Klaas Bakker - Academia.edu (original) (raw)
Papers by Klaas Bakker
Journal of Physics: Condensed Matter, 1993
Specific-heat measurements have been performed on polycrystalline R2Zn17 compounds (R identical t... more Specific-heat measurements have been performed on polycrystalline R2Zn17 compounds (R identical to Pr, Nd, Tb, Dy, Ho, Er and Y) in the temperature range from 0.3 to 150 K. For all the compounds, except for R identical to Y, magnetic anomalies in the specific heat have been observed, indicating the existence of magnetic order at low temperatures.
Progress in Nuclear Energy, 2001
The inert matrix materials CeO2, MgO, Y2O3, MgAl2O4 and Y3Al5O12 were selected as candidates for ... more The inert matrix materials CeO2, MgO, Y2O3, MgAl2O4 and Y3Al5O12 were selected as candidates for inert matrices for the EFTTRA22Experimental Feasibility of Targets for TRAnsmutation, a European project in which CEA, NRG, EdF, FzK, JRC-ITU and JRC-IAM cooperate.-T3 neutron irradiation experiment. Most targets contain 20% enriched 235U fissile inclusions with an average size of roughly 150 μm. The volume fraction of the fissile phase is either 2.5 vol% UO2 or 19.6 vol% of Y5.78UOx in the inert matrices. The samples were irradiated for 198.9 full power days in the High Flux Reactor in Petten. The calculated burn-up is between 17.3 and 19.5% FIMA. The temperature of the cladding was kept at 600 ± 25 K. A dimensional change of at least +5 % is measured after neutron irradiation for Y3Al5O12 and MgAl2O4 with macro dispersions of UO2; the other targets with a macro dispersion of UO2 show a volume change of less than + 1 vol%. The fractional release of the fission gas Xe is more than 40% for the MgAl2O4 and Y3Al5O12 matrices with a macro dispersion of UO2, the other targets show a fractional release of Xe of less than 15%. Cracks are observed in MgO and MgAl2O4 targets which is possibly related to the stress caused by swelling of the UO2 inclusions.
Solid State Communications, 1993
Physica B: Condensed Matter, 1993
ABSTRACT The coefficients of linear thermal expansion, α(T), of the heavy-fermion compound CeInCu... more ABSTRACT The coefficients of linear thermal expansion, α(T), of the heavy-fermion compound CeInCu2 and its non-heavy analog LaInCu2 have been measured at low temperatures (0.3 K<T<12K). In the heavy-fermion regime α(T) of CeInCu2 shows a large positive contribution (with an electronic Grüneisen parameter Γel≃40), while below ∼4K a crossover to a pronounced negative contribution takes place. The negative contribution is associated with (short-range) antiferromagnetic order (Γaf=−32). The temperature variation of α of CeInCu2 bears a close resemblance to that of CeAl3.
Physica B: Condensed Matter, 1993
We report on high-field (B < 38 T) magnetoresistance experiments on a single-crystalline sample o... more We report on high-field (B < 38 T) magnetoresistance experiments on a single-crystalline sample of the heavy-fermion antiferromagnet UPd2A13 (T N = 14 K) at liquid-helium temperatures. The antiferromagnetic phase boundary, previously detected by magnetization measurements at B c = 18 T for a field in the basal plane (T = 1.3 K), is reflected as a sharp peak in the longitudinal (I II a) and as a precipitous drop in the transverse (1 II e) magnetoresistance.
Physica B: Condensed Matter, 1993
The electronic instability in the highly correlated electron system UPt 3 gives rise to various i... more The electronic instability in the highly correlated electron system UPt 3 gives rise to various intriguing phenomena at liquid-helium temperatures, among which the occurrence of unconventional superconductivity (T + = 0.49 K, T c = 0.44 K) has attracted most attention. In a magnetic field three superconducting phases are observed that meet at a tetracritical point. We here present a discussion of a number of puzzling aspects of a superconducting phase diagram (B±c) of unprecedented accuracy, determined by dilatometry. The possible interplay of superconductivity and reduced moment antiferromagnetism (T N = 5 K) is investigated. Furthermore, we report on recent studies of the suppression of T¢, by alloying with Pd, Y, Th, Au and Ir.
Journal of Nuclear Materials, 1999
Polycrystalline pellets of yttrium aluminate garnet (Y 3 Al 5 O 12), magnesium aluminate spinel (... more Polycrystalline pellets of yttrium aluminate garnet (Y 3 Al 5 O 12), magnesium aluminate spinel (MgAl 2 O 4) and aalumina (a-Al 2 O 3) have been irradiated in the high¯ux reactor (HFR) at Petten to a neutron¯uence of 1.7´10 26 m À2 (i b 0X1 MeV) at a temperature of about 815 K. Volume changes smaller than 1% have been measured for Y 3 Al 5 O 12 and MgAl 2 O 4. Transmission electron microscopy (TEM) results of Y 3 Al 5 O 12 show no dierence between the unirradiated TEM samples and neutron-irradiated samples. For MgAl 2 O 4 , dislocation loops in some grains are found in the irradiated samples. TEM results of Al 2 O 3 show a dense network of dislocation loops after neutron irradiation. The increase in volume is 4.2% for a neutron¯uence of 1.7´10 26 m À2 .
Journal of Alloys and Compounds, 1993
} I Fig. 1. Unit cell of SmMn2Ge2 (ThCr2Si2-type) showing antiferromagnetically coupled Mn layers... more } I Fig. 1. Unit cell of SmMn2Ge2 (ThCr2Si2-type) showing antiferromagnetically coupled Mn layers sandwiched between layers of Ge (@) and Sm (O).
Journal of Alloys and Compounds, 1993
As part of a systematic research programme on equiatomic ternary compounds of the type RTX (R is ... more As part of a systematic research programme on equiatomic ternary compounds of the type RTX (R is a rare earth, T a transition metal and X a metal out of the p block of the periodic table) crystallizing in the ZrNiAI structure, results for CePdxRh,_xln (x=0, 0.2, 0.4, 0.6, 0.8, 0.85, 0.9, 0.95, 1) are presented. The magnetic properties, specific heat and electrical resistivity as a function of magnetic field and temperature are reported. The development of the electronic properties from CeRhln with unstable 4f moments towards CePdln with localized 4f moments is discussed in terms of the influence on the valence state of Ce of the increase in the d-electron concentration due to gradual substitution of Rh in CeRhln by Pd. The almost trivalent state is found to be most favourable for the formation of the heavy-fermion state.
Journal of Nuclear Materials, 1998
The thermal properties and the response to fission-product damage of CePO4 were studied in view o... more The thermal properties and the response to fission-product damage of CePO4 were studied in view of its potential application as inert matrix for the transmutation of transuranium elements in nuclear reactors. The thermal expansion of CePO4 has been recorded from 293 K to 1323 K using X-ray diffraction. The reduced enthalpy increment of CePO4 has been measured by drop calorimetry
… Engineering and Design, 2010
The analytical PYCASSO (PYrocarbon irradiation for Creep and Swelling/Shrinkage of Objects) irr... more The analytical PYCASSO (PYrocarbon irradiation for Creep and Swelling/Shrinkage of Objects) irradiations focus on determining the effects of neutron irradiation in the temperature range of 9001100° C, excluding effects due to the presence of fuel, such as ...
Nuclear Technology
The technical and economic aspects of the use of molybdenum depleted in the isotope {sup 95}Mo (D... more The technical and economic aspects of the use of molybdenum depleted in the isotope {sup 95}Mo (DepMo) for the transmutation of actinides in a light water reactor are discussed. DepMo has a low neutron absorption cross section and good physical and chemical properties. ...
Nuclear Technology
The thermal conductivity of UO{sub 2} is an important parameter in the design of nuclear fuel ass... more The thermal conductivity of UO{sub 2} is an important parameter in the design of nuclear fuel assemblies. The thermal conductivity can be reduced by radiation-induced porosity, leading to increased safety risks. In the literature, an analytical equation has been suggested to describe the influence of randomly ordered ellipsoidal porosity on thermal conductivity. However, in the case where the shape and the distribution of the pores is very complex, as in irradiated nuclear fuel, this equation is less well suited. The finite element method is introduced as a computational technique to take into account the influence of complex porosity structures on the thermal conductivity. Using the combination of image analysis and the finite element method, an equation has been obtained that describes the relation between the average elongated form of the pores and the overall thermal conductivity. Both the finite element method and image analysis are tools to estimate the thermal conductivity of high-burnup nuclear fuel.
Nucl Technol, 1996
The thermal conductivity of UO{sub 2} is an important parameter in the design of nuclear fuel ass... more The thermal conductivity of UO{sub 2} is an important parameter in the design of nuclear fuel assemblies. The thermal conductivity can be reduced by radiation-induced porosity, leading to increased safety risks. In the literature, an analytical equation has been suggested to describe the influence of randomly ordered ellipsoidal porosity on thermal conductivity. However, in the case where the shape and the distribution of the pores is very complex, as in irradiated nuclear fuel, this equation is less well suited. The finite element method is introduced as a computational technique to take into account the influence of complex porosity structures on the thermal conductivity. Using the combination of image analysis and the finite element method, an equation has been obtained that describes the relation between the average elongated form of the pores and the overall thermal conductivity. Both the finite element method and image analysis are tools to estimate the thermal conductivity of high-burnup nuclear fuel.
High Temperatures-High Pressures, 1998
ABSTRACT The parameters that influence the thermal conductivity of high burnup uranium dioxide fu... more ABSTRACT The parameters that influence the thermal conductivity of high burnup uranium dioxide fuel are discussed and the thermal conductivity of uranium dioxide fuel with a burnup of approximately 39 MWd kgUO(2)(-1) has been analysed. The main parameters are changes in the pore structure, dissolution of fission products in the matrix, formation of precipitates, and the formation of cracks. The influence of dissolution or precipitation of fission products can be approximated by the use of data for SIMFUEL (Lucuta et all. The influence of porosity can be estimated by the use of the finite element method. The influence of cracks depends strongly on the width of the fuel-to-cladding gap.
Progress in Nuclear Energy, 2001
Journal of Physics: Condensed Matter, 1993
Specific-heat measurements have been performed on polycrystalline R2Zn17 compounds (R identical t... more Specific-heat measurements have been performed on polycrystalline R2Zn17 compounds (R identical to Pr, Nd, Tb, Dy, Ho, Er and Y) in the temperature range from 0.3 to 150 K. For all the compounds, except for R identical to Y, magnetic anomalies in the specific heat have been observed, indicating the existence of magnetic order at low temperatures.
Progress in Nuclear Energy, 2001
The inert matrix materials CeO2, MgO, Y2O3, MgAl2O4 and Y3Al5O12 were selected as candidates for ... more The inert matrix materials CeO2, MgO, Y2O3, MgAl2O4 and Y3Al5O12 were selected as candidates for inert matrices for the EFTTRA22Experimental Feasibility of Targets for TRAnsmutation, a European project in which CEA, NRG, EdF, FzK, JRC-ITU and JRC-IAM cooperate.-T3 neutron irradiation experiment. Most targets contain 20% enriched 235U fissile inclusions with an average size of roughly 150 μm. The volume fraction of the fissile phase is either 2.5 vol% UO2 or 19.6 vol% of Y5.78UOx in the inert matrices. The samples were irradiated for 198.9 full power days in the High Flux Reactor in Petten. The calculated burn-up is between 17.3 and 19.5% FIMA. The temperature of the cladding was kept at 600 ± 25 K. A dimensional change of at least +5 % is measured after neutron irradiation for Y3Al5O12 and MgAl2O4 with macro dispersions of UO2; the other targets with a macro dispersion of UO2 show a volume change of less than + 1 vol%. The fractional release of the fission gas Xe is more than 40% for the MgAl2O4 and Y3Al5O12 matrices with a macro dispersion of UO2, the other targets show a fractional release of Xe of less than 15%. Cracks are observed in MgO and MgAl2O4 targets which is possibly related to the stress caused by swelling of the UO2 inclusions.
Solid State Communications, 1993
Physica B: Condensed Matter, 1993
ABSTRACT The coefficients of linear thermal expansion, α(T), of the heavy-fermion compound CeInCu... more ABSTRACT The coefficients of linear thermal expansion, α(T), of the heavy-fermion compound CeInCu2 and its non-heavy analog LaInCu2 have been measured at low temperatures (0.3 K<T<12K). In the heavy-fermion regime α(T) of CeInCu2 shows a large positive contribution (with an electronic Grüneisen parameter Γel≃40), while below ∼4K a crossover to a pronounced negative contribution takes place. The negative contribution is associated with (short-range) antiferromagnetic order (Γaf=−32). The temperature variation of α of CeInCu2 bears a close resemblance to that of CeAl3.
Physica B: Condensed Matter, 1993
We report on high-field (B < 38 T) magnetoresistance experiments on a single-crystalline sample o... more We report on high-field (B < 38 T) magnetoresistance experiments on a single-crystalline sample of the heavy-fermion antiferromagnet UPd2A13 (T N = 14 K) at liquid-helium temperatures. The antiferromagnetic phase boundary, previously detected by magnetization measurements at B c = 18 T for a field in the basal plane (T = 1.3 K), is reflected as a sharp peak in the longitudinal (I II a) and as a precipitous drop in the transverse (1 II e) magnetoresistance.
Physica B: Condensed Matter, 1993
The electronic instability in the highly correlated electron system UPt 3 gives rise to various i... more The electronic instability in the highly correlated electron system UPt 3 gives rise to various intriguing phenomena at liquid-helium temperatures, among which the occurrence of unconventional superconductivity (T + = 0.49 K, T c = 0.44 K) has attracted most attention. In a magnetic field three superconducting phases are observed that meet at a tetracritical point. We here present a discussion of a number of puzzling aspects of a superconducting phase diagram (B±c) of unprecedented accuracy, determined by dilatometry. The possible interplay of superconductivity and reduced moment antiferromagnetism (T N = 5 K) is investigated. Furthermore, we report on recent studies of the suppression of T¢, by alloying with Pd, Y, Th, Au and Ir.
Journal of Nuclear Materials, 1999
Polycrystalline pellets of yttrium aluminate garnet (Y 3 Al 5 O 12), magnesium aluminate spinel (... more Polycrystalline pellets of yttrium aluminate garnet (Y 3 Al 5 O 12), magnesium aluminate spinel (MgAl 2 O 4) and aalumina (a-Al 2 O 3) have been irradiated in the high¯ux reactor (HFR) at Petten to a neutron¯uence of 1.7´10 26 m À2 (i b 0X1 MeV) at a temperature of about 815 K. Volume changes smaller than 1% have been measured for Y 3 Al 5 O 12 and MgAl 2 O 4. Transmission electron microscopy (TEM) results of Y 3 Al 5 O 12 show no dierence between the unirradiated TEM samples and neutron-irradiated samples. For MgAl 2 O 4 , dislocation loops in some grains are found in the irradiated samples. TEM results of Al 2 O 3 show a dense network of dislocation loops after neutron irradiation. The increase in volume is 4.2% for a neutron¯uence of 1.7´10 26 m À2 .
Journal of Alloys and Compounds, 1993
} I Fig. 1. Unit cell of SmMn2Ge2 (ThCr2Si2-type) showing antiferromagnetically coupled Mn layers... more } I Fig. 1. Unit cell of SmMn2Ge2 (ThCr2Si2-type) showing antiferromagnetically coupled Mn layers sandwiched between layers of Ge (@) and Sm (O).
Journal of Alloys and Compounds, 1993
As part of a systematic research programme on equiatomic ternary compounds of the type RTX (R is ... more As part of a systematic research programme on equiatomic ternary compounds of the type RTX (R is a rare earth, T a transition metal and X a metal out of the p block of the periodic table) crystallizing in the ZrNiAI structure, results for CePdxRh,_xln (x=0, 0.2, 0.4, 0.6, 0.8, 0.85, 0.9, 0.95, 1) are presented. The magnetic properties, specific heat and electrical resistivity as a function of magnetic field and temperature are reported. The development of the electronic properties from CeRhln with unstable 4f moments towards CePdln with localized 4f moments is discussed in terms of the influence on the valence state of Ce of the increase in the d-electron concentration due to gradual substitution of Rh in CeRhln by Pd. The almost trivalent state is found to be most favourable for the formation of the heavy-fermion state.
Journal of Nuclear Materials, 1998
The thermal properties and the response to fission-product damage of CePO4 were studied in view o... more The thermal properties and the response to fission-product damage of CePO4 were studied in view of its potential application as inert matrix for the transmutation of transuranium elements in nuclear reactors. The thermal expansion of CePO4 has been recorded from 293 K to 1323 K using X-ray diffraction. The reduced enthalpy increment of CePO4 has been measured by drop calorimetry
… Engineering and Design, 2010
The analytical PYCASSO (PYrocarbon irradiation for Creep and Swelling/Shrinkage of Objects) irr... more The analytical PYCASSO (PYrocarbon irradiation for Creep and Swelling/Shrinkage of Objects) irradiations focus on determining the effects of neutron irradiation in the temperature range of 9001100° C, excluding effects due to the presence of fuel, such as ...
Nuclear Technology
The technical and economic aspects of the use of molybdenum depleted in the isotope {sup 95}Mo (D... more The technical and economic aspects of the use of molybdenum depleted in the isotope {sup 95}Mo (DepMo) for the transmutation of actinides in a light water reactor are discussed. DepMo has a low neutron absorption cross section and good physical and chemical properties. ...
Nuclear Technology
The thermal conductivity of UO{sub 2} is an important parameter in the design of nuclear fuel ass... more The thermal conductivity of UO{sub 2} is an important parameter in the design of nuclear fuel assemblies. The thermal conductivity can be reduced by radiation-induced porosity, leading to increased safety risks. In the literature, an analytical equation has been suggested to describe the influence of randomly ordered ellipsoidal porosity on thermal conductivity. However, in the case where the shape and the distribution of the pores is very complex, as in irradiated nuclear fuel, this equation is less well suited. The finite element method is introduced as a computational technique to take into account the influence of complex porosity structures on the thermal conductivity. Using the combination of image analysis and the finite element method, an equation has been obtained that describes the relation between the average elongated form of the pores and the overall thermal conductivity. Both the finite element method and image analysis are tools to estimate the thermal conductivity of high-burnup nuclear fuel.
Nucl Technol, 1996
The thermal conductivity of UO{sub 2} is an important parameter in the design of nuclear fuel ass... more The thermal conductivity of UO{sub 2} is an important parameter in the design of nuclear fuel assemblies. The thermal conductivity can be reduced by radiation-induced porosity, leading to increased safety risks. In the literature, an analytical equation has been suggested to describe the influence of randomly ordered ellipsoidal porosity on thermal conductivity. However, in the case where the shape and the distribution of the pores is very complex, as in irradiated nuclear fuel, this equation is less well suited. The finite element method is introduced as a computational technique to take into account the influence of complex porosity structures on the thermal conductivity. Using the combination of image analysis and the finite element method, an equation has been obtained that describes the relation between the average elongated form of the pores and the overall thermal conductivity. Both the finite element method and image analysis are tools to estimate the thermal conductivity of high-burnup nuclear fuel.
High Temperatures-High Pressures, 1998
ABSTRACT The parameters that influence the thermal conductivity of high burnup uranium dioxide fu... more ABSTRACT The parameters that influence the thermal conductivity of high burnup uranium dioxide fuel are discussed and the thermal conductivity of uranium dioxide fuel with a burnup of approximately 39 MWd kgUO(2)(-1) has been analysed. The main parameters are changes in the pore structure, dissolution of fission products in the matrix, formation of precipitates, and the formation of cracks. The influence of dissolution or precipitation of fission products can be approximated by the use of data for SIMFUEL (Lucuta et all. The influence of porosity can be estimated by the use of the finite element method. The influence of cracks depends strongly on the width of the fuel-to-cladding gap.
Progress in Nuclear Energy, 2001