My scientific knowledge, skills, and expertise in nuclear fuel cycle chemistry, specifically uranium and plutonium chemistry, and characterization of irradiated nuclear materials for environmental remediation projects and advancement of nuclear technologies was gained through years of research work at DOE’s National Laboratories and University
The vapor pressures of the fullerenes Cââ and Cââ have been measured over the temperature range 4... more The vapor pressures of the fullerenes Cââ and Cââ have been measured over the temperature range 400--600 °C by the Knudsen-effusion thermogravimetric technique. For Cââ, a heat of sublimation of 38{plus minus}1 kcal/mol is obtained, and the value for Cââ is 45{plus minus}1 kcal/mol. The vapor pressure of Cââ ranges from 1.8Ã10â»âµ and 1.4Ã10â»Â² Torr and that of Cââ is
Studies being conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washingt... more Studies being conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington are focused on assessing the effectiveness of NDE inspections of control rod drive mechanism (CRDM) nozzles and J-groove weldments. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the effectiveness of ultrasonic testing (UT) and eddy current testing (ET) as related to the in-service inspection of CRDM nozzles and J-groove weldments, and to enhance the knowledge base of primary water stress corrosion cracking (PWSCC) through destructive characterization of the CRDM assemblies. In describing two CRDM assemblies removed from service, decontaminated, and then used in a series of NDE measurements, this paper will address the following questions: 1) What did each technique detect?, 2) What did each technique miss?, 3) How accurately did each technique characterize the detected flaws? Two CRDM assemblies including th...
The modulated molecular beam technique with in situ mass spectrometric phase sensitive detection ... more The modulated molecular beam technique with in situ mass spectrometric phase sensitive detection was used to study the kinetics of atomic hydrogen reduction of hyperstoichiometric uranium dioxide. The atomic hydrogen portion of an incident mixed-collisionless H/Hâ beam chemisorbed onto urania surface with a sticking probability of 0.7 {plus minus} 0.1. A major fraction of the chemisorbed H atom recombined to
The US, through the Global Nuclear Energy Partnership, is currently engaged in efforts aimed at c... more The US, through the Global Nuclear Energy Partnership, is currently engaged in efforts aimed at closing the nuclear fuel cycle. Neptunium behavior is important to understand for transuranic recycling because of its complex oxidation chemistry. The Pacific Northwest National Laboratory is investigating neptunium oxidation chemistry in the context of the PUREX process. Neptunium extraction in the PUREX process relies on
ABSTRACT Among the proposed measures for reducing the damage rate to pressurized water reactor (P... more ABSTRACT Among the proposed measures for reducing the damage rate to pressurized water reactor (PWR) pressure vessels are the following: 1. replacement of fuel rods in peripheral fuel assemblies with dummy rods-the [open quotes]fuel replacement[close quotes] (FR) approach; 2. insertion of neutron reflecting and attenuating materials between the core baffle and the core barrel-the [open quotes]reflector-shield[close quotes] (RS) approach; 3. attachment of shielding patches to the thermal shield-the [open quotes]thermal shield[close quotes] approach. The material commonly proposed for all three approaches is stainless steel (SS). While searching for optimal compact shield compositions, Gilai et al. found that a combination of tungsten and titanium hydride is significantly more effective than SS for attenuating fusion and fission neutrons. A preliminary feasibility study later indicated that tungsten and titanium-hydride can, indeed, make a more effective reflector shield than SS.
The vapor pressures of the fullerenes Cââ and Cââ have been measured over the temperature range 4... more The vapor pressures of the fullerenes Cââ and Cââ have been measured over the temperature range 400--600 °C by the Knudsen-effusion thermogravimetric technique. For Cââ, a heat of sublimation of 38{plus minus}1 kcal/mol is obtained, and the value for Cââ is 45{plus minus}1 kcal/mol. The vapor pressure of Cââ ranges from 1.8Ã10â»âµ and 1.4Ã10â»Â² Torr and that of Cââ is
Studies being conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washingt... more Studies being conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington are focused on assessing the effectiveness of NDE inspections of control rod drive mechanism (CRDM) nozzles and J-groove weldments. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the effectiveness of ultrasonic testing (UT) and eddy current testing (ET) as related to the in-service inspection of CRDM nozzles and J-groove weldments, and to enhance the knowledge base of primary water stress corrosion cracking (PWSCC) through destructive characterization of the CRDM assemblies. In describing two CRDM assemblies removed from service, decontaminated, and then used in a series of NDE measurements, this paper will address the following questions: 1) What did each technique detect?, 2) What did each technique miss?, 3) How accurately did each technique characterize the detected flaws? Two CRDM assemblies including th...
The modulated molecular beam technique with in situ mass spectrometric phase sensitive detection ... more The modulated molecular beam technique with in situ mass spectrometric phase sensitive detection was used to study the kinetics of atomic hydrogen reduction of hyperstoichiometric uranium dioxide. The atomic hydrogen portion of an incident mixed-collisionless H/Hâ beam chemisorbed onto urania surface with a sticking probability of 0.7 {plus minus} 0.1. A major fraction of the chemisorbed H atom recombined to
The US, through the Global Nuclear Energy Partnership, is currently engaged in efforts aimed at c... more The US, through the Global Nuclear Energy Partnership, is currently engaged in efforts aimed at closing the nuclear fuel cycle. Neptunium behavior is important to understand for transuranic recycling because of its complex oxidation chemistry. The Pacific Northwest National Laboratory is investigating neptunium oxidation chemistry in the context of the PUREX process. Neptunium extraction in the PUREX process relies on
ABSTRACT Among the proposed measures for reducing the damage rate to pressurized water reactor (P... more ABSTRACT Among the proposed measures for reducing the damage rate to pressurized water reactor (PWR) pressure vessels are the following: 1. replacement of fuel rods in peripheral fuel assemblies with dummy rods-the [open quotes]fuel replacement[close quotes] (FR) approach; 2. insertion of neutron reflecting and attenuating materials between the core baffle and the core barrel-the [open quotes]reflector-shield[close quotes] (RS) approach; 3. attachment of shielding patches to the thermal shield-the [open quotes]thermal shield[close quotes] approach. The material commonly proposed for all three approaches is stainless steel (SS). While searching for optimal compact shield compositions, Gilai et al. found that a combination of tungsten and titanium hydride is significantly more effective than SS for attenuating fusion and fission neutrons. A preliminary feasibility study later indicated that tungsten and titanium-hydride can, indeed, make a more effective reflector shield than SS.
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Papers by John Abrefah