The Science & Technology
of Glass
Cambridge - Monday 4th to
Wednesday 6th September 2017



Josh Radford
<jtradford1@sheffield.ac.uk>

article posted 14 June 2017




In-Situ Monitoring Of Volatile Radionuclides Produced By The Vitrification Of Intermediate Level Nuclear Waste
Josh Radford1, Russell J Hand1, Charlie Scales2

Nuclear power has the potential to facilitate the increasing global energy demands whilst still remaining a relatively green option. However, it is well established that the major concern surrounding nuclear power is the safe treatment of the waste generated. Thermal processing such as vitrification has been demonstrated to be a safe method of disposal for high level waste and is now being considered as a long term treatment method for intermediate level waste. Due to the nature of the wastestreams associated with intermediate level waste, the issue of volatile species must be addressed. In particular the volatility of caesium-137 and strontium-90 need to be limited, as the combined radioactivity of these species account for around half of the current levels of all ILW currently yet to be processed in the UK. Several parameters have an influence on the retention of volatiles during the vitrification process. These include: temperature, viscosity, melt duration and glass chemistry. Current work has been focussed on identifying glass compositions that can suppress the diffusion rates of the volatile components. Included within this line of work are phosphate based glasses and titanosilicates, as comparative studies have reported these glass types to perform better than borosilicates. Another parameter that is influenced by the glass chemistry is the melt temperature, with current work aiming to minimise the melt temperature in an effort to reduce volatilisation. Amongst others, lead based glasses have been identified as having sufficiently low melt temperatures, with some compositions having melt temperatures lower than the decomposition temperatures of caesium and its compounds. In order to conduct these studies, a laboratory off gas system has been designed and tested, that will facilitate off gas identification and measurement. In doing this, a more complete mass balance can be conducted by combining results from off gas measurements and chemical characterisation of the glass product. The talk given will elaborate on the fundamentals of volatility before addressing recent results and future work.

Institutions:

1Immobilisation Science Laboratory, Department of Material Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD

2National Nuclear Laboratory 5th Floor, Chadwick House, Warrington Road, Birchwood Park, Warrington, WA3 6AE