The kinetics of thermal annealing of radical species /equivalent nitrite (NO
and their difference, (NO
)/ in -irradiated CsNO3 has been investigated. The data have been nalyzed on the basis of models for vacancy interstititial combination and also on the basis of conventional chemical kinetics.
Authors:D. Hellali, H. Zamali, A. Sebaoun, and M. Jemal
The phase diagram of the binary AgNO3–CsNO3 system was constructed using differential thermal analysis (DTA) technique in the range 300–700 K. The apparatus is described briefly. The results exhibit a congruently melting compound CsNO3·AgNO3 (m.p.=453 K) characterized by two allotropic varieties and , an incongruently melting compound AgNO3·CsNO3 (m.p.=450 K) with three forms
, two eutectics (16 mol% CsNO3, 442 K and 32.5 mol% CsNO3, 445 K) and a peritectic (38mol% CsNO3, 450 K). The occurrence of the transitions of intermediates was confirmed by X-ray diffraction at variable temperatures. The phase diagram exhibits also two plateaus at 429 K and 435 K corresponding to the phase transitions of CsNO3 and AgNO3, respectively.
Phase diagram of the binary system CsNO3–LiNO3 has been drawn by using simultaneously direct and differential thermal analysis between 323 and 723 K. This system is characterized by a congruent intermediate equimolar compound with melting point at 463 K, two eutectic reactions at 447 and 433 K; the eutectic points are respectively at 0,47 and 0,63 mol fraction of LiNO3; a plateau due to the phase transition of CsNO3 at 428 K and an other one at 333 K due to the formation of CsLi(NO3)2. The miscibility in solid state seems to be nil or negligible. These results associated with some other thermodynamic data have been used to calculate the activities of the constituents along the liquidus curve and the activities of the liquid constituents at 723 K. The binary liquid (Cs–Li)NO3 exhibits a negative deviation from the ideal behaviour.
Authors:T. White, C. Herman, S. Crump, A. Marinik, D. Lambert, and R. Eibling
A high-level waste (HLW) remediation process scheduled to begin in 2007 at the Savannah River Site is the Modular Caustic
Side Solvent Extraction (CSSX) Unit (MCU). The MCU will use a hydrocarbon solvent (diluent) containing a cesium extractant,
a calixarene compound, to extract radioactive cesium from caustic HLW. The resulting decontaminated HLW waste or raffinate
will be processed into grout at the Saltstone Production Facility (SPF). The cesium containing CSSX stream will undergo washing
with dilute nitric acid followed by stripping of the cesium nitrate into a very dilute nitric acid or the strip effluent stream
and the CSSX solvent will be recycled. The Defense Waste Processing Facility (DWPF) will receive the strip effluent stream
and immobilize the cesium into borosilicate glass. Excess CSSX solvent carryover from the MCU creates a potential flammability
problem during DWPF processing. Bench-scale DWPF process testing was performed with simulated waste to determine the fate
of the CSSX solvent components. A simple high performance liquid chromatography (HPLC) method was developed to identify the
modifier (which is used to increase Cs extraction and extractant solubility) and extractant within the DWPF process. The diluent
and triocytlamine (which is used to suppress impurity effect and ion-pair disassociation) were determined using gas chromatography
mass spectroscopy (GCMS). To close the organic balance, two types of sample preparation methods were needed. One involved
extracting aqueous samples with methylene chloride or hexane, and the second was capturing the off gas of the DWPF process
using carbon tubes and rinsing the tubes with carbon disulfide for analysis. This paper addresses the development of the analytical
methods and the bench-scale simulated waste study results.
Authors:S. Wacharine, D. Hellali, H. Zamali, J. Rogez, and M. Jemal
been detected for the second time. The temperature of this transition depends considerably on the purity of the nitrate. The binary system caesiumnitrate–rubidium nitrate studied at atmospheric pressure, by using a simultaneous direct and differential