Data of groundwater chemistry obtained in the Horonobe Underground Research Laboratory Project (FY2022)

Miyakawa, Kazuya; Nakata, Kotaro*

JAEA-Data/Code 2022-013, 19 Pages, 2023/03

JAEA-Data-Code-2022-013.pdf:1.88MB

In the Horonobe Underground Research Laboratory (URL) project, groundwater chemistry was analyzed to investigate changes due to the excavation of the underground facility and to review geochemical models until the fiscal year 2019. From the fiscal year 2020, to proceed remaining important issues deduced from the conclusion of the investigations during the fiscal year 2015-2019, primary data such as groundwater chemistry need to be successively acquired. Here, the chemical analysis of 54 groundwater samples in 2022 from boreholes drilled in the 140 m, 250 m, 350 m gallery in the Horonobe URL, and water rings settled in three vertical shafts is presented. Analytical results include groundwater chemistry such as pH, electrical conductivity, dissolved components (Na, K, Ca, Mg, Li, NH, F, Cl, Br, NO, NO, PO, SO, Total-Mn, Total-Fe, Al, B, Sr, Ba, I, alkalinity, dissolved organic carbon, dissolved inorganic carbon, CO, HCO, Fe, sulfide), and O, D along with a detailed description of analytical methods.

Evaluation of H and O of water in pores extracted by compression method; Effects of closed pores and comparison to direct vapor equilibration and laser spectrometry method

Nakata, Kotaro*; Hasegawa, Takuma*; Oyama, Takahiro*; Miyakawa, Kazuya

Journal of Hydrology, 561, p.547 - 556, 2018/06

https://doi.org/10.1016/j.jhydrol.2018.03.058

no abstracts in English

Gas composition related to the Horonobe Underground Research Laboratory Project

Miyakawa, Kazuya; Tamamura, Shuji*; Nakata, Kotaro*; Hasegawa, Takuma*

JAEA-Data/Code 2016-021, 60 Pages, 2017/03

JAEA-Data-Code-2016-021.pdf:3.87MB
JAEA-Data-Code-2016-021-appendix(CD-ROM).zip:0.45MB

The Japan Atomic Energy Agency has been involved in ongoing research in the Horonobe area for the purposes of geoscientific research, and research and development (R&D) on technologies to be used for the geological disposal of high-level radioactive waste. The chemistry of groundwater and dissolved gas from deep boreholes has been obtained since H13 fiscal year for R&D on technologies related to geological characterization. Horonobe Research Institute for the Subsurface Environment (H-RISE) has investigated a resources development on promoting effective use of coal bed buried in Hokkaido including the Horonobe area using microbial communities. The data of dissolved gas from the Horonobe groundwater have also been obtained along with the microbiological research by H-RISE. Central Research Institute of Electric Power Industry (CRIEPI) has conducted R&D on technology of groundwater geochronology which is one of technologies to be used for the geological disposal, and noble gas data from the Horonobe groundwater have been obtained by CRIEPI. This report shows a data set which comprises gas data obtained from the Horonobe underground research project during the period from H13 fiscal year to H27 fiscal year.

Comparison of C collected by precipitation and gas-strip methods for dating groundwater

Nakata, Kotaro*; Hasegawa, Takuma*; Iwatsuki, Teruki; Kato, Toshihiro

Radiocarbon, 58(3), p.491 - 503, 2016/09

AA2015-0781.pdf:0.96MB

https://doi.org/10.1017/RDC.2016.22

Dissolved inorganic carbon (DIC) for C analysis of groundwater is usually extracted by a gas-strip or precipitation method. In this study, the certainty of the two methods for C dating were confirmed. DIC and C concentrations obtained by the gas-strip method were close to the theoretically predicted C value. Conversely, the C value obtained by the precipitation method always showed higher values than the predicted values. The difference in C value between gas-strip and precipitation methods was assumed to arise owing to contamination of modern carbon used in the precipitation method. The applicability of the precipitation method for groundwater should be considered carefully according to the DIC, C concentration of groundwater and purpose of the study being conducted.

Shallow groundwater intrusion to deeper depths caused by construction and drainage of a large underground facility; Estimation using H, CFCs and SF as trace materials

Hagiwara, Hiroki; Iwatsuki, Teruki; Hasegawa, Takuma*; Nakata, Kotaro*; Tomioka, Yuichi*

Nihon Suimon Kagakkai-Shi, 45(2), p.21 - 38, 2015/07

https://doi.org/10.4145/jahs.45.21

This study evaluates a method to estimate shallow groundwater intrusion in and around a large underground research facility (Mizunami Underground Research Laboratory - MIU). Water chemistry, stable isotopes (D and O), tritium (H), chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF) in groundwater were monitored around the facility (from 20 m down to a depth of 500 m), for a period of 5 years. The results show that shallow groundwater inflows into deeper groundwater at depths of between 200-400 m. In addition, the content of shallow groundwater estimated using H and CFC-12 concentrations is up to a maximum of about 50%. This is interpreted as the impact on the groundwater environment caused by construction and operation of a large facility over several years. The concomitant use of H and CFCs is an effective method to determine the extent of shallow groundwater inflow caused by construction of an underground facility.

Reduction of Neptunium(V) on Magnetite Surface

Kitamura, Akira; Nakata, Kotaro*; Tanaka, Satoru*; Tomura, Tsutomu*; Kamei, Gento

Saikuru Kiko Giho, (22), p.59 - 66, 2004/03

https://rdreview.jaea.go.jp/gihou/pdf2/n22-07.pdf

Redox reactions between neptunium(V) (Np(V)) and magnetite (Fe(II)1Fe(III)2O4) surface were investigated in N gas atmosphere. A batch method was applied to the experiment. High-pure magnetite and a 0.1 M NaCl were mixed in a polypropylene tube, and pH, redox potential and concentration of dissolved neptunium were measured as a function of shaking time (from 1 hour to 7 days), temperature (298 K and 318 K) and liquid/solid ratio (20, 50 and 100 ml.g). It was observed that the concentration of dissolved neptunium was reduced rapidly within a day, due to the reducing of Np(V) to Np(IV) and the precipitation of Np(IV). This result was shown typically when the magnetite/solution ratio and the temperature were high. The rate constant of the redox reaction and the activation energy for the rate constant were preliminarily obtained. It was suggested that the redox reaction was promoted by not only Fe(II) on magnetite surface but also Fe(II) inside the magnetite.

Sorption and reduction of Neptunium(V) on the surface of iron oxides

Nakata, Kotaro*; Nagasaki, Shinya*; Tanaka, Satoru*; Sakamoto, Yoshiaki; Tanaka, Tadao; Ogawa, Hiromichi

Radiochimica Acta, 90(9-11), p.665 - 669, 2002/12

https://doi.org/10.1524/ract.2002.90.9-11_2002.665

Sorption and desorption experiments of Np on magnetite and hematite under aerobic and anaerobic conditions were carried out to investigate the possibility of reduction of Np(V) to Np(IV) on the surfave of iron oxides including Fe(II). The results indicated that Np sorption mechanism on magnetite under anaerobic condition was completely different from that under aerobic condition. The evidence of the presence of Np(IV) on magnetite surface after sorption was obtained from the extraction experiment with TTA/xylene solution.

Sorption and desorption kinetics of Np(V) on magnetite and hematite

Nakata, Kotaro*; Nagasaki, Shinya*; Tanaka, Satoru*; Sakamoto, Yoshiaki; Tanaka, Tadao; Ogawa, Hiromichi

Radiochimica Acta, 88(8), p.453 - 457, 2000/12

https://doi.org/10.1524/ract.2000.88.8.453

Sorption kinetics of Np(V) on magnetite and hematite were investigated, and a sequential desorption method was applied to investigate changes in the chemical form of Np sorbed according to the amount of time they were in contact with the Np solution. It was found that the sorption process consists of fast sorption and slow sorption which reaches equilibrium in 1 h. From the results of sorption and desorption kinetics, it was concluded that the equilibrium between various chemical forms of sorbed Np was achieved in about 1 week, although the amount of sorbed Np reached an equilibrium in only 1 h.

JAEA-CRIEPI collaboration study on mass transport by groundwater in and around the Mizunami Underground Research Laboratory

Hama, Katsuhiro; Iwatsuki, Teruki; Hasegawa, Takuma*; Nakata, Kotaro*; Tomioka, Yuichi*; Goto, Kazuyuki*

no journal, , 

The dating of groundwater has been carried out by the measurement of radionuclides in groundwater in and around the Mizunami underground research laboratory.

Estimation of groundwater residence time based on He, Cl at Horonobe area, Hokkaido

Nakata, Kotaro*; Hasegawa, Takuma*; Iwatsuki, Teruki

no journal, , 

Groundwater residence time were inferred by He, Cl at Horonobe area, Hokkaido, Japan. Both estimated value based on He and Cl range from 2Ma to 10Ma for the groundwater deeper than -250m S.L. Those values correspond to sedimentation age of rock formations. This indicates the possibility that the groundwaters are in stagnant condition since sedimentation.