Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Nemoto, Yoshiyuki; Kaji, Yoshiyuki; Kanazawa, Toru*; Nakashima, Kazuo*; Tojo, Masayuki*
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05
Oxidation behaviour of Zr cladding in SFP accident condition was evaluated by using a thermobalance in this work, and the obtained data were applied to construct oxidation model for SFP accident condition. For the validation of the constructed oxidation model, oxidation tests using a long cladding tube 500mm in length were conducted in conditions simulating SFP accidents, such as flow rate of the atmosphere in spent fuel rack, temperature gradient along the axis of cladding, and heating-up history. Thickness of oxide layer formed on the surface of cladding samples was evaluated by cross sectional observation, and compared with calculation results obtained by using the oxidation model. The detail of experimental results and validation of the oxidation model will be discussed.
Tojo, Masayuki*; Kanazawa, Toru*; Nakashima, Kazuo*; Iwamoto, Tatsuya*; Kobayashi, Kensuke*; Goto, Daisuke*; Nemoto, Yoshiyuki; Kaji, Yoshiyuki
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 13 Pages, 2019/05
In this study, fuel loading effects in BWR spent fuel rack accidents are widely investigated using three-dimensional analysis methods from both nuclear and thermal hydraulics viewpoints, including: (a) Decay heat of spent fuel after discharge, (b) The maximum temperature of spent fuel cladding in the spent fuel rack depending on heat transfer phenomena, and (c) Criticality of the spent fuel rack after collapsing of the fuel due to a severe accidents in the BWR spent fuel pool (SFP).
Nemoto, Yoshiyuki; Kaji, Yoshiyuki; Onizawa, Takashi*; Kanazawa, Toru*; Nakashima, Kazuo*; Tojo, Masayuki*
Proceedings of Annual Congress of the European Federation of Corrosion (EUROCORR 2018) (USB Flash Drive), 8 Pages, 2018/09
The authors proposed oxidation models based on oxidation data which previously obtained in high temperature oxidation tests on small sample of Zircalloy-2 (Zry2) cladding in dry air and in air/steam mixture environment. The oxidation models were implemented in computational fluid dynamics (CFD) code to analyse oxidation behavior of long cladding sample in hypothetical spent fuel pool (SFP) accident conditions. The oxidation tests were conducted using Zry2 cladding sample 500 mm in length. The oxide layer growth in dry air was well reproduced in the calculation using the oxidation model, meanwhile which in air/steam mixture was overestimated atmosphere composition change anticipated in the spent fuel rack during the accident, and its influence on the oxidation behaviour of the cladding were discussed in consideration of the oxidation model improvement.
Nemoto, Yoshiyuki; Kaji, Yoshiyuki; Ogawa, Chihiro; Kondo, Keietsu; Nakashima, Kazuo*; Kanazawa, Toru*; Tojo, Masayuki*
Journal of Nuclear Materials, 488, p.22 - 32, 2017/05
Times Cited Count:2 Percentile:19.24(Materials Science, Multidisciplinary)The authors previously conducted thermogravimetric analyses on zircaloy-2 in air. By using the thermogravimetric data, an oxidation model was constructed in this study so that it can be applied for the modeling of cladding degradation in spent fuel pool (SFP) severe accident condition. For its validation, oxidation tests of long cladding tube were conducted, and computational fluid dynamics analyses using the constructed oxidation model were proceeded to simulate the experiments. In the oxidation tests, high temperature thermal gradient along the cladding axis was applied and air flow rates in testing chamber were controlled to simulate hypothetical SFP accidents. The analytical outputs successfully reproduced the growth of oxide film and porous oxide layer on the claddings in oxidation tests, and validity of the oxidation model was proved. Influence of air flow rate for the oxidation behavior was thought negligible in the conditions investigated in this study.
Kanazawa, Toru*; Hidaka, Akihide; Kudo, Tamotsu; Nakamura, Takehiko*; Fuketa, Toyoshi
JAERI-Tech 2004-050, 53 Pages, 2004/06
As a part of release evaluation in VEGA program, the mass balances of released and deposited FP onto the test apparatus are estimated from gamma ray measurement for acid solution leached from the apparatus, but short-life or radionuclides without emitting rays and very small quantity of elements cannot be quantified. Therefore, a microanalysis by ICP-AES is planed for acid solution leached from apparatuses. Since Cs have strong ray spectrum, they have to be removed from solution in advance to avoid contamination of ICP system and to decrease exposure to ray. The method for Cs separation using inorganic ion exchanger, AMP was applied to the test solutions. The results showed that more than 99.9% of Cs could be removed from test solution, and once removed Sb by AMP was recovered by using a complexing agent such as citric acid. The ICP-AES analysis showed that amount of U, Sr and Zr were successfully quantified. The release and deposition will be quantified through ICP-AES analysis for acid solutions from which Cs is separated by AMP or other precipitation method.
Hidaka, Akihide; Kudo, Tamotsu; Nakamura, Takehiko; Kanazawa, Toru; Kiuchi, Toshio; Uetsuka, Hiroshi
JAERI-Tech 2003-009, 30 Pages, 2003/03
The VEGA (Verification Experiments of radionuclides Gas/Aerosol release) program is being performed at JAERI to clarify mechanisms of radionuclides release from irradiated fuel during severe accidents and to improve source term predictability. The fifth VEGA-5 test was conducted in January 2002 to confirm the reproducibility of decrease in cesium release under elevated pressure that was observed in the VEGA-2 test and to investigate the release behavior of short-life radionuclides. The PWR fuel of 47GWd/tU after 8.2 years of cooling was re-irradiated at Nuclear Safety Research Reactor (NSRR) for 8 hours before the heat-up test. After that, the two pellets of 10.9g without cladding were heated up to about 2,900K at 1.0MPa under the inert He condition. The experiment reconfirmed the decrease in cesium release under elevated pressure. The release data on short-life radionuclides such as Ru-103 and Ba-140 that has never been observed in the previous VEGA tests without re-irradiation was obtained using the gamma ray measurement.
Nakamura, Jinichi; Sugiyama, Tomoyuki; Nakamura, Takehiko; Kanazawa, Toru; Sasajima, Hideo
JAERI-Tech 2003-008, 32 Pages, 2003/03
no abstracts in English
Kotaki, Hideyuki; Kando, Masaki; Hosokai, Tomonao; Kondo, Shuji; Masuda, Shinichi; Kanazawa, Shuhei; Yokoyama, Takashi*; Matoba, Toru; Nakajima, Kazuhisa
International Journal of Applied Electromagnetics and Mechanics, 14(1-4), p.255 - 262, 2003/03
no abstracts in English
Kotaki, Hideyuki; Kando, Masaki; Oketa, Takatsugu; Masuda, Shinichi; Koga, J. K.; Kondo, Shuji; Kanazawa, Shuhei; Yokoyama, Takashi*; Matoba, Toru; Nakajima, Kazuhisa
Physics of Plasmas, 9(4), p.1392 - 1400, 2002/04
Times Cited Count:47 Percentile:79.38(Physics, Fluids & Plasmas)no abstracts in English
Kando, Masaki; Kotaki, Hideyuki; Kondo, Shuji; Kanazawa, Shuhei; Masuda, Shinichi; Yokoyama, Takashi*; Matoba, Toru; Nakajima, Kazuhisa
Proceedings of 26th Linear Accelerator Meeting in Japan, p.132 - 134, 2001/08
no abstracts in English
Masuda, Shinichi; Kando, Masaki; Kotaki, Hideyuki; Hosokai, Tomonao*; Kondo, Shuji; Kanazawa, Shuhei; Yokoyama, Takashi*; Matoba, Toru; Nakajima, Kazuhisa
Proceedings of 13th Symposium on Accelerator Science and Technology, 3 Pages, 2001/00
no abstracts in English
Kotaki, Hideyuki; Kando, Masaki; Kondo, Shuji; Masuda, Shinichi; Kanazawa, Shuhei; Yokoyama, Takashi*; Matoba, Toru; Nakajima, Kazuhisa
Proceedings of 13th Symposium on Accelerator Science and Technology, 3 Pages, 2001/00
no abstracts in English
Nemoto, Yoshiyuki; Kaji, Yoshiyuki; Ogawa, Chihiro; Nakashima, Kazuo*; Tojo, Masayuki*; Kanazawa, Toru*; Goto, Daisuke*
no journal, ,
In order to investigate the air oxidation behavior of cladding materials for study on improvement of safety in spent fuel pool loss of coolant accident condition, both isothermal oxidation tests by short length specimens and oxidation tests with temperature gradient by long length specimens were conducted and the knowledge on influence of temperature and air flow rate on cladding oxidation behavior was obtained in this study.
Nemoto, Yoshiyuki; Kaji, Yoshiyuki; Ogawa, Chihiro*; Nakashima, Kazuo*; Kanazawa, Toru*; Tojo, Masayuki*
no journal, ,
Concerning the severe accident analysis in spent fuel pools (SFPs), it is important to construct the high temperature oxidation model of the Zirconium claddings exposed in loss-of-coolant accident condition. In this study, an oxidation model of Zry2 in air environment was constructed by using these basic data. The constructed oxidation model was applied for simulation of oxidation tests using long cladding tubes of Zry2 in hypothetical SFP accident conditions. Reproducibility of the calculation was evaluated in comparison with the results of experiment to validate the oxidation model.
Nemoto, Yoshiyuki; Onizawa, Takashi*; Kaji, Yoshiyuki; Nakashima, Kazuo*; Kanazawa, Toru*; Tojo, Masayuki*
no journal, ,
Cladding oxidation model construction and its validation is necessary for the upgrading of severe accidentcode which will be utilized for analysis of the spent fuel pool (SFP) accident. Cladding oxidation tests and analyses using the proposed oxidation model were coducted in the simulated SFP accident condition, and their results were compared. Modification of the oxidation model will be discussed in the lecture.
Tojo, Masayuki*; Kanazawa, Toru*; Kobayashi, Kensuke*; Goto, Daisuke*; Nemoto, Yoshiyuki; Kaji, Yoshiyuki
no journal, ,
Computational fluid dynamics (CFD) analysis for the loss of coolant accident in spent fuel pool (SFP) with Zircalloy-2 cladding was conducted. In the higher region of spent fuel rack internal, oxygen content in the atmosphere was decreased because of oxigen consumption during the oxidation reaction of cladding material. This oxygen depression is thought to surpress the oxidation of claddings.