BWR lower head penetration failure test focusing on eutectic melting

Yamashita, Takuya; Sato, Takumi; Madokoro, Hiroshi; Nagae, Yuji

Annals of Nuclear Energy, 173, p.109129_1 - 109129_15, 2022/08

https://doi.org/10.1016/j.anucene.2022.109129

Online solid-phase extraction-inductively coupled plasma-quadrupole mass spectrometric quantification of Sr using Sr/Sr isotope dilution method

Yanagisawa, Kayo*; Odashima, Mizuki*; Matsueda, Makoto; Furukawa, Makoto*; Takagai, Yoshitaka*

Talanta, 244, p.123442_1 - 123442_7, 2022/07

https://doi.org/10.1016/j.talanta.2022.123442

The determination of a low concentration of Sr was achieved by the combination of online SPE-ICP-QMS and ID method using Sr/Sr ratio. No requirement of radioactive standard material and the preparation process of the calibration curve was in the quantification process and data acquisition can be in one-shot sample injection. The proposed method allowed the rapid (within 15 min/sample) quantification of Sr in the presence of significant interferences such as isobaric Zr and other elements. The LOD for Sr was 5.6 Bq/L for a 10 mL injection and this could be improved by simply increasing the sample volume injected.

Chemical species of iodine during sorption by activated carbon; Effects of original chemical species and fulvic acids

Kato, Tomoaki; Kozai, Naofumi; Tanaka, Kazuya; Kaplan, D. I.*; Utsunomiya, Satoshi*; Onuki, Toshihiko

Journal of Nuclear Science and Technology, 59(5), p.580 - 589, 2022/05

https://doi.org/10.1080/00223131.2021.1993370

This study reports the effect of fulvic acids, which is a natural organic substance generally contained in groundwater, on the oxidation states of radioactive iodine anions (iodide and iodate). Iodide and iodate are contained in the contaminated water of the Fukushima Daiichi Nuclear Power Plant and supposed to be removed by activated carbon (AC) via adsorption. When fulvic acids does not exist in the experimental system, the adsorption of iodide on AC was less than that of iodate and their oxidation states after the adsorption were not changed. When fulvic acids existed, a fraction of the adsorbed iodate was reduced to iodide. This result indicates that the reduction of the adsorbed iodate progresses during the storage of the spent AC.

Simulation of the self-propagating hydrogen-air premixed flame in a closed-vessel by an open-source CFD code

Thwe, T. A.; Terada, Atsuhiko; Hino, Ryutaro; Nagaishi, Ryuji; Kadowaki, Satoshi

Journal of Nuclear Science and Technology, 59(5), p.573 - 579, 2022/05

https://doi.org/10.1080/00223131.2021.1990153

The simulations of the combustion of self-propagating hydrogen-air premixed flame are performed by an open-source CFD code. The flame propagation behavior, flame radius, temperature and pressure are analyzed by varying the initial laminar flame speed and grid size. When the initial laminar speed increases, the thermal expansion effects become strong which leads the increase of flame radius along with the increase of flame surface area, flame temperature and pressure. A new laminar flame speed model derived previously from the results of experiment is also introduced to the code and the obtained flame radii are compared with those from the experiments. The formation of cellular flame fronts is captured by simulation and the cell separation on the flame surface vividly appears when the gird resolution becomes sufficiently higher. The propagation behavior of cellular flame front and the flame radius obtained from the simulations have the reasonable agreement with the previous experiments.

Simultaneous determination of zircon crystallisation age and temperature; Common thermal evolution of mafic magmatic enclaves and host granites in the Kurobegawa granite, central Japan

Yuguchi, Takashi*; Yamazaki, Hayato*; Ishibashi, Kozue*; Sakata, Shuhei*; Yokoyama, Tatsunori; Suzuki, Satoshi*; Ogita, Yasuhiro; Sando, Kazusa*; Imura, Takumi*; Ono, Takeshi*

Journal of Asian Earth Sciences, 226, p.105075_1 - 105075_9, 2022/04

https://doi.org/10.1016/j.jseaes.2021.105075

Simultaneous determination of the U-Pb age of zircon and concentration of titanium in a single analysis spot, using inductively coupled plasma mass spectrometry with laser ablation sample introduction, produces paired age and temperature data of zircon crystallisation, potentially revealing time-temperature () histories for evolved magma. The Kurobegawa granite, central Japan, contains abundant mafic magmatic enclaves (MMEs). We applied this method to evaluate MMEs and their host (enclosing) granites. Cooling behaviour common to both MMEs and host rocks was found between 1.5 and 0.5 Ma. Rapid cooling from the zircon crystallisation temperature to the closure temperature of biotite K-Ar system was within 1 million year. Combining the obtained paths of MMEs and host rocks with petrological information can provide insights into magma chamber processes. This suggests that MME flotation, migration, and spread through the magma chamber ceased at 1.5-0.5 Ma, indicating the emplacement age of the Kurobegawa granitic pluton, as no large-scale reheating episodes have occurred since then.

Post-test analyses of the CMMR-4 test

Yamashita, Takuya; Madokoro, Hiroshi; Sato, Ikken

Journal of Nuclear Engineering and Radiation Science, 8(2), p.021701_1 - 021701_13, 2022/04

https://doi.org/10.1115/1.4051443

Distribution, dynamics, and fate of radiocesium derived from FDNPP accident in the ocean

Otosaka, Shigeyoshi*; Kamidaira, Yuki; Ikenoue, Tsubasa; Kawamura, Hideyuki

Journal of Nuclear Science and Technology, 59(4), p.409 - 423, 2022/04

https://doi.org/10.1080/00223131.2021.1994480

After the accident at Fukushima Daiichi Nuclear Power Plant (FDNPP), many oceanographic observations were carried out from various perspectives. Numerical simulations were also effectively applied to understand the distribution of radionunclides. By integrating these results, the dynamics of the accident-derived radionuclides in the ocean were highlighted. The transport processes of the accident-derived radionuclides to the ocean include (1) direct discharge to the ocean, (2) deposition in the ocean via the atmosphere, and (3) inflow from rivers after deposition to the land surface. In the case of Cs, one of major accident-derived radionuclides, most of the supply to the ocean immediately after the accident (8-21 PBq) was estimated to be due to processes (1) and (2). The amount of Cs accumulated on the seafloor is only about 1% (0.2PBq) of the amount carried to the ocean, but it remains in the sediments in the coastal area for a long period of time and gradually migrates to the seawater and ecosystems near the seafloor.

Time-resolved 3D visualization of liquid jet breakup and impingement behavior in a shallow liquid pool

Kimura, Fumihito*; Yamamura, Sota*; Fujiwara, Kota*; Yoshida, Hiroyuki; Saito, Shimpei*; Kaneko, Akiko*; Abe, Yutaka*

Nuclear Engineering and Design, 389, p.111660_1 - 111660_11, 2022/04

https://doi.org/10.1016/j.nucengdes.2022.111660

Effect of Sr dissolved solution on corrosion potential of type 316L stainless steel

Aoyama, Takahito; Kato, Chiaki; Sato, Tomonori; Sano, Naruto; Yamashita, Naoki; Ueno, Fumiyoshi

Zairyo To Kankyo, 71(4), p.110 - 115, 2022/04

no abstracts in English

Test methods for robots for nuclear emergency response and decommissioning; Test for maneuvering robot arm over an obstacle (JAEA-TM-0006)

Yamada, Taichi; Kawabata, Kuniaki; Abe, Hiroyuki*

JAEA-Technology 2021-033, 18 Pages, 2022/03

JAEA-Technology-2021-033.pdf:1.58MB

This report describes the test procedures for evaluating performances involved in robot arm maneuvering of remotely operated robot utilized for nuclear emergency responses and decommissioning. After the accident at Fukushima Daiichi Nuclear Power Station of the Tokyo Electric Power Company Holdings Inc. (FDNPS) occurred, remotely operated robots have been deployed and utilized in the response tasks. Such post-accident work experience and lessons learned are very valuable for developing the robots in the future. Therefore, we were motivated to develop the test methods for performance evaluation of the robot by referring with such experiences and lessons. In the response and the decommissioning tasks, robots with a robot arm were deployed for door opening, removal objects, decontamination and cleanup and so on. Some of these tasks were conducted in an environment with obstacles by robot arms maneuvering. This report describes test procedures for quantitatively evaluating the performances which are for maneuvering involving in robot arm to approach target objects in an environment with obstacles. A typical course layout and the demonstration of test are also illustrated for the references.