Chemical Durability of Iron-phosphate Glass as the High Level Waste from Pyrochemical Reprocessing

As part of ongoing research and development of nuclear waste disposal techniques suitable for the pyrochemical processing system [1], iron-phosphate glass was examined as an alternative waste form for high level waste generated from the electro-refining process [2]. To enhance the waste element content in the glass matrix and improve the durability of the waste form, optimization experiments of the glass composition were performed, and the effects of other additional transition metal oxides were determined. From the surface analysis of iron phosphate glass, a leaching mechanism was assumed for various elements contained in the glass matrix. We have selected suitable a glass composition for the treatment of radioactive waste generated from the spent electrolytes of pyrochemical processing.

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Applicability of Iron Phosphate Glass Medium for Loading NaCl Originated From Seawater Used for Cooling the Stricken Power Reactors

Volume 1: Low/Intermediate-Level Radioactive Waste Management; Spent Fuel, Fissile Material, Transuranic and High-Level Radioactive Waste Management ◽

10.1115/icem2013-96108 ◽

2013 ◽

Author(s):

Hidekazu Kobayashi ◽

Ippei Amamoto ◽

Takuma Yokozawa ◽

Teruo Yamashita ◽

Takayuki Nagai ◽

...

Keyword(s):

Thermal Expansion ◽

Glass Transition ◽

Phosphate Glass ◽

Glass Formation ◽

Coefficient Of Thermal Expansion ◽

Glass Melting ◽

Glass Network ◽

Iron Phosphate ◽

Chemical Durability ◽

Raw Material

As the part of investigation for immobilization of the sludge as one of the radioactive wastes arising from the treatment of contaminated water at Fukushima Dai-ichi nuclear power plant, applicability of vitrification method has been evaluated as a candidate technique. The aim of this study is to evaluate the influence of NaCl as one of the main constituents of sludge, on glass formation and glass properties. Two kinds of iron phosphate glass (IPG) media in the xFe2O3-(100-x)P2O5, with x = 30 and 35 (mol%) were chosen and the glass formation, structure and properties including density, coefficient of thermal expansion, glass transition temperature, onset crystallization temperature and chemical durability of NaCl-loaded IPG were studied. The results are summarized as follows. Sodium chloride, NaCl could be loaded into IPG medium as Na2O and Cl contents and their loading ratio could be up to 19 and 15 mol%, respectively. Majority of Cl content of raw material NaCl was thought to be volatilized during glass melting. Loading NaCl into IPG induces to depolymerize glass network of phosphate chains, leads to decrease both glass transition and onset crystallization temperatures, and to increase coefficient of thermal expansion. NaCl-loaded IPG indicated good chemical durability in case of using 35Fe2O3-65P2O5 medium.

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Chemical durability of UK vitrified high level waste in Si-saturated solutions

Materials Letters ◽

10.1016/j.matlet.2018.03.115 ◽

2018 ◽

Vol 221 ◽

pp. 154-156 ◽

Cited By ~ 3

Author(s):

M.T. Harrison ◽

G.C. Brown

Keyword(s):

Chemical Durability ◽

High Level Waste ◽

High Level ◽

Saturated Solutions

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Removal of Fission Products in the Spent Electrolyte Using Iron Phosphate Glass as a Sorbent

ASME 2010 13th International Conference on Environmental Remediation and Radioactive Waste Management, Volume 2 ◽

10.1115/icem2010-40272 ◽

2010 ◽

Author(s):

Ippei Amamoto ◽

Naoki Mitamura ◽

Tatsuya Tsuzuki ◽

Yasushi Takasaki ◽

Atsushi Shibayama ◽

...

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Phosphate Glass ◽

Alkali Metals ◽

Fission Products ◽

Iron Phosphate ◽

Experimental Result ◽

Filtration Method ◽

High Level ◽

Filtration Experiment

This study is carried out to make the pyroprocessing hold a competitive advantage from the viewpoint of environmental load reduction and economical improvement. As one of the measures to reduce the volume of the high-level radioactive waste (HLW), the phosphate conversion method is applied for removal of fission products (FP) from the melt, referring to the spent electrolyte in this paper. Among the removing target chlorides in the spent electrolyte i.e., alkali metals, alkaline earth metals and rare earth elements, only the rare earth elements and lithium form the precipitates as insoluble phosphates by reaction with Li3PO4. The sand filtration method was applied to separate FP precipitates from the spent electrolyte. The iron phosphate glass (IPG) powder, which is a compatible material for the immobilization of FP, was used as a filter medium. After filtration experiment, it was proven that insoluble FP could almost be completely removed from the spent electrolyte. Subsequently, we attempted to separate the dissolved FP from the spent electrolyte. The IPG was being used once again but this time as a sorbent instead. This is possible because the IPG has some unique characteristics, e.g., changing the valence of iron, which is one of its network modifiers due to its manufacturing temperature. Therefore, it would be likely to sorb some FP when the chemical condition of IPG is unstable. We produced three kinds of IPG under different manufacturing temperature and confirmed that those glasses could sorb FP as anticipated. According to the experimental result, its sorption efficiency of metal cations was attained at around 20–40%.

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Phase Relations and Chemical Durability of Ceramics in the Pseudo-Binary System: CaZrTi2O7–GdAlO3

MRS Proceedings ◽

10.1557/proc-807-327 ◽

2003 ◽

Vol 807 ◽

Cited By ~ 1

Author(s):

N. P. Mikhailenko ◽

A. V. Ochkin ◽

S. V. Stefanovsky ◽

O. I. Kirjanova

Keyword(s):

Electron Microscopy ◽

Binary System ◽

Chemical Durability ◽

Phase Relations ◽

High Level Waste ◽

X Ray Diffraction ◽

X Ray ◽

Ceramic Samples ◽

High Level ◽

System 1

ABSTRACTPhase relations in a pseudo-binary system (1-x) CaZrTi2O7- x GdAlO3 suggested for immobilization of a zirconium - rare earth – actinide fraction of high level waste were studied with X-ray diffraction and electron microscopy. Zirconolite and perovskite were found to be major phases in the ceramic samples prepared by cold pressing and sintering at 1400 and 1500 °C. At relatively low perovskite content (x < 0.5) zirconolite is the major host for Gd, which is considered as a trivalent surrogate for Am and Cm. At higher perovskite content, perovskite becomes the major host for Gd. Zirconolite is the major host phase for corrosion products (Al, Fe, Ti, Zr). Leach rates of Gd, 238Pu, and 241Am from the ceramics studied are 10−4–10−5 g/(m2d).

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Evaluation of Cesium Sujcotitanates as an Alternative Waste Form

MRS Proceedings ◽

10.1557/proc-465-457 ◽

1996 ◽

Vol 465 ◽

Cited By ~ 6

Author(s):

Yali Su ◽

M. Lou Balmer ◽

Bruce C. Bunker

Keyword(s):

Borosilicate Glass ◽

Thermal Conversion ◽

Chemical Durability ◽

Waste Form ◽

High Level Waste ◽

Ion Exchangers ◽

Heat Treated ◽

High Level ◽

Excellent Chemical ◽

Better Than

ABSTRACTSilicotitanate ion exchangers are potential materials for the removal of radioactive Cs and Sr from tank wastes. In this paper the viability of direct thermal conversion of Cs-loaded silicotitanates to an acceptable high level waste form has been examined. Results show that in aqueous solutions, the Cs leach rates of crystalline silicotitanates (heat treated at 800°C) are 0.04, 0.18, 0.4 g/m2day for Cs loadings of 1, 5, and 20 wt%, respectively. Heating the Cs-loaded (up to 20 wt %) silicotitanates at or above 900 °C for 1 hour further reduces the Cs leach rates to approximately zero (beyond the lppm detection limits). Moreover, Cs volatilization was found to be < 0.8 wt% at temperatures as high as 1000 °C. These results suggest that thermally converted silicotitanate ion exchangers exhibit excellent chemical durability (comparable to or better than borosilicate glass) and thus, have great potential as an alternative waste form.

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