The isothermal corrosion behavior between 1000°C and 1190°C of Inconel 690 and 693 in an iron pho... more The isothermal corrosion behavior between 1000°C and 1190°C of Inconel 690 and 693 in an iron phosphate glass melt containing 26 wt.% of a simulated Hanford low activity nuclear waste (LAW) was investigated. At least three distinct corrosion processes were recognized for both alloys over different temperature ranges. Inconel 690 and 693 both display the best corrosion resistance at an intermediate temperature range (Inconel 690: 1050-1100°C; Inconel 693: 1050-1165°C), and more severe corrosion at both lower and higher temperatures. In general, Inconel 693 is less reactive over a wider temperature range than Inconel 690.
Chemical durability, glass formation tendency, and other properties of iron alumina phosphate gla... more Chemical durability, glass formation tendency, and other properties of iron alumina phosphate glasses containing 70 wt% of a simulated high level nuclear waste (HLW), doped with different amounts of Cr 2 O 3 , have been investigated. All of the iron alumina phosphate glasses had an outstanding chemical durability as measured by their small dissolution rate (1 . 10 -9 g/(cm 2 . min)) in deionized water at 90°C for 128 d, their low normalized mass release as determined by the Product Consistency Test (PCT) and a barely measurable corrosion rate of <0.1 g/(m 2 . d) after 7 d at 200°C by the Vapor Hydration Test (VHT). The solubility limit for Cr 2 O 3 in the iron phosphate melts was estimated at 4.1 wt%, but all of the as-annealed melts contained a few percent of crystalline Cr 2 O 3 that had no apparent effect on the chemical durability. The chemical durability was unchanged after deliberate crystallization, 48 h at 650°C. These iron phosphate waste forms, with a waste loading of at least 70 wt%, can be readily melted in commercial refractory crucibles at 1250°C for 2 to 4 h, are resistant to crystallization, meet all current US Department of Energy requirements for chemical durability, and have a solubility limit for Cr 2 O 3 which is at least three times larger than that for borosilicate glasses.
ABSTRACT a b s t r a c t Iron phosphate glass is a candidate fixation medium for storing radioact... more ABSTRACT a b s t r a c t Iron phosphate glass is a candidate fixation medium for storing radioactive waste. The Department of Energy supported a program to assess the viability of using Fe-phosphate glass for vitrifying low activity waste in a Joule Heated Melter (JHM). In this study, Inconel 693 electrodes were tested in a research-scale joule-heated melter (RSM) at Pacific Northwest National Laboratory. After a 10-day test at 1030 °C that yielded 124 kg of glass, the electrodes exhibited a dimensional loss rate of $1.6 mm/year, which is com-parable to that of Inconel 690 electrodes used in a JHM for processing borosilicate melts. Microstructural changes occurred within the outermost 700 lm of the electrodes and are consistent with an earlier study of Inconel coupons in Fe-phosphate melts. The results indicate that Inconel 693 should have an accept-able corrosion resistance as the electrode for JHM processing of iron phosphate melts. Ó 2013 Elsevier B.V. All rights reserved.
Iron phosphate glasses are of interest for immobilizing high level nuclear waste (HLW). The high ... more Iron phosphate glasses are of interest for immobilizing high level nuclear waste (HLW). The high temperature viscosity and AC electrical conductivity of an iron phosphate melt containing 2.8 mass% chrome oxide were investigated in this work. The viscosity of this melt varied from 10 to 50 poise from 1350 to 1150°C, respectively, while the activation energy for viscous flow was 82 and 126 kJ/mol during heating and cooling the melt, respectively. The viscosity of the melt at 1250°C increased with time due to the reduction of Fe 3+ to Fe 2+. The AC electrical conductivity of the melt varied from 45 to 65 S/m at 1050 and 1350°C, respectively. The activation energy for AC electrical conductivity was 28 and 18 kJ/mol during heating and cooling, respectively. The weight loss rate of the melt at 1250°C after 20 h was only 5 • 10 À4 g/cm 2 /h.
Iron phosphate glasses containing 30 w% of a high sodium and sulfur Hanford low-activity waste (L... more Iron phosphate glasses containing 30 w% of a high sodium and sulfur Hanford low-activity waste (LAW) simulant was successfully melted in electric furnaces at 1000–1050 °C for 2–3 h. No sulfate salt segregation or crystalline phases were detectable in the glassy wasteform when examined by scanning electron microscope and X-ray diffractometer. This suggests that the waste loading in the iron
An iron phosphate composition for vitrifying a high sulfate (~17 wt%) and high alkali (~80 wt%) H... more An iron phosphate composition for vitrifying a high sulfate (~17 wt%) and high alkali (~80 wt%) Hanford low activity waste (LAW), known as AZ-102 LAW, has been developed for processing in a Joule Heated Melter (JHM) or a Cold Crucible Induction Melter (CCIM). This composition produced a glass waste form, designated as MS26AZ102F-2, with a waste loading of 26 wt% of the AZ-102 which corresponded to a total alkali and sulfate (represented as SO 3) content of 21 and 4.4 wt%, respectively. A slurry (7M Na +) of MS26AZ102F-2 simulant was melted continuously at temperatures between 1030 and 1090°C for 10 days in a small JHM at PNNL and for 70 hours in a CCIM at INL. The as-cast glasses produced in both melters and in trial laboratory experiments along with their canister centerline cooled (CCC) counterparts met the requirements for the Product Consistency Test (PCT) and the Vapor Hydration Test (VHT) responses in the Hanford Tank Waste Treatment and Immobilization Plant (WTP) Contract. These glass waste forms retained up to 77 % of the SO 3 (3.3 wt%), 100% of the Cesium, and 33 to 44% of the rhenium (used as a surrogate for Tc) all of which either exceeded or were comparable to the retention limit for these species in borosilicate glass nuclear waste form. Analyses of commercial K-3 refractory lining and the Inconel 693 metal electrodes used in JHM indicated only minimum corrosion of these components by the iron phosphate glass. This is the first time that an iron phosphate composition was melted continuously in a slurry fed JHM and in the US, thereby, demonstrating that iron phosphate glasses can be used as alternative hosts for vitrifying nuclear waste. * Raw materials used for glass formulation work, but these oxide components would be supplied by the waste stream. The contents of the critical oxides are shown in red. Other GFC's: All P 2 O 5 is available from Al(PO 3) 3 and AlPO 4 .
ABSTRACT Optical microresonators have been proven effective for developing sensitive chemical and... more ABSTRACT Optical microresonators have been proven effective for developing sensitive chemical and biological sensors by monitoring the changes in refractive index or mass near the resonator surface. The rotationally symmetric structures support high quality (Q) whispering gallery modes (WGMs) that interact with the local environment through the evanescent field. The long photon lifetime of the high-Q resonator (thus the long light-material interaction path) is the key reason that a microresonator can achieve very high sensitivity in detection. In this paper, we present our recent research on using porous wall hollow glass microsphere (PW-HGM) as an optical microresonator for chemical vapor detection. The diameter of the PW-HGM ranges from 10μm to 100μm. The wall thickness is about 2μm and the pore size is about 20nm. The Q-factors and free spectrum ranges (FSR) of PW-HGMs were measured by coupling light into the PW-HGM using a single mode fiber taper. Various types of chemical vapors were used to characterize the PW-HGM resonator. The resonant wavelength shift was measured as a function of vapor concentration. Comparisons between a PW-HGM and a solid glass microsphere indicated that a PW-HGM can effectively adsorb vapor molecules into its nanosized pores, providing a direct and long light-material interaction path for significant sensitivity enhancement for chemical vapor detection.
ABSTRACT Iron phosphate glasses have been studied as an alternative glass for vitrifying Departme... more ABSTRACT Iron phosphate glasses have been studied as an alternative glass for vitrifying Department of Energy (DOE) high priority wastes. The high priority wastes were the Low Activity Waste (LAW) and the High Level Waste (HLW) with high chrome content stored at Hanford, WA, and the Sodium Bearing Waste (SBW) stored at the Idaho National Engineering and Environmental Laboratory. These wastes were recommended by Tanks Focus Area since they were expected to require special attention when vitrified in borosilicate glasses. All three of these wastes have been successfully vitrified in iron phosphate glasses at waste loadings ranging from a low of 32 wt% for the high sulfate LAW to 40 wt% for the SBW to a high of 75 wt% for the high chrome HLW. In addition to these desirable high waste loadings, the iron phosphate glasses were easily melted, typically between 950 and 1200 C, in less than 4 hours in commercial refractory oxide containers. It is noteworthy that the chemical durability of both glassy and deliberately crystallized iron phosphate wasteforms not only met, but significantly exceeded, all current DOE chemical durability requirements as measured by the Product Consistency Test (PCT) and Vapor Hydration Test (VHT). The high waste loading, low melting temperature, rapid furnace throughput (short melting time) and their outstanding chemical durability could significantly accelerate the clean up effort and reduce the time and cost of vitrifying these high priority wastes.
Inconel alloy 690 and Inconel alloy 693 were chosen as the electrode materials in this study and ... more Inconel alloy 690 and Inconel alloy 693 were chosen as the electrode materials in this study and their corrosion behaviors in iron phosphate glass melt containing low activity(LAW)nuclear waste was explored.The corrosion losses in size and weight of different materials in glass melt were calculated.The corrosion layer formed on the surface of the alloys was analyzed by Scanning Electron Microscope(SEM),Energy Dispersive X-Ray analysis(EDS)and X-ray diffraction(XRD),and the corrosion mechanism was discussed.Results show that the Inconel alloy 693 is more stable than the Inconel alloy 690 in the glass melt.A kind of solid solution,(Fe,Cr)2O3,was believed to be the main crystalline phase in the corrosion layer on the surface of alloy samples.
Inconel alloy 690 and Inconel alloy 693 were chosen as the electrode materials in this study and ... more Inconel alloy 690 and Inconel alloy 693 were chosen as the electrode materials in this study and their corrosion behaviors in iron phosphate glass melt containing low activity(LAW)nuclear waste was explored.The corrosion losses in size and weight of different materials in glass melt were calculated.The corrosion layer formed on the surface of the alloys was analyzed by Scanning Electron Microscope(SEM),Energy Dispersive X-Ray analysis(EDS)and X-ray diffraction(XRD),and the corrosion mechanism was discussed.Results show that the Inconel alloy 693 is more stable than the Inconel alloy 690 in the glass melt.A kind of solid solution,(Fe,Cr)2O3,was believed to be the main crystalline phase in the corrosion layer on the surface of alloy samples.
We report an integrated whispering gallery mode microresonator-based sensor probe for refractive ... more We report an integrated whispering gallery mode microresonator-based sensor probe for refractive index sensing. The probe was made by sealing a borosilicate glass microsphere into a thin-wall glass capillary pigtailed with a multimode optical fiber. The intensities of the resonant peaks were found decreasing exponentially (linearly in a log scale) with the increasing refractive index of the medium surrounding the capillary. The sensing capability of the integrated probe was tested using sucrose solutions of different concentrations and the resolution was estimated to be about 2.5 × 10 −5 in the index range of 1.3458 to 1.3847. The integrated sensor probe may prove useful in many chemical and biological sensing applications where highly sensitive refractive index monitoring is needed.
Iron phosphate glasses have been studied as an alternative glass for vitrifying Department of Ene... more Iron phosphate glasses have been studied as an alternative glass for vitrifying Department of Energy (DOE) high priority wastes. The high priority wastes were the Low Activity Waste (LAW) and the High Level Waste (HLW) with high chrome content stored at Hanford, WA, and the Sodium Bearing Waste (SBW) stored at the Idaho National Engineering and Environmental Laboratory. These wastes were recommended by Tanks Focus Area since they were expected to require special attention when vitrified in borosilicate glasses. All three of these wastes have been successfully vitrified in iron phosphate glasses at waste loadings ranging from a low of 32 wt% for the high sulfate LAW to 40 wt% for the SBW to a high of 75 wt% for the high chrome HLW. In addition to these desirable high waste loadings, the iron phosphate glasses were easily melted, typically between 950 and 1200 C, in less than 4 hours in commercial refractory oxide containers. It is noteworthy that the chemical durability of both glass...
A miniaturized chemical vapor sensor probe was developed using a porous glass microsphere (PGM) a... more A miniaturized chemical vapor sensor probe was developed using a porous glass microsphere (PGM) as the alignment-free optical microresonator. The porous microsphere was placed inside a thin wall silica capillary tube that was fusion-spliced to an optical fiber. The whispering gallery modes (WGMs) of the microsphere were excited by the evanescent field of the light propagating inside the capillary thin wall. Adsorption of chemical vapor molecules into the pores led to a refractive index change of the PGM and thus the resonance wavelength shift of the WGMs. To facilitate the in-taking of chemical vapor molecules into the PGM, a micro window was opened at the backend of the capillary tube using femtosecond laser micromachining. Ethanol vapor was used to demonstrate the probe for chemical vapor sensing. With a miniaturized size, integrated structure and reflection mode of operation, the proposed probe may find useful in many practical applications such as environmental monitoring and biomedical sensing.
ABSTRACT Optical microresonators have been proven effective for developing sensitive chemical and... more ABSTRACT Optical microresonators have been proven effective for developing sensitive chemical and biological sensors by monitoring the changes in refractive index or mass near the resonator surface. The rotationally symmetric structures support high quality (Q) whispering gallery modes (WGMs) that interact with the local environment through the evanescent field. The long photon lifetime of the high-Q resonator (thus the long light-material interaction path) is the key reason that a microresonator can achieve very high sensitivity in detection. In this paper, we present our recent research on using porous wall hollow glass microsphere (PW-HGM) as an optical microresonator for chemical vapor detection. The diameter of the PW-HGM ranges from 10μm to 100μm. The wall thickness is about 2μm and the pore size is about 20nm. The Q-factors and free spectrum ranges (FSR) of PW-HGMs were measured by coupling light into the PW-HGM using a single mode fiber taper. Various types of chemical vapors were used to characterize the PW-HGM resonator. The resonant wavelength shift was measured as a function of vapor concentration. Comparisons between a PW-HGM and a solid glass microsphere indicated that a PW-HGM can effectively adsorb vapor molecules into its nanosized pores, providing a direct and long light-material interaction path for significant sensitivity enhancement for chemical vapor detection.
An iron phosphate composition for vitrifying a high sulfate (~17 wt%) and high alkali (~80 wt%) H... more An iron phosphate composition for vitrifying a high sulfate (~17 wt%) and high alkali (~80 wt%) Hanford low activity waste (LAW), known as AZ-102 LAW, has been developed for processing in a Joule Heated Melter (JHM) or a Cold Crucible Induction Melter (CCIM). This composition produced a glass waste form, designated as MS26AZ102F-2, with a waste loading of 26 wt% of the AZ-102 which corresponded to a total alkali and sulfate (represented as SO 3) content of 21 and 4.4 wt%, respectively. A slurry (7M Na +) of MS26AZ102F-2 simulant was melted continuously at temperatures between 1030 and 1090°C for 10 days in a small JHM at PNNL and for 70 hours in a CCIM at INL. The as-cast glasses produced in both melters and in trial laboratory experiments along with their canister centerline cooled (CCC) counterparts met the requirements for the Product Consistency Test (PCT) and the Vapor Hydration Test (VHT) responses in the Hanford Tank Waste Treatment and Immobilization Plant (WTP) Contract. These glass waste forms retained up to 77 % of the SO 3 (3.3 wt%), 100% of the Cesium, and 33 to 44% of the rhenium (used as a surrogate for Tc) all of which either exceeded or were comparable to the retention limit for these species in borosilicate glass nuclear waste form. Analyses of commercial K-3 refractory lining and the Inconel 693 metal electrodes used in JHM indicated only minimum corrosion of these components by the iron phosphate glass. This is the first time that an iron phosphate composition was melted continuously in a slurry fed JHM and in the US, thereby, demonstrating that iron phosphate glasses can be used as alternative hosts for vitrifying nuclear waste. * Raw materials used for glass formulation work, but these oxide components would be supplied by the waste stream. The contents of the critical oxides are shown in red. Other GFC's: All P 2 O 5 is available from Al(PO 3) 3 and AlPO 4 .
The isothermal corrosion behavior between 1000°C and 1190°C of Inconel 690 and 693 in an iron pho... more The isothermal corrosion behavior between 1000°C and 1190°C of Inconel 690 and 693 in an iron phosphate glass melt containing 26 wt.% of a simulated Hanford low activity nuclear waste (LAW) was investigated. At least three distinct corrosion processes were recognized for both alloys over different temperature ranges. Inconel 690 and 693 both display the best corrosion resistance at an intermediate temperature range (Inconel 690: 1050-1100°C; Inconel 693: 1050-1165°C), and more severe corrosion at both lower and higher temperatures. In general, Inconel 693 is less reactive over a wider temperature range than Inconel 690.
Chemical durability, glass formation tendency, and other properties of iron alumina phosphate gla... more Chemical durability, glass formation tendency, and other properties of iron alumina phosphate glasses containing 70 wt% of a simulated high level nuclear waste (HLW), doped with different amounts of Cr 2 O 3 , have been investigated. All of the iron alumina phosphate glasses had an outstanding chemical durability as measured by their small dissolution rate (1 . 10 -9 g/(cm 2 . min)) in deionized water at 90°C for 128 d, their low normalized mass release as determined by the Product Consistency Test (PCT) and a barely measurable corrosion rate of <0.1 g/(m 2 . d) after 7 d at 200°C by the Vapor Hydration Test (VHT). The solubility limit for Cr 2 O 3 in the iron phosphate melts was estimated at 4.1 wt%, but all of the as-annealed melts contained a few percent of crystalline Cr 2 O 3 that had no apparent effect on the chemical durability. The chemical durability was unchanged after deliberate crystallization, 48 h at 650°C. These iron phosphate waste forms, with a waste loading of at least 70 wt%, can be readily melted in commercial refractory crucibles at 1250°C for 2 to 4 h, are resistant to crystallization, meet all current US Department of Energy requirements for chemical durability, and have a solubility limit for Cr 2 O 3 which is at least three times larger than that for borosilicate glasses.
ABSTRACT a b s t r a c t Iron phosphate glass is a candidate fixation medium for storing radioact... more ABSTRACT a b s t r a c t Iron phosphate glass is a candidate fixation medium for storing radioactive waste. The Department of Energy supported a program to assess the viability of using Fe-phosphate glass for vitrifying low activity waste in a Joule Heated Melter (JHM). In this study, Inconel 693 electrodes were tested in a research-scale joule-heated melter (RSM) at Pacific Northwest National Laboratory. After a 10-day test at 1030 °C that yielded 124 kg of glass, the electrodes exhibited a dimensional loss rate of $1.6 mm/year, which is com-parable to that of Inconel 690 electrodes used in a JHM for processing borosilicate melts. Microstructural changes occurred within the outermost 700 lm of the electrodes and are consistent with an earlier study of Inconel coupons in Fe-phosphate melts. The results indicate that Inconel 693 should have an accept-able corrosion resistance as the electrode for JHM processing of iron phosphate melts. Ó 2013 Elsevier B.V. All rights reserved.
Iron phosphate glasses are of interest for immobilizing high level nuclear waste (HLW). The high ... more Iron phosphate glasses are of interest for immobilizing high level nuclear waste (HLW). The high temperature viscosity and AC electrical conductivity of an iron phosphate melt containing 2.8 mass% chrome oxide were investigated in this work. The viscosity of this melt varied from 10 to 50 poise from 1350 to 1150°C, respectively, while the activation energy for viscous flow was 82 and 126 kJ/mol during heating and cooling the melt, respectively. The viscosity of the melt at 1250°C increased with time due to the reduction of Fe 3+ to Fe 2+. The AC electrical conductivity of the melt varied from 45 to 65 S/m at 1050 and 1350°C, respectively. The activation energy for AC electrical conductivity was 28 and 18 kJ/mol during heating and cooling, respectively. The weight loss rate of the melt at 1250°C after 20 h was only 5 • 10 À4 g/cm 2 /h.
Iron phosphate glasses containing 30 w% of a high sodium and sulfur Hanford low-activity waste (L... more Iron phosphate glasses containing 30 w% of a high sodium and sulfur Hanford low-activity waste (LAW) simulant was successfully melted in electric furnaces at 1000–1050 °C for 2–3 h. No sulfate salt segregation or crystalline phases were detectable in the glassy wasteform when examined by scanning electron microscope and X-ray diffractometer. This suggests that the waste loading in the iron
An iron phosphate composition for vitrifying a high sulfate (~17 wt%) and high alkali (~80 wt%) H... more An iron phosphate composition for vitrifying a high sulfate (~17 wt%) and high alkali (~80 wt%) Hanford low activity waste (LAW), known as AZ-102 LAW, has been developed for processing in a Joule Heated Melter (JHM) or a Cold Crucible Induction Melter (CCIM). This composition produced a glass waste form, designated as MS26AZ102F-2, with a waste loading of 26 wt% of the AZ-102 which corresponded to a total alkali and sulfate (represented as SO 3) content of 21 and 4.4 wt%, respectively. A slurry (7M Na +) of MS26AZ102F-2 simulant was melted continuously at temperatures between 1030 and 1090°C for 10 days in a small JHM at PNNL and for 70 hours in a CCIM at INL. The as-cast glasses produced in both melters and in trial laboratory experiments along with their canister centerline cooled (CCC) counterparts met the requirements for the Product Consistency Test (PCT) and the Vapor Hydration Test (VHT) responses in the Hanford Tank Waste Treatment and Immobilization Plant (WTP) Contract. These glass waste forms retained up to 77 % of the SO 3 (3.3 wt%), 100% of the Cesium, and 33 to 44% of the rhenium (used as a surrogate for Tc) all of which either exceeded or were comparable to the retention limit for these species in borosilicate glass nuclear waste form. Analyses of commercial K-3 refractory lining and the Inconel 693 metal electrodes used in JHM indicated only minimum corrosion of these components by the iron phosphate glass. This is the first time that an iron phosphate composition was melted continuously in a slurry fed JHM and in the US, thereby, demonstrating that iron phosphate glasses can be used as alternative hosts for vitrifying nuclear waste. * Raw materials used for glass formulation work, but these oxide components would be supplied by the waste stream. The contents of the critical oxides are shown in red. Other GFC's: All P 2 O 5 is available from Al(PO 3) 3 and AlPO 4 .
ABSTRACT Optical microresonators have been proven effective for developing sensitive chemical and... more ABSTRACT Optical microresonators have been proven effective for developing sensitive chemical and biological sensors by monitoring the changes in refractive index or mass near the resonator surface. The rotationally symmetric structures support high quality (Q) whispering gallery modes (WGMs) that interact with the local environment through the evanescent field. The long photon lifetime of the high-Q resonator (thus the long light-material interaction path) is the key reason that a microresonator can achieve very high sensitivity in detection. In this paper, we present our recent research on using porous wall hollow glass microsphere (PW-HGM) as an optical microresonator for chemical vapor detection. The diameter of the PW-HGM ranges from 10μm to 100μm. The wall thickness is about 2μm and the pore size is about 20nm. The Q-factors and free spectrum ranges (FSR) of PW-HGMs were measured by coupling light into the PW-HGM using a single mode fiber taper. Various types of chemical vapors were used to characterize the PW-HGM resonator. The resonant wavelength shift was measured as a function of vapor concentration. Comparisons between a PW-HGM and a solid glass microsphere indicated that a PW-HGM can effectively adsorb vapor molecules into its nanosized pores, providing a direct and long light-material interaction path for significant sensitivity enhancement for chemical vapor detection.
ABSTRACT Iron phosphate glasses have been studied as an alternative glass for vitrifying Departme... more ABSTRACT Iron phosphate glasses have been studied as an alternative glass for vitrifying Department of Energy (DOE) high priority wastes. The high priority wastes were the Low Activity Waste (LAW) and the High Level Waste (HLW) with high chrome content stored at Hanford, WA, and the Sodium Bearing Waste (SBW) stored at the Idaho National Engineering and Environmental Laboratory. These wastes were recommended by Tanks Focus Area since they were expected to require special attention when vitrified in borosilicate glasses. All three of these wastes have been successfully vitrified in iron phosphate glasses at waste loadings ranging from a low of 32 wt% for the high sulfate LAW to 40 wt% for the SBW to a high of 75 wt% for the high chrome HLW. In addition to these desirable high waste loadings, the iron phosphate glasses were easily melted, typically between 950 and 1200 C, in less than 4 hours in commercial refractory oxide containers. It is noteworthy that the chemical durability of both glassy and deliberately crystallized iron phosphate wasteforms not only met, but significantly exceeded, all current DOE chemical durability requirements as measured by the Product Consistency Test (PCT) and Vapor Hydration Test (VHT). The high waste loading, low melting temperature, rapid furnace throughput (short melting time) and their outstanding chemical durability could significantly accelerate the clean up effort and reduce the time and cost of vitrifying these high priority wastes.
Inconel alloy 690 and Inconel alloy 693 were chosen as the electrode materials in this study and ... more Inconel alloy 690 and Inconel alloy 693 were chosen as the electrode materials in this study and their corrosion behaviors in iron phosphate glass melt containing low activity(LAW)nuclear waste was explored.The corrosion losses in size and weight of different materials in glass melt were calculated.The corrosion layer formed on the surface of the alloys was analyzed by Scanning Electron Microscope(SEM),Energy Dispersive X-Ray analysis(EDS)and X-ray diffraction(XRD),and the corrosion mechanism was discussed.Results show that the Inconel alloy 693 is more stable than the Inconel alloy 690 in the glass melt.A kind of solid solution,(Fe,Cr)2O3,was believed to be the main crystalline phase in the corrosion layer on the surface of alloy samples.
Inconel alloy 690 and Inconel alloy 693 were chosen as the electrode materials in this study and ... more Inconel alloy 690 and Inconel alloy 693 were chosen as the electrode materials in this study and their corrosion behaviors in iron phosphate glass melt containing low activity(LAW)nuclear waste was explored.The corrosion losses in size and weight of different materials in glass melt were calculated.The corrosion layer formed on the surface of the alloys was analyzed by Scanning Electron Microscope(SEM),Energy Dispersive X-Ray analysis(EDS)and X-ray diffraction(XRD),and the corrosion mechanism was discussed.Results show that the Inconel alloy 693 is more stable than the Inconel alloy 690 in the glass melt.A kind of solid solution,(Fe,Cr)2O3,was believed to be the main crystalline phase in the corrosion layer on the surface of alloy samples.
We report an integrated whispering gallery mode microresonator-based sensor probe for refractive ... more We report an integrated whispering gallery mode microresonator-based sensor probe for refractive index sensing. The probe was made by sealing a borosilicate glass microsphere into a thin-wall glass capillary pigtailed with a multimode optical fiber. The intensities of the resonant peaks were found decreasing exponentially (linearly in a log scale) with the increasing refractive index of the medium surrounding the capillary. The sensing capability of the integrated probe was tested using sucrose solutions of different concentrations and the resolution was estimated to be about 2.5 × 10 −5 in the index range of 1.3458 to 1.3847. The integrated sensor probe may prove useful in many chemical and biological sensing applications where highly sensitive refractive index monitoring is needed.
Iron phosphate glasses have been studied as an alternative glass for vitrifying Department of Ene... more Iron phosphate glasses have been studied as an alternative glass for vitrifying Department of Energy (DOE) high priority wastes. The high priority wastes were the Low Activity Waste (LAW) and the High Level Waste (HLW) with high chrome content stored at Hanford, WA, and the Sodium Bearing Waste (SBW) stored at the Idaho National Engineering and Environmental Laboratory. These wastes were recommended by Tanks Focus Area since they were expected to require special attention when vitrified in borosilicate glasses. All three of these wastes have been successfully vitrified in iron phosphate glasses at waste loadings ranging from a low of 32 wt% for the high sulfate LAW to 40 wt% for the SBW to a high of 75 wt% for the high chrome HLW. In addition to these desirable high waste loadings, the iron phosphate glasses were easily melted, typically between 950 and 1200 C, in less than 4 hours in commercial refractory oxide containers. It is noteworthy that the chemical durability of both glass...
A miniaturized chemical vapor sensor probe was developed using a porous glass microsphere (PGM) a... more A miniaturized chemical vapor sensor probe was developed using a porous glass microsphere (PGM) as the alignment-free optical microresonator. The porous microsphere was placed inside a thin wall silica capillary tube that was fusion-spliced to an optical fiber. The whispering gallery modes (WGMs) of the microsphere were excited by the evanescent field of the light propagating inside the capillary thin wall. Adsorption of chemical vapor molecules into the pores led to a refractive index change of the PGM and thus the resonance wavelength shift of the WGMs. To facilitate the in-taking of chemical vapor molecules into the PGM, a micro window was opened at the backend of the capillary tube using femtosecond laser micromachining. Ethanol vapor was used to demonstrate the probe for chemical vapor sensing. With a miniaturized size, integrated structure and reflection mode of operation, the proposed probe may find useful in many practical applications such as environmental monitoring and biomedical sensing.
ABSTRACT Optical microresonators have been proven effective for developing sensitive chemical and... more ABSTRACT Optical microresonators have been proven effective for developing sensitive chemical and biological sensors by monitoring the changes in refractive index or mass near the resonator surface. The rotationally symmetric structures support high quality (Q) whispering gallery modes (WGMs) that interact with the local environment through the evanescent field. The long photon lifetime of the high-Q resonator (thus the long light-material interaction path) is the key reason that a microresonator can achieve very high sensitivity in detection. In this paper, we present our recent research on using porous wall hollow glass microsphere (PW-HGM) as an optical microresonator for chemical vapor detection. The diameter of the PW-HGM ranges from 10μm to 100μm. The wall thickness is about 2μm and the pore size is about 20nm. The Q-factors and free spectrum ranges (FSR) of PW-HGMs were measured by coupling light into the PW-HGM using a single mode fiber taper. Various types of chemical vapors were used to characterize the PW-HGM resonator. The resonant wavelength shift was measured as a function of vapor concentration. Comparisons between a PW-HGM and a solid glass microsphere indicated that a PW-HGM can effectively adsorb vapor molecules into its nanosized pores, providing a direct and long light-material interaction path for significant sensitivity enhancement for chemical vapor detection.
An iron phosphate composition for vitrifying a high sulfate (~17 wt%) and high alkali (~80 wt%) H... more An iron phosphate composition for vitrifying a high sulfate (~17 wt%) and high alkali (~80 wt%) Hanford low activity waste (LAW), known as AZ-102 LAW, has been developed for processing in a Joule Heated Melter (JHM) or a Cold Crucible Induction Melter (CCIM). This composition produced a glass waste form, designated as MS26AZ102F-2, with a waste loading of 26 wt% of the AZ-102 which corresponded to a total alkali and sulfate (represented as SO 3) content of 21 and 4.4 wt%, respectively. A slurry (7M Na +) of MS26AZ102F-2 simulant was melted continuously at temperatures between 1030 and 1090°C for 10 days in a small JHM at PNNL and for 70 hours in a CCIM at INL. The as-cast glasses produced in both melters and in trial laboratory experiments along with their canister centerline cooled (CCC) counterparts met the requirements for the Product Consistency Test (PCT) and the Vapor Hydration Test (VHT) responses in the Hanford Tank Waste Treatment and Immobilization Plant (WTP) Contract. These glass waste forms retained up to 77 % of the SO 3 (3.3 wt%), 100% of the Cesium, and 33 to 44% of the rhenium (used as a surrogate for Tc) all of which either exceeded or were comparable to the retention limit for these species in borosilicate glass nuclear waste form. Analyses of commercial K-3 refractory lining and the Inconel 693 metal electrodes used in JHM indicated only minimum corrosion of these components by the iron phosphate glass. This is the first time that an iron phosphate composition was melted continuously in a slurry fed JHM and in the US, thereby, demonstrating that iron phosphate glasses can be used as alternative hosts for vitrifying nuclear waste. * Raw materials used for glass formulation work, but these oxide components would be supplied by the waste stream. The contents of the critical oxides are shown in red. Other GFC's: All P 2 O 5 is available from Al(PO 3) 3 and AlPO 4 .
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Papers by Cheol-woon Kim