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Journal Articles

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

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

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

 Times Cited Count:8 Percentile:61.68(Nuclear Science & Technology)

Sludge-like uranium wastes (SUWs) have been generated with neutralization of acidic aqueous solutions used for decontamination of metal wastes containing a large amount of iron. We have examined the method for recovering uranium from such SUWs using ${{it N-cyclohexyl}}$-2-pyrrolidone (NCP) as a precipitate. As a result, it was found that precipitation ratios (PRs) of uranium in the solutions prepared by dissolving SUWs in HNO$$_{3}$$ is 97.7% at [NCP]/[U(VI)] = 20, and that the PRs of iron, aluminum, fluorine, and sulfate species are less than 1%. This indicates that uranium species are precipitated selectively. The content ratios of U, Fe, Ca, F, and S in the materials after calcining precipitates obtained at [NCP]/[U(VI)] = 20 were in accordance with the conditions of uranium ore concentrate. From these results, it is expected that highly purified uranium can be efficiently recovered from SUWs by using NCP as the precipitant.

Journal Articles

Applicability of polyvinylpolypyrrolidone adsorbent to treatment process of wastes containing uranium

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

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

 Times Cited Count:1 Percentile:10.71(Chemistry, Analytical)

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

Journal Articles

Studies on electrochemical behavior of uranium species in choline chloride-urea eutectic for developing electrolytically treating method of uranium-bearing wastes

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

Journal of Radioanalytical and Nuclear Chemistry, 309(2), p.627 - 636, 2016/08

 Times Cited Count:7 Percentile:55.37(Chemistry, Analytical)

As one of methods for recovering uranium from the uranium-bearing wastes, we have proposed the electrolytic deposition method using choline chloride-urea (CCU) which is known as an ambient temperature molten salt. More than 92% of uranium components in inactivated alumina and spent sodium fluoride adsorbent was dissolved into CCU solution. Cyclic voltammograms (CVs) of the solutions prepared by dissolving uranium-bearing wastes in CCU were measured in the potential range of -2.0 to 1.1 V (vs. Ag/AgCl). The one reduction peak was observed around -0.7 V for all solutions. Based on the results of CVs, bulk electrolyses of the solutions dissolving uranium-bearing wastes were also carried out at -1.5V at 80 $$^{circ}$$C. The deposits were formed on a carbon electrode as cathode. Consequently, we confirmed that CCU is effective media for recovering uranium selectively from uranium-bearing waste.

Journal Articles

Application of support vector machine to rapid classification of uranium waste drums using low-resolution $$gamma$$-ray spectra

Hata, Haruhi; Yokoyama, Kaoru; Ishimori, Yuu; Ohara, Yoshiyuki; Tanaka, Yoshio; Sugitsue, Noritake

Applied Radiation and Isotopes, 104, p.143 - 146, 2015/10

 Times Cited Count:9 Percentile:64.82(Chemistry, Inorganic & Nuclear)

We investigated the feasibility of using support vector machine (SVM), a computer learning method, to classify uranium waste drums as natural uranium or reprocessed uranium based on their origins. The method was trained using 12 training datasets were used and tested on 955 datasets of $$gamma$$-ray spectra obtained with NaI(Tl) scintillation detectors. The results showed that only 4 out of 955 test datasets were different from the original labels-one of them was mislabeled and the other three were misclassified by SVM. These findings suggest that SVM is an effective method to classify a large quantity of data within a short period of time. Consequently, SVM is a feasible method for supporting the scaling factor method and as a supplemental tool to check original labels.

JAEA Reports

Evaluation formulas of manpower needs for dismantling of equipments in uranium refining and conversion plant

Izumo, Sari; Usui, Hideo; Kubota, Shintaro; Tachibana, Mitsuo; Kawagoshi, Hiroshi; Takahashi, Nobuo; Morimoto, Yasuyuki; Tokuyasu, Takashi; Tanaka, Yoshio; Sugitsue, Noritake

JAEA-Technology 2014-021, 79 Pages, 2014/07

JAEA-Technology-2014-021.pdf:22.8MB

Japan Atomic Energy Agency has developed PROject management data evaluation code for DIsmantling Activities (PRODIA) to make an efficient decommissioning for nuclear facilities. PRODIA is a source code which provides estimated value such as manpower needs, costs, etc., for dismantling by evaluation formulas according to the type of nuclear facility. Evaluation formulas of manpower needs for dismantling of equipments about reprocessed uranium conversion in Uranium Refining and Conversion Plant are developed in this report. In the result, 7 formulas for prepare process, 24 formulas for dismantling process and 8 formulas for clean-up process are derived. It is confirmed that an unified evaluation formula can be used instead of 8 formulas about dismantling process of steel equipment for uranium conversion process, and 3 types of simplified formula can be used for preparation process and clean-up process respectively.

Journal Articles

Technique for recovering uranium from sludge-like uranium-bearing wastes using hydrochloric acid

Ohashi, Yusuke; Nomura, Mitsuo; Tsunashima, Yasumichi; Ando, Shion; Sugitsue, Noritake; Ikeda, Yasuhisa*; Tanaka, Yoshio

Journal of Nuclear Science and Technology, 51(2), p.251 - 265, 2014/02

 Times Cited Count:8 Percentile:53.55(Nuclear Science & Technology)

Sludge-like uranium-bearing wastes generated from uranium refining and conversion R&D facilities are stored at the Ningyo-toge Environmental Engineering Center. We have proposed an aqueous process for recovering uranium from spent filter aid and CaF$${_2}$$ precipitate using hydrochloric acid. The distributions of the dissolved species in the sample solutions at different pH levels were calculated using the chemical equilibrium modeling system. Calculated results of fluorine contents of recovered uranium were compared with the experimental results. The fluorine content in the recovered uranium decreased as the aluminum concentration of the solution increased. On the other hand, uranium of spent filter aid was recovered selectively. The size of the particles of recovered uranium tends to decrease with increasing pH in the precipitation treatments. Also, the uranium concentration of the precipitate generated by the neutralization of the barren solution falls below 1 Bq/g.

Journal Articles

Existing status of uranium refining and conversion plant decommissioning project

Sugitsue, Noritake; Morimoto, Yasuyuki; Tokuyasu, Takashi; Tanaka, Yoshio

Nihon Genshiryoku Gakkai Wabun Rombunshi, 12(3), p.242 - 256, 2013/09

This technical report showed the situation of the dismantling of the main equipment in the radiation controlled area of a uranium refining and conversion plant. And, the dismantling which we did is the work of the beginning of a uranium refining and conversion plant decommissioning project. We started dismantling in April 2008, and finished dismantling of the main equipment in a radiation controlled area in 29 September 2011. The dismantling waste and equipment was stored in the 200 little drum. All the contamination equipment can be sealed and kept in this stage. The radioactivity inventory of a uranium refining and conversion plant does not change in this stage. However, the risk of contamination by aged deterioration of this facility became remarkable small. Moreover, we were able to get many information and experience about dismantling.

Journal Articles

Development of evaluation models of manpower needs for dismantling the dry conversion process-related equipment in Uranium Refining and Conversion Plant (URCP)

Izumo, Sari; Usui, Hideo; Tachibana, Mitsuo; Morimoto, Yasuyuki; Takahashi, Nobuo; Tokuyasu, Takashi; Tanaka, Yoshio; Sugitsue, Noritake

Proceedings of 15th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2013) (CD-ROM), 9 Pages, 2013/09

 Times Cited Count:0 Percentile:0.1

Journal Articles

Separation technology of uranium using inorganic acid for sludge

Ohashi, Yusuke; Tsunashima, Yasumichi; Tanaka, Yoshio; Sugitsue, Noritake

Proceedings of 5th International Conference and Exhibition on Decommissioning Challenges; Industrial Reality and Prospects (CD-ROM), 10 Pages, 2013/04

Technologies for uranium refining and conversion for production of UF$$_{6}$$ had been developed in Ningyo-Toge environmental engineering center. As a result, a significant sludge like uranium bearing waste and adsorbent was generated. These wastes total 1500 tons. They are dissolved using hydrochloric acid and dissolved uranium is recovered as uranium peroxide. Impurities in uranium peroxide and uranium content were compared with the requirement defined by ASTM. Consequently, highly pure uranium which met the requirement was recovered at low pH. The uranium remaining in the solution was removed using chelating resin in order to decrease uranium radioactivity of the neutralized precipitate that is generated later in the process. It is confirmed that aluminum in the neutralized precipitate is recovered selectively using sodium hydroxide.

Journal Articles

Study on evaluation of project management data for decommissioning of uranium refining and conversion plant

Usui, Hideo; Izumo, Sari; Shibahara, Yuji; Morimoto, Yasuyuki; Tokuyasu, Takashi; Takahashi, Nobuo; Tanaka, Yoshio; Sugitsue, Noritake; Tachibana, Mitsuo

Proceedings of International Waste Management Symposia 2012 (WM2012) (CD-ROM), 13 Pages, 2012/02

Dismantling of dry conversion facility in the uranium refining and conversion plant at Ningyo-toge began in 2008. During dismantling activities, project management data have been collected. Establishment of the calculation formula for dismantling of each kind of equipment makes it possible to evaluate manpower for dismantling the whole facility. However, it is not easy to prepare calculation formula for all kinds of equipment in the facility. Therefore, a simpler evaluation method was considered to calculate manpower based on facility characteristics. The results showed promise for evaluating dismantling manpower with respect to each chemical process. To create an effective dismantling plan, it is necessary to carefully consider use of a GH preliminarily. Thus, an evaluation method of project management data such as manpower and secondary waste generation was considered. The results showed promise for evaluating project management data of GH by using established calculation formula.

Journal Articles

Application of systems engineering to decommissioning of nuclear fuel cycle facilities

Sugitsue, Noritake; Tanaka, Yoshio; Tokizawa, Takayuki; Annen, Sotonori; Yonekawa, Shigeru; Nakakura, Hiroyuki*; Tokuyasu, Takashi*; Aritomi, Tadahiko*

Dekomisshoningu Giho, (30), p.53 - 66, 2004/09

In the Ningyo-Toge Environmental Engineering Center, we clarify a relation of all works about the decommissioning. And, as an information base to plan promotion of efficiency of a work, we develop the Decommissioning Engineering System. The Decommissioning Engineering System consists of the function to do work support of a decommissioning, the function to gather the results information the decommissioning technology and the general evaluation function of the decommissioning plan on the basis of facilities information collected by three-dimensional CAD. The decommissioning of the nuclear fuel cycle facility has the characteristics that a period from the plan to the decommissioning is long in comparison with the general chemical plant. And the peculiarity to handle radioactive waste is a reason. In addition the System Decontamination, Dismantling, Treatment and Waste disposal are each other influence it closely in the decommissioning process. Therefore as for the decommissioning process, system engineering is important.

Journal Articles

None

Tanaka, Yoshio

Ningyotoge Jigyosho Shonaiho "11-Gatsi Go: Warera Gijutsusha Saizensen Shirizu", , 

None

Oral presentation

Decommissioning project of uranium conversion plant, 2; Analysis of work management data

Tanimoto, Masataka; Morimoto, Yasuyuki; Ikegami, Sohei; Tokuyasu, Takashi; Tanaka, Yoshio; Sugitsue, Noritake; Tachibana, Mitsuo; Ishigami, Tsutomu

no journal, , 

no abstracts in English

Oral presentation

Decommissioning Project of Uranium Conversion Plant, 4; The Secondary waste features of dismantling

Takahashi, Nobuo; Morimoto, Yasuyuki; Ikegami, Sohei; Tanaka, Yoshio; Tokuyasu, Takashi; Sugitsue, Noritake

no journal, , 

no abstracts in English

Oral presentation

Decommissioning project of uranium conversion plant, 3; Comparison between estimation and track record concerning wastes volume

Tokuyasu, Takashi; Tanaka, Yoshio; Morimoto, Yasuyuki; Ikegami, Sohei; Takahashi, Nobuo; Sugitsue, Noritake

no journal, , 

no abstracts in English

Oral presentation

Decommissioning project of uranium conversion plant, 1; Decommissioning progress

Ikegami, Sohei; Tanaka, Yoshio; Tokuyasu, Takashi; Takahashi, Nobuo; Sugitsue, Noritake; Morimoto, Yasuyuki

no journal, , 

no abstracts in English

Oral presentation

Decommissioning project of uranium conversion plant, 3; Analysis concerning quantity consumed tracking of materials used for dismantlement

Takahashi, Nobuo; Morimoto, Yasuyuki; Ikegami, Sohei; Tanaka, Yoshio; Tokuyasu, Takashi; Sugitsue, Noritake

no journal, , 

no abstracts in English

Oral presentation

Decommissioning project of uranium conversion plant, 1; Decommissioning result, The First half of 2009

Morimoto, Yasuyuki; Ikegami, Sohei; Tanaka, Yoshio; Tokuyasu, Takashi; Takahashi, Nobuo; Sugitsue, Noritake

no journal, , 

no abstracts in English

Oral presentation

Decommissioning project of uranium conversion plant, 2; Analysis concerning approximation process of weight of dismantlement object

Tanaka, Yoshio; Morimoto, Yasuyuki; Ikegami, Sohei; Tokuyasu, Takashi; Takahashi, Nobuo; Sugitsue, Noritake

no journal, , 

no abstracts in English

Oral presentation

Decommissioning project of uranium conversion plant, 1; Decommissioning result in FY 2009

Morimoto, Yasuyuki; Tanaka, Yoshio; Tokuyasu, Takashi; Takahashi, Nobuo; Sugitsue, Noritake

no journal, , 

no abstracts in English

37 (Records 1-20 displayed on this page)