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Ito, Tatsuya; Nagaishi, Ryuji; Kuwano, Ryo*
Nuclear Technology, 210(8), p.1427 - 1443, 2024/08
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)The retention of hydrogen (H
) bubbles generated by water radiolysis was quantitatively studied in a high-viscous suspension of carbonate slurry consisting of a mixture of suspended solid (SS) of magnesium and calcium precipitates under strongly alkaline conditions, like the radioactive wastes discharged from the coagulation sedimentation (co-precipitation) process at the multinuclide removal equipment in the Fukushima Daiichi Nuclear Power Station. The H retention properties were evaluated in two types of carbonate slurry with different hydrophilicity: the hydrophilic "current type" and the hydrophobic "return type". Then, their properties were compared with those in another suspension of clay suspension of bentonite. From the comparison between the amounts of chemical adsorption and HO in the slurry, it was confirmed that HO molecules must be shared among the SS particles, and this sharing formed the structural viscosity in the slurry, different from that in the clay suspension where electrostatic bonding between the fine clay minerals forms the viscosity. The retention of H bubbles in (by) the slurry was evaluated from the difference in the amount of H observed with and without stirring the slurry after 
Co 
-irradiation. From the comparison of the retention properties of the hydrophilic slurry, the hydrophobic slurry, the clay suspension, and treated water, it was suggested that H2 bubbles were retained not only by the structural viscosity but also by the steric hindrance in the hydrophilic slurry.
Kato, Tomoaki; Yamagishi, Isao
JAEA-Technology 2023-018, 53 Pages, 2023/11
JAEA-Technology-2023-018.pdf:2.6MB
In the decommissioning of Fukushima Daiichi Nuclear Power Station, radioactive carbonate slurry waste was generated using the Advanced Liquid Processing System (ALPS) pretreatment and temporarily stored in a high integrity container (HIC). In 2015, overflow of supernatant from HIC estimate as bubble retention in the carbonate slurry was discovered, increasing the need for a safety assessment of the carbonate slurry stored the HIC (HIC slurry). In this study, a carbonate slurry (simulated slurry) was prepared according to the Mg/Ca mass ratio in the ALPS inlet water of the HIC slurry which overflew the HIC. The effects of reaction time during the pretreatment process, suspended solids concentration (SS concentration), and settling time on the particle composition, morphology and rheological properties of the slurry were investigated. Evaluating the effect of reaction time and concentration process on chemical properties in slurry production, the effect of the reaction time was not confirmed in the simulated slurry that had undergone the concentration process, and slurry prepared at SS concentration of 150 g/L was composed of formless particles have a particle diameter of 0.4 
m or less. We also investigate the effect of SS concentration on sedimentability, decrease in SS concentration by dilution with processing solution contributed to an increase in the initial slurry settling velocity. Furthermore, two different flow characteristics were observed depending on the settling time, suggesting that the slurry at the initial settling time has non-Bingham flow properties, whereas it changes to Bingham flow properties as the settling time becomes longer. In addition, yield stress was increased with settling time, and this yield stress was found to be exponentially proportional to the density of the slurry. These results provide knowledge to estimate the current state of HIC slurry and are expected to contribute to the safety assessment.
Horita, Takuma; Yamagishi, Isao; Nagaishi, Ryuji; Kashiwaya, Ryunosuke*
JAEA-Technology 2021-012, 34 Pages, 2021/07
JAEA-Technology-2021-012.pdf:2.1MBJAEA-Technology-2021-012(errata).pdf:0.18MB
Waste mainly consisting of carbonate precipitates (carbonate slurry) from the Advanced Liquid Processing System (ALPS) and the improved ALPS at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Holdings, Inc. have been storing in the High Integrity Container (HIC). The supernatant solution of carbonate slurry contained in some of HICs were overflowed in April of 2015. The all of level of liquid in the HICs were investigated; however, almost of the HICs were under the level of overflow. The mechanism of overflow suggested to be depending on the difference of the properties of the carbonate slurry such as the retention/release characteristics of the bubbles. Therefore, in order to clarify the mechanism of leakage, the repeatability experiment was carried out by using simulated carbonate slurry. The simulated carbonate slurry was perpetrated by using the same cross-flow filter system of the actual ALPS. Moreover, the preparative conditions for the simulated carbonate slurry were the same as Mg/Ca concentration ratio in inlet water of the ALPS (raw water) and the ALPS operating conditions. The chemical characteristics of simulated carbonate slurries were revealed by ICP-AES, pH meter, etc. The density of the settled slurry layer tended to increase depending on the calcium concentration in the raw water. The bubble injection test was conducted in order to investigate the bubble retention/release behavior in the simulated carbonate slurry layer. The simulated carbonate slurry with high settling density, which was generated by high calcium concentration solution was revealed to retain the injected bubbles. Since the ratio of concentration calcium and magnesium during the carbonate slurry generation is assumed to affect the retention of bubbles in the slurry layer, the information on the composition of raw water is one of important factor for overflow of HICs.
-ray irradiationMotooka, Takafumi; Nagaishi, Ryuji; Yamagishi, Isao
QST-M-2; QST Takasaki Annual Report 2015, P. 95, 2017/03
We conducted ray irradiation test using simulated carbonate slurry to investigate the cause of stagnant water over the high integrity container (HIC). This test was performed at Co-60 irradiation facility in Takasaki Advanced Radiation Research Institute. We observed a rise in water level, air bubbles in the slurry, a supernatant when the carbonate slurry with 95 g/L density was irradiated by ray at a dose rate of 8.5 kGy/h. The cause of the rise in water level was regarded as the volume expansion by the gas retention of the carbonate slurry. It was suggested that the cause of stagnant water over the high integrity container might be the volume expansion by the gas retention.
Kubo, Shinji; Akino, Norio; Tanaka, Amane*; Nagashima, Akira*
Nihon Kikai Gakkai Rombunshu, B, 64(625), p.3013 - 3020, 1998/09
no abstracts in English
;
Nuclear Technology, 122(3), p.265 - 275, 1998/00
Times Cited Count：2 Percentile：24.27(Nuclear Science & Technology)no abstracts in English
Kubo, Shinji; Akino, Norio; Tanaka, Amane*; Nakano, Fumihiko*; Nagashima, Akira*
Thermal Science and Engineering, 5(1), p.9 - 13, 1997/01
no abstracts in English
Akino, Norio; Nakano, Fumihiko*; Kubo, Shinji; Tanaka, Amane*; Nagashima, Akira*; ;
Dai-33-Kai Nihon Dennetsu Shimpojiumu Koen Rombunshu, 0, p.233 - 234, 1996/00
no abstracts in English
Okuno, Hiroshi;
PHYSOR 96: Int. Conf. on the Physics of Reactors, 4, p.L74 - L82, 1996/00
no abstracts in English
Okuno, Hiroshi; Naito, Yoshitaka;
Journal of Nuclear Science and Technology, 31(9), p.986 - 995, 1994/09
Times Cited Count：2 Percentile：27.84(Nuclear Science & Technology)no abstracts in English
Okuno, Hiroshi; ;
JAERI-M 92-192, 105 Pages, 1992/12
no abstracts in English
; Yamaguchi, Koichi; ; ; ; Takehisa, Masaaki
JAERI-M 5477, 44 Pages, 1973/12
no abstracts in English
Garc
a-Lodeiro, I.*; Lebon, R.*; Mahoney, D.*; Zhang, B.*; Irisawa, Keita; Osugi, Takeshi; Nakazawa, Osamu; Kinoshita, Hajime*
no journal, ,
Hinai, Hiroshi; Arai, Yoichi; Fukuda, Yuhei; Kurosawa, Akira; Koma, Yoshikazu; Shibata, Atsuhiro; Nomura, Kazunori
no journal, ,
Multi-Radionuclide Removal System (MRRS) has been operating to decontaminate the contaminated water in Fukushima Daiichi Nuclear Power Station. MRRS consist of pretreatment facilities (Iron coprecipitation treatment facility and Carbonate precipitation treatment facility) and adsorption towers. This system is able to remove most of the radioactive materials except Tritium. However, Associated with a this process, the secondary radioactive wastes (slurry, spent adsorbent) were generated and stored temporary in the High Integrity Container (HIC). It is necessary to various properties investigation for the inventory evaluation and future disposal. Therefore, the carbonate slurry samples were transported from Fukushima Daiichi Nuclear Power Station to our laboratories in Tokai-mura and analyzed. High concentration of Sr-90 (1.3
10
[Bq/cm
]) was determined in the sample by the radioactive measurement, it is inferred that the contaminated water has been concentrate. And small amount of 
-ray emitting nuclides were determined. As the result of ICP-AES, it is estimated that most of slurry occupy CaCO
and Mg(OH). These obtained data showed that decontamination system is operating normally. Also, the particle size of the slurry was analyzed by image analyzing method. The particles of slurry was found to have a median particle diameter of several m.
Yamagishi, Isao; Motooka, Takafumi
no journal, ,
Highly radioactive wastes such as carbonate slurry and zeolite are generated from the contaminated water treatment system at Fukushima Daiichi Nuclear Power Station. We have studied radiolytic gas generation in wet wastes for their safe storage. Carbonate slurry or wet zeolite as a simulated waste was irradiated by -ray. Radiolytic gas generation resulted in the slurry expansion and supernatant separation from the slurry. The supernatant was observed during irradiation of the zeolite immersed fully in seawater but not in case of the partial immersion.
