Use of Triflic Acid in the Recycling of Thoria from Nuclear Fuel Production Scrap

Studies on the Thoria Fuel Recycling Loop Using Triflic Acid: Effects of Powder Characteristics, Solution Acidity, and Radium Behavior

“…Detailed information on the starting powders is provided in Table 2. A clear difference was observed in the times required for dissolution of thoria in triflic acid and in the THO-REX acid mixture. It took just a few minutes to dissolve a sample of thoria powder with a specific surface area of 2.4 m 2 g −1 in boiling THOREX acid, whereas it took about 30 min to dissolve the same sample in boiling triflic acid [7]. On the other hand, such comparison, being technologically important, should be taken with care as the THOREX medium contains catalytic amounts of HF.…”

“…This work was extended by Cagno et al proving the possibility of the process to be a closed loop reusing TA (Fig. 1.) [7]. Moreover, Bulemela et al showed the ability of TA to dissolve mixed oxide fuel (UO 2 -ThO 2 ) and the need for highly concentrated TA in order to obtain fast dissolution kinetics [8].…”

“…Taking into account the above mentioned information, high acid concentrations are needed for efficient dissolution, which can have negative consequences for the efficient recovery of thorium from the solution by precipitation with oxalic acid. Oxalates present an easy way of conversion of Th 4+ from aqueous solution to oxide and finally to a pellet [7,13,14].…”

“…Closed loop of the ThO 2 recycling process based on triflic acid describing the dissolution (right), oxalate precipitation (top), and conversion to oxide (left), along with the recovery of triflic acid by distillation[7] …”

Ammonium Pertechnetate in Mixtures of Trifluoromethanesulfonic Acid and Trifluoromethanesulfonic Anhydride

“…Even though metal trifluoromethanesulfonates (triflates, − OTf) see wide applications as catalysts [1, 2] or leaving groups in both organic [3–6] and inorganic chemistry, [7–9] their solid‐state chemistry has not seen much attention. Homoleptic triflates are crystallographically poorly investigated, even though these weakly coordinating anions (WCAs) [10, 11] are, amongst others, widely used in organic reactions, [12–15] and have been proposed for novel applications such as the recycling of thoria in thorium‐based nuclear fuels [16] . There may be a variety of reasons for this, as triflates generally crystallise rather poorly, and they are readily displaced by stronger donors such as water.…”