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Journal Articles

Simple pretreatment method for tritium measurement in environmental water samples using a liquid scintillation counter

Nakasone, Shunya*; Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; et al.

Plasma and Fusion Research (Internet), 16, p.2405035_1 - 2405035_5, 2021/02

Removal of impurities such as organic and other types of dissolved matters from environmental water samples is required for precise analysis of tritium with a liquid scintillation counting method. In general, a distillation method is a conventional one for tritium analysis in environmental water samples, but is a time-consuming process that takes 24 hours for removal of impurities. We have proposed a rapid pretreatment method for tritium analysis, that uses ion exchange resins. In this study, we performed batch experiments, to evaluate the effectiveness of the ion exchange resins on the tritium measurement. The results obtained demonstrated that removal of impurities in the sample water by ion exchange resins can be achieved during a short period of time (i.e., in 5 min).

Journal Articles

Preliminary investigation of pretreatment methods for liquid scintillation measurements of environmental water samples using ion exchange resins

Nakasone, Shunya*; Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; et al.

Plasma and Fusion Research (Internet), 15, p.2405027_1 - 2405027_3, 2020/05

A quick preprocessing system for tritium analysis of environmental samples is important to judge environmental influence of tritium releases due to accident or tritium-handling facilities. Analysis of tritium in water samples with liquid scintillation counting method requires removal of impurities such as organic matter and ion species from water samples. Generally, a distillation method is adopted as a pretreatment of analysis for tritium; however, the distillation method is a time-consuming process. The aim of this study is to evaluate a rapid pretreatment method for tritium analysis with ion exchange resin. From batch and column experiments that used inland water and ion exchange resin, we confirmed removals of impurities of the water sample and that the removal of impurities was possible for a short time (by 5 minutes).

Journal Articles

Development of field estimation technique and improvement of environmental tritium behavior model

Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; Atarashi-Andoh, Mariko; et al.

Plasma and Fusion Research (Internet), 14(Sp.2), p.3405099_1 - 3405099_4, 2019/06

The Large Helical Device of the National Institute for Fusion Science started D-D experiments in 2017. To ensure the safety of the facility, it is important to develop evaluation methods for environmental tritium transfer. Tritiated water (HTO) in atmosphere and soil is transferred to plants, and organically bound tritium (OBT) is formed by photosynthesis. Prediction of OBT formation is important, because OBT accumulates in plants and causes dose through ingestion. The objective of this study is to estimate environmental tritium transfer using a simple compartment model and practical parameters. We proposed a simple compartment model consisting of air-soil-plant components, and tried to validate the model by comparison with a sophisticated model, SOLVEG. In this study, we plan to add wet deposition to the model and obtain parameters from measurements of soil permeability and tritium concentrations in air, soil and plants. We also establish rapid pretreatment methods for OBT analysis.

JAEA Reports

Corrosion countermeasure for demonstration scale steam reforming system

Nakanishi, Yoshiki; Aoyama, Yoshio; Nonaka, Kazuharu; Sone, Tomoyuki; Nakazawa, Osamu; Tashiro, Kiyoshi

JAEA-Testing 2011-008, 31 Pages, 2012/03

JAEA-Testing-2011-008.pdf:2.8MB

Steam reforming technology has been developed to reduce the volume of liquid uranium waste such as a Tri-n-butyl phosphate adding n-dodecane solvent (TBP/nDD), which is difficult to incinerate. The localized corrosion like pitting corrosion occurred on the inner surface of the gasification chamber of the demonstration scale steam reforming system during the treatment of TBP/nDD. Therefore we conducted the corrosion tests to identify the form of corrosion. It is found that the form of corrosion is crevice corrosion which caused by the residues generated by treatment of TBP/nDD. The cathodic protection system using a galvanic anode was selected as the corrosion protection method of the gasification chamber. The continuous treatment test of TBP/nDD was conducted using the steam reforming system with the cathodic protection system. As a result, the crevice corrosion did not occur during 600 hours continuous treatment of TBP/nDD, and the effectiveness of the protection method was verified.

Journal Articles

Performance of steam reforming technology in a long term treatment of waste TBP/dodecane

Nakagawa, Akinori; Sone, Tomoyuki; Sasaki, Toshiki; Nakazawa, Osamu; Tashiro, Kiyoshi

Proceedings of International Waste Management Symposia 2011 (WM 2011) (CD-ROM), 7 Pages, 2011/03

JAEA Reports

Treatment technology development of uranium contaminated spent TBP/n-dodecane solvent by steam reforming

Nakagawa, Akinori; Sone, Tomoyuki; Sasaki, Toshiki; Nakazawa, Osamu; Tashiro, Kiyoshi

JAEA-Technology 2010-014, 46 Pages, 2010/06

JAEA-Technology-2010-014.pdf:1.76MB

Steam reforming treatment system was developed for volume reduction of Tri-n-butyl phosphate contaminated with uranium, which is difficult to treat with incineration, due to generation of corrosive compounds, a large amount of secondary waste, etc. This system consists of a steam reforming process in which organic waste is decomposed/gasified in steam atmosphere and a submerged combustion process in which vaporized waste is burned in water and has good features such as high volume reduction rate of waste, low secondary waste generation rate, etc. Results obtained this study were as follows: Volume reduction rate of waste was 99.6%. Uranium entrainment to off-gas was suppressed and the concentration of uranium in waste water was under 0.037mg/L. The concentration of CO and NOx in the off-gas were less than 100ppm and 250ppm respectively. Plugging and corrosion control technologies were developed and it was confirmed that the waste treatment system can run for long periods.

JAEA Reports

Study of "Inadvertent Human Intrusion or Rare Natural Event Scenarios" for sub-surface disposal of radioactive waste

Nakatani, Takayoshi; Ishitoya, Kimihide; Funabashi, Hideyuki; Sugaya, Toshikatsu; Sone, Tomoyuki; Shimada, Hidemitsu*; Nakai, Kunihiro*

JAEA-Research 2009-064, 104 Pages, 2010/03

JAEA-Research-2009-064.pdf:14.45MB

The purpose of this study was to assess exposure dose of "Inadvertent Human Intrusion or Rare Natural Event Scenarios" on sub-surface disposal. It was one of "Classification of three types scenarios" in "Basic Policy for Safety Regulation Concerning Land Disposal of Low-Level Radioactive Waste (Interim Report)" formulated by the Nuclear Safety Commission of Japan. Selection of the assessed scenarios, development of the assessment tool and preliminary exposure dose assessment were conducted. Exposure dose of "Well water drinking scenario" was the highest in the assessed scenarios. This scenario assumed that the groundwater in Excavation Disturbed Zone (EDZ) was directly used as drinking water without any dilution. Although this was very conservative condition and the result exceeded 10 mSv/y, it was under the upper limit of standard dose value (10$$sim$$100 mSv/y) in the Interim Report for "Inadvertent Human Intrusion or Rare Natural Event Scenarios".

JAEA Reports

Study of "Likely Scenarios" and "Less-likely Scenarios" for sub-surface disposal of radioactive waste

Sugaya, Toshikatsu; Sone, Tomoyuki; Nakatani, Takayoshi; Ishitoya, Kimihide; Funabashi, Hideyuki; Sasaki, Ryoichi*; Shimoda, Satoko*; Kurosawa, Mitsuru*

JAEA-Research 2009-063, 80 Pages, 2010/03

JAEA-Research-2009-063.pdf:8.35MB

The purpose of this study was to assess exposure dose of "Likely Scenarios" and "Less-likely Scenarios" on sub-surface disposal. They were two of "Classification of three types scenarios" in "Basic Policy for Safety Regulation Concerning Land Disposal of Low-Level Radioactive Waste (Interim Report)" formulated by the Nuclear Safety Commission of Japan. Selection of the assessed scenarios, development of the assessment tool and preliminary exposure dose assessment were conducted. Maximum exposure doses for "Likely Scenarios" and "Less-likely Scenarios" were less than each standard dose value in the Interim Report (Likely Scenarios: 10$$mu$$Sv/y, Less-likely Scenarios: 300$$mu$$Sv/y).

JAEA Reports

Long term treatment of waste TBP/n-dodecane with steam reforming system

Sone, Tomoyuki; Nakagawa, Akinori; Koyama, Hayato; Gunji, Kiyoshi; Nonaka, Kazuharu; Sasaki, Toshiki; Tashiro, Kiyoshi; Yamashita, Toshiyuki

JAEA-Technology 2009-023, 33 Pages, 2009/06

JAEA-Technology-2009-023.pdf:8.11MB

Steam reforming (SR) method consists of the gasification process in which organics are vaporized and decomposed with superheated steam and the oxidation process in which vaporized organics are decomposed by oxidizing reaction with heated air. 2,500L of waste TBP/n-dodecane contaminated with uranium was treated using the demonstration scale steam reforming system to examine the performance of the system. Results obtained in this study show that the temperature in the SR system was controlled under the self-regulation temperature, the concentration of CO and NOx in the off-gas were controlled less than 100ppm and 250ppm respectively, the distribution ratio of uranium to off-gas treatment system was under 0.12% and the gasification ratio of waste TBP was more than 99%. This long-term waste treatment test has demonstrated that the SR system can safely and effectively reduce the volume of the waste.

Journal Articles

Steam-assisted pyrolysis system for decontamination and volume reduction of radioactive organic waste

Sasaki, Toshiki; Sone, Tomoyuki; Koyama, Hayato; Yamaguchi, Hiromi

Journal of Nuclear Science and Technology, 46(3), p.232 - 238, 2009/03

 Times Cited Count:10 Percentile:56.98(Nuclear Science & Technology)

A demonstration scale steam reforming treatment system was tested for the treatment of waste tri-n-butyl phosphate/n-dodecane contaminated uranium and simulated halogenated organic wastes stored in the Japan Atomic Energy Agency. The steam reforming treatment system was designed for the organic waste which produced a lot of acidic compounds by incineration and gave severe damage to incinerators. The system comprises a gasification process for decontamination by pyrolysis and steam reforming in a gasification chamber and a destruction process by oxidation with heated air in a submerged combustion type reactor for corrosion prevention. Wastes were reduced by 98 to 99.4% in weight during the treatment without any trouble by the acidic compounds. Almost all uranium was retained in the gasification chamber and uranium concentration of secondary waste water was very low that can permit the discharge of the neutralized waste water in the river.

JAEA Reports

Stabilization of simulated radioactive lead waste and simulated low level radioactive liquid waste using reformed sulfur (Joint research)

Sone, Tomoyuki; Sasaki, Toshiki; Miyamoto, Yasuaki; Yamaguchi, Hiromi; Inoue, Haruka*; Kihara, Tsuyoshi*; Takei, Yoshihisa*; Tatekawa, Takaiki*; Fukaya, Masaaki*; Iriya, Keishiro*; et al.

JAEA-Technology 2008-032, 25 Pages, 2008/03

JAEA-Technology-2008-032.pdf:5.54MB

Reformed sulfur (RS) is superior in water interception and acid resistance compared with cement. Therefore solidified wastes with RS should have the high resistance to leaching. Unconfined compressive strength test and leaching test using solidified simulated wastes containing lead contaminated with radioactive nuclides (Lead waste) with RS and solidified simulated low level radioactive liquid waste (LLLW) with RS were conducted to examine the applicability of reformed sulfur solidification method (RSSM) as solidification technique of Lead waste and LLLW. The results of these studies show that RSSM is effective technique for stabilization of lead compared with cement solidification method because solidified lead with RS has much stronger resistance to leaching of lead than solidified lead with cement. It also show that the applicability of RSSM as solidification technique of the waste containing lead oxide and LLLW is low because the resistance to leaching of solidified lead oxide with RS and of solidified simulated LLLW with RS were equal to or lower than those of solidified products with cement respectively.

JAEA Reports

Treatment of waste TBP/n-dodecane with steam reforming system

Sone, Tomoyuki; Nonaka, Kazuharu; Sasaki, Toshiki; Yamaguchi, Hiromi

JAEA-Technology 2008-006, 23 Pages, 2008/03

JAEA-Technology-2008-006.pdf:3.54MB

Steam reforming method consists of the gasification process (GP) in which organics are vaporized and decomposed with superheated steam and the oxidation process in which vaporized organics are decomposed with heated air. Experimental study in which waste TBP/n-dodecane (WTBP) containing uranium was used was conducted with the steam reforming system (SRS) to examine the distribution ratio of uranium in the system, the feasibility of treatment of WTBP and the effect of treatment with SRS on the volume reduction of WTBP. The results of these studies are as follows: (1) Most of uranium compounds in WTBP are separated from organics in GP. (2) Only the solid waste remained in GP is the radioactive secondary waste from the treatment of WTBP with SRS. (3) The maintenance operation of the equipments installed downstream of GP become easy to perform. (4) The volume of secondary solid wastes is very small because more than 99% of the WTBP were evaporated in GP. (5) It was estimated that the effect of treatment with SRS on the volume reduction of WTBP is 30 times more than that of pyrolysis method. These results show that SRS can achieve high volume reduction of WTBP.

JAEA Reports

Treatment of simulated waste TBP/n-dodecan and halogenated oils with steam reforming system

Sone, Tomoyuki; Nonaka, Kazuharu; Sasaki, Toshiki; Yamaguchi, Hiromi

JAEA-Technology 2007-063, 42 Pages, 2008/01

JAEA-Technology-2007-063.pdf:2.17MB

Steam reforming method has been developed for the treatment of organic wastes which are not suitable materials (tributyl phosphate, halogenated oil) for the incineration due to large quantities of secondary wastes generation. Process demonstration tests were conducted with the demonstration scale steam reforming system to examine the feasibility of treatment of simulated waste solvent (TBP and n-dodecane mixture) and simulated waste oils (halogenated oils and mineral oil mixture). These tests were also conducted to optimize the process conditions. The results of these studies are as follows: (1)More than 98wt% of the simulated wastes were evaporated in the gasification process. Solid residues removed from the gasification process as secondary wastes were inorganic compounds. (2)While the simulated waste oils were treated, the stacking of the filter is reduced by increasing the feed rate of steam from 1.5 kg/h to 3.0 kg/h. (3)Most of phosphoric acids produced by thermal decomposition of TBP were vaporized in the gasification process at 600$$sim$$650$$^{circ}$$C. This result shows that volume of radioactive secondary waste can be effectively reduced.

Journal Articles

Application of a comprehensive sensitivity analysis method on the safety assessment of TRU waste disposal in Japan

Oi, Takao; Takase, Hiroyasu*; Inagaki, Manabu; Oyamada, Kiyoshi*; Sone, Tomoyuki; Mihara, Morihiro; Ebashi, Takeshi; Nakajima, Kunihiko*

Materials Research Society Symposium Proceedings, Vol.985, p.129 - 134, 2007/00

A comprehensive sensitivity analysis method has been developed with the aim of providing quantitative information in an efficient manner. This methodology is composed of the following two components: (1) a statistical method with random sampling of independent parameters, which identifies important parameters and extracts threshold values of parameters and/or combinations yielding a "successful condition" where maximum dose does not exceed a target value, (2) A nuclide migration model that as far as possible incorporates a comprehensive set of phenomena occurring within the repository. This approach was applied as part of a safety assessment of the geological disposal of TRU waste in Japan (TRU-2). It was shown that the concept of TRU waste disposal is robust from the point of view of safety.

Journal Articles

Reduction of radioactive secondary waste with steam reforming in treatment of waste TBP/dodecane

Sone, Tomoyuki; Sasaki, Toshiki; Yamaguchi, Hiromi

Proceedings of 11th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '07) (CD-ROM), 5 Pages, 2007/00

We have stored waste TBP/dodecane generated from R&D activities on recycle of nuclear fuel. Those wastes can be incinerated, however a large quantity of contaminated phosphorous compounds generate. The objective of this study is to reduce the generation of radioactive secondary waste by the treatment of those wastes using steam reforming system. We conducted process demonstration tests using waste TBP/dodecane with 0.07g/L of uranium. We studied the temperature dependence of the gasification ratio of inorganic phosphorus compounds and removal of uranium by the filter. As the results, more than 95% of phosphorus compounds were gasified at temperature of 600$$^{circ}$$C or more, and more than 98% of uranium compounds were separated from the vaporized waste. The separated phosphorus compounds can be disposed of as the liquid wastes of which concentration of uranium is under the regulatory level. These results show the steam reforming system is effective in the reduction of radioactive secondary waste in the treatment of TBP/dodecane.

Journal Articles

Extraction of Successful Conditions on TRU Waste Disposal using Comprehensive Sensitivity Analysis Method

; Sone, Tomoyuki; Inagaki, Manabu; Mihara, Morihiro

Saikuru Kiko Giho, (25), p.69 - 84, 2004/00

A panoramic sensitivity analysis approach based on a statistic sampling method has been developed and applied for preliminary analysis on geological disposal of TRU waste considering variety of geological conditions and uncertainty. This approach can identify the parameters with the high importance for safety assessment and can extract the successful conditions for safety geological disposal.

Oral presentation

Treatment of low level radioactive organic wastes by steam reforming, 4

Sone, Tomoyuki; Nonaka, Kazuharu; Sasaki, Toshiki; Yamaguchi, Hiromi

no journal, , 

no abstracts in English

Oral presentation

Treatment of uranium waste by steam reforming

Sasaki, Toshiki; Sone, Tomoyuki; Nonaka, Kazuharu; Yamaguchi, Hiromi

no journal, , 

no abstracts in English

Oral presentation

Long-term treatment test of steam reformer for waste oraganic solvent containing uranium

Koyama, Hayato; Sone, Tomoyuki; Sasaki, Toshiki; Yamashita, Toshiyuki

no journal, , 

no abstracts in English

Oral presentation

Corrosion test of materials for steam reformer

Nakagawa, Akinori; Sone, Tomoyuki; Sasaki, Toshiki; Nakazawa, Osamu; Tashiro, Kiyoshi

no journal, , 

no abstracts in English

67 (Records 1-20 displayed on this page)