Studies of the setting of engineered barrier configuration utilized in geologic disposal, 1; Dissolution life-time of vitrified waste glass

Oe, Toshiaki*; Wakasugi, Keiichiro

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 24(1), p.27 - 32, 2017/06

https://doi.org/10.3327/jnuce.24.1_27

The report estimates the life-time of the waste glass dissolution in the geologic disposal environment. The overall safety report on the geologic disposal in Japan showed very short life-time of approximately 70,000 years under pessimistic assumptions ignoring the temperature decrease due to radioactive decay and dissolution rate reduction due to surface shrinkage. These factors are physically established phenomena and may not be excluded. The dissolution models including these factors of temperature and surface area decreases are discussed and used for re-evaluation. Three fracture models are presented for evaluating the surface area decreases; a single plate, monotonic spheres, spheres having power-law distribution. All models have the same initial volume as the waste glass block for mass conservation and the total surface areas are 10 times higher than the initial pristine block because of the fracture development during production. The results indicate the retention time of 50% of initial mass exceed 100,000 years even by different fracture models and the dissolution life-times are expected for 260,000700,000 years depending on models. These results imply more strong isolation capability of the waste glass than that estimated in the overall safety report.

Burning of MOX fuels in LWRs; Fuel history effects on thermal properties of hull and end piece wastes and the repository performance

Hirano, Fumio; Sato, Seichi*; Kozaki, Tamotsu*; Inagaki, Yaohiro*; Iwasaki, Tomohiko*; Oe, Toshiaki*; Kato, Kazuyuki*; Kitayama, Kazumi*; Nagasaki, Shinya*; Niibori, Yuichi*

Journal of Nuclear Science and Technology, 49(3), p.310 - 319, 2012/03

AA2011-0278.pdf:0.56MB

https://doi.org/10.1080/00223131.2012.660021

The thermal impacts of hull and end piece wastes from the reprocessing of MOX spent fuels burned in LWRs on repository performance were investigated. The heat generation rates in MOX spent fuels and the resulting heat generation rates in hull and end piece wastes change depending on the fuel histories including the burn-up of UO spent fuels, the cooling period before reprocessing, the storage period of fresh MOX fuels. The heat generation rates of hull and end piece wastes from the reprocessing of MOX spent fuels with any of those histories are significantly larger than those from UO spent fuels with burn-ups of 45 GWd/THM. If a temperature below 80C is specified for cement-based materials used in waste packages after disposal, the allowable number of canisters containing compacted hull and end pieces in a package for 45 GWd-MOX needs to be limited to a value of 0.7 to 1.6, which is significantly lower than the value of 4.0 for 45 GWd-UO.

Moderation of uncertainty in a database of sorption coefficients, 2; Analysis of data scatter by adopting ion exchange model

Oe, Toshiaki*; Nagasaki, Shinya*; Kimura, Hideo; Takeda, Seiji; Sekioka, Yasushi; Kato, Hiroyasu*; Akahori, Kuniaki*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 7(3), p.210 - 220, 2008/00

https://doi.org/10.3327/taesj.J07.029

Uncertainty found in the statistical data of Cs sorption coefficients was investigated. Careful data treatment indicated the major reason of data scatter was caused by the differences of the concentrations of co-existing ions and initial Cs concentrations. Analysis of the pH dependence of the data by adopting PHREEQC or MINEQL-TO which enable to treat ion exchange model coupled with the surface complexation model indicated the sorption coefficients could be represented for both cases obtained by batch method and diffusion method. In this analysis the same data set was used even for the extremely different experimental setup and the perturbation of environmental condition such as the Na concentration and pH brought strong influence on the data stability. The results also suggested that the scatter of the Cs sorption coefficient could be understandable and minimized through the analysis adopting mechanistic sorption model.

Mass yield curves in low-energy proton-induced fission of U, U, U, Np, Pu, Pu, Pu, Am and Am

Otsuki, Tsutomu*; Nagame, Yuichiro; Tsukada, Kazuaki*; Shinohara, Nobuo; ; Hashimoto, Kazuyuki; ; Sueki, Keisuke*; ; ; et al.

Physical Review C, 44(4), p.1405 - 1423, 1991/10

https://doi.org/10.1103/PhysRevC.44.1405

no abstracts in English

Cost Estimation for the Geological Disposal System of High Level Radioactive Waste (for 1989); The Improvement of Cost Integration System

Yoshiki, Nobuya*; Oe, Toshiaki*; Tsukamoto, Masaki*; Tanaka, Hiroshi*

JNC TJ1400 2005-003, 149 Pages, 1990/03

JNC-TJ1400-2005-003.pdf:4.97MB

None

Symmetric and asymmetric mass divisions of the compound nucleus Ag

Nagame, Yuichiro; Ikezoe, Hiroshi; ; ; Sekine, Toshiaki; ; Ideno, K.; Yokoyama, Akihiko*; ; Otsuki, Tsutomu*

Heavy-Ion Reaction Dynamics in Tandem Energy Region, p.265 - 274, 1988/00

no abstracts in English

Development of micro-chemical probe for characterization of geological environment

Hama, Katsuhiro; Uchida, Masahiro; Amano, Kenji; Takeuchi, Ryuji; Hagiwara, Hiroki; Yoshida, Takuma*; Noshita, Kenji*; Nagasaki, Shinya*; Oe, Toshiaki*; Futakuchi, Katsuhito*

no journal, , 

The micro-chemical probe for characterization of geological environment has been developed. The performance test shows that this equipment can be applicable for the in-situ experiment.

Preparation of an information basis for development of practical performance assessment models on waste glass corrosion in geological disposal

Mitsui, Seiichiro; Oe, Toshiaki*; Inagaki, Yaohiro*; Okubo, Takahiro*; Kurosawa, Susumu*; Goto, Takahiro*; Inagaki, Manabu*; Ishiguro, Katsuhiko*; Takase, Hiroyasu*; Takahashi, Hirokazu*

no journal, , 

In order to develop robust performance assessment models, we have been preparing an information basis regarding glass properties and glass dissolution/alteration processes under disposal conditions as a part of NUMO-JAEA joint project. Our iterative working process for the preparation of the information basis comprises five steps: (1) integration of current knowledge; (2) development of glass dissolution scenarios based on current knowledge; (3) development of conceptual model; (4) sensitivity analyses to evaluate relative importance of relevant processes and associated uncertainties; and (5) identification of future R&D issues towards further improvement of the information basis. The current status will be presented in this talk.

Physico-chemical properties of pore water in compacted bentonite; Pore water condition measured by osmotic pressure

Oe, Toshiaki*; Suzuki, Masashi*; Tachi, Yukio; Kato, Hiroyasu*

no journal, , 

Physico-chemical properties of pore water in water saturated compacted bentonite was investigated by the osmotic pressure measurement. Osmotic pressure reached the peak value at dry density of 1.2 g/cm, implying that physico-chemical properties change drastically at this desity.

Surface structure of Anodic Oxide Layer with Si Micro-Nano Rolls

Arai, Taiki*; Qiao, Y.*; Suzuki, Toshiaki*; Yoshigoe, Akitaka; Niwa, Masaaki*; Motohashi, Mitsuya*

no journal, , 

In this study, it was found that the relationship between anodisation time and surface morphology after anodic oxidation of silicon oxide layers on p-type Si substrates. The unique meso-materials (Si rolls) are formed by using extremely diluted HF solution for anodization. The resistance between the electrodes during anodization initially increased with increasing anodization time and then becomes constant value. After some time, it gradually increased again. It seems to consider an important parameter to control the formation of Si rolls and those numbers.