The Effect of Glass Chemistry on Caesium Volatility in Iron Phosphate Glass Systems - 19344
- Immobilisation Science Laboratory, Department of Material Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD (United Kingdom)
- National Nuclear Laboratory, 5th Floor Chadwick House, Birchwood Park, Warrington, Cheshire, WA3 6AE (United Kingdom)
The UK currently has a stockpile of 99,000 m{sup 3} of intermediate level waste (ILW), with this figure expected to rise to 191,000 m{sup 3} by 2125. Current immobilisation options include cementation and thermal treatment, with cementation being the preferred candidate due to the simplicity of processing. However, thermal processing such as vitrification could offer significant volume reductions, up to 75 % for some waste-streams. In comparison, cementation is generally associated with a volume increase, with a typical waste package seeing a volume increase of 200 - 400 %. For vitrification to be accepted as the preferred treatment option of ILW in the UK, the issue of volatility during the vitrification process must be addressed. Volatile components of ILW such as Cs-137 and Sr-90 account for almost 50 % of the current total radioactivity produced by the UK's ILW stockpile. Therefore, the efficient retention of these elements into the glass immobilisation medium must be considered. Various approaches can be employed when trying to increase volatile retention, however this project has focussed on the influence of glass chemistry on volatility. A series of iron phosphate glasses containing 5 mol % of B{sub 2}O{sub 3}, MnO and ZnO have been produced, where additives have been substituted in place of Fe{sub 2}O{sub 3} in a standard 40Fe{sub 2}O{sub 3}-60P{sub 2}O{sub 5} system. All glass samples were characterised using Raman spectroscopy, SEM-EDX, thermal analysis, XRD and XRF. The glasses were then doped with caesium carbonate and re-melted in the system described below. A simple off-gas system has been developed and commissioned to capture and characterise volatiles released from the glass during melting. The off-gas system has been refined several times, with the most recent design comprising of a sealed stainless steel system, connected to two gas washing bottles containing 150 ml of 50 % nitric acid. Nitrogen gas is passed through the system for the duration of the experiment at a flow rate of ∼ 0.9 L/min to ensure efficient carryover of the volatiles released from the glass melt into the solutions in the gas washing bottles. The total retention of the volatiles can be measuring by analysing the contents of the gas washing bottles using ICP-MS and XRF of the final glass product. (authors)
- Research Organization:
- WM Symposia, Inc., PO Box 27646, 85285-7646 Tempe, AZ (United States)
- OSTI ID:
- 23003077
- Report Number(s):
- INIS-US-21-WM-19344; TRN: US21V1193043410
- Resource Relation:
- Conference: WM2019: 45. Annual Waste Management Conference, Phoenix, AZ (United States), 3-7 Mar 2019; Other Information: Country of input: France; 26 refs.; available online at: https://www.xcdsystem.com/wmsym/2019/index.html
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ADDITIVES
BORATES
CERAMIC MELTERS
CESIUM
CESIUM 137
CESIUM CARBONATES
FLOW RATE
HEAT TREATMENTS
ICP MASS SPECTROSCOPY
INTERMEDIATE-LEVEL RADIOACTIVE WASTES
IRON PHOSPHATES
MANGANESE OXIDES
NITRIC ACID
PHOSPHATE GLASS
RADIOACTIVITY
RAMAN SPECTROSCOPY
SCANNING ELECTRON MICROSCOPY
STAINLESS STEELS
STRONTIUM 90
THERMAL ANALYSIS
VOLATILITY
X-RAY DIFFRACTION
X-RAY FLUORESCENCE ANALYSIS