Vitrification of high-level radioactive waste by phosphate-type glass

Amamoto, Ippei; Myochin, Munetaka; Fukui, Toshiki*

New Glass, 22(2), p.21 - 26, 2007/06

As the electrolyte [LiCl-KCl] used in the pyrochemical reprocessing process by the electrorefining method will likely be contaminated by the accumulation of various fission products [FPs] after prolonged electrolytic operation, some measures, e.g., its replacement by a virgin electrolyte, etc. are necessary. The constant replacement of electrolyte, however, could lead to the generation of enormous amount of high level radioactive waste [HLW] because the spent electrolyte is a waste salt and is classified as HLW. From the viewpoints of environmental load reduction and economical improvement, it is desirable to have the spent electrolyte purified for recycling by removing its FPs. The FPs precipitation method by converting FPs to insoluble compounds such as phosphates could be one of the potential techniques to remove FPs. Subsequently, it is necessary to immobilise FPs precipitates by vitrification or some other methods. The possibility and potential advantages of the vitrification of FPs phosphates using the iron phosphate glass is introduced in this paper. At the same time, comparisons are made with the borosilicate immobilisation method.

Study on Microbial Influence Assessment in Geological Disposal (II) (Summary Report)

Fukunaga, Sakae*; Iwata, Yumiko*; Kanno, Takeshi*; Kudo, Akira*

JNC TJ8400 2003-070, 45 Pages, 2003/02

JNC-TJ8400-2003-070.pdf:0.13MB

This report summarizes two investigations concerned with microbial influence in geological disposal facilities. 1)Literature survey on simulation models for the microbial-influence evaluation, 2) Experiment for the interaction between bacteria and Pu at Eh=-135mV.

Study on Model for Bentonite Buffer Intrusion Phenomenon

Kanno, Takeshi*; Iwata, Yumiko*

JNC TJ8400 2003-026, 63 Pages, 2003/02

JNC-TJ8400-2003-026.pdf:0.56MB

Modelling study on the extrusion phenomenon in a geological repository for the high-level radioactive is performed to enhance the reliability of existing model described in H12 report. Main conclusions of this study are as follows: (1) The methods and pysical interpretation of bentonite gel viscosity measurements are clarified and input data of the viscosity for the solid diffusivity are obtained. (2) The input data of the swelling pressure and hydraulic conductivity of bentonite in the low- density region necessary for the solid diffusivity are determined. (3) The consolidation-type model proposed by Ahn et al. is surveyed and compared with that used in this study. The consolidation-type model is thought to be equivalent to the solid diffusion model used in this study. (4) The numerical analyses for BENTFLOW experiments and model experiments on extrusion in a pipe are performed. The analyses for the BENTFLOW reproduce the experimental results better than the past studies. The agreement between the calculated and experimental results of the model experiments is not good. Thus further study is required for the evaluation of density distribution in extruding bentonite gel.

Study on microbial influence assessment in geological disposal

Fukunaga, Sakae*; Nakayama, Mamoru*; Jintoku, Takashi*; *; Kudo, Akira*

JNC TJ8400 2002-036, 186 Pages, 2002/02

JNC-TJ8400-2002-036.pdf:1.34MB

We conducted the following four investigations concerned with microbial influence in geological disposal facilities. (1)Improvement of the FEP dictionary and investigation on chemical evolution of nitrate by microbes. (2)Experimental estimation of microbial mobility in compacted Na bentonite saturated by synthetic seawater with 30wt% silica sand and Ca bentonite with 30wt% silica sand. (Both dry densities are 1.6 g/cm.) (3)Habitation of microbes in Na rich bentonite deposit and Ca rich one. (4)Interaction between SRB (sulfate reducing bacteria) and Np in a reducing environment at Eh=-85mV. As the result, it was revealed that (1)microbial activity in near field rock and microbial denitrification of nitrate under the existence of electron donor are important, (2)microbes didn't move in Na bentonite in 3 weeks and moved to the distance of 20mm in Ca bentonite, and (3)microoragnisms existed at the inside of the deposits. (4)The difference between distribution coefficient of Eh=-85mV and Eh=-500mV was evaluated.

Technical investigation on remote excavation and handling in the mine for the development of the handling system for engineered barrier

Awano, Toshihiko*; Sakai, Akira*; Sugino, Hiroyuki*

JNC TJ1400 2002-012, 94 Pages, 2001/06

JNC-TJ1400-2002-012.pdf:3.56MB

None

Study on microbial transport and adsorption behavior on engineering barrier for geological disposal of radioactive wastes

Fukunaga, Sakae*; Yokoyama, Hidekazu*; Arai, Kazuhiro*; Asano, Hidekazu*; Senjyu, Takafumi*; Kudo, Akira*

JNC TJ8400 2000-029, 36 Pages, 2000/02

JNC-TJ8400-2000-029.pdf:1.28MB

It is easy to assume from the past data that microbial transport do not find at 100%-sodium bentonite. Microbial transport do not find at 100%-calcium bentonite too. There are no effects to distribution ration (Kd) of Neptunium (Np) and Plutonium (Pu) with bentonite by sterilizing on low Eh condition (Eh = -500mv). Kd values of Np and Pu show behavior, which are increasing on the hard acidic and alkali conditions. Especially, Kd values of Pu shows one of Kd value is about 100 ml/g on pH = 36, but the other of Kd value is about 400,000 ml/g on pH = 13. Precipitating plutonium hydrates occurred the large Kd value on alkali condition.

Study on cathodic reaction control efficiency by low alloy steels

Akashi, Masatsune*; Fukaya, Yuichi*; Asano, Hidekazu*

JNC TJ8400 2000-014, 22 Pages, 2000/02

JNC-TJ8400-2000-014.pdf:0.75MB

Difference of hydrogen generation phenomena on the surface of the Steels were not observed between carbon steel, atmospheric corrosion resisting steel and 5%-Ni steel. Rust layer was formed on these three-type of steels by steam oxidation method. And the chemical composition of the rust for the steels were basically two(2) layers structure for the previous two steels as hematite(FeO) based for the outer layer and magnetite(FeO) based for the inner layer. And for the last steel, it had three(3) layer in the rust as hematite(FeO) based for the outer layer, magnetite(FeO) based for the intermediate layer and Ni based layer for the inner layer. These steels showed mostly same Tafel gradient in their cathodic polarization curves compare with that for no rust specimens. However, the exchange current density which reaction is assumed as a hydrogen generation reaction was largely increased. The cathodic reaction for each steels whose surface is covered by magnetite layer might be accelerated, then the corrosion rate was considered as accelerated, too.

Development of reconstitution technique of irradiated speciments, 3; Report for FY 1995 and FY 1996 on JAERI-IHI cooperated research program (Joint research)

Nishiyama, Yutaka; Fukaya, Kiyoshi; Onizawa, Kunio; Suzuki, Masahide; *; *; *; *

JAERI-Tech 98-041, 30 Pages, 1998/10

JAERI-Tech-98-041.pdf:2.0MB

no abstracts in English

None

PNC TJ1150 98-003, 99 Pages, 1998/03

PNC-TJ1150-98-003.pdf:4.39MB

None

None

PNC TJ1150 98-001, 25 Pages, 1998/02

PNC-TJ1150-98-001.pdf:0.93MB

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