Examination of the wet analysis for the (U-Th)/He method; Attempt to determine the contents of parent nuclides based on the calibration curve method

Fukuda, Shoma; Kagami, Saya

Fisshion, Torakku Nyusureta, (36), p.14 - 18, 2023/12

For the determination of parent nuclides in the (U-Th)/He method, the isotope dilution method using U and Th isotope spikes is commonly employed worldwide, and much knowledge has been accumulated. On the other hand, the possession and use of these spikes are strictly restricted, which makes the application of the isotope dilution method itself difficult. After the complete dissolution of apatite and zircon by the wet method, we have therefore attempted to verify the calibration curve method for measuring the concentration of the parent nuclides. Durango apatite and Fish Canyon Tuff zircon, which are well-known as the age standard samples for the fission track method, were used as analytical samples. In this presentation, we will introduce some of the results of the determination of parent nuclides (U, Th, Sm) in each mineral sample based on the calibration curve method as well as results of evaluating the suitable internal standards (Bi, Tl) to determine the contents of parent nuclides.

An Experiment of complete dissolution of zircon crystals by high-temperature and pressure acid digestion for the (U-Th)/He method

Fukuda, Shoma; Kagami, Saya

Fisshion, Torakku Nyusureta, (35), p.11 - 14, 2022/12

In this study, we firstly attempted the wet-chemical analyses at Tono Geoscience Center based on a high-temperature and pressure acid digestion for determination of U-Th contents in zircon crystals. In the beginning, zircon crystals were annealed at 900 degrees Celsius for 48 hours to recover radiation damages, and annealed zircons were transferred and sunk into 29 M HF, and finally zircons were digested at 220 degrees Celsius for 70 hours. To verify that zircons were digested completely, Zr contents in zircons were measured as major elements by using ICP-MS (Agilent 7700x) based on the calibration curve method. As a result, theoretical values for Zr contents were obtained, these experimental conditions are thus valid for zircon digestion. Now, we are considering to perform these analyses in the clean booth and to select more appropriate analyses instruments and conditions for decreasing a blank level, which contributes to improve the determination of U-Th contents for zircon (U-Th)/He dating.

Collection of measurement data from in-situ experiment for performance confirmation of engineered barrier system at Horonobe Underground Research Laboratory (FY2015)

Nakayama, Masashi; Ono, Hirokazu; Nakayama, Mariko*; Kobayashi, Masato*

JAEA-Data/Code 2016-005, 55 Pages, 2016/07

JAEA-Data-Code-2016-005.pdf:11.32MB
JAEA-Data-Code-2016-005-appendix(CD-ROM).zip:32.68MB

The Horonobe URL Project has being pursued by JAEA to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The Project consists of two major research areas, "Geoscientific Research" and "Research and Development on Geological Disposal Technologies", and proceeds in three overlapping phases, "Phase I: Surface-based investigations", "Phase II: Investigations during tunnel excavation" and "Phase III: Investigations in the underground facilities". Phase III investigation was started in 2010 fiscal year. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) had been prepared from 2013 to 2014 fiscal year at GL-350m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the experiment is acquiring data concerned with Thermal-Hydrological-Mechanical-Chemical (THMC) coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. This report summarizes the measurement data acquired from the EBS experiment from December, 2014 to March, 2016.

Collection of measurement data from in-situ experiment for performance confirmation of engineered barrier system at Horonobe Underground Research Laboratory (FY2014)

Nakayama, Masashi; Ono, Hirokazu; Nakayama, Mariko*; Kobayashi, Masato*

JAEA-Data/Code 2015-013, 53 Pages, 2015/09

JAEA-Data-Code-2015-013.pdf:9.78MB
JAEA-Data-Code-2015-013(errata).pdf:0.37MB
JAEA-Data-Code-2015-013-appendix(CD-ROM).zip:5.76MB

The Horonobe Underground Research Laboratory (URL) Project has being pursued by Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The URL Project consists of two major research areas, "Geoscientific Research" and "Research and Development on Geological Disposal Technologies", and proceeds in three overlapping phases, "Phase I: Surface-based investigations", "Phase II: Investigations during tunnel excavation" and "Phase III: Investigations in the underground facilities", over a period of around 20 years. Phase III investigation was started in 2010 fiscal year. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) had been prepared from 2013 to 2014 fiscal year at G.L.-350m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the experiment is acquiring data concerned with Thermal-Hydrological-Mechanical-Chemical (THMC) coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. This report summarizes the measurement data acquired from the EBS experiment. The period of data acquisition is from December, 2014 to March, 2015. It will be periodically published summarized data of EBS experiment.

Research on engineering technology in the full-scale demonstration of EBS and operation technology for HLW disposal; Research report in 2012 (Joint research)

Nakatsuka, Noboru; Sato, Haruo; Tanai, Kenji; Nakayama, Masashi; Sawada, Sumiyuki*; Asano, Hidekazu*; Saito, Masahiko*; Yoshino, Osamu*; Tsukahara, Shigeki*; Hishioka, Sosuke*; et al.

JAEA-Research 2013-034, 70 Pages, 2014/01

JAEA-Research-2013-034.pdf:9.11MB

Japan Atomic Energy Agency (JAEA) and Radioactive Waste Management Funding and Research Center (RWMC) concluded the letter of cooperation agreement on the research and development of radioactive waste disposal in April, 2005, and have been carrying out the collaboration work based on the agreement. JAEA have been carrying out the Horonobe Underground Research Laboratory (URL) Project which is intended for a sedimentary rock in the Horonobe town, Hokkaido, since 2001. In the project, geoscientific research and research and development on geological disposal technology are being promoted. Meanwhile, the government (the Agency for Natural Resources and Energy, Ministry of Economy, Trade and Industry) has been promoting construction of equipments for the full-scale demonstration of engineered barrier system and operation technology for high-level radioactive waste (HLW) disposal since 2008, to enhance public's understanding to the geological disposal of HLW, e.g. using underground facility. RWMC received an order of the project in fiscal year 2012 (2011/2012) continuing since fiscal year 2008 (2008/2009). Since topics in this project are included in the Horonobe URL Project, JAEA carried out this project as collaboration work continuing in fiscal year 2008. This report summarizes the results of engineering technology carried out in this collaboration work in fiscal year 2012. In fiscal year 2012, part of the equipments for emplacement of buffer material was produced and visualization test for water penetration in buffer material were carried out.

Research on engineering technology in the full-scale demonstration of EBS and operation technology for HLW disposal; Research report in 2010 (Joint research)

Nakatsuka, Noboru; Hatanaka, Koichiro; Sato, Haruo; Sugita, Yutaka; Nakayama, Masashi; Asano, Hidekazu*; Saito, Masahiko*; Suyama, Yasuhiro*; Hayashi, Hidero*; Honda, Yuko*; et al.

JAEA-Research 2013-026, 57 Pages, 2013/11

JAEA-Research-2013-026.pdf:7.48MB

JAEA and RWMC concluded the letter of cooperation agreement on the research and development of radioactive waste disposal in April, 2005, and have been carrying out the collaboration work described above based on the agreement. JAEA have been carrying out the Horonobe URL Project which is intended for a sedimentary rock in the Horonobe town, Hokkaido, since 2001. In the project, geoscientific research and research and development on geological disposal technology are being promoted. Meanwhile, the government (the Agency for Natural Resources and Energy, Ministry of Economy, Trade and Industry) has been promoting construction of equipments for the full-scale demonstration of engineered barrier system and operation technology for high-level radioactive waste (HLW) disposal since 2008, to enhance public's understanding to the geological disposal of HLW, using underground facility, etc. RWMC received an order of the project in fiscal year 2010 continuing since fiscal year 2008. Since topics in this project are included in the Horonobe URL Project, JAEA carried out this project as collaboration work continuing in FY 2008. This report summarizes the results of engineering technology carried out in this collaboration work in fiscal year 2010. In fiscal year 2010, part of the equipments for emplacement of buffer material was produced and a house for the equipments and apparatus was opened in the adjoining land of Public Information House of JAEA Horonobe.

Long term integrity of overpack closure weld for HLW geological disposal, 2; Corrosion properties under anaerobic conditions

Kobayashi, Masato*; Yokoyama, Yutaka*; Takahashi, Rieko*; Asano, Hidekazu*; Taniguchi, Naoki; Naito, Morimasa

Corrosion Engineering, Science and Technology, 46(2), p.212 - 216, 2011/04

https://doi.org/10.1179/1743278210Y.0000000021

The corrosion behaviour of a carbon steel weld joint under anaerobic conditions was investigated to estimate the long-term integrity of the carbon steel overpack. The weld specimens in this study were produced using three welding methods: GTAW, GMAW and EBW. General corrosion was observed for each immersion specimen and the weld joint corrosion rate was the same as or less than that of the base metal. The hydrogen concentration absorbed during immersion testing was less than 2.4810 mol kg[Fe](0.05 ppm) after three years, a value regarded as having little influence on hydrogen embrittlement. The susceptibility to hydrogen embrittlement was highest in the base metal, suggesting that there was little adverse effect on the weld joint from welding. The welded carbon steel overpack is assumed to maintain its resistance to corrosion as a disposal container for the expected lifetime under anaerobic underground conditions.

Research on engineering technology in the full-scale demonstration of EBS and operation technology for HLW disposal; Research report in 2008 (Joint research)

Nakatsuka, Noboru; Hatanaka, Koichiro; Sato, Haruo; Sugita, Yutaka; Nakayama, Masashi; Miyahara, Shigenori; Asano, Hidekazu*; Saito, Masahiko*; Suyama, Yasuhiro*; Hayashi, Hidero*; et al.

JAEA-Research 2009-044, 53 Pages, 2010/01

JAEA-Research-2009-044.pdf:9.03MB

Japan Atomic Energy Agency (JAEA) and Radioactive Waste Management Funding and Research Center (RWMC) effect an agreement about research and development of high level radioactive waste (HLW) disposal and carried out research and technological development about geological disposal technology. JAEA has been carried out the Horonobe Underground Research Laboratory (URL) Project which is intended for sedimentary rock and the Project includes geoscientific research and geological disposal technology. RWMC carried out an investigation about full-scale demonstration of engineered barrier system (EBS) and operation technology for HLW disposal, under the contract with the Natural Resources and Energy Agency, Ministry of Economy, the Trade and Industry. The investigation aims to obtain the citizens' understanding of the geological disposal. This work includes the full-scale demonstration of operation technology in the Horonobe URL. This joint research is about engineering technology concerned with the work. In 2008 fiscal year (2008/2009), the master plan of the work was made, and a part of the device for transportation of engineered barrier was made, and it has begun the exhibition of full-scale bentonite block and overpack.

Research on advanced technology of performance assessment and monitoring for geological disposal of high-level radioactive waste (Joint research)

Geological Isolation Research and Development Directorate; Advanced Waste System Research Project, Radioactive Waste Management Funding and Research Center*

JAEA-Research 2008-060, 72 Pages, 2008/06

JAEA-Research-2008-060.pdf:20.38MB

JAEA and RWMC have carried out a joint research program on advanced technologies that could be used to support performance assessment and monitoring of geological disposal concepts for high-level radioactive waste. The 5 items regarding to performance assessment and 1 item for monitoring were considered in the program. The items were discussed in the context of technological experiences gained by JAEA and RWMC in previous repository-related studies. According to the results of these discussions, development strategies for each of the technology areas identified above were efficiently formulated by appropriate task allocations. Specific technical subjects requiring further investigation were identified using this approach, and a priority of subject was also discussed.

Study on the corrosion assessment of overpack welds, 3 (Joint research)

Mitsui, Hiroyuki*; Takahashi, Rieko*; Taniguchi, Naoki; Otsuki, Akiyoshi*; Asano, Hidekazu*; Yui, Mikazu

JAEA-Research 2006-080, 322 Pages, 2006/12

JAEA-Research-2006-080.pdf:90.52MB

There is some possibility that the corrosion resistance of overpack welds is different from that of base metal due to the differences of material properties. In this study, corrosion behavior of welded joint for carbon steel was compared with base metal using the specimens taken from welded joint model fabricated by TIG, MAG and EBW respectively. The corrosion tests were performed for following four items. (1) Passivation behavior and corrosion type, (2) Propagation of general corrosion, pitting corrosion and crevice corrosion under aerobic condition, (3) Stress corrosion cracking susceptibility, (4) Propagation of general corrosion and hydrogen embrittlement under anaerobic condition. The results of these corrosion tests indicated that the corrosion resistance of welded metal by TIG and MAG was inferior to base metal for general corrosion, pitting corrosion and crevice corrosion. It was implied that the filler materials used for welding affected the corrosion resistance. No deterioration of corrosion resistance was observed in any corrosion modes for EBW, which does not need filler material. The susceptibility to stress corrosion cracking of welded metal and heat affected zone was lower than that of base metal.