Ifsttar PhD subject

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Title : Development of reactive materials in low carbon footprint binder from nuclear and industrial wastes

Main host Laboratory - Referent Advisor MAST - CPDM  -  BOURCHY Agathe

Director of the main host Laboratory ROUSSEL Nicolas  -

PhD Speciality Physico-chemistry of materials

Axis of the performance contract 2 - COP2017 - More efficient and resilient infrastructure

Main location Marne-la-Vallée

Doctoral affiliation UNIVERSITE GUSTAVE EIFFEL

PhD school SCIENCES, INGENIERIE ET ENVIRONNEMENT (SIE)

Planned PhD supervisor ROUSSEL Nicolas  -  Université Gustave Eiffel  -  MAST - CPDM

Planned financing Contrat doctoral  - Université Gustave Eiffel

Abstract

Nuclear industry produces nuclear wastes which need to be managed on the long term. Depending on their classification based on radioactivity levels and lasting for various periods of time, radioactive wastes are treated and stored differently: intermediate and high level long-life wastes are most of the time immobilized into glass matrices while low and intermediate level wastes with short or long life are immobilized in cement or bitumen matrices (Abdel Rahman, Rakhimov et al. 2015, Andra 2023). One of the best ways to enhance the stabilisation of contaminants and radionuclides from the wastes is to have it directly react with the components of the cement to be incorporated within the mineral phases by redox, sorption and/or chemical reaction processes (Zatloukalová, Zatloukal et al. 2021, Bourchy, Saslow et al. 2022, Mukiza, Phung et al. 2023). However, many of the wastes have several competing species that exist in large excess compared to the target (e.g. sodium Na+, sulphate SO42- and ammonium NH4+) and these can be detrimental to cement hydration (hydration delay, difference of hydrates produced) or induce pathologies at different age (gas release, Delayed Ettringite Formation – DEF) (Collepardi 2003). However, these species can be harnessed to generate beneficial phases to ensure the long-term integrity of the resulting cement waste form.

Considering that, the objective of this research is to understand the interactions between the waste and the cementitious matrix with regard to composition (impact of sodium and sulphate), radioactivity and characteristics as they can impact cement hydration, heat produced and durability (Zhu, Zheng et al. 2022, Bourchy, Fujii Yamagata et al. 2023).
The methodology used will begin by a literature review of waste inventory from nuclear powered countries, a short list of waste compositions will be established. Several non-radiological formulations (using a surrogate) adapted from the reference nuclear wastes-free (such as geopolymer, alkali activated or ternary cement) will be developed considering a possible range of variation around targeted oxide values leading to hydration, setting and targeted mineralogy. The evolution of mineralogy, activation, hydration and mechanical properties will be monitored with time. Based on these properties, a selection of the best candidate formulations will be done before testing their durability through leach test when loaded with radionuclide surrogates (EPA 2013). An effort will be focused on tracking the evolution of these beneficial or deleterious phases in how they form during setting and how they evolve with environmental exposures.
Depending on the results, it is possible that the PhD student would collaborate with international partners to test the best formulations with radioactive materials and research visits.

Keywords : Cement, formulation, mineral incorporation, durability, nuclear waste

Main host Laboratory - Referent Advisor	MAST - CPDM - BOURCHY Agathe
Director of the main host Laboratory	ROUSSEL Nicolas -
PhD Speciality	Physico-chemistry of materials
Axis of the performance contract	2 - COP2017 - More efficient and resilient infrastructure
Main location	Marne-la-Vallée
Doctoral affiliation	UNIVERSITE GUSTAVE EIFFEL
PhD school	SCIENCES, INGENIERIE ET ENVIRONNEMENT (SIE)
Planned PhD supervisor	ROUSSEL Nicolas - Université Gustave Eiffel - MAST - CPDM
Planned financing	Contrat doctoral - Université Gustave Eiffel
Abstract Nuclear industry produces nuclear wastes which need to be managed on the long term. Depending on their classification based on radioactivity levels and lasting for various periods of time, radioactive wastes are treated and stored differently: intermediate and high level long-life wastes are most of the time immobilized into glass matrices while low and intermediate level wastes with short or long life are immobilized in cement or bitumen matrices (Abdel Rahman, Rakhimov et al. 2015, Andra 2023). One of the best ways to enhance the stabilisation of contaminants and radionuclides from the wastes is to have it directly react with the components of the cement to be incorporated within the mineral phases by redox, sorption and/or chemical reaction processes (Zatloukalová, Zatloukal et al. 2021, Bourchy, Saslow et al. 2022, Mukiza, Phung et al. 2023). However, many of the wastes have several competing species that exist in large excess compared to the target (e.g. sodium Na+, sulphate SO42- and ammonium NH4+) and these can be detrimental to cement hydration (hydration delay, difference of hydrates produced) or induce pathologies at different age (gas release, Delayed Ettringite Formation – DEF) (Collepardi 2003). However, these species can be harnessed to generate beneficial phases to ensure the long-term integrity of the resulting cement waste form. Considering that, the objective of this research is to understand the interactions between the waste and the cementitious matrix with regard to composition (impact of sodium and sulphate), radioactivity and characteristics as they can impact cement hydration, heat produced and durability (Zhu, Zheng et al. 2022, Bourchy, Fujii Yamagata et al. 2023). The methodology used will begin by a literature review of waste inventory from nuclear powered countries, a short list of waste compositions will be established. Several non-radiological formulations (using a surrogate) adapted from the reference nuclear wastes-free (such as geopolymer, alkali activated or ternary cement) will be developed considering a possible range of variation around targeted oxide values leading to hydration, setting and targeted mineralogy. The evolution of mineralogy, activation, hydration and mechanical properties will be monitored with time. Based on these properties, a selection of the best candidate formulations will be done before testing their durability through leach test when loaded with radionuclide surrogates (EPA 2013). An effort will be focused on tracking the evolution of these beneficial or deleterious phases in how they form during setting and how they evolve with environmental exposures. Depending on the results, it is possible that the PhD student would collaborate with international partners to test the best formulations with radioactive materials and research visits.
Keywords :	Cement, formulation, mineral incorporation, durability, nuclear waste

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