article posted 29 Mar 2016
Mr Kunihiko Nakano graduated from Yokohama National University, in Japan with ME degree in mechanical engineering and joined IHI Corporation in 1995.
After joining the company, he worked in research and development about the field of the exhaust gas treatment of coal-fired power station for five years. And then, he worked in designing of the melting furnace for the refuse incineration ash for four years. Now, he belongs to the department of chemical engineering development and work in development of the glass melter for the high level radioactive waste.
Investigation of volatile constituents migration during vitrification
using small scale melter
Kunihiko Nakano*1, Yuichi Nishiyama1, Shun-ichiro Ueno1,
Kouji Takewaki2, Hidenori Kawashima3, Toshiki Fukui3
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, 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 vitrification technology of low level waste and high level liquid waste (HLLW). In these programs, melter control method at the high waste loading operation with the newly developed glass matrix has been studied for the vitrification of HLLW. (Fig.1) The possibility to adopt the high-waste loading operation by air-bubbling.
In the vitrification process of HLLW, some volatile fission products (FP) such caesium and technetium are exhausted into the off-gas due to their high vapor pressure. By bubbling operation these volatile components may cause some problems and some difficulties to keep the off-gas system plugging the target glass composition of the vitrified products.
In here, the behavior of the volatile components in FP, rhenium which is substitute of technetium, ruthenium and caesium, have been verified by small scale melter test and the simulated HLLW.
The rates of the volatile components to melting glass and to the off-gas line are investigated from the compositions of poured glass samples, off-gas samples and resided glass samples inside the melter after the tests.
Few amounts of rhenium are incorporated in the vitrified glass and the other is volatilized into the off-gas system in the small scale tests. On the other hand, most of ruthenium and caesium are in the glass. (Fig.2) These transition rates are affected by the cold cap coverage and thickness determined by bubbling operating conditions and the plenum temperature.
1 Chemical Engineering Dept. Corporate R&D of IHI Corporation, Japan
2 Testing & Engineering Dept. Corporate R&D of IHI Corporation, Japan
3 Nuclear Fuel Cycle Project Dept. Nuclear Power Operations IHI Corporation, Japan