Effect of Process Variables During the Head-End Treatment of Spent Oxide Fuel

Abstract

The development of a head-end processing step for spent oxide fuel that applies to both aqueous and pyrometallurgical technologies is being performed by the Idaho National Laboratory, the Oak Ridge National Laboratory, and the Korean Atomic Energy Research Institute through a joint International Nuclear Energy Research Initiative. The processing step employs high temperatures and oxidative gases to promote the oxidation of UO 2 to U 3 O 8 . Potential benefits of the head-end step include the removal or reduction of fission products as well as separation of the fuel from cladding. The effects of temperature, pressure, oxidative gas, and cladding have been studied with irradiated spent oxide fuel to determine the optimum conditions for process control.Experiments with temperatures ranging from 500 o C to 1250 o C have been performed on spent fuel using either air or oxygen gas for the oxidative reaction. Various flowrates and applications have been tested with the oxidative gases to discern the effects on the process. Tests have also been performed under vacuum conditions, following the oxidation cycle, at high temperatures to improve the removal of fission products. The effects of cladding on fission product removal have also been investigated with released fuel under vacuum and high temperature conditions. Results from these experiments will be presented as well as operating conditions based on particle size and decladding characteristics.

Effect of alkali and alkaline-earth chloride addition on electrolytic reduction of UO2 in LiCl salt bath

“…Because of the difficulty in separating CsCl from the LiCl salt bath, the removal of Cs from spent oxide fuels before the electrolytic reduction process is desirable to reduce the amount of salt waste. It has been suggested in the literature that most of the Cs can be removed from spent oxide fuels by volatilization at a high temperature [23,24]. …”

Recoveryof actinidesand fission products from spent nuclear fuel via electrolytic reduction: Thematic overview

“…Therefore, before starting the electrolytic reduction process, it is desirable to minimize the Cs content in the SNF. This can be achieved, for example, by Cs evaporation at high temperatures 34,35 …”

Innovative Separations Technologies

“…According to another reference, complete removal of I, Tc, and Cs has already been demonstrated [Westphal, 2008]. Much testing with INL and KAERI has already been completed and documented to optimize the fuel oxidation and initial FP volatilization portion of the proposed project.…”