Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage, 3; Progress report on NUMO-JAEA collaborative research in FY2013 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Kitamura, Akira; Yoshikawa, Hideki; Oda, Chie; Ishidera, Takamitsu; et al.

JAEA-Research 2014-030, 457 Pages, 2015/03

JAEA-Research-2014-030.pdf:199.23MB

JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and post-closure performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, based on some examples of developing method of hydro-geological structure model, acquired knowledge are arranged using the tree diagram, and model uncertainty and its influence on the evaluation items were discussed. With regard to (2) study on scenario development, the developed approach for "defining conditions" has been reevaluated and improved from practical viewpoints. In addition, the uncertainty evaluation for the effect of use of cementitious material, as well as glass dissolution model, was conducted with analytical evaluation. With regard to (3) study on setting radionuclide migration parameters, based on survey of precedent procedures, multiple-approach for distribution coefficient of rocks was established, and the adequacy of the approach was confirmed though its application to sedimentary rock and granitic rock. Besides, an approach for solubility setting was developed including the procedure of selection of solubility limiting solid phase. The adequacy of the approach was confirmed though its application to key radionuclides.

Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage; Progress report on NUMO-JAEA collaborative research in FY2011 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Hayano, Akira; Mitsui, Seiichiro; Taniguchi, Naoki; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.

JAEA-Research 2012-032, 298 Pages, 2012/09

JAEA-Research-2012-032.pdf:33.68MB

JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation phase. The topics and the conducted research are follows; (1) Study on selection of host rock: in terms of hydraulic properties, items for assessing rock property, and assessment methodology of groundwater travel time has been organized with interaction from site investigation. (2) Study on development of scenario: the existing approach has been embodied, in addition, the phenomenological understanding regarding dissolution of and nuclide release from vitrified waste, corrosion of the overpack, long-term performance of the buffer are summarized. (3) Study on setting nuclide migration parameters: the approach for parameter setting has been improved for sorption and diffusion coefficient of buffer/rock, and applied and tested for parameter setting of key radionuclides. (4) Study on ensuring quality of knowledge: framework for ensuring quality of knowledge has been studied and examined aimed at the likely disposal facility condition.

A Triple-scale crystal plasticity modeling and simulation on size effect due to fine-graining

Kurosawa, Eisuke*; Aoyagi, Yoshiteru; Tadano, Yuichi*; Shizawa, Kazuyuki*

Nihon Kikai Gakkai Rombunshu, A, 76(764), p.483 - 492, 2010/04

In this paper, a triple-scale crystal plasticity model bridging three hierarchical material structures, i.e., dislocation structure, grain aggregate and practical macroscopic structure is developed. The homogenization method is introduced into the Geometrically necessary (GN) dislocation-crystal plasticity model for derivation of the governing equation of macroscopic structure with the mathematical and physical consistencies. Using the present model, a triple-scale FE simulation bridging the above three hierarchical structures is carried out for f.c.c. polycrystals with different mean grain size. It is shown that the present model can qualitatively reproduce size effects of macroscopic specimen with ultrafine-grain. Moreover, the relationship between macroscopic yielding of specimen and microscopic grain yielding is discussed and the mechanism of the poor tensile ductility due to fine-graining is clarified.

Construction, management and operation on advanced volume reduction facilities

Higuchi, Hidekazu; Osugi, Takeshi; Nakashio, Nobuyuki; Momma, Toshiyuki; Tohei, Toshio; Ishikawa, Joji; Iseda, Hirokatsu; Mitsuda, Motoyuki; Ishihara, Keisuke; Sudo, Tomoyuki; et al.

JAEA-Technology 2007-038, 189 Pages, 2007/07

JAEA-Technology-2007-038-01.pdf:15.13MB
JAEA-Technology-2007-038-02.pdf:38.95MB
JAEA-Technology-2007-038-03.pdf:48.42MB
JAEA-Technology-2007-038-04.pdf:20.53MB
JAEA-Technology-2007-038-05.pdf:10.44MB

The Advanced Volume Reduction Facilities (AVRF) is constructed to manufacture the waste packages of radioactive waste for disposal in the Nuclear Science Research Institute of the Japan Atomic Energy Agency. The AVRF is constituted from two facilities. The one is the Waste Size Reduction and Storage Facility (WSRSF) which is for reducing waste size, sorting into each material and storing the waste package. The other is the Waste Volume Reduction Facility (WVRF) which is for manufacturing the waste package by volume reducing treatment and stabilizing treatment. WVRF has an induction melting furnace, a plasma melting furnace, an incinerator, and a super compactor for treatment. In this report, we summarized about the basic concept of constructing AVRF, the constitution of facilities, the specifications of machineries and the state of trial operation until March of 2006.

Scenario development for the risk-informed safety assessment of geological disposal

Makiuchi, Akie*; Ishida, Keisuke*; Kurosawa, Susumu*; Inagaki, Manabu*; Umeki, Hiroyuki*; Ebashi, Takeshi; Wakasugi, Keiichiro; Makino, Hitoshi; Shibata, Masahiro

no journal, , 

NUMO is developing a safety case for the geological disposal of vitrified high-level radioactive wastes and TRU wastes on the basis of the latest findings. In parallel, JAEA starts to investigate the geological disposal of spent fuel as an alternative disposal option. In such a situation, NUMO and JAEA have jointly established a scenario development method. Since the considerations of both probabilities and influences of scenarios or processes are focused on, the disaggregated approach is adopted. This approach had been recommended by ICRP, and applied to Japanese safety regulations for disposing low-level waste. To efficiently identify processes that may influence geological disposal systems, various supposable processes are analyzed in terms of their probabilities and influences on the safety function by conducting audits using FEP information. One remarkable feature of this method is its demand of high-level traceability of various judgments through analysis and definition of scenarios. Traceability is ensured by various tools and/or products. One such example is a "Safety Function/Variable/Process Diagram", which structurally illustrates interrelations between safety functions, processes and variables of geological disposal systems. This presentation will show the features of the abovementioned method in detail along with some examples of developed scenarios.

Research and development of the "SELECT process" for Actinide separation

Matsumura, Tatsuro; Ban, Yasutoshi; Hotoku, Shinobu; Suzuki, Hideya; Tsubata, Yasuhiro; Tsutsui, Nao; Morita, Keisuke; Toigawa, Tomohiro; Shibata, Mitsunobu*; Kurosawa, Tatsuya*; et al.

no journal, , 

no abstracts in English

Study on the generation process of radioactive particles emitted from Unit 1 of FDNPP

Ishii, Tatsuya*; Sueki, Keisuke*; Matsuo, Kazuki*; Kurosawa, Masanori*; Satou, Yukihiko; Kobata, Masaaki; Fukuda, Tatsuo; Yoshii, Kenji; Tanida, Hajime; Okane, Tetsuo; et al.

no journal, , 

Radioactive particles were released into the environment by the accident of Fukushima Daiichi Nuclear Power Plant (FDNPP). They have information to understand the inside of the reactor during the accident. Now, nobody knows the generation process of radioactive particles. In this study, we analyzed (1) elements of particles' cross section with SEM-EDS to reveal what is the material and (2) chemical states of elements on particles' surface with HAXPES. (1) Radioactive particles are composed of the two parts. One is the basic material and the other is the heavy elemental materials. We considered the basic material was soda-lime glass and the heavy elemental materials included lead glass. (2) HAXPES brought out that the chemical states of Cs on particles, surface was different in the Na-poor areas and the Na-rich areas. In the Na-poor areas, the chemical state of Cs showed CsFeSiO mainly, but zero valence partly. In the Na-rich areas, the chemical state of Cs couldn't be identified. For above analyses, we can reveal the generation process of radioactive particles.

Development of a new extraction method for americium separation from high-level liquid waste, 2

Suzuki, Hideya*; Ban, Yasutoshi; Hotoku, Shinobu; Morita, Keisuke; Tsutsui, Nao; Kurosawa, Tatsuya*; Shibata, Mitsunobu*; Kawasaki, Tomohiro*; Matsumura, Tatsuro

no journal, , 

The Japan Atomic Energy Agency (JAEA) has been studying partitioning technology. Recently, JAEA proposed a new liquid-liquid extraction technology called SELECT (Solvent Extraction from Liquid-waste using Extractants of CHON-type for Transmutation) process to separate minor actinide (MA) from high-level liquid waste (HLLW) for transmutation. In this process, new extractants (HONTA, ADAAM) with highly practical and high extraction ability for MA was developed. In the present study, a new solvent extraction method using a mixture of HONTA and ADAAM was investigated. In the tests, it was found that the separation of Am from the simulated HLLW was achieved with very high yield.