuwabara, Kazumichi
JAEA-Research 2014-027, 25 Pages, 2015/02
JAEA-Research-2014-027.pdf:16.92MB
The rock and the rock mass are known to show time-dependent behavior such as creep and the stress-relaxation. It is to evaluate long-term rock mechanics stability that the important theme understanding the property. From the research study until now, it is rock mechanics and chemical coupled phenomenon to have an influence on the long-term behavior. It is a theme to develop technique to model this coupled phenomenon, and to analyze. About an evaluation of the microcrack to have an influence on this coupled phenomenon, it is the theme that we should work on in a long-term rock mass behavior study chiefly. This study developed numerical analysis to check the ultrasonic scattering decrement behavior by the microcrack of the crystalline rock and the measurement technique. The FDTD method which modelled a crack was used for numerical analysis by split node. It depends on the simulation technique that it developed that useful knowledge was provided by elastic wave modeling. On the other hand, the ultrasonic measurement in a rock sample was measured by the water immersion method. As a result, we understood that we could acquire useful information to evaluate the scattering decrement of an elastic wave in a rock sample.
Takai, Shizuka; Takeda, Seiji; Kimura, Hideo
JAEA-Research 2014-028, 13 Pages, 2015/02
JAEA-Research-2014-028.pdf:1.92MB
A large amount of waste contaminated by radioactive cesium released by Fukushima Daiichi Nuclear Power Plant has been recycled as much as possible in order to reduce the quantity to be disposed of and to use resources effectively. At present, a standard concentration of radioactive cesium for recycled products from disaster waste is defined as 100 Bq/kg. In order to understand the actual situation of radioactivity concentration of recycled products, Ministry of the Environment conducted a survey on recycled products. The survey found that several recycled products had relatively high radioactive cesium concentration. In this study, we specified exposure pathways to calculate doses for using the recycled products detected high cesium concentration in the survey. We calculate the doses based on the survey of concentration of the recycled products and compare them with a dose criterion of 10
Sv/y for the use of recycled products. It was shown that the calculated doses were less than 10Sv/y for all recycled products but one sample of recycled asphalt with 26Sv/y. However, 26Sv/y is within the range of trivial dose indicated in ICRP Pub.104 and safety for reuse of the recycled asphalt is ensured.
Tamura, Itaru; Kashima, Yoichi; Soyama, Kazuhiko
JAEA-Research 2014-029, 12 Pages, 2015/03
JAEA-Research-2014-029.pdf:1.89MB
Neutron guide tubes, which are installed near reactor cores, are damaged by neutrons and rays irradiation. Those glass substrates which contain boron material are affected by (n, 
) reaction, and ionization effect of rays on material strength decrease duration of use of neutron guide tubes. In order to increase resistance to radiation, we have fabricated a supermirror with Ni-P metallic substrate. The substrate roughness with 0.2 - 0.3 nm (rms) was produced by super- polishing. The neutron reflectivity reached 76 % for an m=3 supermirror.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Kitamura, Akira; Yoshikawa, Hideki; Oda, Chie; Ishidera, Takamitsu; et al.
JAEA-Research 2014-030, 457 Pages, 2015/03
JAEA-Research-2014-030.pdf:199.23MB
JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and post-closure performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, based on some examples of developing method of hydro-geological structure model, acquired knowledge are arranged using the tree diagram, and model uncertainty and its influence on the evaluation items were discussed. With regard to (2) study on scenario development, the developed approach for "defining conditions" has been reevaluated and improved from practical viewpoints. In addition, the uncertainty evaluation for the effect of use of cementitious material, as well as glass dissolution model, was conducted with analytical evaluation. With regard to (3) study on setting radionuclide migration parameters, based on survey of precedent procedures, multiple-approach for distribution coefficient of rocks was established, and the adequacy of the approach was confirmed though its application to sedimentary rock and granitic rock. Besides, an approach for solubility setting was developed including the procedure of selection of solubility limiting solid phase. The adequacy of the approach was confirmed though its application to key radionuclides.
Fujita, Tomoo; Tanai, Kenji; Nakayama, Masashi; Sawada, Sumiyuki*; Asano, Hidekazu*; Saito, Masahiko*; Yoshino, Osamu*; Kobayashi, Masato*
JAEA-Research 2014-031, 44 Pages, 2015/03
JAEA-Research-2014-031.pdf:16.11MB
Japan Atomic Energy Agency (JAEA) and Radioactive Waste Management Funding and Research Center (RWMC) concluded the letter of cooperation agreement on the research and development of radioactive waste disposal in April, 2005, and have been carrying out the collaboration work based on the agreement. JAEA have been carrying out the Horonobe Underground Research Laboratory (URL) Project which is intended for a sedimentary rock in the Horonobe town, Hokkaido, since 2001. In the project, geoscientific research and research and development on geological disposal technology are being promoted. Meanwhile, the government (the Agency for Natural Resources and Energy, Ministry of Economy, Trade and Industry) has been promoting construction of equipments for the full-scale demonstration of engineered barrier system (EBS) and operation technology for high-level radioactive waste (HLW) disposal since 2008, to enhance public's understanding to the geological disposal of HLW, e.g. using underground facility. RWMC received an order of the project in fiscal year 2012 (2011/2012) continuing since fiscal year 2008 (2008/2009). Since topics in this project are included in the Horonobe URL Project, JAEA carried out this project as collaboration work continuing since fiscal year 2008. This report summarizes the results of engineering technology carried out in this collaboration work in fiscal year 2013. In fiscal year 2013, emplacement tests using buffer material block for the vertical emplacement concept were carried out and visualization tests for water penetration in buffer material were carried out.
Nishihara, Kenji
JAEA-Research 2014-032, 29 Pages, 2015/03
JAEA-Research-2014-032.pdf:5.0MB
Environment impact, economy and proliferation resistance were estimated for nuclear fuel cycles involving transmutation by fast reactor and accelerator-driven system in equilibrium state. As the result, the transmutation scenario using only fast reactor was superior to the scenarios combined with accelerator-driven system in all estimation, but the differences were insignificant.
Iwamoto, Hiroki; Nishihara, Kenji; Katano, Ryota*; Fukushima, Masahiro; Tsujimoto, Kazufumi
JAEA-Research 2014-033, 82 Pages, 2015/03
JAEA-Research-2014-033.pdf:6.53MB
The effect of experiments using Transmutation Physics Experimental Facility (TEF-P) is analysed from the viewpoint of the reduction of uncertainties in reactor physics parameters (criticality and coolant void reactivity) of an accelerator-driven system (ADS). The analysis is conducted by the nuclear-data adjustment method using JENDL-4.0 on the assumption that ve types of reactor physics experiments (a total of 44 experiments) are performed in TEF-P: (1) criticality experiment, (2) lead void reactivity experiment, (3) reaction rate ratio experiment, (4) sample reactivity experiment, and (5) fuel replacement reactivity experiment. As the result, 1.0% of uncertainty in criticality is found to be reduced to approximately 0.4%, and effective experiments for the reduction of uncertainty in criticality and coolant void reactivity are shown to be fuel replacement reactivity experiments and lead void reactivity experiments, respectively. Although these effects depend largely on the composition and amount of minor-actinide (MA) fuels, it is found that a combination of different types of experiments and database of existing experiments is effective in reducing the uncertainties.