Concentration of Cesium and Strontium Elements Involved in a LiCl Waste Salt by a Melt Crystallization Process

Cho, Yung-Zun; Park, Gil-Ho; Lee, Han-Su; Kim, In-Tae; Han, Dongil

doi:10.13182/nt09-7

Cited by 30 publications

(24 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Cold finger crystal growth separation is similar to a melt crystallization process called layer crystallization that concentrates used electrolyte as purified electrolyte is solidified on a cooled wall and removed. Layer crystallization was proposed and explored by the Korea Atomic Energy Research Institute (KAERI) and was experimentally proven to minimize the amount of lithium chloride (LiCl) salt waste [6]. Despite the successful demonstration of this technique, there are still missing fundamental aspects to be explored such as heat and mass transfers and process optimization.…”

Section: Department Of Energy (Doe) Has Since Organized the Office Ofmentioning

confidence: 99%

“…Two melt crystallization separating techniques have been explored to reduce used electrolyte waste volume and lower operating expenses by recycling used electrolyte. Zone freezing has been explored by KAERI and University of Idaho (U of I) where KAERI studied a LiCl salt system [6] and U of I studied a LiCl-KCl salt system [14]. Layer crystallization, a separation technique similar to cold finger crystal growth, has been explored by KAERI for a LiCl salt system [6].…”

Section: Cold Finger Crystal Growth Separationmentioning

confidence: 99%

See 1 more Smart Citation

Fission Product Separation from Pyrochemical Electrolyte by Cold Finger Melt Crystallization

Versey¹

2013

View full text Add to dashboard Cite

This work contributes to the development of pyroprocessing technology as an economically viable means of separating used nuclear fuel from fission products and cladding materials. Electrolytic oxide reduction is used as a head-end step before electrorefining to reduce oxide fuel to metallic form. The electrolytic medium used in this technique is molten LiCl-Li 2 O. Groups I and II fission products, such as cesium (Cs) and strontium (Sr), have been shown to partition from the fuel into the molten LiCl-Li 2 O.Various approaches of separating these fission products from the salt have been investigated by different research groups. One promising approach is based on a layer crystallization method studied at the Korea Atomic Energy Research Institute (KAERI). Despite successful demonstration of this basic approach, there are questions that remain, especially concerning the development of economical and scalable operating parameters based on a comprehensive understanding of heat and mass transfer. This research explores these parameters through a series of experiments in which LiCl is purified, by concentrating CsCl in a liquid phase as purified LiCl is crystallized and removed via an argon-cooled cold finger. All experiments were conducted in an inert argon atmosphere. The experimental LiCl-CsCl operating temperature was 650˚C with a cold finger temperature held at the freezing temperature of LiCl (≈605˚C). Molten salt and cold finger exhaust temperatures were measured throughout experiments and argon cooling gas flow was controlled manually via a needle valve. The varied parameters of interest were initial contaminant concentration, cold finger cooling rate, and separation time. CsCl concentration was measured via Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) for purified LiCl crystals and concentrated LiCl-CsCl bulk.Preliminary results revealed that co-deposition of CsCl along with LiCl crystal formation due to slightly non-equilibrium mass transport is a problem that must be minimized. Analysis of experiments with initial 5 wt% CsCl concentration showed that for an experimental matrix of varying cold finger coolant flow rates (7.4, 9.8, 12.3, and 14.9 L/min) and separation times (5, 10, 15, and 30 min), the optimal cooling flow rate and separation time are 14.9 L/min and 15 min, respectively, producing a 0.33 wt% CsCl crystal purity at a production rate of 0.36 g/min. Experimental results for initial concentrations of 1, 3, and 7.5 wt% CsCl at the aforementioned coolant flow rates for separation times of 15 min were analyzed and showed iv that as initial bulk concentration increased from 1 to 7.5 wt% CsCl, the change in purified crystal concentration for experiments was less than 0.5 wt% CsCl for all but one data point.The optimal result of the initial 5 wt% CsCl experiments along with results of initial 1, 3, and 7.5 wt% CsCl bulk concentration experiments were used to predict a scale-up scenario that provided a potential separation rate and purity of 136 g/hr and 0.24 wt% CsCl, respectively, to provide in...

show abstract

Section: Department Of Energy (Doe) Has Since Organized the Office Ofmentioning

confidence: 99%

Section: Cold Finger Crystal Growth Separationmentioning

confidence: 99%

Fission Product Separation from Pyrochemical Electrolyte by Cold Finger Melt Crystallization

Versey¹

2013

View full text Add to dashboard Cite

show abstract

“…Researchers at the Korea Atomic Energy Research Institute (KAERI) have proposed a zone freezing method for the separation of fission products from the molten salt that may reduce the amount of ceramic waste generated [5][6]. Work conducted at KAERI focused primarily on feasibility, and several parameters were left unexplored.…”

Section: Motivationmentioning

confidence: 99%

“…Crystallization of the melt is initiated by slowly advancing the material through the temperature gradient. Several different Bridgman configurations have been used in the past; they are horizontal [31], vertical [32], and reverse vertical [6]. The difference between the vertical and reverse vertical configurations is the direction of the temperature gradient with respect to gravity.…”

Section: Melt Crystallization Processesmentioning

confidence: 99%

Zone Freezing Study for Pyrochemical Process Waste Minimization

Williams¹

2012

View full text Add to dashboard Cite

Pyroprocessing technology is a non-aqueous separation process for treatment of used nuclear fuel. At the heart of pyroprocessing lies the electrorefiner, which electrochemically dissolves uranium from the used fuel at the anode and deposits it onto a cathode. During this operation, sodium, transuranics, and fission product chlorides accumulate in the electrolyte salt (LiCl-KCl). These contaminates change the characteristics of the salt overtime and as a result, large volumes of contaminated salt are being removed, reprocessed and stored as radioactive waste. To reduce the storage volumes and improve recycling process for cost minimization, a salt purification method called zone freezing has been proposed at Korea Atomic Energy Research Institute (KAERI).Zone freezing is melt crystallization process similar to the vertical Bridgeman method. In this process, the eutectic salt is slowly cooled axially from top to bottom. As solidification occurs, the fission products are rejected from the solid interface and forced into the liquid phase. The resulting product is a grown crystal with the bulk of the fission products near the bottom of the salt ingot, where they can be easily be sectioned and removed. Despite successful feasibility report from KAERI on this process, there were many unexplored parameters to help understanding and improving its operational routines. Thus, this becomes the main motivation of this proposed study. The majority of this work has been focused on the CsCl-LiCl-KCl ternary salt. CeCl 3 -LiCl-KCl was also investigated to check whether or not this process is feasible for the trivalent species-surrogate for rare-earths and transuranics. For the main part of the work, several parameters were varied, they are: (1) the retort advancement rate-1.8, 3.2, and 5.0 mm/hr, (2) the crucible lid configurations-lid versus no-lid, (3) the amount or size of mixture-50 and 400 g, (4) the composition of CsCl in the salt-1, 3, and 5 wt%, and (5) the temperature differences between the high and low furnace zones-200 and 300 qC.During each experiment, the temperatures at selected locations around the crucible were measured and recorded to provide temperature profiles. Following each experiment, samples were collected and elemental analysis was done to determine the composition of iv the salt. Several models-non-mixed, well-mixed, Favier, and hybrid-were explored to describe the zone freezing process.For CsCl-LiCl-KCl system, experimental results indicate that through this process up to 90% of the used salt can be recycled, effectively reducing waste volume by a factor of ten. The optimal configuration was found to be a 5.0 mm/hr rate with a lid configuration and a ΔT of 200°C. The larger 400 g mixtures had recycle percentages similar to the 50 g mixtures; however, the throughput per time was greater for the 400 g case. As a result, the 400 g case is recommended. For the CeCl 3 -LiCl-KCl system, the result implies that it is possible to use this process to separate the rare-earth and transuranics chlorides. ...

show abstract

“…In particular, the benefits of the electrolytic reduction process by the removal of semi-volatile fission products such as I and Cs from fuel material by a thermal pretreatment are Pt anode protection from interaction with I and an extension of the salt replacement cycle due to a very low Cs buildup rate [8,9]. In addition, a layer crystallization method can be used to separate Sr and Ba from salt waste generated from an electrolytic reduction, which can reduce the amount of salt waste [10]. Purified salt can then be recycled into the electrolytic reduction process.…”

Section: Introductionmentioning

confidence: 99%