Ruthenium Volatilisation in Nuclear Waste Systems -Comparison of Ru(III)Cl{sub 3} and Ru(III)NO(NO{sub 3}){sub 3} - 17113

Conference · Sat Jul 01 04:00:00 EDT 2017

OSTI ID:22794520

Johal, Sukhraaj K.; Boxall, Colin ^[1]; Gregson, Colin ^[2]; Steele, Carl J. ^[3]

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1. The Lloyd's Register Foundation Centre for Nuclear Engineering, Engineering Department, Lancaster University, Bailrigg, Lancashire, LA1 4YR (United Kingdom)
2. National Nuclear Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG (United Kingdom)
3. Sellafield Ltd., Sellafield, Seascale, Cumbria, CA20 1PG (United Kingdom)

Ruthenium is a fission product possessed of two relatively long lived isotopes; {sup 103}Ru and {sup 106}Ru, both of which form part of the Highly Active (HA) waste raffinate during spent nuclear fuel reprocessing. During reprocessing, ruthenium, which may be in the form of the RuNO{sub 3}+ complex, encounters temperatures conducive to volatilisation. Due to ruthenium's high specific radioactivity it is important to understand the mechanism by which volatilisation occurs. Here we use combined cyclic voltammetry (CV) and electrochemical micro-gravimetry experiments in a study of both NO free Ru (III), in the form of a RuCl{sub 3} solution and NO complexed Ru (III), in the form of RuNO{sub 3}+ solutions. We do this in order to establish baseline behaviour of NO free Ru (III) and compare it to NO complexed Ru (III) to determine the effect of complexation on the system. We have observed discrete oxidations in both systems from solution phase Ru (III) to solid phase RuO{sub 2} and volatile RuO{sub 4}. Two key differences emerged between the two systems, the first being the mass changes associated with deposition and stripping of RuO{sub 2} are significantly smaller in the RuNO{sub 3}+ solutions than those for solutions of RuCl{sub 3}. The second difference is the difference in onset of volatile RuO{sub 4} generation, in the RuNO{sub 3}+ solution, RuO{sub 4} generation is 100 mV positive than that for the RuCl{sub 3} solution. This suggests NO complexation protects Ru (III) against oxidation and, to a certain extent, volatilisation as RuO{sub 4}. (authors)

• Research Organization: WM Symposia, Inc., PO Box 27646, 85285-7646 Tempe, AZ (United States)
• OSTI ID: 22794520
• Report Number(s): INIS-US--19-WM-17113
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
COMPLEXES
ELECTROCHEMISTRY
FISSION PRODUCTS
NITRATES
NITRIC OXIDE
RADIOACTIVE WASTES
RADIOACTIVITY
REPROCESSING
RUTHENIUM
RUTHENIUM 103
RUTHENIUM 106
RUTHENIUM CHLORIDES
RUTHENIUM OXIDES
SOLUTIONS
SPENT FUELS