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Tanaka, Satoru*; Nagasaki, Shinya*; *; *; Muraoka, Susumu; *; *; *; *; *; et al.
Nihon Genshiryoku Gakkai-Shi, 39(12), p.1008 - 1018, 1997/00
Times Cited Count：3 Percentile：30.37(Nuclear Science & Technology)no abstracts in English
Kamei, Gento; Yusa, Yasuhisa; Sasaki, Noriaki
PNC TN8410 91-253, 8 Pages, 1992/01
Time-temperature conditions and water chemistry on illitization at the Murakami deposit in central Japan were determined. The extent of the illitization and time-temperature condition estimated were as follows: the duration for conversion from 0 to 80% illite (volumetric ratio) was approximately 3.5 Ma in the temperature range from 340 to 100
C, Conversion from 0 to 40% requires approximately 3.0 Ma in the temperature range from 240 to 100C, During 2.0Ma in the temperature range from 160 to 100C, however, illite was scaroely observed, Water chemistry is estimated from two approaches, namely laboratory experiment and numerical analysis. The former is an interactive experiment between seawater and the tuff of the deposit. The latter is a calculation based on the difference of bulk composition between illitized and non-illitized tuff. The extent of each ionic concentration is inferred to be as follows: K
; 560 to 6400, Mg
; 800 to 1700, Ca; 360 to 2900, Na; 9400 to 15000 (mg/l).
Yusa, Yasuhisa; ; Arai, Takashi
PNC TN8410 91-007, 18 Pages, 1990/12
This paper contains an overview of analogue studies for the assessment of long-term durability of engineered barrier materials at PNC Tokai. Materials of young age and with simple history are the most suitable for study as: (1)properties of the materials tend to deteriorate over longer historical time intervals; and (2) detailed quantitative data on time intervals and environmental conditions are more likely to be available. The following materials and their alteration phenomena were selected: (1)weathering alteration of basaltic glass (as vitrified waste form), (2)corrosion of iron in soil (as overpack), (3)illitization of smectite associated with contact metamorphism (as buffer material), (4)alteration of cement (as buffer or backfill material). (1)Weathering alteration of basaltic glass: Basaltic g1asses, from the Fuji and the Izu-Ohshima pyroclastic fall deposits were studied. The observations were made: (a)Climatological conditions have not varied significantly during the last three thousand years. Therefore, values for temperature, amount, and chemistry of ground water are quantified. (b)The cases studied could be regarded as leaching experiments in groundwater, using mass balances in water-g1ass interaction. (c)Although the groundwater is of Ca(Mg)-HCO
type in the Fuji area and of Na-Cl type in the Izu-Ohshima, similar alteration ratios (2
3
m/1000yr) were obtained. (2)Corrosion of iron in soil: Industrial materials, such as gas/water service pipes of carbon steel or cast iron embedded in soil for 20 110 years, were selected for an analogue study of corrosion of iron in bentonite. The maximum corrosion rates obtained so far fall in the range of 0.040.09 mm/yr. (3)Illitization of smectite associated with contact metamorphism: In the Murakami bentonite deposit in central Japan, lateral variation of smectite to smectite/illite mixed-layer minerals are found in the aureole of the rhyolite intrusion body. Conversion of smectite to the
