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Yoneyama, Kai*; Sato, Isamu*; Matsuura, Haruaki*; Koshigoe, Koki*; Miyahara, Naoya*; Kurihara, Norihiko*; Suzuki, Eriko; Osaka, Masahiko
no journal, ,
For the safety and rational management of radioactive concrete waste generated in the decommissioning of Fukushima-Daiichi Nuclear Power Station, we have developed the estimation technology for Cs penetration into concrete, considering the fraction/distribution of mortar and aggregate. In this work, the Cs distribution and diffusion coefficients of mortar, aggregate and concrete were evaluated by the Cs penetration tests to identify the influencing factor on Cs penetration behavior. While the distribution and diffusion coefficients of aggregate were smaller than that of mortar, the diffusion coefficient of concrete, which contained aggregates, was smaller than that of mortar. This result suggests that the existence of aggregate could significantly affect the Cs penetration behavior.
Yoneyama, Kai*; Sato, Isamu*; Matsuura, Haruaki*; Koshigoe, Koki*; Miyahara, Naoya*; Kurihara, Norihiko*; Suzuki, Eriko; Osaka, Masahiko
no journal, ,
For the rational management of radioactive concrete waste generated in the decommissioning of LWR severe accident, the influence of mortar and aggregate on Cs penetration behavior based on the Cs penetration test using mortar, aggregate and concrete. While the distribution and diffusion coefficients of aggregate were smaller than that of mortar, the diffusion coefficient of concrete, which contained aggregates, was smaller than that of mortar. This result suggests that the boundary surfaces between aggregate and mortar could affect the Cs penetration behavior.
Yoneyama, Kai*; Sato, Isamu*; Matsuura, Haruaki*; Koshigoe, Koki*; Miyahara, Naoya*; Kurihara, Norihiko*; Suzuki, Eriko; Osaka, Masahiko
no journal, ,
For the management of radioactive concrete waste generated in a severe accident of light water reactor, the cesium (Cs) penetration tests into the mortar, aggregate and concrete were performed in order to evaluate the influence of aggregate on Cs penetration behavior. While the diffusion coefficient of aggregate was very smaller than that of mortar, the diffusion coefficient of concrete, which contained the aggregate, was larger than that of mortar. This result suggests that the interface between mortar and aggregate promoted the Cs penetration.
Yoneyama, Kai*; Sato, Isamu*; Matsuura, Haruaki*; Miyahara, Naoya*; Kurihara, Norihiko*; Suzuki, Eriko; Miwa, Shuhei
no journal, ,
In order to contribute for the clarification of Cs penetration behavior into concrete, the penetration tests using low Cs concentration solution and the neutron activation analysis of concentration of penetrated Cs were carried out. Since the neutron activation analysis can improve the accuracy of concentration analysis, the distribution coefficient and diffusion coefficient of low Cs concentration solution were obtained. Furthermore, the dependence of Cs concentration in solution on the penetration behavior into concrete were revealed based on comparing with the previous studies of penetration tests using high Cs concentration solution.
Kondo, Kosuke*; Yoneyama, Kai*; Sato, Isamu*; Matsuura, Haruaki*; Kurihara, Norihiko*; Suzuki, Eriko
no journal, ,
In order to contribute to the evaluation of contamination distribution in decommissioning and to evaluate of radioactivity of dismantled wastes in the Fukushima Daiichi Nuclear Power Plant, we conducted penetration and elution experiments of Cs into concrete, which are used as a structural material inside and outside the containment vessel of the nuclear power plant. Furthermore, it is aimed to create an evaluation method of Cs mass flow under various behavior by combining Neutron Activation Analysis, Particle Induced X-ray Emission, and Inductively Coupled Plasma Mass Spectrometry. As a result, it was revealed that diffusion coefficient of Cs into concrete is increased with Cs concentration of solution and elution ratio of Cs is decreased with depth from surface.
Yoneyama, Kai*; Sato, Isamu*; Kondo, Kosuke*; Matsuura, Haruaki*; Kurihara, Norihiko*; Suzuki, Eriko
no journal, ,
In order to contribute to the elucidation of Cs adsorption behavior on stainless steel, heating experiments were conducted, in which aerosolized CsI reacted with stainless steel. Moreover, solution experiments of Cs compounds containing Si or Cr was performed. INAA, SEM / EDS and ICP-MS were used for determination of Cs material flows. As a result, quantitative data of water-soluble/ water-insoluble Cs compounds generated by the reaction of aerosolized CsI and stainless steel.
Kondo, Kosuke*; Sato, Isamu*; Matsuura, Haruaki*; Fujino, Daiki*; Kurihara, Norihiko*; Nakajima, Kunihisa
no journal, ,
Cs penetration and leaching experiments into/from concrete materials, simulating exposed to dry and wet environmental changes, showed different behavior depending on the number of dry/wet cycles. In our study, the microstructure of concrete with different number of dry/wet cycles is observed using fluorescent epoxy resin to examine the details structural changes. As a result, it was found that when the mortar is heated in an air atmosphere of 400
C or higher, voids are formed due to the decomposition of Ca(OH)
resulting in a complicated path and deep permeation of the resin.