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Suzuki, Eriko; Nakajima, Kunihisa; Osaka, Masahiko
Progress in Nuclear Science and Technology (Internet), 5, p.165 - 167, 2018/11
In severe accident condition, CsFeSiO could be formed by Cesium (Cs) chemisorption onto reactor structural materials. For evaluation of re-vaporization behavior, effect of atmosphere on the vaporization behavior of CsFeSiO at high temperature was investigated by thermal gravimetric-differential thermal analyzer (TG-DTA) experiments. As a result, it was found that vaporization of CsFeSiO in reducing atmosphere (Ar-5%H
) started at relatively low temperature, about 800
C, compared with in atmosphere containing HO (Ar-5%H-5%HO). It was inferred that a possible chemical reaction for the weight loss at around 800C would occurred by the decomposition of CsFeSiO into volatile Cs vapor species under H.
Suzuki, Eriko; Di Lemma, F. G.*; Nakajima, Kunihisa; Yamashita, Shinichiro; Osaka, Masahiko
no journal, ,
In order to clarify the re-vaporization behavior of caesium (Cs) chemisorbed compounds which formed onto reactor structural materials during Severe Accident (SA), Cs chemisorbed samples were reheated at 1000C and then microstructural analysis of the chemisorbed samples was conducted. In the case of stainless steel containing Mo, Cs-Mo-O compounds were formed on surface, together with major Cs-Fe-Si-O compounds, and re-vaporized easier than Cs-Fe-Si-O compounds at 1000 C.
Suzuki, Eriko; Nakajima, Kunihisa; Osaka, Masahiko
no journal, ,
In severe accident condition, CsFeSiO could be formed by Cesium(Cs) chemisorption onto reactor structural materials. For evaluation of re-vaporization behavior, effect of atmosphere on the vaporization behavior of CsFeSiO at high temperature was investigated by TG-DTA experiments. As a result, it was found that vaporization of CsFeSiO in atmosphere containing H was promoted more than those in air and in Ar(inert) atmosphere.
Suzuki, Eriko; Nishioka, Shunichiro; Nakajima, Kunihisa; Osaka, Masahiko
no journal, ,
In order to clarify the behaviour of Cs chemisorption onto stainless steel under various LWR severe accident conditions, simulated Cs chemisorption tests, the parameters were temperature and atmosphere, were performed. As a results, it was observed that Cs chemisorbed amounts and Cs revaporization behaviour from Cs chemisorbed compounds were different between the atmosphere containing HO or not. It means that Cs chemisorption behaviour is greatly affected by not only temperature but also atmosphere.
Suzuki, Eriko; Nakajima, Kunihisa; Osaka, Masahiko; Oishi, Yuji*; Muta, Hiroaki*; Kurosaki, Ken*
no journal, ,
In LWR severe accident condition, Cesium(Cs)-silicates (CsFeSiO, CsSiO
, CsSiO
) could be formed by Cs chemisorption onto reactor structural materials. For evaluation of chemisorption/re-vaporization behaviour, thermal property of each Cesium-silicates were investigated by low temperature heat capacity measurement. As a result, actual measurement values of standard entropy, which have evaluated by estimate values, were obtained. Especially for CsSiO, more reliable value of standard formation Gibbs energy was able to be evaluated.
Suzuki, Eriko; Ogawa, Hiroaki; Nakajima, Kunihisa; Nishioka, Shunichiro; Osaka, Masahiko; Yamashita, Shinichiro; Kurishiba, Ryoko*; Endo, Takashi*; Isobe, Shigehito*; Hashimoto, Naoyuki*
no journal, ,
To elucidate Cs chemisorption behaviour onto stainless steel under LWR severe accident condition, elemental distribution measurement at microlevel was performed by using XPS and TEM. As a result, it was found that Cs-(Fe)-Si-O compounds, which have different composition, could be distributed.
Suzuki, Eriko; Ogawa, Hiroaki; Nakajima, Kunihisa; Nishioka, Shunichiro; Osaka, Masahiko; Yamashita, Shinichiro; Kurishiba, Ryoko*; Endo, Takashi*; Isobe, Shigehito*; Hashimoto, Naoyuki*
no journal, ,
To elucidate Cs chemisorption behaviour onto stainless steel under LWR severe accident condition, elemental distribution measurement at microlevel was performed by using XPS and TEM. As a result, it was found that Cs-(Fe)-Si-O compounds, which have different composition, could be distributed.
Suzuki, Eriko; Nakajima, Kunihisa; Miwa, Shuhei; Osaka, Masahiko; Hashimoto, Naoyuki*; Isobe, Shigehito*
no journal, ,
In order to clarify the revaporization behaviour of cesium (Cs) chemisorbed onto stainless steel under severe accident conditions, the chemical form and distribution of fine Cs chemisorbed compounds were investigated using microscopic analytical methods. It was found that the chemical form and crystal structure differed according to the temperature of Cs chemisorption and depth from the surface. The difference can affect the revaporization rate and revaporized species.
Suzuki, Eriko; Nakajima, Kunihisa; Miwa, Shuhei; Osaka, Masahiko; Hashimoto, Naoyuki*; Isobe, Shigehito*
no journal, ,
In order to study the cesium (Cs) chemisorption behavior onto stainless steel (SUS) under severe accident conditions, the chemical form and distribution of Cs compounds formed inside of the SUS oxide layer were investigated based on the microscopic observation such as TEM/EDS. As a result, it was revealed that chemical forms of Cs compounds varies along chemisorption temperature and depth from the SUS oxide layer surface.
Suzuki, Eriko; Nakajima, Kunihisa; Miwa, Shuhei; Osaka, Masahiko; Hashimoto, Naoyuki*; Isobe, Shigehito*; Oka, Hiroshi*
no journal, ,
In order to evaluate the properties of chemisorbed cesium (Cs) onto the structural materials in nuclear reactors during severe accidents, temperature dependency of the chemical forms of Cs chemisorbed compounds was investigated based on the compilation of previous studies, the simulation tests of Cs chemisorption onto stainless steel, the acquisition of thermodynamic data and the thermodynamic equilibrium calculations, and the microstructure observation of chemical forms inside the oxide layer. It was revealed that the different Cs chemisorbed compounds were formed depending on the temperature conditions, such as Cs-Fe-O at 873-973 K, Cs-Fe-Si-O at 973-1273 K and Cs-Si-O at 1073-1273 K.
