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Kyono, Atsushi*; Yamamoto, Genichiro*; Yoneda, Yasuhiro; Okada, Satoru*
Isotope News, (783), p.23 - 27, 2022/10
Mineral traps are attracting attention as an underground storage method for carbon dioxide. Carbon dioxide laden groundwater reacts with basalt to form magnesite. The formed magnesium carbonate phase varies in many ways, but we tried to clarify the structure because all of them pass through amorphous magnesium carbonate. Pair distribution function using high-energy X-ray diffraction revealed that amorphous magnesium carbonate has a structure similar to that of hydromagnesite. It can be said that it is a safe sequestration method as a carbon dioxide storage technology.
Suzuki, Satoru; Sato, Haruo
JNC TN8410 2001-028, 36 Pages, 2002/03
JNC-TN8410-2001-028.pdf:1.81MB
For a safety assessment of the high-level radioactive waste disposal, effective diffusion coefficients (D
) of radionuclides in bentonite have been accumulated by the through-diffusion method. It has been found recently that experimental results on Ds for several cations (cesium and strontium) by the fairly standard experimental method in JNC differ from those previously reported in several papers. Discrepancy can be considered to be due to different design of diffusion cell and system. In order to confirm influences of the experimental design on cation diffusivities in bentonite, a flow-through diffusion system was developed and several diffusion experiments were conducted.As a result, magnitude of D and its salinity dependence were relatively different between the standard and flow-through diffusion system. Since the latter system can control boundary conditions of the experiment more strictly than the standard method, we can conclude that the flow-through diffusion system provide correct results. In addition, we apply this flow-through diffusion system to a modification of controlling boundary condition during the experiment and to the diffusion experiment under controlled temperature.
; Ohno, Shuji;
JNC TN2400 2000-006, 56 Pages, 2000/12
JNC-TN2400-2000-006.pdf:1.22MB
Sodium combustion analyses were performed using ASSCOPS version 2.1 in order to obtain background data for evaluating the validity of the mitigation system against secondary sodium leak of MONJU. The calculated results are summarized as follows. (1)Peak atmospheric pressure 
4.3 kPa[gage] (2)Peak floor liner temperature 870
C, Maximum thinning of liner 2.6mm (3)Peak hydrogen concentration <2% (4)Peak floor liner temperature in the spilt sodium storage eell 400C , Peak floor concrete temperature in the spilt sodium storage cell 140C.
; Aoto, Kazumi;
PNC TN9450 97-012, 75 Pages, 1996/11
This report described the results of tensile and creep tests under a high temperature with the welded joints of liner plate (SM400B) used in SHTS cells of leaked sodium storage system of "NONJU plant". Results obtained are summarized as follows. (1)Foundmental high temperature strength characteristics data of the welded Joints were acquired. (2)There is no effect of heat treatment and cut-out direction on tensile strength and rupture elongation of liner plate. (3)The rupture ductility (rupture elongation and reduction of area) is lower than one of the base metal. Especially, rapidly droped in the temperature over 800 C. (4)The creep strength of welded joint is almost same as one of the based metal. It will be estimated the effect of change of the micro-structure on the ductility. (5)Generally speaking, two phases of 
phase and 
phase intermingled exist under about 800C, and phases transform to the phase under about 900C over Ac3 transformation point. Then the grain boundary in HAZ, begin to grow, and the intergranular failure appears in over 900C. The results will be applied to evaluate the stractural integrity of SHTS cells of leaked sodium storage system of "MONJU plant". (SHTS ; Secondary Heat Transfer System)
Niimi, Ken; Osawa, Hideaki; Yanagizawa, Koichi; ; Yoshida, Hidekazu; Seo, Toshihiro;
PNC TN7410 94-022, 190 Pages, 1994/03
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