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Redox Chemistry in Radiation Induced Dissolution of Spent Nuclear Fuel: from Elementary Reactions to Predictive Modeling
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The focus of this doctoral thesis is the redox chemistry involved in radiation induced oxidative dissolution of spent nuclear fuel and UO2 (as a model substance for spent nuclear fuel). It is shown that two electron oxidants are more efficient than one electron oxidants in oxidative dissolution of UO2 at low oxidant concentrations. Furthermore, it is shown that H2O2 is the only oxidant that has to be taken into account in radiation induced dissolution of UO2 under deep repository conditions (granite groundwater dominated by α-radiolysis). Previously determined rate constants for oxidation of UO2 by H2O2 and O2, and rate constants for dissolution of U(VI) from the surface are successfully used to reproduce numerous UO2 dissolution rates reported in the literature. The impact of reactive solutes (Fe(II)(aq), 2-propanol and chloride) and Pd-inclusions (as a model for ε-particles) in combination with H2, on radiation induced oxidative dissolution of UO2 is investigated. It is shown that both the studied reactive solutes (under oxygen free conditions) and the combination of Pd inclusions and H2 inhibit the dissolution. Calculations (based on the fuel inventory) show that 1 µM Fe(II)(aq) decreases the dissolution rate by a factor of ~50 and that 1 ppm surface coverage of ε-particles is sufficient to completely stop the dissolution of 100 year old fuel (assuming 40 bar H2).The dissolution behavior of NpO2 and PuO2 in H2O2 containing aqueous solution without complexing agent is studied and compared to UO2. Based on the measured dissolution rates, we would not expect the dissolution of the actinides to be congruent. Instead, in a system without complexing agent, the rates Np and Pu are expected to be lower than the U release rate. The effect of ionizing irradiation on the UO2 reactivity is studied in order to elucidate the effect of self-irradiation on the reactivity of the spent fuel matrix. It is shown that a threshold dose must be achieved before any effect of irradiation can be seen. Beyond the threshold the reactivity seems to increase with increasing dose. Furthermore, the effect appears to be permanent. The effect of particle size on the reactivity of UO2 powder is studied in view of proposed theories suggesting a particle size dependence of both the pre-exponential factor and the activation energy for redox reactions. The rate constant and activation energy for oxidation of UO2 by MnO4- seems to agree with the proposed equations. The radiation chemical synthesis of UO2 nanoparticles is studied. It is shown that U(VI) released by dissolution of spent nuclear fuel could be reduced to UO2 nanoparticles.These particles could, due to their high reactivity towards H2O2, act as oxidant scavenger in a future deep repository for spent nuclear fuel.

Abstract [sv]

Denna doktorsavhandling behandlar redoxprocesser involverade i strålnings­inducerad oxidativ upplösning av använt kärnbränsle och UO2 (som modellsubstans för använt kärn­bränsle).Detta arbete visar att två-elektron oxidanter är mer effektiva än en-elektron oxidanter i oxidativ upplösning av UO2 vid låga oxidantkoncentrationer. Dessutom visas, på kinetiska grunder,att H2O2 är den enda oxidant som måste tas hänsyn till vid stålningsinducerad oxidativ upplösning av UO2 under djupförvarsförhållanden (granitiskt grundvatten dominerat av α-radiolys). Tidigare bestämda hastighets­konstanter för oxidation av UO2 med H2O2 och O2, samt hastighets­konstanter för upplösning av U(VI) från ytan har framgångrikt använts för att återskapa UO2 upplösningshastigheter rapporterade i litteraturen. Inverkan av reaktiva ämnen i vattenfas (Fe(II)(aq), 2-propanol och klorid) samt av Pd-inneslutningar (som modell av ε-partiklar) i UO2 matrisen i kombination med H2, på strålningsinducerad upplösning av UO2 har studerats. Studien visar att både de reaktiva ämnena i vattenfasen (under syrefria förhållanden) och Pd- inneslutningar i kombination med H2 hämmar upplösningen. Beräkningar (baserade på ett bränsle­inventarie) visar att 1 µM Fe(II)(aq) minskar upplösningshastigheten med en faktor ~50 samt att 1 ppm ytbeläggning av ε-partiklar är tillräckligt för att effektivt stoppa uppslöningen av 100 år gammalt bränsle (vid 40 bar H2).Upplösning av NpO2 och PuO2, i jämförelse med UO2,har studerats i vatten­lösning innehållande H2O2 utan komplexbildare. Baserat på de uppmätta upp­lösnings­hastigheterna förväntas upplösningen av dessa aktinider från UO2-bränsle vara inkongruent. I ett system utan komplexbildare kan NpO2 odh PuO2 upplösningshastighetern förvantas vara lägre än UO2 upplösningshastigheten. Effekten av joniserande strålning på reaktiviteten hos UO2 har studerats för att klargöra effekten av egen-bestrålning. Studien visar att dosen måste nå ett visst tröskelvärde innan någon effekt på reaktiviteten kan observeras. Vid doser över tröskelvärdet ökar reaktiviteten med ökande dos. Effekten verkar vara permanent. Partikelstorlekens inverkan på reaktiviteten hos UO2 pulver har studerats med utgångspunkt i föreslagna samband mellan partikelstorlek och pre-exponentiell faktor och mellan partikelstorlek och aktiveringsenergi. Studien visar att hastighets­konstanten och aktiveringsenergin för reaktionen mellan UO2 och MnO4- överenstämmer med de föreslagna sambanden. Stålningskemisk syntes av UO2 nanopartiklar har studerats. Studien visar att U(VI) frigjort genom upplösning av använt kärnbränsle i ett djupförvar kan reduceras till UO2 nanopartiklar. Dessa partiklar kan, på grund av sin höga reaktivitet med H2O2, fungera som infångare av oxidanter i ett framtida djupförvar för använt kärnbränsle.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , 73 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2008:60
National Category
Inorganic Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-4901ISBN: 978-91-7415-100-8 (print)OAI: oai:DiVA.org:kth-4901DiVA: diva2:2101
Public defence
2008-09-19, F3, KTH, Lindstedtsvägen 26, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
QC 20100908Available from: 2008-09-18 Created: 2008-09-18 Last updated: 2010-09-08Bibliographically approved
List of papers
1. Dissolution of UO2 by one- and two-electron oxidants
Open this publication in new window or tab >>Dissolution of UO2 by one- and two-electron oxidants
2004 (English)In: Materials Research Society Symposium Proceedings, ISSN 0272-9172, E-ISSN 1946-4274, Vol. 807, 77-82 p.Article in journal (Refereed) Published
Abstract [en]

In this work, the efficiency of one- and two-electron oxidants in oxidative dissolution Of UO2 has been investigated. This was accomplished by measuring the U(VI)-concentration in solution after exposing UO2-powder to controlled amounts of oxidants in aqueous solution. The oxidants used in this study are H2O2, IrCl62-, CO3.- and OH..H2O2 acts as a two-electron oxidant while the remaining three oxidants are one-electron oxidants. CO3.- and OH. were generated using gamma-radiolysis. The results clearly show that the dissolution yields for one-electron oxidants (per electron pair) are lower than the yields for two-electron oxidants. Furthermore, the yields for one-electron oxidants increase with increasing amount of oxidant (especially at low amounts of oxidant). The rationale for this is that U(VI) is the main soluble species which is formed directly upon two-electron oxidation. For one-electron oxidants the primary oxidation product is U(V) which can form U(VI) upon reaction with a second oxidant. The probability for a second oxidation is however low at low concentrations of oxidant.

Keyword
Carbonates, Concentration (process), Dissolution, Negative ions, Nuclear fuels, Probability, Radiolysis, Reaction kinetics, Solutions, Uranium dioxide, Carbonate radical anion, Magnetic stirrer, Oxidants, Oxidation products
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-9087 (URN)000225038400013 ()2-s2.0-12844256411 (Scopus ID)
Note
QC 20100907Available from: 2006-02-10 Created: 2006-02-10 Last updated: 2017-12-14Bibliographically approved
2. The relative impact of radiolysis products in radiation induced oxidative dissolution of UO2
Open this publication in new window or tab >>The relative impact of radiolysis products in radiation induced oxidative dissolution of UO2
2006 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 355, no 1-3, 38-46 p.Article in journal (Refereed) Published
Abstract [en]

The relative impact of radiolysis products in radiation induced oxidative dissolution Of UO2 has been studied experimentally. The experiments were performed by y-irradiating an aqueous solution containing HCO3 and a UO2-pellet. The U(VI) concentration in the solution was measured as a function of irradiation time. The aqueous solution was saturated with Ar, N2O, N2O/O-2 (80/20), air and O-2 in order to vary the conditions and the initial oxidant yields. The measured rate of oxidation was significantly higher for the O-2- and air saturated systems compared to the other systems. Using oxidant concentrations derived from numerical simulations of the corresponding homogeneous systems and previously determined rate constants for oxidation Of UO2, the relative trend in rate of oxidation in the different systems was reproduced. The results from the simulations were also used to estimate the relative impact of the oxidative radiolysis products as a function of irradiation time, both for gamma- and alpha-irradiated systems. For 7-irradiated systems saturated with Ar, air or 02, the most important oxidant is H2O2 while for N2O- and N2O/O-2-saturated systems the most important oxidant is CO3.-. For a-irradiated systems the most important oxidant was found to be H2O2.

Keyword
fuel corrosion, one-electron, carbonate, irradiation, oxidants, uranium, media, water
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-9088 (URN)10.1016/j.jnucmat.2006.04.001 (DOI)000239868800006 ()2-s2.0-33746368836 (Scopus ID)
Note
QC 20100907Available from: 2008-10-23 Created: 2008-10-23 Last updated: 2017-12-14Bibliographically approved
3. Oxidation of UO2(s) in aqueous solution
Open this publication in new window or tab >>Oxidation of UO2(s) in aqueous solution
2008 (English)In: Central European Journal of Chemistry, ISSN 1895-1066, Vol. 6, no 1, 1-14 p.Article in journal (Refereed) Published
Abstract [en]

In this review the kinetics and mechanism of oxidative dissolution of UO2(s), mainly under conditions of relevance for the safety assessment of a deep geological repository for spent nuclear fuel, are discussed. Rate constants for the elementary processes involved (oxidation of UO2 and dissolution of oxidized UO2) are used to calculate the rates of oxidative UO2(s) dissolution under various conditions (type of oxidant, oxidant concentration and HCO3-/CO32- concentration) for which experimental data are also available. The calculated rates are compared to the corresponding experimental values under the assumption that the experimental numbers reflect the steady-state conditions of the system. The agreement between the calculated rates and the corresponding experimental ones is very good, in particular for the higher rates. In general, the calculated rates are somewhat higher than the experimental numbers. This can be due partly to the use of initial concentrations rather than steady-state concentrations in the calculations. The kinetic data are also used to quantitatively discuss the dynamics of spent nuclear fuel dissolution under deep geological repository conditions.

Keyword
radiolysis, surface reaction, dissolution, kinetics, mechanism
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-9367 (URN)10.2478/s11532-007-0067-z (DOI)000252467300001 ()2-s2.0-38749146531 (Scopus ID)
Note
QC 20100908Available from: 2008-10-23 Created: 2008-10-23 Last updated: 2010-09-08Bibliographically approved
4. On the impact of reactive solutes on radiation induced oxidative dissolution of UO2
Open this publication in new window or tab >>On the impact of reactive solutes on radiation induced oxidative dissolution of UO2
2009 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 385, no 3, 595-600 p.Article in journal (Refereed) Published
Abstract [en]

The impact of 2-propanol (100 mM), NaCl (0.1 - 2 M) and Fe(II)(aq) (10 mu M) on the radiation induced oxidative dissolution of UO2 is investigated experimentally by gamma-irradiating a UO2 pellet immersed in aqueous solution containing 10 mM HCO3- together with one of the studied solutes and measure the U(VI) concentration in solution as a function of irradiation time. The solution was saturated with one of the following gases; Air, N2O, inert gas (N-2 or At) in order to vary the experimental conditions and/or avoid the influence of oxygen. The results show that, in the presence of oxygen, 2 M chloride decrease the rate of UO2 dissolution whereas the dissolution rate increases somewhat in the presence of 100 mM 2-propanol. Under oxygen-free conditions both 2 M chloride, 100 mM 2-propanol and 10 mu M Fe(II)(aq) decrease the rate of UO2 dissolution. The trends in dissolution rates were reproduced by calculations based on previously determined rate constants for UO2 oxidation and oxidant concentrations obtained from numerical simulation of radiolysis in the corresponding homogeneous systems (taking reactions between the different solutes and the products of water radiolysis as well as changes in oxygen solubility into account). However, the results indicate that we cannot fully account for the G-values in 2 M chloride solution or all reactions involving CI- in the aqueous phase. This calls for further studies of the chloride system.

Keyword
SPENT NUCLEAR-FUEL, REPOSITORY CONDITIONS, DISPOSAL CONDITIONS, AQUEOUS-SOLUTIONS, UNIRRADIATED UO2, RADIOLYSIS, H2O2, CORROSION, KINETICS, NACL
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-18363 (URN)10.1016/j.jnucmat.2009.01.030 (DOI)000265468100015 ()2-s2.0-62349104117 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
5. Hinhibition of radiation induced dissolution of spent nuclear fuel
Open this publication in new window or tab >>Hinhibition of radiation induced dissolution of spent nuclear fuel
2009 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 383, no 3, 226-230 p.Article in journal (Refereed) Published
Abstract [en]

In order to elucidate the effect of noble metal clusters in spent nuclear fuel on the kinetics of radiation induced spent fuel dissolution we have used I'd particle doped UO2 pellets. The catalytic effect of Pd particles on the kinetics of radiation induced dissolution Of UO2 during gamma-irradiation in HCO3- containing solutions purged with N-2 and H-2 was studied in this work. Four pellets with Pd concentrations of 0%, 0.1%, 1% and 3% were produced to mimic spent nuclear fuel. The pellets were placed in 10 mM HCO3- aqueous solutions and gamma-irradiated, and the dissolution of UO22+ was measured spectrophotometrically as a function of time. Under N-2 atmosphere, 3% I'd prevent the dissolution of uranium by reduction with the radiolytically produced H-2, while the other pellets show a rate of dissolution of around 1.6 x 10(-9) mol m(-2) s(-1). Under H-2 atmosphere already 0.1% Pd effectively prevents the dissolution of uranium, while the rate of dissolution for the pellet without Pd is 1.4 x 10(-9) mol m(-2) s(-1). It is also shown in experiments without radiation in aqueous solutions containing H2O2 and O-2 that epsilon-particles catalyze the oxidation of the UO2 matrix by these molecular oxidants, and that the kinetics of the catalyzed reactions is close to diffusion controlled.

Keyword
WASTE-DISPOSAL CONDITIONS, OXIDATIVE DISSOLUTION, AQUEOUS-SOLUTION, URANIUM-DIOXIDE, UO2, KINETICS, H2O2, REDUCTION, CORROSION, MECHANISM
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-9369 (URN)10.1016/j.jnucmat.2008.09.021 (DOI)000261905600004 ()2-s2.0-56349130830 (Scopus ID)
Note
QC 20100908. Uppdaterad från submitted till published (20100908).Available from: 2008-10-23 Created: 2008-10-23 Last updated: 2017-12-14Bibliographically approved
6. Radiation induced spent nuclear fuel dissolution under deep repository conditions
Open this publication in new window or tab >>Radiation induced spent nuclear fuel dissolution under deep repository conditions
Show others...
2007 (English)In: Environmental Science and Technology, ISSN 0013-936X, Vol. 41, no 20, 7087-7093 p.Article in journal (Refereed) Published
Abstract [en]

The dynamics of spent nuclear fuel dissolution in groundwater is an important part of the safety assessment of a deep geological repository for high level nuclear waste. In this paper we discuss the most important elementary processes and parameters involved in radiation induced oxidative dissolution of spent nuclear fuel. Based on these processes, we also present a new approach for simulation of spent nuclear fuel dissolution under deep repository conditions. This approach accounts for the effects of fuel age, burn up, noble metal nanoparticle contents, aqueous H-2 and HCO3- concentration, water chemistry, and combinations thereof. The results clearly indicate that solutes consuming H2O2 and combined effects of noble metal nanoparticles and H-2 have significant impact on the rate of spent nuclear fuel dissolution. Using data from the two possible repository sites in Sweden, we have employed the new approach to estimate the maximum rate of spent nuclear fuel dissolution. This estimate indicates that H-2 produced from radiolysis of groundwater alone will be sufficient to inhibit the dissolution, completely for spent nuclear fuel older than 100 years.

Keyword
Computer simulation, Concentration (process), Dissolution, Groundwater, Nanoparticles, Nuclear fuels, Radiation, Radioactive wastes, Radiolysis, Noble metal, Nuclear fuel dissolution, Water pollution, bicarbonate, ground water, hydrogen peroxide, metal, nanoparticle, nuclear fuel, water, Computer simulation, Concentration (process), Dissolution, Groundwater, Nanoparticles, Nuclear fuels, Radiation, Radioactive wastes, Radiolysis, Water pollution, assessment method, concentration (composition), dissolution, fuel, groundwater, oxidation, radioactive waste, repository, safety, water chemistry, article, concentration response, dissolution, oxidation, radiation, radioactive waste processing, radiolysis, Sweden
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-8390 (URN)10.1021/es070832y (DOI)000250110800036 ()2-s2.0-35348828672 (Scopus ID)
Note
QC 20100811Available from: 2008-05-08 Created: 2008-05-08 Last updated: 2012-05-30Bibliographically approved
7. Oxidative dissolution of actinide oxides in H2O2 containing aqueous solution: A preliminary study
Open this publication in new window or tab >>Oxidative dissolution of actinide oxides in H2O2 containing aqueous solution: A preliminary study
Show others...
2010 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 397, no 1-3, 128-131 p.Article in journal (Refereed) Published
Abstract [en]

Oxidative dissolution Of Spent nuclear fuel is an important issue in the safety assessment of a future geological repository for Spent nuclear fuel. Although UO2 Constitutes, in terms of mass, the majority of the spent fuel material, its main radiotoxicity is (after extended storage times) contained in actinides with half lives shorter than that of 238-uranium, such as isotopes of Np and Pu. Relatively little information is available on the dissolution behavior of Np and Pu in comparable environments. This work investigates the oxidative dissolution of NpO2 and PuO2 in non-complexing aqueous solutions containing H2O2 and compares their behavior with that of UO2. We have found that oxidative dissolution takes place for all three actinides in the presence of H2O2. Based on the obtained dissolution rates, we Would not expect the dissolution of the actinides to be congruent. Instead, in a System Without complexing agent, the release rates of Np and Pu are expected to be lower than the U release rate.

Keyword
HYDROGEN-PEROXIDE, SOLVENT-EXTRACTION, UO2, STATES
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-9370 (URN)10.1016/j.jnucmat.2009.11.027 (DOI)000275132000019 ()2-s2.0-75149114051 (Scopus ID)
Note
QC 20100908. Uppdaterad från submitted till published (20100908).Available from: 2008-10-23 Created: 2008-10-23 Last updated: 2017-12-14Bibliographically approved
8. Radiation enhanced reactivity of UO2
Open this publication in new window or tab >>Radiation enhanced reactivity of UO2
2006 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 354, no 1-3, 131-136 p.Article in journal (Refereed) Published
Abstract [en]

Pure UO2 is often used as a model compound when studying reactions of importance in a future deep repository for spent nuclear fuel. The reactivity of pure UO2 is not expected to be identical to the reactivity of the UO2-matrix of spent nuclear fuel for several reasons. One reason is that the spent fuel, due to the content of radionuclides, is continuously being self-irradiated. The aim of this study is to investigate how irradiation of solid UO2 surfaces affects their reactivity towards oxidants. The effect of irradiation (gamma or electrons) on the reaction between solid UO2 and MnO4- in aqueous solutions containing carbonate has been studied. It was found that irradiation with high doses (> 40 kGy) increased the reactivity of the UO2 to about 1.3 times the reactivity of unirradiated UO2.

Keyword
Carbonates, Electron irradiation, Manganese compounds, Mathematical models, Nuclear fuels, Radioisotopes, F0700, U0200, W0200
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-8387 (URN)10.1016/j.jnucmat.2006.03.011 (DOI)000239109300011 ()2-s2.0-33745422542 (Scopus ID)
Note
QC 20100908Available from: 2008-05-08 Created: 2008-05-08 Last updated: 2017-12-14Bibliographically approved
9. The influence of particle size on the kinetics of UO2 oxidation in aqueous powder suspensions
Open this publication in new window or tab >>The influence of particle size on the kinetics of UO2 oxidation in aqueous powder suspensions
2006 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 353, no 1-2, 75-79 p.Article in journal (Refereed) Published
Abstract [en]

Previous studies have indicated that the rate of a heterogeneous liquid-solid reaction depends on the size of the solid particles. It has been suggested that both the pre-exponential factor and the activation energy depend on the particle size. The processes involved in dissolution of UO2 have been extensively studied because of their importance for the safety analysis of a future deep repository for spent nuclear fuel and in many of these studies powder suspensions of UO2 are used as a model system. Therefore, it is of importance to investigate and quantify the particle size effect on the kinetics of UO2 oxidation in order to enable comparison of data from studies oil different solid substrates. In this work the influence of particle size on the second order rate constant and on the activation energy of the reaction between MnO4- and UO2 was studied using aqueousUO(2)-particle suspensions of four different size distributions. A comparative study of the activation energy for the reaction using a UO2 pellet was also performed.

Keyword
dissolution mechanism, uranium-dioxide, one-electron, reduction, oxidants
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-15821 (URN)10.1016/j.jnucmat.2006.03.005 (DOI)000238770300009 ()2-s2.0-33744994983 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
10. Radiation chemical synthesis and characterization of UO2 nanoparticles
Open this publication in new window or tab >>Radiation chemical synthesis and characterization of UO2 nanoparticles
2009 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 383, no 3, 231-236 p.Article in journal (Refereed) Published
Abstract [en]

In a deep repository for spent nuclear fuel, U(VI)(aq) released upon dissolution of the fuel matrix could, in reducing parts of the system, be converted to U(IV) species which might coalesce and form nanometersized UO2 particles. This type of particles is expected to have different properties compared to bulk UO2(s). Hence, their properties, in particular the capacity for oxidant consumption, must be investigated in order to assess the effects of formation of such particles in a deep repository. In this work, methods for radiation chemical synthesis of nanometer-sized UO2 particles, by electron- and gamma-irradiation of U(VI) solutions, are presented. Electron-irradiation proved to be the most efficient method, showing high conversions of U(VI) and yielding small particles with a narrow size distribution (22-35 nm). Stable colloidal suspensions were obtained at low pH and ionic strength (pH 3, I = 0.03). Furthermore, the reactivity of the produced UO2 particles towards H2O2 is investigated. The U(IV) fraction in the produced particles was found to be similar to 20% of the total uranium content, and the results show that the UO2 nanoparticles are significantly more reactive than micrometer-sized UO2 when it comes to H2O2 consumption, the major part of the H2O2 being catalytically decomposed on the particle surface.

Keyword
Actinides, Dissolution, Electron irradiation, Ionic strength, Irradiation, Nanostructures, Nuclear fuels, Reactivity (nuclear), Synthesis (chemical), Thickness measurement, Transuranium elements, Uranium, Uranium compounds, Vegetation, Chemical syntheses, Colloidal suspensions, Efficient methods, Fuel matrixes, Narrow size distributions, Oxidant consumptions, Particle surfaces, Small particles, Spent nuclear fuels, Uranium contents
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-18064 (URN)10.1016/j.jnucmat.2008.09.026 (DOI)000261905600005 ()2-s2.0-56349105082 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved

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