Diffusion Behaviour of Nuclides Considering Pathways in Fractured Crystalline Rocks

Sato, Haruo; ; ; *; *; Yui, Mikazu

PNC TN8410 97-127, 57 Pages, 1997/08

PNC-TN8410-97-127.pdf:1.51MB

Retardation of key nuclides is one of the most important mechanisms to be examined specifically and modelled for the performance assessment of geological disposal of radioactive waste. We have been studing diffusion of nuclides into the pore spaces of the rock matrix, sorption of nuclides on the rock pore surfaces and pore properties to quantify the degree of nuclide retardation in fractured crystalline rock. The work has concentrated on predominant water conducting fracture system in the host granodiorite in the Kamaishi In Situ Test Site, which consists of fracture fillings and altered granodiorite. Through-diffusion experiements to obtain effective and apparent diffusion coefficients (Da and De, respectively) for Na, Cs, HTO, Cl and Se as a function of ionic charge at 22 25C and batch sorption experiments for Cs, Sr, Se, U and Pu were conducted on fracture fillings, altered and intact granodiorite. The experiments only for Se, a redox sensitive element, were done in an N2-atmospheric glove box (O 1 ppm) to keep the chemical species. In situ groundwater (pH8.79.5) sampled from the same place as rock samples was used for the experiments. Porosity and density of cach rock sample were determined by both water saturation method and mercury porosimetry, and pore-size distribution and specific surface area of pores were measured by mercury porosimetry. The porosity is in the order; fracture fillings (5.6%) altered rock (3.2%) intact rock (2.3%). The pore-size distribution of the intact and altered granodiorite is ranging from 10 nm to 0.2 mm, and the fracture fillings have that of 50 nm to 0.2 mm, but a lot of pores were found around 100 nm and 0.2 mm in the fracture fillings. The effective diffusion coefficients for all species (Na, Cs, HTO, Cl, Se0) are in the order of fracture fillings altered rock intact rock in proportion to these porosities. Effective diffusion ...

None

PNC TJ1635 95-001, 9 Pages, 1995/03

PNC-TJ1635-95-001.pdf:0.31MB

no abstracts in English

The Measurement of Gas Permeability in Various Graphites

; Iwamoto, K.

JAERI-M 5937, 30 Pages, 1974/12

JAERI-M-5937.pdf:4.22MB

no abstracts in English

The Characteristic Physical Properties of the Powder Polyethylene Produced by Radiation-Induced Polymerization (Takathene)

Yamaguchi, Koichi; Takehisa, Masaaki

JAERI-M 5524, 32 Pages, 1974/01

JAERI-M-5524.pdf:0.88MB

no abstracts in English

Improvement of pretreatment method for organically bound tritium analysis

Fujiwara, Kenso; Kuwata, Haruka*; Terashima, Motoki; Akata, Naofumi*

no journal, , 

The analysis method for organically bound tritium is summarized in the radioactivity measurement method series managed by the regulatory agency, but the pretreatment takes time. So far, joint research has investigated shortening the pretreatment, but the pretreatment still takes about a week, and speeding up is expected. This time, we investigated the relationship between the shape and weight of the sample and the time to reach a constant weight during freeze-drying. In the freeze-drying process, by increasing the surface area of the sample, the process that used to take about two days was shortened to about one day. In addition, with the aim of promoting efficient combustion, we attempted to accumulate data that would contribute to the control of combustion temperature by suggestive thermal analysis of organic matter samples.