Glass - Back to the Future!

Presenting Author:
Toshiro Oniki

article posted 06 April 2016

Toshiro Oniki March 2004 Graduate from Yokohama National University
April 2004 Enter IHI Corporation
From 2004 to 2016 Engaged in development of treatment and vitrification technology for radioactive waste

Development of glass melting process for LLW-Glass formulation testing to be compatible with composition changes

Toshiro Oniki*1, Yasutomo Tajiri1, Takahiro Tachibana1, Toyonobu Nabemoto1, Toshiki Fukui1, Sohei Sukenaga2, Hiroyuki Shibata2
1Nuclear Fuel Cycle Project Department, Nuclear Power Operations, IHI Corporation, Japan
2Institute of Multidisciplinary Research for Advanced Materials,Tohoku University, Japan

The basic research programs for the next generation vitrification technology, which are commissioned project from Ministry of Economy, Trade and Industry of Japan to IHI Corporation, Japan Nuclear Fuel Limited (JNFL), Japan Atomic Energy Agency (JAEA) and Central Research Institute of Electric Power Industry (CRIEPI), have been implemented from 2014 for developing the advanced vitrification technology of low level wastes (LLW) and high level liquid wastes (Fig.1).
Various kinds of LLW generated from reprocessing plant and nuclear power plant in Japan have been typically treated by various methods such as incineration, compression, cement solification, however, not introduced verification.
On the other hand, there is a potential generation of LLW which has relatively high radioactivity level in case of conducting the decommissioning of reprocessing plant and nuclear power plants. Therefore, various kinds of the solidification and the volume reduction technologies have been developed in order to ensure the stable forms with smaller volumes for the LLW disposal. Some kinds of LLW such as ion-exchange resin, ash, concentrated waste liquid, and sludge have selected as target waste in this development. In order to improve process capabilities and product quality requirements, the vitrification technology has been selected for LLW treatment in some countries.
This study describes the results of a series of tests that have been performed to assess the potential application of the vitrification technology to concentrated waste liquid with high concentration sodium, which is one of the major LLW. Laboratory-scale testing was performed to develop appropriate LLW glass formulations that could have higher waste loading and higher durability. The product glasses have been assessed by XRD, SEM/EDS analysis. At the some compositions which added Al for improving durability, it could confirm to be fully melted without phase separation (Fig.2). The candidate glass formulations have been assessed with respect to the glass leaching rate by PCT method, glass properties such as density and viscosity, and glass structure in order to evaluate and select the optimum glass formulation by the crucible tests.