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JAEA Reports

Horonobe Underground Research Laboratory Project; Synthesis of phase I investigation 2001 - 2005, Volume "Geological disposal research"

Fujita, Tomoo; Taniguchi, Naoki; Matsui, Hiroya; Tanai, Kenji; Maekawa, Keisuke; Sawada, Atsushi; Makino, Hitoshi; Sasamoto, Hiroshi; Yoshikawa, Hideki; Shibata, Masahiro; et al.

JAEA-Research 2011-001, 193 Pages, 2011/03

JAEA-Research-2011-001.pdf:5.23MB

This report summarizes the progress of research and development on geological disposal during the surface-based investigation phase (2001-2005) in the Horonobe Underground Research Laboratory project, of which aims are to apply the design methods of geological disposal and mass transport analysis to actual geological conditions obtained from the surface-based investigations in the Horonobe Underground Research Laboratory project as an example of actual geological environment.

JAEA Reports

Research and development for treatment and disposal technologies of TRU waste; JFY 2009 annual report

Kamei, Gento; Honda, Akira; Mihara, Morihiro; Oda, Chie; Ichige, Satoru; Kurimoto, Yoshitaka; Hoshino, Seiichi; Akagi, Yosuke; Sato, Nobuyuki; Murakami, Hiroshi*; et al.

JAEA-Research 2011-002, 82 Pages, 2011/03

JAEA-Research-2011-002.pdf:5.64MB

Based on Japanese governmental policy and general scheme, research and development of geological disposal technology for TRU waste has been proceeding to improve reliability of the safety assessment of the co-locational disposal of TRU waste and of HLW, to expand the basement of generic safety assessment, and to develop the alternative technology to cope with the broad geologic environment of Japan. Japan Atomic Energy Agency is dealing with the assignments in the governmental generic scheme. We report here the progress of the studies at the end of H20 (2008) Japanese fiscal year, which are (1) evaluation of long-term mechanical stability in the near-field including development of a creep mode of rock and analyses of mechanical behavior of TRU waste repository, (2) performance assessment of the disposal system including data acquisition and preparation on radionuclides migration, cementitious material alteration, bentonite and hostrock alteration with alkaline solution and nitrate effect, and (3) alternative technology development including decomposition of nitrate.

JAEA Reports

A Study for the safety evaluation of geological disposal of TRU waste and influence on disposal site design by change of amount of TRU waste (Joint research)

Hasegawa, Makoto; Kondo, Hitoshi; Kamei, Gento; Hirano, Fumio; Mihara, Morihiro; Takahashi, Kuniaki; Funabashi, Hideyuki; Kawatsuma, Shinji; Ueda, Hiroyoshi*; Oi, Takao*; et al.

JAEA-Research 2011-003, 47 Pages, 2011/02

JAEA-Research-2011-003.pdf:3.99MB

In 2009, NUMO and JAEA set up a technical commission to investigate the reasonable TRU waste disposal following a cooperation agreement between these two organizations. In this report, the calculation result of radionuclide transport for a TRU waste geological disposal system was described, by using the TIGER code and the GoldSim code at identical terms. Comparing the calculation result, a big difference was not seen. Therefore, the reliability of both codes was able to be confirmed. Moreover, the influence on the disposal site design (Disposal capacity: 19,000 m$$^{3}$$) was examined when 10% of the amount of TRU waste increased. As a result, it was confirmed that the influence of the site design was very little based on the concept of the Second Progress Report on Research and Development for TRU Waste Disposal in Japan.

JAEA Reports

Inventories of high burn up LWR UO$$_{2}$$ spent fuel and ATR MOX spent fuel in Tokai Reprocessing Plant

Shirai, Nobutoshi; Inano, Masatoshi; Fukuda, Kazuhito; Kosaka, Ichiro; Yamanaka, Atsushi

JAEA-Research 2011-004, 60 Pages, 2011/03

JAEA-Research-2011-004.pdf:1.79MB

This report describes calculated results of inventory of radioactivity in the Tokai Reprocessing Plant with calculation code, based on initial conditions and nuclear data library. The inventories were compared with three types of spent fuels, High burn up U oxide for light water reactor, U-Pu mixed oxide for advanced thermal reactor and the design based fuel for Tokai Reprocessing Plant.

JAEA Reports

Criticality safety evaluation in Tokai Reprocessing Plant; High burn up LWR UO$$_{2}$$ spent fuel and ATR MOX spent fuel

Shirai, Nobutoshi; Inano, Masatoshi; Fukuda, Kazuhito; Kosaka, Ichiro; Yamanaka, Atsushi

JAEA-Research 2011-005, 95 Pages, 2011/03

JAEA-Research-2011-005.pdf:2.46MB

This report presents criticality safety evaluation of each equipment in Tokai Reprocessing Plant for two types of spent fuels, High burn up 4.2% enrichment U oxide spent fuel for light water reactor and U-Pu mixed oxide spent fuel for advanced thermal reactor. As a result, it was confirmed that the equipments were safe enough for two types of the spent fuels from view point of criticality safety of single unit and multiple units.

JAEA Reports

Study on relationship between multiple safety functions in the engineered barrier system

Wakasugi, Keiichiro; Koo, Shigeru*; Shibata, Masahiro

JAEA-Research 2011-006, 31 Pages, 2011/06

JAEA-Research-2011-006.pdf:2.37MB

Although confirmation of the long-term safety of the constructed geological disposal system has been conducted by using scenario, model and data according to the internationally agreed methodology, there were a few researches that focused on individual safety functions and their relationships. This is because multiple safety functions are a fundamental concept for ensuring the safety of the geological disposal, and the long-term safety is accomplished by the whole system. Therefore, we developed a methodology to identify performance of the individual safety functions and their relationships considering the characteristic of the multiple safety functions, and examined the safety functions in the engineered barrier system based on this methodology. The results from this study are useful for constructing design requirements for the system components of the geological disposal as well as developing repository concept.

JAEA Reports

Theoretical study of rock for estimating long-term behavior; FY2009 (Contract research)

Ichikawa, Yasuaki*; Choi, J. H.*; Tanno, Takeo; Hirano, Toru*; Matsui, Hiroya

JAEA-Research 2011-007, 91 Pages, 2011/06

JAEA-Research-2011-007.pdf:8.75MB

We first surveyed the classical theories of fracture mechanics, and discussed the subcritical crack growth (SCG), which is observed under less load than the fracture toughness Kc. This SCG is a result of coupled mechanical and chemical effect. The SCG for granite was treated on this basis. We performed pressure dissolution experiments using specimens of single crystal quartz, since the dissolution reaction is engaged with a deformation and failure process of polycrystalline rock. The series of experiments were managed by a flow-through type changing temperature, pH and applied stress. Si concentrations we here measured. We first surveyed the theories of pressure solution. Then we proposed a theory of saluting velocity of quart which accounts for the effects of temperature, chemical (pH), solid pressure and pore pressure.

JAEA Reports

Estimation of runoff volume by geomorphometry and statistics analysis using digital elevation model in Tono area

Takeuchi, Ryuji; Kosaka, Hiroshi; Sato, Atsuya*; Tomiyama, Shingo*; Kageyama, Soichiro*; Ikeda, Makoto*

JAEA-Research 2011-008, 77 Pages, 2011/06

JAEA-Research-2011-008.pdf:4.76MB

Subsurface water balance observation is a kind of methods in order to estimate a recharge rate. Results of the observation are affected by the various factors such as the scale, the topography, a geological feature, the climate. Therefore, the observation in the regional scale is necessary at many basins. The purpose of this study is to confirm the applicability of the method for the evaluation of runoff volume, which is one of parameters to evaluate the recharge rate by surface water balance observation, by geomorphometry and statistical analyses using digital elevation model (DEM). The runoff index which is the original indicator to evaluate the degree of flow rate on a catchment was calculated by the comparison between the result of geomorphometry and statistics analyses, and the observed data of river flow rate in the monitoring stations. Using this index, the flow rate of the Hiyoshi River was evaluated. The evaluated flow rate was about 60% against the observed flow rate.

JAEA Reports

Horonobe Underground Research Laboratory Project; Research and development plan (H22-H26)

Iwatsuki, Teruki; Sato, Haruo; Nohara, Tsuyoshi; Tanai, Kenji; Sugita, Yutaka; Amano, Kenji; Yabuuchi, Satoshi; Oyama, Takuya; Amano, Yuki; Yokota, Hideharu; et al.

JAEA-Research 2011-009, 73 Pages, 2011/06

JAEA-Research-2011-009.pdf:4.41MB

The research and development plan in Horonobe Underground Research Laboratory are summarized according to the 2nd Midterm Plan till 2014 fiscal year of JAEA. In this midterm, galleries and the infrastructures for the research and development up to the depth of 350 m are constructed by Private Financial Initiative (PFI). Additionally Phase 3: Operation phase at the galleries begins in parallel to Phase 2: Construction phase. In these phases various research and development including collaboration with other institutes are conducted at the galleries. Generallic applicable techniques on the subject of the investigation of geological environment, facility construction in deep underground and the reliability of geological deposal are developed during the phase. The feasibility and reliance of various technologies concerning geological disposal is demonstrated by widely opening the outcome to the public in the society.

JAEA Reports

Groundwater/porewater hydrochemistry at Horonobe URL; Data freeze II; Preliminary data quality evaluation for boreholes HDB-1 to 8

Kunimaru, Takanori; Ota, Kunio; Alexander, W. R.*; Yamamoto, Hajime*

JAEA-Research 2011-010, 52 Pages, 2011/06

JAEA-Research-2011-010.pdf:2.29MB

Work has been currently ongoing to establish an appropriate quality management system (QMS), which is applicable to all aspects of the site characterisation process, in the Horonobe Underground Research Laboratory project. A quality assurance (QA) audit of hydrochemical datasets for JAEA's deep boreholes HDB-1 to HDB-8 was carried out, along similar lines to that of the previous study for boreholes HDB-9 to HDB-11, by applying both the groundwater QA methodology employed in the recent site assessments in Sweden and a porewater QA regime proposed in this study. The results of the QA audit indicated that data were classified into low QA categories because mainly of a lack of relevant information, such as the records of groundwater sampling, which are necessary for more fully assessing the data quality. As such, a formalised field manual for hydrochemical sampling was developed. In addition, work to further improve the site characterisation QMS progressed.

JAEA Reports

Stepwise evolution of core and fuel design toward a sustainable fuel cycle with FLWR

Uchikawa, Sadao

JAEA-Research 2011-011, 50 Pages, 2011/06

JAEA-Research-2011-011.pdf:7.75MB

An advanced LWR with hard neutron spectrum, named FLWR, aims at efficient and flexible utilization of nuclear resources by evolving its fuel assembly design under the same core configuration, mainly corresponding to available fuel cycle technologies and related infrastructures. The paper summarizes an evolution process of the FLWR fuel assembly design toward a sustainable fuel cycle by dividing the reactor operation into three stages, that is, the one based on the current LWR MOX fuel cycle infrastructure such as reprocessing of UO$$_{2}$$ spent fuel and fabrication of MOX fuel, the one for transitioning from the LWR fuel cycle to the FR fuel cycle, and the one based on the FR fuel cycle infrastructures such as MOX spent fuel reprocessing.

JAEA Reports

In situ stress measurements at 250m gallery off the ventilation shaft

Nakamura, Takahiro; Sanada, Hiroyuki; Sugita, Yutaka; Kato, Harumi*

JAEA-Research 2011-012, 217 Pages, 2011/06

JAEA-Research-2011-012.pdf:28.59MB

For the purpose of studying the in situ state of stress around Horonobe Underground Research Laboratory, hydraulic fracturing technique was carried out three boreholes drilled from the 250m gallery located near the bottom of the ventilation shaft. The results of the measurements are summarized as follows. Shut-in pressure of inclined transverse cracks and the circumferential position of longitudinal cracks on the wellbore surface were used to determine the magnitude and orientation of principal stress around the 250m gallery on the assumption that all of the target zones of hydraulic fracturing were in a uniform stress state. The determined in situ stress state showed a little difference of magnitude between intermediate stress and minimum stress. The vertical component of the in situ stress was evaluated to be about a half of the overburden at the test site. The maximum principal stress was inclined to about 40 degrees from the level with azimuth of NE orientation.

JAEA Reports

Mizunami Underground Research Laboratory Project; Rock mechanical investigations annual report for fiscal year 2009

Tanno, Takeo; Hirano, Toru*; Matsui, Hiroya

JAEA-Research 2011-013, 59 Pages, 2011/06

JAEA-Research-2011-013.pdf:5.39MB

This report presents the following FY2009 activities undertaken to achieve the above goals. (1) Suitability of Laboratory Tests of Physical and Mechanical Properties on Waste Rock from Excavation of the Shaft, (2) Suitability of the Phase I Rock Mechanical Environment Model, (3) Preliminary Deformation Analysis of Rock Mass around the Underground Facilities, (4) Phenomenological Study on Crystalline Rock for Evaluating Long-term Behavior, (5) Theoretical Study on Crystalline Rock for Evaluating of Long-term Behavior, (6) Fundamental Study on Evaluation Methods of Excavation Distributed Zones. As the result of above 6 activities, suitability of laboratory test and Phase I Rock mechanical Environment Model are confirmed and also methods for EDZ estimation were specified by estimation of in situ stress with core and SWD (Seismic While Drilling).

JAEA Reports

Extrusion and erosion of bentonite buffer, 3

Matsumoto, Kazuhiro; Fujita, Tomoo

JAEA-Research 2011-014, 26 Pages, 2011/06

JAEA-Research-2011-014.pdf:1.98MB

The extrusion of bentonite buffer is one of the important issues on the physical stability in the geological disposal of the high level radiation waste. In this report, the long-term extrusion experiment of the bentonite buffer material to an imitation crack was carried out, and the behavior was observed. Moreover, in consideration of the evaluation subject of the closing performance of a disposal site, the extrusion experiment with material with a large sand combination rate was carried out.

JAEA Reports

Experiment on evaluation of confinement capability of fuel cycle facility under combustion of glove-box and cable sheath materials (Contract research)

Abe, Hitoshi; Kashima, Takao; Uchiyama, Gunzo

JAEA-Research 2011-015, 27 Pages, 2011/06

JAEA-Research-2011-015.pdf:1.81MB

To contribute on confirmation of safety of fuel cycle facilities, evaluation method for soundness of confinement capability of the facilities under fire has been investigated. Panel materials of glove-box and cable sheath materials were considered to be an examination object as the representative organic materials in the facilities. Combustion property data, such as mass loss rate and soot generation ratio of the materials, and clogging property data of HEPA filter with combustion of the materials were measured as a parameter with radiation heat given to the materials, supply flow rate to the materials and oxygen concentration in the supply flow. Furthermore, progress of rising differential pressure of HEPA filter under hypothetical scenario of fire accident was evaluated quantitatively by applying these data mutually.

JAEA Reports

Experiment on the gaseous iodine release from irradiated cesium iodide solutions (Contract research)

Moriyama, Kiyofumi; Tashiro, Shinsuke; Chiba, Noriaki; Maruyama, Yu; Nakamura, Hideo; Watanabe, Atsushi*

JAEA-Research 2011-016, 125 Pages, 2011/06

JAEA-Research-2011-016.pdf:2.71MB

The volatile iodine production due to radiation chemical effects in the containment vessel of light water reactors (LWRs) during severe accidents was investigated by experiments in small scale and with well controlled conditions. Cesium iodide solutions, 10$$^{-4}$$M, labeled with $$^{131}$$I, at controlled pH by boric acid-sodium hydroxide buffer, were $$gamma$$-irradiated and swept with a constant gas flow rate. The gaseous iodine released from the solution was collected by species selective filters and quantified separately for I$$_2$$ and organic iodines. The influences of pH, temperature, inorganic and organic impurities, oxygen and hydrogen concentrations in the cover gas on the iodine release behavior were examined. Data including time dependent gaseous iodine release fractions, comparison of the final iodine release fractions in terms of the parameter effects, as well as the initial, boundary and interface conditions necessary for simulating the experiments by computer codes are provided.

JAEA Reports

Mizunami Underground Research Laboratory Project (Study on hydrogeology in crystalline fractured rock); Hydrogeological modeling and groundwater flow simulation based on data of hydraulic impacts during construction of the MIU facilities; FY2006 - 2007

Shimo, Michito*; Kumamoto, So*; Onoe, Hironori; Saegusa, Hiromitsu

JAEA-Research 2011-017, 132 Pages, 2011/09

JAEA-Research-2011-017.pdf:9.55MB

In this study, hydrogeological modeling and groundwater flow simulations on the Local scale area have been carried out in order to predict hydraulic impacts around the MIU Construction Site and inflow rate into the MIU facilities using the result of Surface-based Investigation phase (Phase 1), the data of hydraulic responses in monitoring boreholes, inflow rate into the MIU facilities and the result of pilot borehole investigation in Construction phase (Phase 2). As a result of this study, the significant hydrogeological structures around the MIU Construction Site could be estimated. The inflow rate into the MIU facilities and hydraulic impacts around the MIU Construction Site with the MIU facilities construction could be predicted. The effect of pre-grouting to the MIU facilities could be also confirmed.

JAEA Reports

Feasibility study of oxygen getter materials for FBR MOX fuel, 2; Investigation of loading options, evaluation of oxidation behavior and compatibilities of the candidate materials

Morihira, Masayuki

JAEA-Research 2011-018, 32 Pages, 2011/07

JAEA-Research-2011-018.pdf:2.73MB

In the FaCT project, high bundle peak burn-up to 250 GWd/t is targeted. Cladding inner corrosion is one of the life control factors of FBR MOX fuels. Because it increases with extension of burn-up, significant corrosion is expected in the high burn-up. Considering the excess oxygen during fission is the cause of corrosion, reduction of initial O/M ratio of MOX fuel pellets is one of the solutions. But it is not always easy to obtain low O/M ratio pellets especially in mass production. Oxygen getter option is an idea to coexistence of oxidizable metal fragments in a fuel element as an excess oxygen absorber. A feasibility study for oxygen getter options which was focused on pellet type MOX fuel was conducted. This report describes latest evaluation result for the loading options of oxygen getter materials and the oxidation behavior of the candidates such as Ti and Zr as well as their compatibilities with FMS cladding material and UO$$_{2}$$.

JAEA Reports

Mizunami Underground Research Laboratory Project; Rock mechanical investigations measurement of the rock strain and displacement during shaft excavation at the GL.-200m level of research galley

Hirano, Toru*; Seno, Yasuhiro*; Hikima, Ryoichi; Matsui, Hiroya

JAEA-Research 2011-019, 51 Pages, 2011/09

JAEA-Research-2011-019.pdf:2.93MB

In order to establish the scientific and technical basis for geological disposal of high-level radioactive waste, Japan Atomic Energy Agency (JAEA) is proceeding with the geoscientific research in the research galleries excavated at the Mizunami Underground Research Laboratory (MIU). One of the scientific and technical objective of this project is to understand the change of geological environment due to excavation of research galleries. The investigation described herein is the measurement of the rock strain / displacement while pre-excavation grouting or excavating of the shaft around the GL.-200m level research gallery.

JAEA Reports

Analysis of experimental results of boiling event of reprocessed radioactive liquid waste

Yoshida, Kazuo

JAEA-Research 2011-020, 16 Pages, 2011/08

JAEA-Research-2011-020.pdf:1.93MB

An experimental study of boiling event using actual radioactive liquid waste has been conducted and reported by CEA for safety analysis of radioactive release accident of reprocessing plant. These experimental results obtained from open document have been analyzed to clarify the transfer mechanisms of radioactive material for applying these results to safety analysis of an actual plant. From analysis of these data, information have been obtained about concentration and activity of nitric acid of radioactive liquid waste in boiling condition on which ruthenium (Ru) transfer into gas phase depends. Transfer rate into gas phase of Ru has been estimated using these data. The result is over estimated by 200 times compared with experiment. It could be explained that NO$$_{x}$$ coexisting with nitrous acid generated radio-chemically suppress the Ru(VIII) formation in the liquid waste.

JAEA Reports

Proposed guideline of flow-induced vibration evaluation for hot-leg piping of primary cooling system in sodium-cooled fast reactor

FBR Safety Unit

JAEA-Research 2011-021, 35 Pages, 2011/09

JAEA-Research-2011-021.pdf:2.27MB

JAEA has been developing a flow-induced vibration methodology applied to the JSFR piping under the FaCT project. As part of this development, flow pattern in the single-elbow pipe has been investigated with the measurement of fluid force induced by turbulence flow and of the flow-induced vibration response. The experimental results have served to the development and vibration of the flow-induced vibration evaluation methodology. Based on these outcomes, JAEA has established a working group on a guideline of large-diameter piping flow-induced vibration evaluation under the JAEA's Thermal-Hydraulic Research Committee for creating the guideline. This report is a first proposal of the guideline from the achievements of the working group activity.

JAEA Reports

Preliminary test for elution of uranium waste; Concept and application for elution test

Hata, Haruhi; Yokoyama, Kaoru; Tsunashima, Yasumichi; Ohashi, Yusuke; Koga, Osamu; Sugitsue, Noritake

JAEA-Research 2011-022, 35 Pages, 2011/09

JAEA-Research-2011-022.pdf:2.92MB

For disposal of Very low-level radioactive Waste (VLLW) from nuclear related facilities, one of important factors for safety assessment is the characteristics of elution. As for VLLW from the nuclear power plant, concrete pit and trench disposals have been performed and the evaluation methods for the characteristics have been established. On the other hand, as for the uranium waste, the concept on how to test the elution characteristics is not shown yet. Based on these circumstances, preliminary tests have been conducted to study elution characteristics of uranium waste. The results show that the important factors for the uranium elution are how uranium exists in waste. In addition, the elution characteristics also depend on the precipitation amount on the disposal site. Therefore, to assess the elution rate from uranium waste, these factors must be considered.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal years 2010

Yasue, Kenichi; Asamori, Koichi; Tanikawa, Shinichi; Yamada, Kunimi; Yamasaki, Seiko; Kokubu, Yoko; Niwa, Masakazu; Doke, Ryosuke; Kusano, Tomohiro; Hanamuro, Takahiro; et al.

JAEA-Research 2011-023, 113 Pages, 2011/10

JAEA-Research-2011-023.pdf:10.9MB

This annual report documents the progress of R&D in the first fiscal year during the JAEA 2nd Midterm Plan (FY 2010 - 2014) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planed framework is structured into the following categories: (1) development and systematization of investigation techniques for selecting suitable sites in geosphere stability, (2) development, application and verification of prediction models for evaluating the changes of geological environment in thermal, hydraulic, mechanical and geochemical conditions for a long period of time, and (3) development of new dating techniques for providing information about geologic history and the timing of geologic events. In this paper, the current status of R&D activities with previous scientific and technological progress is summarized.

JAEA Reports

The Distinct element analysis for swelling pressure test of bentonite; Discussion on the effects of wall friction force and aspect ratio of specimen

Shimizu, Hiroyuki*; Kikuchi, Hirohito; Tanai, Kenji; Fujita, Tomoo

JAEA-Research 2011-024, 74 Pages, 2011/10

JAEA-Research-2011-024.pdf:7.23MB

For geological isolation systems for HLW, due to the lack of standardization of swelling test method for bentonite as a buffer material, the accuracy and reproducibility of the results are not sufficiently proved. In this study, bentonite swelling pressure test were simulated by newly developed distinct element method, and the effects of wall friction force and aspect ratio of bentonite specimen were discussed.

JAEA Reports

Study on helium behavior in oxide fuel, 1; Deformation of microstructure induced by precipitation of helium (Joint research)

Serizawa, Hiroyuki; Matsunaga, Junji*; Haga, Yoshinori; Nakajima, Kunihisa; Kashibe, Shinji*; Iwai, Takashi

JAEA-Research 2011-025, 32 Pages, 2011/11

JAEA-Research-2011-025.pdf:10.17MB

This report deals with the precipitation of helium in UO$$_{2}$$ matrix to deform the microstructure. The examination was performed using single and polycrystalline UO$$_{2}$$ sample. The helium-treated samples under 900 atm at 1473 K were reheat-treated at much more high temperature, 1573 K or 1973 K to release the infused helium. The microstructure of the sample was examined by FIB, FE-STEM and FE-TEM. It was confirmed that precipitated helium atoms form a negative crystal in the grain or the matrix of the single crystal. At 1573 K, helium can be released without formation of intergranular tunnel since the surface diffusion coefficient of helium is large. However, some open grain boundaries were observed in the sample heat-treated at 1973 K. This might be related to the activity of helium in the grain boundary region. The structure of the negative crystal was analyzed from the view point of the thermodynamics of the surface growth.

JAEA Reports

Investigation of radiocesium volatilization from soil by in-situ ground heating

Department of Partnership Operations for Environmental Remediation, Headquarters of Fukushima Partne; Ningyo-toge Environmental Engineering Center; Vitrification Technology Development Department, Tokai Reprocessing Technology Development Center; Environmental Protection Section, Radiation Protection Department

JAEA-Research 2011-026, 74 Pages, 2011/11

JAEA-Research-2011-026.pdf:5.9MB

After the Fukushima nuclear accident, extensive area was contaminated with radionuclides from the Fukushima Daiichi Nuclear Power Plant and various methods have been investigated to remedy such contamination. To understand potential of in-situ ground heating and radionuclide desorption, behaviors of ground temperature and of radiocesium volatility by in-situ heating was investigated. More than 15 minutes was necessary to accomplish melting temperature of several cesium compounds by heating using portable burner and maximum temperature was about 700 degree in Celsius. At the time ground surface temperature was about 600 degree, the temperature at 1cm depth was about 300 degree, whereas the temperature at 5cm depth was 50-60 degree. Under the condition of heating temperature of 600-1,300 degree and heating period of 5-60 minutes, activity of Cs-134 and Cs-137 varied in the range of -9.8 to +14.0% after heating using electric furnace and any volatility of radiocesium was not recognized. TG/DTA analysis for soil and zeolite (mordenite) which mixed with nonradioactive Cs compound each were also carried out to understand chemical form and volatility behavior of radiocesium. It is suggested that chemical compound e.g., CsAlSiO$$_{4}$$ would be formed when SiO$$_{2}$$ and Al$$_{2}$$O$$_{3}$$3 were composed in the system and radiocesium would remain in soil under the high temperature condition, whereas Cs in CsCO$$_{3}$$ would be volatized in the SiO$$_{2}$$ and/or Al$$_{2}$$O$$_{3}$$ free system.

JAEA Reports

Effects of Misasa hot spring water on the growth of vegetables (Joint research)

Yamada, Satoshi*; Kita, Makoto*; Goto, Yukari*; Ishimori, Yuu

JAEA-Research 2011-027, 38 Pages, 2011/11

JAEA-Research-2011-027.pdf:3.21MB

Tottori University and Japan Atomic Energy Agency started a joint study to investigate the effect of hot spring water on the growth of vegetable plants in 2009. The aim of the study is to examine a feasibility of producing a regionally special vegetable with considering the characteristics of the Misasa district, where radon hot springs are historically famous. This report illustrates the intermediate results obtained from the study carried out from 2009 to 2010. (1) Screening test: Eighteen plants were examined for screening. As the results, Misasa hot spring water used in the water culture enlarged the growths of 14 plants. Lastly, 9 plants were selected as candidate plants for further examinations. (2) Sample preparation: Plants sampled in the water culture were lyophilized and stored in a freezer for nutrio-physiological analyses to select the suitable plant from the 9 plants. (3) Examination in labor-saving cultivation: Preliminary examinations were performed with a large-scale system to establish a practical labor-saving water culture system.

JAEA Reports

Studies about strength recovery and generalized relaxation behavior of rock, 4

Sanada, Masanori; Hayashi, Katsuhiko*; Kishi, Hirokazu; Takebe, Atsuji*; Okubo, Seisuke*

JAEA-Research 2011-028, 102 Pages, 2011/11

JAEA-Research-2011-028.pdf:3.08MB

In this study, strength recovery, generalized stress relaxation and two tensile strength tests were carried out using shale sampled in the Wakkanai-formation. As the results, recovery of failed rocks in strength and hydraulic conductivity were observed under a certain condition. We believe this result is very important for the stability evaluation of underground space in the bedrock that needs good sealing up characteristic, isolation characteristic, safety and high reliability for long term. Generalized stress relaxation test was conducted submerging samples in water. Experimental results showed comparatively smaller scatter than those in air-dried condition. It was also found that testing results were affected by strain rate up to the starting point of generalized relaxation test. Indirect and uniaxial tensile strength tests were also conducted submerging samples in water and smaller tensile strength with smaller scatter were obtained than those in air-dried condition.

JAEA Reports

Study on validation method of regional groundwater flow model; Case study for Horonobe area and Niigata basin (Contract research)

Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo; Ooka, Masao*; Seguchi, Mariko*

JAEA-Research 2011-029, 24 Pages, 2011/11

JAEA-Research-2011-029.pdf:3.67MB

In the safety assessment for a geological disposal of radioactive waste, it is important to establish validation methods for regional groundwater flow system to estimate radionuclide migration to human environment through groundwater flow. It is necessary to validate the groundwater flow property and flow boundary, as multi-groundwater systems including the different groundwater origins are possible to exist at deep underground. This results show that mixing analysis based on hydrochemical data and spatial plotting with hydrochemical data and thermal data are applicable to validate groundwater flow pattern and groundwater flow boundary in case of Horonobe area. It also demonstrates that mixing analysis based on hydrochemical data and spatial plotting with hydrological and hydrochemical data are applicable to validate the groundwater flow property and groundwater flow boundary in case of Nagaoka area.

JAEA Reports

Development of simulation tool for boiling event of reprocessed radioactive liquid waste

Ishikawa, Jun; Yoshida, Kazuo

JAEA-Research 2011-030, 24 Pages, 2011/11

JAEA-Research-2011-030.pdf:1.71MB

Development of accident consequence analysis method bas been under carried out at Japan Atomic Energy Agency as a part of research activities for development of probabilistic safety assessment method of nuclear fuel facilities. A computer tool has been developed to simulate boiling event of reprocessed liquid waste which is postulated to be occurred caused by the loss of cooling function at a fuel reprocessing plant. Thermodynamic properties of boiling and condensed nitric acid aqueous solution containing radioactive waste are necessary to assess quantitatively the amount of radioactive materials transferring to gas phase. The developed tool simulates boiling and condensation process of liquid waste based on the ebullioscopy. A simulation study of experimental result has been carried out and it was demonstrated that behavior of temperature and concentration of nitric acid of liquid waste are simulated well.

JAEA Reports

Collection and analysis of existing information on applicability of investigation methods for estimation of beginning age of faulting in present faulting pattern

Doke, Ryosuke; Yasue, Kenichi; Nakayasu, Akio; Niizato, Tadafumi; Tanikawa, Shinichi; Tanaka, Takenobu*; Aoki, Michinori*; Sekiya, Ayako*

JAEA-Research 2011-031, 109 Pages, 2011/12

JAEA-Research-2011-031.pdf:7.23MB

In this study, existing information related to methods for the estimation of the beginning age of the faulting in the present faulting pattern on the active fault were collected and reviewed. A principle of method, noticing points and technical know-hows in the application of the methods, data uncertainty, and so on were extracted from the existing information. Based on these extracted information, task-flows indicating working process on the estimation of the beginning age for the faulting of the active fault were illustrated on each method. Additionally, the distribution map of the beginning age with accuracy of faulting in the present faulting pattern on the active fault was illustrated.

JAEA Reports

Study on uncertainty of soil-to-plant transfer factor for the safety assessment (Contract research)

Saito, Hironori*; Takeda, Seiji; Kimura, Hideo

JAEA-Research 2011-032, 92 Pages, 2011/11

JAEA-Research-2011-032.pdf:2.11MB

The objective of this study is to estimate the parameter uncertainty of soil-to-plant transfer factor used in the safety assessment. The database on the soil-to-plant factors was improved to clarify the factors associated with the uncertainty of soil-to-plant transfer factor. The factors were specified based on investigating the relation between published data of soil-to-plant transfer factor and some kinds of experimental conditions. Under the assumption of stylization by both general habits of ingestion of farm products and soil conditions in Japan, we proposed the procedure to estimate the parameter uncertainty of soil-to-plant transfer factor according to the investigation results of the factors. Based on the procedure, the variation of soil-to-plant transfer factors for main radionuclides of high level radioactive waste and TRU waste were estimated in this report.

JAEA Reports

Interdisciplinary approach to improve and systematize the investigation and evaluation techniques on geological environment in relation to radioactive waste repository; Japanese fiscal year, 2010 (Contract research)

Kojima, Keiji*; Onishi, Yuzo*; Watanabe, Kunio*; Nishigaki, Makoto*; Tosaka, Hiroyuki*; Shimada, Jun*; Aoki, Kenji*; Tochiyama, Osamu*; Yoshida, Hidekazu*; Ogata, Nobuhisa; et al.

JAEA-Research 2011-033, 126 Pages, 2012/02

JAEA-Research-2011-033.pdf:31.33MB

The next advancements for the research of radioactive waste repository was started to improve and systematize the investigation and evaluation techniques on geological environment in consideration of intra-field of science and technology. Intra-field means the various fields among each study area of (a) geological environment, (b) design and engineering, (c) safety evaluation for radioactive waste repository, here. The following items were studied and discussed this year. (1) To Reconstruct Near Field (NF) Concept in consideration of coupled phenomena on geological environment. (2) To develop systematic investigation techniques on the geological environment in consideration of intra-field among each study area above mentioned (a), (b) and (c). Regarding (1), examination of NF concept focused on the realistic crystalline rock was carried out. Also through the overall discussion in the committee, comments from the all commissioners in relation to the intra-field of their study area were made to reflect on reconstruction of NF concept. Regarding (2), the research and development in consideration of NF and intra-field among each study area were conducted.

JAEA Reports

Uncertainty quantification of Doppler coefficient for MONJU

Chiba, Go*; Hazama, Taira; Kinjo, Hidehito*; Nishi, Hiroshi; Suzuki, Takayuki

JAEA-Research 2011-034, 42 Pages, 2011/12

JAEA-Research-2011-034.pdf:1.88MB

Uncertainty of Doppler coefficient is quantified for a Monju core, reflecting present knowledge. Various uncertainty sources are evaluated: (1) Nuclear data and numerical method, (2) Fission product nuclear data, (3) Control rod position, (4) Approximated treatment of temperature dependence, (5) Averaged fuel temperature, (6) Approximated treatment of temperature spatial distribution, etc. Resulting uncertainty for Doppler coefficient is estimated at 11.7% for the 2 $$sigma$$ reliability.

JAEA Reports

Study on efficiency of dry decontamination technique by numerical method, 3 (Joint research)

Hyakutake, Toru*; Muto, Akinori*; Sasakura, Mariko*; Minowa, Hirotsugu*; Suzuki, Kazuhiko*; Yokoyama, Kaoru; Takahashi, Nobuo; Hata, Haruhi; Sugitsue, Noritake

JAEA-Research 2011-035, 53 Pages, 2012/01

JAEA-Research-2011-035.pdf:3.13MB

System decontamination has been generally carried out with the aim of reducing the amount of radioactive waste generated and minimizing exposure to radiation released from nuclear fuel facilities. At the Ningyo-Toge Environmental Engineering Center, metal surfaces that are contaminated by uranium are dry decontaminated by using iodine heptafluoride (IF$$_{7}$$) as a system decontaminator. Only a few studies have been carried out on the decontamination efficiency, mechanism, level, etc. of dry decontamination techniques that use a decontamination gas. Therefore, the generalization of dry decontamination techniques is required. In the present study, the efficiency of a dry decontamination technique was assessed by a numerical method using decontamination data obtained at the Ningyo-Toge Environmental Engineering Center. A concrete analytical content is a depositing of uranium hexafluoride.

JAEA Reports

Analysis of transmutation systems using JENDL-4.0

Iwamoto, Hiroki; Nishihara, Kenji; Tsujimoto, Kazufumi; Sugino, Kazuteru; Numata, Kazuyuki*

JAEA-Research 2011-036, 64 Pages, 2012/01

JAEA-Research-2011-036.pdf:3.76MB

An analytical study of minor actinide (MA) transmutation systems was conducted using JENDL-4.0, with a comparison to JENDL-3.3 in terms of reactor physics parameters (criticality, void reactivity and the Doppler reactivity) and those uncertainties. As objects of the analyses, Accelerator driven system (ADS) and MA loaded fast reactor (FR) were assumed. It was found that there were considerable changes for both systems. As the results of the sensitivity and uncertainty analysis, we found that the difference of the parameters of ADS is due mainly to the inelastic scattering cross sections of lead isotopes and several reactions of $$^{241}$$Am. For FR, a large difference of the void reactivity uncertainty results primarily from the covariance data of the inelastic cross section of $$^{23}$$Na.

JAEA Reports

Adsorption properties of Cs by inorganic adsorbents in sodium chloride solution

Ban, Yasutoshi; Yamagishi, Isao; Morita, Yasuji

JAEA-Research 2011-037, 11 Pages, 2012/01

JAEA-Research-2011-037.pdf:1.88MB

Adsorption of Cs with five types of inorganic adsorbents (CST: Crystalline SilicoTitanate) powder, CST grain, synthetic mordenite powder, synthetic mordenite grain, and natural mordenite) was carried out by batch methods in the aqueous solution of NaCl at room temperature, respectively. The concentration of Cs after the batch experiments decreased compared with the initial concentration of Cs when the ratio of the solution volume (ml) to the amount of the adsorbent (g) was 100 ml/g, and it was confirmed that the adsorbents used in the present study adsorbed Cs$$^{+}$$ ion in the presence of Na$$^{+}$$ and Cl$$^{-}$$ ions.

JAEA Reports

Mizunami Underground Research Laboratory Project; Rock mechanical investigations in situ stress measurements using core-based methods on the -300 m stage

Sanada, Hiroyuki; Hikima, Ryoichi; Tanno, Takeo; Matsui, Hiroya; Sato, Toshinori; Kato, Harumi*

JAEA-Research 2011-038, 26 Pages, 2012/01

JAEA-Research-2011-038.pdf:3.35MB

The Mizunami Underground Research Laboratory Project has been implemented to establish the techniques for investigation, analysis and assessment of the deep geological environment and to develop a range of engineering techniques for application deep underground. In this paper, results of differential strain curve analysis (DSCA) and elastic wave measurements using polyhedral specimens at the 08MI13 and 09MI20 boreholes in -300 m stage are described. The objectives of this work are to evaluate in situ stress condition on the -300 m stage.

JAEA Reports

Compatibility of zirconium alloys in high-temperature sodium

Furukawa, Tomohiro; Kato, Shoichi; Maeda, Shigetaka; Yamamoto, Masaya; Sekine, Takashi; Ito, Chikara

JAEA-Research 2011-039, 20 Pages, 2012/02

JAEA-Research-2011-039.pdf:3.4MB

Application of zirconium alloy as a neutron reflector around the driver fuel region of the Japanese experimental fast reactor JOYO has been planned for a further increase of core average burn-up. In order to investigate the compatibility of the zirconium alloys with high-temperature sodium which is coolant of the JOYO, corrosion test in sodium and tensile test of the exposed alloys were performed. The corrosion test was done at 500$$^{circ}$$C and 650$$^{circ}$$C in stagnant/flowing sodium for two kinds of zirconium alloys, and then weight change measurement and metallurgical observation were carried out. The tensile test was performed in air at the same temperature with the sodium exposure.

JAEA Reports

Phenomenological study on crystalline rock for evaluating of long-term behavior (Contract research)

Okubo, Seisuke*; Fukui, Katsunori*; Hashiba, Kimihiro*; Hikima, Ryoichi; Tanno, Takeo; Sanada, Hiroyuki; Matsui, Hiroya; Sato, Toshinori

JAEA-Research 2011-040, 54 Pages, 2012/02

JAEA-Research-2011-040.pdf:2.85MB

With respect to high-level radioactive waste disposal, knowledge of the long-term mechanical stability of shafts and galleries excavated in rock are required, not only during construction and operation but also over a period of thousands of years after closure. Therefore, it is very important to understand the time-dependent behavior of rock for evaluating long-term mechanical stability. This report describes the results of the activities in FY2010. In Chapter 1, we provide an overview and the background to this study. In Chapter 2, the results of a long-term creep test on Tage tuff, started in FY1997 are described. In Chapter 3, the relation of loading-rate dependency of strength and stress dependency of creep life, the relationship of time dependency and probability distribution of strength or creep life and size effects are discussed to indicate more clearly the meaning of the value of "n" to express the degree of time dependency of the rock. In Chapter 4, failure criterions of a rock mass considering time dependency are discussed. In Chapter 5, the FEM analysis implemented with a generalized variable-compliance-type constitutive equation considering the change of "n" in confining pressure and strength distribution of rock mass carried out to clarify the long-term behavior of Toki granite is described. Finally, based on the numerical analysis, an in situ testing method is proposed.

JAEA Reports

Conceptual study on HTGR-IS hydrogen supply system using organic hydrides

Terada, Atsuhiko; Noguchi, Hiroki; Takegami, Hiroaki; Kamiji, Yu; Inagaki, Yoshiyuki

JAEA-Research 2011-041, 62 Pages, 2012/02

JAEA-Research-2011-041.pdf:6.83MB

We have proposed a hydrogen supply-chain system, which is a storage/supply system of large amount of hydrogen produced by HTGR-IS hydrogen production system. The organic chemical hydride method is one of the candidate techniques in the system for hydrogen storage and transportation. In this study, properties of organic hydrides and conventional hydrogen storage/supply system were examined to help the conceptual design of the hydrogen supply system using an organic hydrides method with VHTR-IS hydrogen production process (hydrogen production: 85,400 Nm$$^{3}$$/h). Conceptual specifications of the main apparatus were designed for the hydrogen supply system with hydrogenation and dehydrogenation process. It was also clarified the problems of hydrogen supply system, such as efficiency of energy and system optimization.

JAEA Reports

Estimation of groundwater recharge rate and spatial distribution of hydrological quantities in surface hydrogeological investigation basin of Horonobe URL Project; From December 2004 to November 2009

Yamamoto, Yoichi; Maekawa, Keisuke; Yokota, Hideharu; Yamazaki, Masanori

JAEA-Research 2011-042, 97 Pages, 2012/02

JAEA-Research-2011-042.pdf:11.05MB

The surface hydrogeological investigation has been carried out in and around the Horonobe Underground Research Laboratory area as a part of Horonobe URL project. Observations of meteorological, river flux, water quality, soil moisture and groundwater level have been continued in order to understand the groundwater recharge rate and groundwater flow in the shallow part, which are required for the setting of boundary and initial condition of the groundwater flow analysis. This report shows the summary of the surface hydrogeological investigation and results of recharge rates of investigation basins from December 2004 to November 2009 are calculated by using the water budget method. Spatial estimation of hydrological quantities for the groundwater recharge rate is demonstrated by the runoff analysis. As a result, average of the groundwater recharge rate of whole basins is estimated to 131mm/yr. Suggestive observations related to hydraulic properties of the geology and faults are obtained from consideration to the groundwater recharge rate for each basin.

JAEA Reports

Development of a simplified seismic tomography survey system

Sugita, Yutaka; Sanada, Hiroyuki; Aizawa, Takao*; Ito, Shunichiro*

JAEA-Research 2011-043, 25 Pages, 2012/02

JAEA-Research-2011-043.pdf:3.18MBJP, 2010-116655   Patent publication (In Japanese)

A simplified seismic velocity survey system was developed for the repeat performance of surveys in conjunction with tunnel excavation, to monitor the various changes that occur in a rock mass around tunnels or galleries as they are excavated in the deep underground. The simplified seismic velocity survey system developed consists of a hammer to transfer seismic energy to the borehole wall and receivers installed and anchored in the borehole, and then backfilled. The hammer is operated with compressed air, necessitated by the potential presence of flammable gas such as methane. The system developed was used in the EDZ Experiment in a horizontal tunnel in the Horonobe URL. Changes in seismic velocity were monitored during and after excavation of the tunnel and the tomograms obtained are high quality. These results show that the system developed can provide the information needed to monitor the development and the variations in an EDZ.

JAEA Reports

Proposed guideline of flow-induced vibration evaluation for hot-leg piping of primary cooling system in sodium-cooled fast reactor; Supplemental interpretation

FBR Safety Unit

JAEA-Research 2011-044, 185 Pages, 2012/02

JAEA-Research-2011-044.pdf:12.52MB

JAEA has been developing a flow-induced vibration methodology applied to the JSFR piping under the FaCT project. As part of this development, flow pattern in the single-elbow pipe has been investigated with the measurement of fluid force induced by turbulence flow and of the flow-induced vibration response. The experimental results have served to the development and vibration of the flow-induced vibration evaluation methodology. Based on these outcomes, JAEA has established a working group on a guideline of large-diameter piping flow-induced vibration evaluation under the JAEA's Thermal-Hydraulic Research Committee for creating the JAEA internal guideline. The first proposal of the guideline was summarized from the achievements of the working group activity. Since technical discussion has been made deeply in developing the guideline, this report summarizes technical background and understanding for the guideline.

JAEA Reports

Bi-directional reflectance distribution function of a tungsten block for ITER divertor

Iwamae, Atsushi*; Ogawa, Hiroaki; Sugie, Tatsuo; Kusama, Yoshinori

JAEA-Research 2011-045, 11 Pages, 2012/02

JAEA-Research-2011-045.pdf:2.36MB

In order to investigate reflection properties on plasma-facing material in ITER, the bi-directional reflectance distribution function (BRDF) of a tungsten block sample has been measured. On the machining surface of the block, one-directional machining lines are engraved. Two laser diodes $$lambda$$652 nm and $$lambda$$473 nm were used to simulate H$$_{alpha}$$ and H$$_{beta}$$ emissions, respectively. The reflected light is affected by the machining surface. The reflected light traces a line when the incident light is injected in the perpendicular direction to the engraved line. On the other hand the reflected light traces an arc shape when the incident light is injected in the parallel direction to the engraved lines. Ray tracing simulation qualitatively explains the experimental results.

JAEA Reports

Study of parameters for safety assessment of sub-surface disposal; Tunnel-excavating speed and thickness of additional soil in residential land development by filling

Ishitoya, Kimihide; Sugaya, Toshikatsu; Funabashi, Hideyuki

JAEA-Research 2011-046, 32 Pages, 2012/02

JAEA-Research-2011-046.pdf:3.52MB

Nuclear Safety Commission of Japan (NSC) issued "Policy of the Safety Assessment of Sub-surface Disposal after the Period for Active Control" (April 1, 2010). Then, we investigated the parameters for dose assessment in tunnel excavation scenario and large-scale land use scenario which were described in the "Policy of the Safety Assessment", in order to perform the assessment based on actual conditions. To be concrete, we investigated the tunnel excavating speeds in Japan for the former scenario, and investigated technical standards of the filling for the latter scenario. We studied the realistic parameters for the dose assessment with the results of those investigations.

JAEA Reports

Investigation of the advanced diffusion model in compacted bentonite based on modified Poisson-Boltzmann equations

Yotsuji, Kenji; Tachi, Yukio; Nishimaki, Yuichiro*

JAEA-Research 2011-047, 105 Pages, 2012/02

JAEA-Research-2011-047.pdf:4.34MB

We have developed integrated sorption and diffusion model (ISD model) for assessment of diffusion parameters consistent with sorption processes in compacted bentonite. Conventional ISD model is unsatisfactory because for multivalent cation/anion and complex ion model predictions disagree with experimental data, and because the model contains additional non-physical fitting parameter. Accordingly we extract the factors influencing the assessment from fundamental assumptions of the conventional ISD model. In this report we incorporated the excluded volume effect, the dielectric saturation effect and the fluctuation potential effect caused by ion-ion electrostatic interaction into ISD model. As results of numerical analysis of these models the considering factors influence hardly the effective diffusivity. Therefore it does not mean that the disagreement with experimental data are caused by considering factors in this report.

JAEA Reports

Development of a groundwater monitoring system at Horonobe Underground Research Center

Nanjo, Isao; Amano, Yuki; Iwatsuki, Teruki; Kunimaru, Takanori; Murakami, Hiroaki; Hosoya, Shinichi*; Morikawa, Keita

JAEA-Research 2011-048, 162 Pages, 2012/03

JAEA-Research-2011-048.pdf:8.53MB
JAEA-Research-2011-048-appendix(CD-ROM)-1.pdf:0.74MB
JAEA-Research-2011-048-appendix(CD-ROM)-2.pdf:7.55MB
JAEA-Research-2011-048-appendix(CD-ROM)-3.pdf:18.71MB
JAEA-Research-2011-048-appendix(CD-ROM)-4.pdf:0.11MB
JAEA-Research-2011-048-appendix(CD-ROM)-5.pdf:0.07MB
JAEA-Research-2011-048-appendix(CD-ROM)-6.pdf:0.68MB

The observation technique of hydrochemical condition in low permeable sedimentary rock around the facility is one of R&D subjects. We report, (1) development of hydrochemical monitoring system to observe water pressure, pH, electric conductivity, dissolved oxygen, redox potential and temperature, (2) hydrochemical observation results around URL under construction. The applicability of the hydrochemical monitoring system is evaluated for low permeable sedimentary rock bearing abundant dissolved gases. The hydrochemical observation during facility construction demonstrates that pH and redox potential of groundwater almost did not changed even at hydraulic disturbed zone (water pressure decreased zone).

JAEA Reports

Expertize of hydrochemical investigation Know-how for deep underground

Iwatsuki, Teruki; Mizuno, Takashi; Amano, Yuki; Kunimaru, Takanori; Semba, Takeshi

JAEA-Research 2011-049, 68 Pages, 2012/03

JAEA-Research-2011-049.pdf:7.24MB

This report summarizes technical basis and the Know-how on hydrochemical investigations for deep underground as a part of METI project "Development of Information Synthesis and Interpretation System (ISIS)". We describe the procedures and methods of hydrochemical investigation in following stages; (1) initial analysis of previous information, (2) planning of borehole investigation, (3) borehole investigation at field, and (4) construct the "hydrochemical model" representing hydrochemical condition and the evolution process. The contents of this report are inputted to "Expert system" developed by METI project and are available via WEB system (internet).

JAEA Reports

A Low noise amplifier and its noise performances (Contract research)

Yamagishi, Hideshi*; To, Kentaro

JAEA-Research 2011-050, 16 Pages, 2012/10

JAEA-Research-2011-050.pdf:1.47MB

For development of two-dimensional position sensitive (2-D) neutron detectors with fast response and high spatial resolution, an ASIC with fast response and low noise performances is required. The MP8 and MP16, consisting of p-MOSFETs, with high g$$_{rm m}$$ and low noise have been proposed (1) to develop the ASIC. In this paper a simple low noise amplifier (LNA) was designed and the noise power and the noise figure were analytically calculated. The results were also applied to LNAs using MP8 or MP16 configuration. The results showed that the MP8 and MP16 had enough performances for the ASIC.

JAEA Reports

A Low noise ASIC for two dimensional neutron gas detector with performance of high spatial resolution (Contract research)

Yamagishi, Hideshi*; To, Kentaro; Nakamura, Tatsuya; Sakasai, Kaoru; Soyama, Kazuhiko

JAEA-Research 2011-051, 19 Pages, 2012/02

JAEA-Research-2011-051.pdf:2.42MB

An ASD-ASIC (Amplifier-Shaper-Discriminator ASIC) with fast response and low noise performances has been designed for two-dimensional position sensitive neutron gas detectors (InSPaD). The InSPaD is a 2D neutron detector system with $$^{3}$$He gas and provides a high spatial resolution by making distinction between proton and triton particles generated in the gas chamber. The new ASD-ASIC is required to have very low noise, a wide dynamic range, good output linearity and high counting rate. The new ASD-ASIC has been designed by using CMOS and consisted of 64-channel ASDs, a 16-channel multiplexer with LVTTL drivers and sum amplifier system for summing all analog signals. The performances were evaluated by the Spice simulation. It was confirmed that the new ASD-ASIC had very low noise performance, wide dynamic range and fast signal processing functions.

JAEA Reports

An Evaluation of fracture characteristic for replica specimen casted by granite artificial tensile fracture

Sato, Hisashi; Sawada, Atsushi

JAEA-Research 2011-052, 55 Pages, 2012/02

JAEA-Research-2011-052.pdf:12.39MB
JAEA-Research-2011-052-appendix(CD-ROM).zip:5.14MB

In order to obtain the hydraulic property, mass transport property and three-dimensional fracture void geometry which need for elucidate the permeability and mass transport phenomena in a single fracture, we conducted a flow test, measurement of fracture shape, aperture measurement by optical method, tracer test by optical method for three transparent replica specimens. As a result, the flow rate of two-dimensional seepage flow analysis based on LCL became about 1.5 to 2 times of the flow test results, which results was consistent with previously reported results. To investigate the influence of fracture shape for the flow analysis results, corrected the transmissivity using the acquired data of aperture distribution and fracture shape data. As a results, the fracture permeability by applying the corrected transmissivity considering local slope of the fracture was decreased which is closer to the flow test results.

JAEA Reports

Study on experimental models to analyze radionuclide migration behaviors through porous geologic media

Tanaka, Tadao; Mukai, Masayuki

JAEA-Research 2011-053, 41 Pages, 2012/08

JAEA-Research-2011-053.pdf:1.55MB

To understand the migration phenomenon of radionuclide, actual migration data are experimentally acquired by a batch test, a column test and field trial. In the present study, experimental models about the interactions of radionuclide between the solid phase and the liquid phase were discussed systematically to interpret the migration data acquired by the various techniques and conditions. Equilibrium, reversibility, linearity, mechanism and chemistry in the interactions were considered in discussion of the experimental models. A calculation program, which can analyze migration data obtained under various conditions by applying the selected 9 types of experimental models, was maintained. The calculation program makes it be able to predict the migration behavior of radionuclide under various conditions and to decide the important parameter by a fitting analysis of the migration data.

JAEA Reports

Study on evaluation methodology for groundwater flow based on geochemical data; Case study for Horonobe area (Contract research)

Sakai, Ryutaro; Munakata, Masahiro; Kimura, Hideo

JAEA-Research 2011-054, 19 Pages, 2012/03

JAEA-Research-2011-054.pdf:2.07MB

In the safety assessment for a geological disposal of radioactive waste, it is important to establish validation methods for deep groundwater flow system to estimate radionuclide migration to human environment through groundwater flow. This study discussed the method which estimates groundwater mixing condition and groundwater flow process using principal component analysis (PCA) to groundwater chemistry and isotopic compositions, together with data of groundwater age and trace element in case of Horonobe area. The results show that hydrochemical system can be divided into two systems: (1) three deep groundwater mixing system at depths greater than 200 to 400 m, (2) mixing area of deep groundwater and surface water at depths less than 200 to 400 m. Groundwater in the deep aquifer is suggested to be discharged at surface through Omagari Fault.

JAEA Reports

Studies on the design method of multi tunnels in geological disposal facility, 5

Sanada, Masanori; Kishi, Hirokazu; Hayashi, Katsuhiko*; Takebe, Atsuji*

JAEA-Research 2011-055, 79 Pages, 2012/03

JAEA-Research-2011-055.pdf:4.11MB

In order to refine and rationalize a design method of multi tunnels in the deep geological repository, various study have been conducted. In this study, an effect of procedure for excavating multi-tunnels on extent of EDZ was examined by 3D FEM analysis. In modeling the multi tunnels and setting cases of analysis, workability, cost and safeness under construction were considered. Results of 3D FEM analysis showed that 3D effect of procedure for excavating such as a gap of progress with tunnel faces can be considered by 3D FEM and extent of EDZ is demonstrated more practically compared with 2D FEM. Another 2D FEM analysis modeling for crystalline rock (granite) was executed and the results showed that plastic zone did not appear in all cases.

JAEA Reports

Preliminary study on development of a methodology for evaluating the performance of host rock for geological disposal based on surface-based investigations

Inagaki, Manabu*; Tanaka, Tatsuya*; Hashimoto, Shuji*; Maekawa, Keisuke; Shibata, Masahiro

JAEA-Research 2011-056, 37 Pages, 2012/03

JAEA-Research-2011-056.pdf:8.64MB

In Japan, a step-wise approach is applied in the site selection process for the geologic disposal site. Preliminary surface-based investigations will be followed by detailed investigations. The basic repository concept, including underground design and layout, will be discussed at the end of surface-based investigations. The repository concept will depend on the spatial extent of the candidate rock formation(s) and their barrier performance. However, information obtained from the surface is limited and includes uncertainties. It is thus important to assess host rock performance considering uncertainties. In this study, methodology for evaluation of geological conditions has been developed that focuses on determining the usable volume of host rock with specific performance characteristics. Initially, multiple performance indices have been discussed and defined from the viewpoint of barrier performance. Then the evaluation procedure is illustrated by using the dataset obtained from the Horonobe Underground Research Laboratory Project. Finally the proposed procedure is reviewed and future challenges are extracted.

JAEA Reports

Dissolutions of oxide dispersion strengthened ferritic steels in various nitric acid solutions; Martensitic 9Cr-ODS steels

Inoue, Masaki; Ikeuchi, Hirotomo; Takeuchi, Masayuki; Koyama, Shinichi; Suto, Mitsuo

JAEA-Research 2011-057, 100 Pages, 2012/03

JAEA-Research-2011-057.pdf:3.23MB

Corrosion resistance of fuel pin cladding tube materials is one of the most important properties to design aqueous reprocessing process. The martensitic oxide dispersion strengthened ferritic steel, names as "9Cr-ODS" steel, is the primary candidate of high burnup fuel pin cladding tube for fast reactor cycle. Because 9Cr-ODS steel contains lower chromium than stainless steels, oxidizing species in nitric acid medium needs to reduce its corrosion rate. In spent fuel dissolvers, although both nitric acid and metallic ions concentrations change, corrosion potential of 9Cr-ODS steel tends to increase gradually and stabilize protective passive layer effectively.

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