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Mihara, Morihiro; Harasawa, Shuichi*; Torii, Kazuyuki*
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(1), p.15 - 23, 2019/06
Hardened cement pastes (HCPs) of water/cement ratio (W/C) 50% and 30% using fly ash (FA), blast furnace slag (BFS) and silica fume (SF) for 28 days were prepared. Apparent diffusion coefficients (D
) of Cs and I in HCPs were obtained using electron probe microanalysis. For Cs, BFS and SF contributed to a reduction of D for W/C=50% and 30%, respectively. For I, BFS reduced D for W/C=50%, however a significant reduction in D for W/C=30% was not observed. Using SF enhanced sorption of Cs on HCP, and using BFS slightly improved sorption of Cs on HCP. It was also confirmed that the pore structures of HCP using SF and BFS were connected by fine pores. It was therefore considered that using SF and BFS contributes to the reduction of D in HCP.
Fujita, Hideki*; Harasawa, Shuichi*
JNC TJ8410 2005-005, 103 Pages, 2005/02
JNC-TJ8410-2005-005.pdf:0.75MB
Some of radioactive waste generated from JNC's facilities contain the poisonous substances such as lead and mercury. In order to establish an appropriate method of the treatment of these heavy metals, solidification performance was evaluated using cementitious materials. The results are summarized below:1. The test of stabilization process of mercuryThe conversion process from mercury to the powdery mercury sulfide(red) was examined. It was confirmed that the conversion was possible using the liquid phase reaction at 80
C by the addition of sulfur powder with the NaOH solution. 2. The fabrication and evaluation of solidified wastes (1) solidification test of the lead wasteAs for the elution ratio of lead, it had obtained the better result (0.06 mg/L) at the case of solidification of sulfide lead 30mass% packed in the total solidified waste by using Highly Fly-ash contained Silicafume Cement (HFSC) than standard value(0.3mg/L) at Regulations of Waste Management and Public Cleansing Law. Additionally, it was confirmed the using admixture of the inorganic reducing agent such as the Iron (II) chloride tetrahydrate deceased the elution ratio of lead to the under limit of measurement (0.01 mg/L) at the case of solidification of sulfide lead 30 mass% packed in the total solidified waste by using Low Alkalinity Cement contained calcium sulpho-aluminate (LAC). (2)solidification test of the mercury waste Four types of solidified waste were fabricated with different binder. It was confirmed one-axis compressive strength for all solidified waste to pass the technical standards 15kg/cm2 (1.5 Mpa) for homogeneously solidified waste as the Low-level Radioactive Waste Disposal Center in Aomori Prefecture, and the elution ratio of mercury, it had obtained the result for all solidified waste to pass the standard value (0.005 mg/L) at Regulations of Waste Management and Public Cleansing Law.
Takei, Akihiko*; Fujita, Hideki*; Harasawa, Shuichi*
JNC TJ8410 2004-007, 108 Pages, 2004/02
JNC-TJ8410-2004-007.pdf:3.03MB
In order to establish an appropriate method of the treatment of these heavy metals such as lead, cadmium and mercury, solidification performance was evaluated using cementitious materials. In this report, the solidification performance of lead, which accounts for relatively high ratio in total wastes, was evaluated.
Takei, Akihiko*; Fujita, Hideki*; Harasawa, Shuichi*
JNC TJ8400 2004-025, 79 Pages, 2004/02
JNC-TJ8400-2004-025.pdf:5.79MB
We experimentally investigated the influence of several phenomena at the disposal environment, to evaluate the long-term alteration of cementitious material. The results are shown below. (1)Hardened cement paste specimens were altered and characterized after artificial seawater permeation. The calcium dissolution was accelerated, and secondary minerals containing magnesium were deposited. The permeability became one to three orders of magnitude smaller than data from specimens altered by deionized water permeation. It was estimated that secondary mineral formations reduced the permeability. These results meant that seawater and pure water differ remarkably from each other in influence to alteration of cementitious material. (2)Two type mixture proportions concrete, two type mixture proportions mortar and a cement paste under same W/C ratio 55% were characterized, to apply the accumulated data of paste to concrete or mortar. Compressive strength of paste was lower than that of concrete and mortar. It was contrary to the previous report. The behavior of Young's modulus and Poisson's ratio could be explained well using amount of aggregate. The data of permeability meant that boundary between aggregate and cement paste didn't become path of water flow, and that aggregate disturbed permeation. (3)Self-sealing property of cracked specimen of cementitious material were investigated by the water permeation test using sodium bicarbonate solution. The permeability decreased in two orders of magnitude, and possibility of sealing was suggested. By the morphology, the deposits in the cracks might be portlandite and C-S-H, and be not calcium carbonate. (4)Alteration of characteristics of cementitious material in sodium-nitrate and ammonia solution was evaluated by the water permeation test. Alteration degree of the nitrate and ammonia solution case showed similar trend to that of the sodium nitrate solution case. This result meant that ammonia solution would not ...
Takei, Akihiko*; Fujita, Hideki*; Harasawa, Shuichi*
JNC TJ8400 2004-024, 184 Pages, 2004/02
JNC-TJ8400-2004-024.pdf:10.86MB
A study on the alteration of hydrogeological and mechanical prorperties of the cementitious material.
