The Experts below are selected from a list of 8541 Experts worldwide ranked by ideXlab platform
Shaddy Shokralla - One of the best experts on this subject based on the ideXlab platform.
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surface profiling with high density eddy current non Destructive Examination data
Ndt & E International, 2014Co-Authors: Shaddy Shokralla, Thomas W Krause, Jordan MorelliAbstract:Abstract The pressure tubes (PT) in CANDU (CANada Deuterium Uranium) reactors undergo creep induced deformation due to operating pressure, temperature and radiation conditions. While global deformation of the tube in the form of elongation and diametral creep is well characterized and monitored by station inspection systems, local PT deformation and the presence of inner surface artifacts due to wear are not as directly monitored, but can still provide additional information of fuel channel condition. A surface profiling technique for monitoring local deformation and identification of surface wear using an eddy current probe mounted in a small (50 mm×25 mm) planar probe body is presented. The sensitivity of the eddy current probe to small lift-off variations combined with high density C-Scan information is used to extract information on smoothly varying local deformation as well as monitor more significant wear on the inner surface of pressure tubes. Vector separation of components permits independent identification of axial and circumferential surface features. Analysis of this data can be used to characterize local PT deformation due to constrictions at fuel bundle ends and loaded garter spring spacers, as well as identify areas where shallow mechanical wear has occurred. Examples of the features that may be identified are presented.
Jordan Morelli - One of the best experts on this subject based on the ideXlab platform.
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surface profiling with high density eddy current non Destructive Examination data
Ndt & E International, 2014Co-Authors: Shaddy Shokralla, Thomas W Krause, Jordan MorelliAbstract:Abstract The pressure tubes (PT) in CANDU (CANada Deuterium Uranium) reactors undergo creep induced deformation due to operating pressure, temperature and radiation conditions. While global deformation of the tube in the form of elongation and diametral creep is well characterized and monitored by station inspection systems, local PT deformation and the presence of inner surface artifacts due to wear are not as directly monitored, but can still provide additional information of fuel channel condition. A surface profiling technique for monitoring local deformation and identification of surface wear using an eddy current probe mounted in a small (50 mm×25 mm) planar probe body is presented. The sensitivity of the eddy current probe to small lift-off variations combined with high density C-Scan information is used to extract information on smoothly varying local deformation as well as monitor more significant wear on the inner surface of pressure tubes. Vector separation of components permits independent identification of axial and circumferential surface features. Analysis of this data can be used to characterize local PT deformation due to constrictions at fuel bundle ends and loaded garter spring spacers, as well as identify areas where shallow mechanical wear has occurred. Examples of the features that may be identified are presented.
Ronald G. Ballinger - One of the best experts on this subject based on the ideXlab platform.
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On-Line Monitoring of Environment-Assisted Cracking in Nuclear Piping Using Array Probe Direct Current Potential Drop
Journal of Nondestructive Evaluation, 2015Co-Authors: J Y Yoon, P. W. Stahle, I.s. Hwang, Leslie Bromberg, S Choi, Ronald G. BallingerAbstract:A direct current potential drop method utilizing array probes with measurement ends maintaining an equalized potential designated as equi-potential switching array probe direct current potential drop (ESAP-DCPD) technique has been developed earlier at Seoul National University. This paper validates ESAP-DCPD technique by showing consistency among experimental measurements, analytical solution and numerical predictions using finite element analysis (FEA) of electric field changes with crack growth in metals. In order to examine its viability as an on-line monitoring of environment assisted crack growth at the inner surface of piping welds, artificial inner surface cracks were introduced in a full-scale weldment mockup pipe and stainless steel metal mockup pipe. The weldment was joined by low alloy steel and stainless steel pipes. The pipes were monitored by using ESAP-DCPD in laboratory environments. Optimization of electrical wiring configuration has produced results with significantly reduced noise for adequately long period of time. Then optimized experimental results were compared with the FEA prediction results for the mockup to show a good agreement. Also a round-robin measurement has been made at three laboratories. It has been found that the developed ESAP-DCPD can detect circumferential cracks with a depth of 40 % of wall thickness in stainless steel with a good detectability for further growth behaviors. For axial cracks, however, the measurements showed poor detectability. Hence the developed ESAP-DCPD system can be used to monitor large circumferential cracks that existing non-Destructive Examination techniques often fail to detect until leakage takes place.
Ballinger, Ronald G - One of the best experts on this subject based on the ideXlab platform.
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On-Line Monitoring of Environment-Assisted Cracking in Nuclear Piping Using Array Probe Direct Current Potential Drop
'Springer Science and Business Media LLC', 2016Co-Authors: Kim Y., Choi S., Yoon J. Y., Nam W. C., Hwang I. S., Bromberg Leslie, Stahle, Peter W, Ballinger, Ronald GAbstract:A direct current potential drop method utilizing array probes with measurement ends maintaining an equalized potential designated as equi-potential switching array probe direct current potential drop (ESAP-DCPD) technique has been developed earlier at Seoul National University. This paper validates ESAP-DCPD technique by showing consistency among experimental measurements, analytical solution and numerical predictions using finite element analysis (FEA) of electric field changes with crack growth in metals. In order to examine its viability as an on-line monitoring of environment assisted crack growth at the inner surface of piping welds, artificial inner surface cracks were introduced in a full-scale weldment mockup pipe and stainless steel metal mockup pipe. The weldment was joined by low alloy steel and stainless steel pipes. The pipes were monitored by using ESAP-DCPD in laboratory environments. Optimization of electrical wiring configuration has produced results with significantly reduced noise for adequately long period of time. Then optimized experimental results were compared with the FEA prediction results for the mockup to show a good agreement. Also a round-robin measurement has been made at three laboratories. It has been found that the developed ESAP-DCPD can detect circumferential cracks with a depth of 40 % of wall thickness in stainless steel with a good detectability for further growth behaviors. For axial cracks, however, the measurements showed poor detectability. Hence the developed ESAP-DCPD system can be used to monitor large circumferential cracks that existing non-Destructive Examination techniques often fail to detect until leakage takes place.Korea (South). Ministry of Trade, Industry and Energy. Korea Institute of Energy Technology Evaluation and Plannin
S. E. Fisher - One of the best experts on this subject based on the ideXlab platform.
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performance of near weapons grade plutonium fuel pins in commercial light water reactors
Nuclear Technology, 2001Co-Authors: F C Difilippo, S. E. FisherAbstract:Important decisions related to the kind of reactors to be used for the disposition of the surplus weapons-grade plutonium are going to be based on calculations. Benchmarking computational methods in all aspects of the fuel cycle with measured data is then an obvious necessity. Analysis of public domain data reveals that the cycle-2 irradiation in the Quad Cities-1 boiling water reactor is the most recent U.S. Destructive Examination, involving the irradiation of five mixed-oxide (MOX) assemblies using 80 and 90% fissile Pu, quite close to weapons-grade Pu isotopic. Such measurements are rare, and they might be the only source of information to quantify differences in key neutronics parameters between high-fissile Pu systems and the well-characterized use of reactor-grade Pu. The pin neutronic performances for the UO{sub 2} and MOX fuels are compared with assembly-level calculation in which {approx}20% of the pins are MOX pins surrounded by UO{sub 2} pins. For MOX rods, HELIOS models the chains for the isotopes of uranium and plutonium reasonably well when compared with measured data at {approx}12,000 MWd/tonne. However, indications are that the amounts of heavier actinides are underpredicted. Measurements and calculations of the relative pin power distribution for the last few weeks of themore » irradiation and the burnup are fairly consistent. The critical effects of the contribution of the 0.296-eV resonance to the production of higher actinides and the destruction of {sup 239}Pu are discussed.« less
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neutronics benchmark of a mox assembly with near weapons grade plutonium
International conference on the physics of nuclear science and technology Long Island NY (United States) 5-8 Oct 1998, 1998Co-Authors: F C Difilippo, S. E. FisherAbstract:One of the proposed ways to dispose of surplus weapons-grade plutonium (Pu) is to irradiate the high-fissile material in light-water reactors in order to reduce the Pu enrichment to the level of spent fuels from commercial reactors. Considerable experience has been accumulated about the behavior of mixed-oxide (MOX) uranium and plutonium fuels for plutonium recycling in commercial reactors, but the experience is related to Pu enrichments typical of spent fuels quite below the values of weapons-grade plutonium. Important decisions related to the kind of reactors to be used for the disposition of the plutonium are going to be based on calculations, so the validation of computational algorithms related to all aspects of the fuel cycle (power distributions, isotopics as function of the burnup, etc.), for weapons-grade isotopics is very important. Analysis of public domain data reveals that the cycle-2 irradiation in the Quad cities boiling-water reactor (BWR) is the most recent US Destructive Examination. This effort involved the irradiation of five MOX assemblies using 80 and 90% fissile plutonium. These benchmark data were gathered by General Electric under the sponsorship of the Electric Power Research Institute. It is emphasized, however, that global parameters are not the focus of this benchmark, since the five bundles containing MOX fuels did not significantly affect the overall core performance. However, since the primary objective of this work is to compare against measured post-irradiation assembly data, the term benchmark is applied here. One important reason for performing the benchmark on Quad Cities irradiation is that the fissile blends (up to 90%) are higher than reactor-grade and, quite close to, weapons-grade isotopics.