Reduction reactions of vanadium as a neptunium analogue with nitrogen oxide species

Chimes, M. and Boxall, C. and Edwards, S. and Sarsfield, M. and Taylor, R.J. and Woodhead, D. (2020) Reduction reactions of vanadium as a neptunium analogue with nitrogen oxide species. In: 14th International Nuclear Fuel Cycle Conference, GLOBAL 2019 and Light Water Reactor Fuel Performance Conference, TOP FUEL 2019, 2019-09-222019-09-26, The Westin Seattle.

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Abstract

Neptunium has been previously shown to present challenges within a used nuclear fuel reprocessing scheme due to its tendency to exist in the (IV), (V), and (VI) oxidation states simultaneously. In order to control this neptunium speciation, and informed by relevant work in the literature, we are currently engaged in a study of nitric/nitrous acid redox chemistry with Np(V) and Np(VI). To minimize radiological exposure risks, we are also exploring the validity of using vanadium as an analogue for the study of the kinetics of the Np(VI)/Np(V) reduction by nitrous acid. The kinetics of the reduction of vanadium(V) by nitrous acid in solutions of nitric acid was investigated spectrophotometrically by the method of initial rates. Orders of reaction with respect to V(V), and HNO2 were previously found to be 0.90, and 1.25 respectively, in reasonable agreement with the analogous reaction orders for the reduction of Np(VI) by nitrous acid previously reported by Precek and Paulenova - suggesting that, for this particular reduction, V(V) can serve as a good kinetic analogue for Np(VI). Within this study orders of reaction with respect to [H +], [NO3 -], [SO4 2-], and [ClO4 -] have also been found to be 0.1, -0.2, 0.1, and 0 respectively. Preliminary experiments have also been conducted on the reduction of V(V) by the known reducing agent NO which has hitherto not been considered in the reduction of Np(VI) to Np(V).

Item Type:
Contribution to Conference (Paper)
Journal or Publication Title:
14th International Nuclear Fuel Cycle Conference, GLOBAL 2019 and Light Water Reactor Fuel Performance Conference, TOP FUEL 2019
Additional Information:
Funding text 1: MC is supported by both the EPSRC (via a “Next Generation Nuclear” Centre for Doctoral Training PhD studentship) and the Lloyds Register Foundation (LRF). Part of the work was conducted in Lancaster University’s UTGARD Lab (Uranium / Thorium beta-Gamma Active R&D Lab), a National Nuclear User Facility supported by the EPSRC. CB is also supported by the LRF (award no. G0025). The LRF supports the advancement of engineering-related education, and funds research and development that enhances safety of life at sea, on land and in the air.
Subjects:
ID Code:
142571
Deposited By:
Deposited On:
21 Jul 2020 14:40
Refereed?:
Yes
Published?:
Published
Last Modified:
23 Nov 2020 15:22