Photon Factory Activity Report 2016 #34 (2017)

BL-27B/2015G566

Local Structure of Simulated Radioactive Wastes in Molten Borosilicate Glasses
Including Vanadium - Effect of Alkali Oxide Contents
Yuri Tajimi1, Kei Shiina1, Takafumi Uchiyama2, Taku Hashimoto 3, Hidenori Kawashima3,Toshiaki Kakihara3, and Haruaki Matsuura1,2
1

Cooperative Major in Nuclear Engineering, Tokyo City University, 1-28-1, Tamazutsumi,
Setagaya-ku, Tokyo, 1588557, Japan2
Atomic Energy Research Laboratory, Tokyo City University, 971, Ozenji, Asao-ku, Kawasaki,Kanagawa, 2150013, Japan3IHI Corp., 1, Shin-nakahara-cho, Isogo-ku,Yokohama, 2358501, Japan
1 Introduction
At present, high-level liquid wastes are planned to bedisposed below 300 meters underground as vitrified glassin Japan.
One of major fission products, Mo tends to turn into
alkali molybdate, so called “yellow phase”. It makes
problematic not only at stable operation of glass melter,but also at less homogeneity of final product. It is known
that adding vanadium in borosilicate glass increases theincluding amount of fission products and reduces alkali
molybdate. Extended X-ray Absorption Fine Structure,
which can be focused on the local structure around atargetted atom. Vanadium containing borosilicate glasswith variated alkali contents have been molten in a
furnace, and EXAFS spectra at various temperature havebeen obtained.
We have investigated which kind of alkali content isappropriate for making strucurally stable glass.
2 Experiment
EXAFS measurement by transmission method has been
carried out using an electric furnace at BL-27B.
The temperature was gradually decreased from 1200 oC,
800 oC and room temperature, and the Mo - K absorption
edge was used for obtaining data.
Data has been analysed by EXAFS analysis program
WinXAS version 3.02. An EXAFS oscillation wasextracted using the cubic spline method and the structure
function was obtained by the Fourier transformation.
Structural parameters were derived from fitting based on
EXAFS equation.
3 Results and Discussion
Alkali content 0.27 mol% of 1200 oC , 800 oC and RT,
the distance of Mo - O is almost constant, so it wasconfirmed that local structure was kept constant frommelting to solidification.
Fig. 1 shows structural functions of alkali content 0.23mol% (all components) at each temperature.

In the case of alkali content 0.23 mol%, it is found thatthe distance of Mo - O is extended at 1200 oC with regard
to 800 oC and RT, so it was observed that the glass
structure was changed at solidified from molten state.
Therefore, it is found that the alkali content of 0.27
mol% is nearly kept constant from molten state untilroom temperature.

Fig. 1: Structural functions of alkali content 0.23 mol% (all components) at each temperature
Summary
It is considered that the glass with an alkali content of0.27 mol% is more ideal glass which can be kept thesame local structure from molten state up to solid state.
Acknowledgement
This research is part of the result of the Ministry ofEconomy, Trade and Industry, Agency of Natural
Resources and Energy, FY2016, the development of nextgeneration glass vitrification technology research project.
Research Achievements
1. The 6th Asian Conference on Molten Salt Chemistry
and Technology Gyeongju , Korea, June 13-16, 2017
* ymrt.yr@gmail.com