Hydrothermal stability of β-Cs2U2O7 and SrZrO3 in fluids

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The stability of β-Cs2U2O7 and SrZrO3, two possible phases of spent fuel elements, in hydrothermal fluids was investigated. β-Cs2U2O7 was unstable under hydrothermal conditions of 100, 200 and 300°C/300 bars releasing substantial amounts of its Cs in deionized water and all of its Cs in a bittern (high-Mg and-Ca) brine. SrZrO3 was found to be quite stable in deionized water but not in a bittern brine. For example, Sr released into solution decreased from 3.9 to 2.8% with an increase in temperature from 100 to 300°C probably because of better crystallization of SrZrO3 at higher temperatures. In bittern brine, 23.3, 94.9 and 100% of Sr was released into solution at 100, 200 and 300°C respectively as a result of acidic conditions generated by the hydrolysis of MgCl2 and formation of brucite. These results suggest that bittern brine which may be encountered in a salt repository is highly corrosive and may release all the Cs and Sr into solution under hydrothermal conditions if the containment were breached. The use of tailor-made overpacks or backfill barriers of highly stable and sorptive materials is essential especially in a salt repository in order to minimize the threat of highly hazardous Cs and Sr radionuclides finding their way into ground waters.

Original languageEnglish (US)
Pages (from-to)2833-2837
Number of pages5
JournalJournal of Inorganic and Nuclear Chemistry
Volume43
Issue number11
DOIs
StatePublished - Jan 1 1981

Fingerprint

Deionized water
Fluids
fluids
Salts
brucite
nuclear fuel elements
salts
Nuclear fuel elements
spent fuels
containment
Magnesium Hydroxide
Spent fuels
releasing
ground water
Radioisotopes
Caustics
radioactive isotopes
water
Magnesium Chloride
hydrolysis

Cite this

@article{f2d9e71b154447b8bc6def71a043ed92,
title = "Hydrothermal stability of β-Cs2U2O7 and SrZrO3 in fluids",
abstract = "The stability of β-Cs2U2O7 and SrZrO3, two possible phases of spent fuel elements, in hydrothermal fluids was investigated. β-Cs2U2O7 was unstable under hydrothermal conditions of 100, 200 and 300°C/300 bars releasing substantial amounts of its Cs in deionized water and all of its Cs in a bittern (high-Mg and-Ca) brine. SrZrO3 was found to be quite stable in deionized water but not in a bittern brine. For example, Sr released into solution decreased from 3.9 to 2.8{\%} with an increase in temperature from 100 to 300°C probably because of better crystallization of SrZrO3 at higher temperatures. In bittern brine, 23.3, 94.9 and 100{\%} of Sr was released into solution at 100, 200 and 300°C respectively as a result of acidic conditions generated by the hydrolysis of MgCl2 and formation of brucite. These results suggest that bittern brine which may be encountered in a salt repository is highly corrosive and may release all the Cs and Sr into solution under hydrothermal conditions if the containment were breached. The use of tailor-made overpacks or backfill barriers of highly stable and sorptive materials is essential especially in a salt repository in order to minimize the threat of highly hazardous Cs and Sr radionuclides finding their way into ground waters.",
author = "Sridhar Komarneni",
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Hydrothermal stability of β-Cs2U2O7 and SrZrO3 in fluids. / Komarneni, Sridhar.

In: Journal of Inorganic and Nuclear Chemistry, Vol. 43, No. 11, 01.01.1981, p. 2833-2837.

Research output: Contribution to journalArticle

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AB - The stability of β-Cs2U2O7 and SrZrO3, two possible phases of spent fuel elements, in hydrothermal fluids was investigated. β-Cs2U2O7 was unstable under hydrothermal conditions of 100, 200 and 300°C/300 bars releasing substantial amounts of its Cs in deionized water and all of its Cs in a bittern (high-Mg and-Ca) brine. SrZrO3 was found to be quite stable in deionized water but not in a bittern brine. For example, Sr released into solution decreased from 3.9 to 2.8% with an increase in temperature from 100 to 300°C probably because of better crystallization of SrZrO3 at higher temperatures. In bittern brine, 23.3, 94.9 and 100% of Sr was released into solution at 100, 200 and 300°C respectively as a result of acidic conditions generated by the hydrolysis of MgCl2 and formation of brucite. These results suggest that bittern brine which may be encountered in a salt repository is highly corrosive and may release all the Cs and Sr into solution under hydrothermal conditions if the containment were breached. The use of tailor-made overpacks or backfill barriers of highly stable and sorptive materials is essential especially in a salt repository in order to minimize the threat of highly hazardous Cs and Sr radionuclides finding their way into ground waters.

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