Measurement of Cerium and Gadolinium in Solid Lithium Chloride-Potassium Chloride Salt Using Laser-Induced Breakdown Spectroscopy (LIBS).

Title Measurement of Cerium and Gadolinium in Solid Lithium Chloride-Potassium Chloride Salt Using Laser-Induced Breakdown Spectroscopy (LIBS).
Authors A. Williams; K. Bryce; S. Phongikaroon
Journal Appl Spectrosc
DOI 10.1177/0003702817709298
Abstract

Pyroprocessing of used nuclear fuel (UNF) has many advantages-including that it is proliferation resistant. However, as part of the process, special nuclear materials accumulate in the electrolyte salt and present material accountability and safeguards concerns. The main motivation of this work was to explore a laser-induced breakdown spectroscopy (LIBS) approach as an online monitoring technique to enhance the material accountability of special nuclear materials in pyroprocessing. In this work, a vacuum extraction method was used to draw the molten salt (CeCl3-GdCl3-LiCl-KCl) up into 4?mm diameter Pyrex tubes where it froze. The salt was then removed and the solid salt was measured using LIBS and inductively coupled plasma mass spectroscopy (ICP-MS). A total of 36 samples were made that varied the CeCl3 and GdCl3 (surrogates for uranium and plutonium, respectively) concentrations from 0.5?wt% to 5?wt%. From these samples, univariate calibration curves for Ce and Gd were generated using peak area and peak intensity methods. For Ce, the Ce 551.1?nm line using the peak area provided the best calibration curve with a limit of detection (LOD) of 0.099?wt% and a root mean squared error of cross-validation (RMSECV) of 0.197?wt%. For Gd, the best curve was generated using the peak intensities of the Gd 564.2?nm line resulting in a LOD of 0.027?wt% and a RMSECV of 0.295?wt%. The RMSECV for the univariate cases were determined using leave-one-out cross-validation. In addition to the univariate calibration curves, partial least squares (PLS) regression was done to develop a calibration model. The PLS models yielded similar results with RMSECV (determined using Venetian blind cross-validation with 17% left out per split) values of 0.30?wt% and 0.29?wt% for Ce and Gd, respectively. This work has shown that solid pyroprocessing salt can be qualitatively and quantitatively monitored using LIBS. This work has the potential of significantly enhancing the material monitoring and safeguards of special nuclear materials in pyroprocessing.

Citation A. Williams; K. Bryce; S. Phongikaroon.Measurement of Cerium and Gadolinium in Solid Lithium Chloride-Potassium Chloride Salt Using Laser-Induced Breakdown Spectroscopy (LIBS).. Appl Spectrosc. 2017;71(10):23022312. doi:10.1177/0003702817709298

Related Elements

Chlorine

Chlorine is a Block P, Group 17, Period 3 element. Its electron configuration is [Ne]3s23p5. The chlorine atom has a covalent radius of 102±4 pm and its Van der Waals radius is 175 pm. Chlorine ModelIn its elemental form, chlorine is a yellow-green gas. Chlorine is the second lightest halogen after fluorine. It has the third highest electronegativity and the highest electron affinity of all elements, making it a strong oxidizing agent. It is rarely found by itself in nature. Chlorine was discovered and first isolated by Carl Wilhelm Scheele in 1774. It was first recognized as an element by Humphry Davy in 1808.

Lithium

Lithium Bohr ModelSee more Lithium products. Lithium (atomic symbol: Li, atomic number: 3) is a Block S, Group 1, Period 2 element with an atomic weight of 6.94. The number of electrons in each of Lithium's shells is [2, 1] and its electron configuration is [He] 2s1. The lithium atom has a radius of 152 pm and a Van der Waals radius of 181 pm. Lithium was discovered by Johann Arvedson in 1817 and first isolated by William Thomas Brande in 1821. The origin of the name Lithium comes from the Greek wordlithose which means "stone." Lithium is a member of the alkali group of metals. It has the highest specific heat and electrochemical potential of any element on the period table and the lowest density of any elements that are solid at room temperature. Elemental LithiumCompared to other metals, it has one of the lowest boiling points. In its elemental form, lithium is soft enough to cut with a knife its silvery white appearance quickly darkens when exposed to air. Because of its high reactivity, elemental lithium does not occur in nature. Lithium is the key component of lithium-ion battery technology, which is becoming increasingly more prevalent in electronics.

Potassium

Elemental PotassiumSee more Potassium products. Potassium (atomic symbol: K, atomic number: 19) is a Block S, Group 1, Period 4 element with an atomic weight of 39.0983. The number of electrons in each of Potassium's shells is [2, 8, 8, 1] and its electron configuration is [Ar] 4s1. The potassium atom has a radius of 227.2 pm and a Van der Waals radius of 275 pm. Potassium was discovered and first isolated by Sir Humphrey Davy in 1807. Potassium is the seventh most abundant element on earth. It is one of the most reactive and electropositive of all metals and rapidly oxidizes. As with other alkali metals, potassium decomposes in water with the evolution of hydrogen because of its reacts violently with water, it only occurs in nature in ionic salts.Potassium Bohr Model In its elemental form, potassium has a silvery gray metallic appearance, but its compounds (such as potassium hydroxide) are more frequently used in industrial and chemical applications. The origin of the element's name comes from the English word 'potash,' meaning pot ashes, and the Arabic word qali, which means alkali. The symbol K originates from the Latin word kalium.

Cerium

See more Cerium products. Cerium (atomic symbol: Ce, atomic number: 58) is a Block F, Group 3, Period 6 element with an atomic weight of 140.116. The number of electrons in each of cerium's shells is 2, 8, 18, 19, 9, 2 and its electron configuration is [Xe]4f2 6s2. Cerium Bohr ModelThe cerium atom has a radius of 182.5 pm and a Van der Waals radius of 235 pm. In its elemental form, cerium has a silvery white appearance. Cerium is the most abundant of the rare earth metals. It is characterized chemically by having two valence states, the +3 cerous and +4 ceric states. The ceric state is the only non-trivalent rare earth ion stable in aqueous solutions. Elemental CeriumIt is therefore strongly acidic and oxidizing, in addition to being moderately toxic.The cerous state closely resembles the other trivalent rare earths. Cerium is found in the minerals allanite, bastnasite, hydroxylbastnasite, monazite, rhabdophane, synchysite and zircon. Cerium was discovered by Martin Heinrich Klaproth, Jöns Jakob Berzelius, and Wilhelm Hisinger in 1803 and first isolated by Carl Gustaf Mosander in 1839. The element was named after the asteroid Ceres, which itself was named after the Roman god of agriculture.

Gadolinium

See more Gadolinium products. Gadolinium (atomic symbol: Gd, atomic number: 64) is a Block F, Group 3, Period 6 element with an atomic radius of 157.25. Gadolinium Bohr ModelThe number of electrons in each of Gadolinium's shells is [2, 8, 18, 25, 9, 2] and its electron configuration is [Xe] 4f7 5d1 6s2. The gadolinium atom has a radius of 180 pm and a Van der Waals radius of 237 pm. Gadolinium was discovered by Jean Charles Galissard de Marignac in 1880 and first isolated by Lecoq de Boisbaudran in 1886. In its elemental form, gadolinium has a silvery-white appearance. Gadolinium is a rare earth or lanthanide element that possesses unique properties advantageous to specialized applications such as semiconductor fabrication and nuclear reactor shielding. Elemental Gadolinium PictureIt is utilized for both its high magnetic moment (7.94μ B) and in phosphors and scintillator crystals. When complexed with EDTA ligands, it is used as an injectable contrast agent for MRIs. The element is named after the Finnish chemist and geologist Johan Gadolin.

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