A Simple Model Predicting Iodine Profile in a Packed Bed of Silica-Gel Impregnated with Silver Nitrate

Abstract

Based on a simple adsorption theory, a mathematical model was proposed to predict axial iodine profiles of the column of silica gel impregnated with silver nitrate (hereinafter referred to as Ag-S) in an off-gas treatment system for spent fuel dissolution. The unknown parameters of the model: the effective diffusion coefficient D ea and the Langmuir coefficient K were determined by curve fitting of iodine profile experimentally obtained. At 423 K, D ea and K were found to be 5.60×10−7 m 2 ·s −1 and 1.0×10 5 m 3 ·kg −1 , respectively. Using the parameter values, the model could well predict the iodine profiles obtained at 423 K in the previous works under different experimental conditions. Furthermore, the effect of silver contents on the iodine profiles was reasonably predicted. It was suggested that the proposed model is simple and would be useful to predict the iodine profiles in Ag-S adsorbent columns.

Applicability of a Model Predicting Iodine-129 Profile in a Silver Nitrate Silica-Gel Column for Dissolver Off-Gas Treatment of Fuel Reprocessing

“…It can be seen from the figure that the adsorbent was not saturated with iodine. [7] In the table, the iodine-stripping operation using NO 2 gas evolved about 2:7 £ 10 25 kg of iodine-129. Table 3 lists the total amount of iodine captured by Ag-S column (Column B) at each dissolution test.…”

“…Management of the iodine is, therefore, indispensable to ensure the safety of a reprocessing plant. Recently, a simple mathematical model was proposed by the authors, [7] which could well predict the iodine profiles in Ag-S columns obtained at around 423 K in previous works under different experimental conditions. Because an adsorbent system has advantages over the caustic scrubbing system, [1,2] several types of adsorbents for iodine have been developed.…”

“…[7] In using those D ea and K values, iodine profiles were respectively predicted for the dissolution of spent fuel with different burnups. [7] In using those D ea and K values, iodine profiles were respectively predicted for the dissolution of spent fuel with different burnups.…”

Molten Salt Reactor Engineering Study for Off-Gas Management

“…Solid sorbent options include porous functional silica-based aerogels (Matyáš et al, 2011b;Riley et al, 2017a), porous-metal-exchanged/impregnated zeolites (e.g., faujasite, Linde type A, mordenite) (Thomas et al, 1978;Jubin, 1981;Wilhelm and Puppe, 1989;Riley and Chong, 2020), AgNO 3 -impregnated silica (Mineo et al, 2002;Mineo et al, 2003), and AgNO 3 -impregnated alumina (Tanabe et al, 2010). Additives without metal getters include sulfide-based aerogels (chalcogels) (Riley et al, 2011;Riley et al, 2013b;Riley et al, 2014), graphene aerogels (Scott et al, 2015), graphene powders (Scott et al, 2015), granular activated carbon (Jubin, 1988), and metal-organic frameworks (MOFs) (Sava et al, 2011;Sava et al, 2012;Sava et al, 2013).…”

Recent advances in the removal of radioactive iodine by bismuth-based materials

“…However, the thermal stability of activated carbon is poor, and its adsorption capacity is diminished at the operating temperature of spent fuel processing. Silver-based materials have been widely studied in iodine capture because silver can react with iodine to generate insoluble AgI ( Kikuchi et al, 1978 ; Kindel et al, 1993 ; Sakurai and Takahashi, 1994 ; Funabashi et al, 1995 ; Modolo and Odoj, 1997 ; Mineo et al, 2002 ; Mineo et al, 2003 ; Takeshita and Azegami, 2004 ; Tanabe et al, 2010 ; Kulyukhin et al, 2012 ). Although silver-based materials have excellent performance in capturing ability and stability, the high cost and toxic of silver make it necessary to explore alternatives.…”