Research on chemical durability of iron phosphate glass wasteforms vitrifying SrF2 and CeF3

Hot Isostatically Pressed (HIPed) fluorite glass‐ceramic wasteforms for fluoride molten salt wastes

“…Fluoride‐based nuclear wastes are challenging to immobilize in borosilicate glass, the most widely used class of wasteform material, due to both fluoride gas generation and the low solubility of fluoride in the glass matrix. The oxidation of fluoride waste into an oxide form followed by vitrification in borosilicate glass could be an option, but additional reprocessing may not be economically viable and will result in secondary waste generation 1,3 . Hence, it is vital to design and establish chemically and mechanically stable, durable wasteform alternatives to incorporate fluoride‐based radioactive wastes with reasonable waste loadings for safe disposal.…”

“…Several studies on incorporation of simulated fluoride waste from MSR were reported on phosphate glass, primarily due to lower melting temperature and relatively high solubility of halides 3 . Sodium aluminophosphate glass with waste loading 20 mol% (18.92 wt%) was reported by Sun et.al, 4,5 but crystallization occurs with a waste loading of 27.5 mol% (24.29 wt%).…”

“…An iron phosphate glass was adopted to capture CsCl and SrF 2 , and the hydration resistant Fe–O–P bonds in the glass provided high chemical durability and ease of fabrication, although the majority of the halides were released during melting 6 . In this regard, an iron phosphate glass which consisted of Fe 2 O 3 –P 2 O 5 –B 2 O 3, and incorporating SrF 2 and CeF 3 as surrogate waste with 10 wt% waste loading, was produced without crystallization 3 . The normalized elemental mass release of Sr, Ce, and F were calculated as 10 −3 g/m 2 from the PCT test with deionized water at 90°C for 7 days, which is equivalent to that of borosilicate glass 3 .…”

“…The oxidation of fluoride waste into an oxide form followed by vitrification in borosilicate glass could be an option, but additional reprocessing may not be economically viable and will result in secondary waste generation. 1,3 Hence, it is vital to design and establish chemically and mechanically stable, durable wasteform alternatives to incorporate fluoride-based radioactive wastes with reasonable waste loadings for safe disposal.…”

“…6 In this regard, an iron phosphate glass which consisted of Fe 2 O 3 -P 2 O 5 -B 2 O 3, and incorporating SrF 2 and CeF 3 as surrogate waste with 10 wt% waste loading, was produced without crystallization. 3 The normalized elemental mass release of Sr, Ce, and F were calculated as 10 −3 g/m 2 from the PCT test with deionized water at 90°C for 7 days, which is equivalent to that of borosilicate glass. 3 However, limited evidence was provided in the discussed literature to verify the fluoride retention within the glass matrix.…”