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A L Keksis - One of the best experts on this subject based on the ideXlab platform.
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Fission Product data measured at los alamos for Fission spectrum and thermal neutrons on 239pu 235u 238u
Nuclear Data Sheets, 2010Co-Authors: H D Selby, M B Chadwick, M Mac R Innes, D W Barr, A L Keksis, R A Meade, C J Burns, T C WallstromAbstract:Abstract We describe measurements of Fission Product data at Los Alamos that are important for determining the number of Fissions that have occurred when neutrons are incident on plutonium and uranium isotopes. The Fission-spectrum measurements were made using a Fission chamber designed by the National Institute for Standards and Technology (NIST) in the BIG TEN critical assembly, as part of the Inter-laboratory Liquid Metal Fast Breeder Reactor (LMFBR) Reaction Rate (ILRR) collaboration. The thermal measurements were made at Los Alamos' Omega West Reactor. A related set of measurements were made of Fission-Product ratios (so-called R-values) in neutron environments provided by a number of Los Alamos critical assemblies that range from having average energies causing Fission of 400–600 keV (BIG TEN and the outer regions of the Flattop-25 assembly) to higher energies (1.4–1.9 MeV) in the Jezebel, and in the central regions of the Flattop-25 and Flattop-Pu, critical assemblies. From these data we determine ratios of Fission Product yields in different fuel and neutron environments (Q-values) and Fission Product yields in Fission spectrum neutron environments for 99Mo, 95Zr, 137Cs, 140Ba, 141,143Ce, and 147Nd. Modest incident-energy dependence exists for the 147Nd Fission Product yield; this is discussed in the context of models for Fission that include thermal and dynamical effects. The Fission Product data agree with measurements by Maeck and other authors using mass-spectrometry methods, and with the ILRR collaboration results that used gamma spectroscopy for quantifying Fission Products. We note that the measurements also contradict earlier 1950s historical Los Alamos estimates by ∼5–7%, most likely owing to self-shielding corrections not made in the early thermal measurements. Our experimental results provide a confirmation of the England-Rider ENDF/B-VI evaluated Fission-spectrum Fission Product yields that were carried over to the ENDF/B-VII.0 library, except for 99Mo where the present results are about 4%-relative higher for neutrons incident on 239Pu and 235U. Additionally, our results illustrate the importance of representing the incident energy dependence of Fission Product yields over the fast neutron energy range for high-accuracy work, for example the 147Nd from neutron reactions on plutonium. An upgrade to the ENDF library, for ENDF/B-VII.1, based on these and other data, is described in a companion paper to this work.
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Fission Product yields from Fission spectrum n 239pu for endf b vii 1
Nuclear Data Sheets, 2010Co-Authors: M B Chadwick, H D Selby, M Mac R Innes, D W Barr, C J Burns, T Kawano, A C Kahler, Todd L Graves, W C Inkret, A L KeksisAbstract:We describe a new cumulated Fission Product yield (FPY) evaluation for Fission spectrum neutrons on plutonium that updates the ENDF/B-VI evaluation by England and Rider, for the forthcoming ENDF/B-VII.1 database release. We focus on FPs that are needed for high accuracy burnup assessments; that is, for inferring the number of Fissions in a neutron environment. Los Alamos conducted an experiment in the 1970s in the Bigten fast critical assembly to determine Fission Product yields as part of the Interlaboratory Reaction Rate (ILRR) collaboration, and this has defined the Laboratory's Fission standard to this day. Our evaluation includes use of the LANL-ILRR measurements (not previously available to evaluators) as well as other Laboratory FPY measurements published in the literature, especially the high-accuracy mass spectrometry data from Maeck and others. Because the measurement database for some of the FPs is small - especially for {sup 99}Mo - we use a meta-analysis that incorporates insights from other accurately-measured benchmark FP data, using R-value ratio measurements. The meta-analysis supports the FP measurements from the LANL-ILRR experiment. Differences between our new evaluations and ENDF/B-VI are small for some FPs (less than 1-2%-relative for {sup 95}Zr, {sup 140}Ba, {sup 144}Ce), but are larger for {sup 99}Momore » (4%-relative) and {sup 147}Nd (5%-relative, at 1.5 MeV) respectively. We present evidence for an incident neutron energy dependence to the {sup 147}Nd Fission Product yield that accounts for observed differences in the FPY at a few-hundred keV average energy in fast reactors versus measurements made at higher average neutron energies in Los Alamos' fast critical assemblies. Accounting for such FPY neutron energy dependencies is important if one wants to reach a goal of determining the number of Fissions to accuracies of 1-2%. An evaluation of the energy-dependence of Fission Product yields is given for all A values based on systematical trends in the measured data, with a focus on the energy dependence over the fast neutron energy range from 0.2-2 MeV. Based on these trends, we present an evaluation of the FPY data at 0.5 and 2.0 MeV average incident neutron energies. This new set of ENDF/B-VII data will enable users to linearly interpolate between the pooled FPY data at {approx}0.5 MeV and our new data at 2 MeV to obtain FPYs at other energies.« less
M B Chadwick - One of the best experts on this subject based on the ideXlab platform.
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Fission Product yields from Fission spectrum n 239pu for endf b vii 1
Nuclear Data Sheets, 2010Co-Authors: M B Chadwick, H D Selby, M Mac R Innes, D W Barr, C J Burns, T Kawano, A C Kahler, Todd L Graves, W C Inkret, A L KeksisAbstract:We describe a new cumulated Fission Product yield (FPY) evaluation for Fission spectrum neutrons on plutonium that updates the ENDF/B-VI evaluation by England and Rider, for the forthcoming ENDF/B-VII.1 database release. We focus on FPs that are needed for high accuracy burnup assessments; that is, for inferring the number of Fissions in a neutron environment. Los Alamos conducted an experiment in the 1970s in the Bigten fast critical assembly to determine Fission Product yields as part of the Interlaboratory Reaction Rate (ILRR) collaboration, and this has defined the Laboratory's Fission standard to this day. Our evaluation includes use of the LANL-ILRR measurements (not previously available to evaluators) as well as other Laboratory FPY measurements published in the literature, especially the high-accuracy mass spectrometry data from Maeck and others. Because the measurement database for some of the FPs is small - especially for {sup 99}Mo - we use a meta-analysis that incorporates insights from other accurately-measured benchmark FP data, using R-value ratio measurements. The meta-analysis supports the FP measurements from the LANL-ILRR experiment. Differences between our new evaluations and ENDF/B-VI are small for some FPs (less than 1-2%-relative for {sup 95}Zr, {sup 140}Ba, {sup 144}Ce), but are larger for {sup 99}Momore » (4%-relative) and {sup 147}Nd (5%-relative, at 1.5 MeV) respectively. We present evidence for an incident neutron energy dependence to the {sup 147}Nd Fission Product yield that accounts for observed differences in the FPY at a few-hundred keV average energy in fast reactors versus measurements made at higher average neutron energies in Los Alamos' fast critical assemblies. Accounting for such FPY neutron energy dependencies is important if one wants to reach a goal of determining the number of Fissions to accuracies of 1-2%. An evaluation of the energy-dependence of Fission Product yields is given for all A values based on systematical trends in the measured data, with a focus on the energy dependence over the fast neutron energy range from 0.2-2 MeV. Based on these trends, we present an evaluation of the FPY data at 0.5 and 2.0 MeV average incident neutron energies. This new set of ENDF/B-VII data will enable users to linearly interpolate between the pooled FPY data at {approx}0.5 MeV and our new data at 2 MeV to obtain FPYs at other energies.« less
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Fission Product data measured at los alamos for Fission spectrum and thermal neutrons on 239pu 235u 238u
Nuclear Data Sheets, 2010Co-Authors: H D Selby, M B Chadwick, M Mac R Innes, D W Barr, A L Keksis, R A Meade, C J Burns, T C WallstromAbstract:Abstract We describe measurements of Fission Product data at Los Alamos that are important for determining the number of Fissions that have occurred when neutrons are incident on plutonium and uranium isotopes. The Fission-spectrum measurements were made using a Fission chamber designed by the National Institute for Standards and Technology (NIST) in the BIG TEN critical assembly, as part of the Inter-laboratory Liquid Metal Fast Breeder Reactor (LMFBR) Reaction Rate (ILRR) collaboration. The thermal measurements were made at Los Alamos' Omega West Reactor. A related set of measurements were made of Fission-Product ratios (so-called R-values) in neutron environments provided by a number of Los Alamos critical assemblies that range from having average energies causing Fission of 400–600 keV (BIG TEN and the outer regions of the Flattop-25 assembly) to higher energies (1.4–1.9 MeV) in the Jezebel, and in the central regions of the Flattop-25 and Flattop-Pu, critical assemblies. From these data we determine ratios of Fission Product yields in different fuel and neutron environments (Q-values) and Fission Product yields in Fission spectrum neutron environments for 99Mo, 95Zr, 137Cs, 140Ba, 141,143Ce, and 147Nd. Modest incident-energy dependence exists for the 147Nd Fission Product yield; this is discussed in the context of models for Fission that include thermal and dynamical effects. The Fission Product data agree with measurements by Maeck and other authors using mass-spectrometry methods, and with the ILRR collaboration results that used gamma spectroscopy for quantifying Fission Products. We note that the measurements also contradict earlier 1950s historical Los Alamos estimates by ∼5–7%, most likely owing to self-shielding corrections not made in the early thermal measurements. Our experimental results provide a confirmation of the England-Rider ENDF/B-VI evaluated Fission-spectrum Fission Product yields that were carried over to the ENDF/B-VII.0 library, except for 99Mo where the present results are about 4%-relative higher for neutrons incident on 239Pu and 235U. Additionally, our results illustrate the importance of representing the incident energy dependence of Fission Product yields over the fast neutron energy range for high-accuracy work, for example the 147Nd from neutron reactions on plutonium. An upgrade to the ENDF library, for ENDF/B-VII.1, based on these and other data, is described in a companion paper to this work.
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evaluation of Fission Product yields from Fission spectrum n 239pu using a meta analysis of benchmark data
4TH INTERNATIONAL WORKSHOP ON NUCLEAR FISSION AND FISSION‐PRODUCT SPECTROSCOPY, 2009Co-Authors: M B ChadwickAbstract:Los Alamos conducted a dual Fission‐chamber experiment in the 1970s in the Bigten critical assembly to determine Fission Product data in a fast (Fission neutron spectrum) environment, and this defined the Laboratory’s Fission basis today. We describe how the data from this experiment are consistent with other benchmark Fission Product yield measurements for 95,97Zr, 140Ba, 143,144Ce, 137Cs from the NIST‐led ILRR Fission chamber experiments, and from Maeck’s mass‐spectrometry data. We perform a new evaluation of the Fission Product yields that is planned for ENDF/B‐VII.1. Because the measurement database for some of the FPs is small—especially for 147Nd and 99Mo—we use a meta‐analysis that incorporates insights from other accurately‐measured benchmark FP data. The %‐relative changes compared to ENDF/B‐VI are small for some FPs (less than 1% for 95Zr, 140Ba, 144Ce), but are larger for 99Mo (3%) and 147Nd (5%). We suggest an incident neutron energy dependence to the 147Nd Fission Product yield that accounts ...
H D Selby - One of the best experts on this subject based on the ideXlab platform.
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Fission Product data measured at los alamos for Fission spectrum and thermal neutrons on 239pu 235u 238u
Nuclear Data Sheets, 2010Co-Authors: H D Selby, M B Chadwick, M Mac R Innes, D W Barr, A L Keksis, R A Meade, C J Burns, T C WallstromAbstract:Abstract We describe measurements of Fission Product data at Los Alamos that are important for determining the number of Fissions that have occurred when neutrons are incident on plutonium and uranium isotopes. The Fission-spectrum measurements were made using a Fission chamber designed by the National Institute for Standards and Technology (NIST) in the BIG TEN critical assembly, as part of the Inter-laboratory Liquid Metal Fast Breeder Reactor (LMFBR) Reaction Rate (ILRR) collaboration. The thermal measurements were made at Los Alamos' Omega West Reactor. A related set of measurements were made of Fission-Product ratios (so-called R-values) in neutron environments provided by a number of Los Alamos critical assemblies that range from having average energies causing Fission of 400–600 keV (BIG TEN and the outer regions of the Flattop-25 assembly) to higher energies (1.4–1.9 MeV) in the Jezebel, and in the central regions of the Flattop-25 and Flattop-Pu, critical assemblies. From these data we determine ratios of Fission Product yields in different fuel and neutron environments (Q-values) and Fission Product yields in Fission spectrum neutron environments for 99Mo, 95Zr, 137Cs, 140Ba, 141,143Ce, and 147Nd. Modest incident-energy dependence exists for the 147Nd Fission Product yield; this is discussed in the context of models for Fission that include thermal and dynamical effects. The Fission Product data agree with measurements by Maeck and other authors using mass-spectrometry methods, and with the ILRR collaboration results that used gamma spectroscopy for quantifying Fission Products. We note that the measurements also contradict earlier 1950s historical Los Alamos estimates by ∼5–7%, most likely owing to self-shielding corrections not made in the early thermal measurements. Our experimental results provide a confirmation of the England-Rider ENDF/B-VI evaluated Fission-spectrum Fission Product yields that were carried over to the ENDF/B-VII.0 library, except for 99Mo where the present results are about 4%-relative higher for neutrons incident on 239Pu and 235U. Additionally, our results illustrate the importance of representing the incident energy dependence of Fission Product yields over the fast neutron energy range for high-accuracy work, for example the 147Nd from neutron reactions on plutonium. An upgrade to the ENDF library, for ENDF/B-VII.1, based on these and other data, is described in a companion paper to this work.
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Fission Product yields from Fission spectrum n 239pu for endf b vii 1
Nuclear Data Sheets, 2010Co-Authors: M B Chadwick, H D Selby, M Mac R Innes, D W Barr, C J Burns, T Kawano, A C Kahler, Todd L Graves, W C Inkret, A L KeksisAbstract:We describe a new cumulated Fission Product yield (FPY) evaluation for Fission spectrum neutrons on plutonium that updates the ENDF/B-VI evaluation by England and Rider, for the forthcoming ENDF/B-VII.1 database release. We focus on FPs that are needed for high accuracy burnup assessments; that is, for inferring the number of Fissions in a neutron environment. Los Alamos conducted an experiment in the 1970s in the Bigten fast critical assembly to determine Fission Product yields as part of the Interlaboratory Reaction Rate (ILRR) collaboration, and this has defined the Laboratory's Fission standard to this day. Our evaluation includes use of the LANL-ILRR measurements (not previously available to evaluators) as well as other Laboratory FPY measurements published in the literature, especially the high-accuracy mass spectrometry data from Maeck and others. Because the measurement database for some of the FPs is small - especially for {sup 99}Mo - we use a meta-analysis that incorporates insights from other accurately-measured benchmark FP data, using R-value ratio measurements. The meta-analysis supports the FP measurements from the LANL-ILRR experiment. Differences between our new evaluations and ENDF/B-VI are small for some FPs (less than 1-2%-relative for {sup 95}Zr, {sup 140}Ba, {sup 144}Ce), but are larger for {sup 99}Momore » (4%-relative) and {sup 147}Nd (5%-relative, at 1.5 MeV) respectively. We present evidence for an incident neutron energy dependence to the {sup 147}Nd Fission Product yield that accounts for observed differences in the FPY at a few-hundred keV average energy in fast reactors versus measurements made at higher average neutron energies in Los Alamos' fast critical assemblies. Accounting for such FPY neutron energy dependencies is important if one wants to reach a goal of determining the number of Fissions to accuracies of 1-2%. An evaluation of the energy-dependence of Fission Product yields is given for all A values based on systematical trends in the measured data, with a focus on the energy dependence over the fast neutron energy range from 0.2-2 MeV. Based on these trends, we present an evaluation of the FPY data at 0.5 and 2.0 MeV average incident neutron energies. This new set of ENDF/B-VII data will enable users to linearly interpolate between the pooled FPY data at {approx}0.5 MeV and our new data at 2 MeV to obtain FPYs at other energies.« less
D W Barr - One of the best experts on this subject based on the ideXlab platform.
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Fission Product data measured at los alamos for Fission spectrum and thermal neutrons on 239pu 235u 238u
Nuclear Data Sheets, 2010Co-Authors: H D Selby, M B Chadwick, M Mac R Innes, D W Barr, A L Keksis, R A Meade, C J Burns, T C WallstromAbstract:Abstract We describe measurements of Fission Product data at Los Alamos that are important for determining the number of Fissions that have occurred when neutrons are incident on plutonium and uranium isotopes. The Fission-spectrum measurements were made using a Fission chamber designed by the National Institute for Standards and Technology (NIST) in the BIG TEN critical assembly, as part of the Inter-laboratory Liquid Metal Fast Breeder Reactor (LMFBR) Reaction Rate (ILRR) collaboration. The thermal measurements were made at Los Alamos' Omega West Reactor. A related set of measurements were made of Fission-Product ratios (so-called R-values) in neutron environments provided by a number of Los Alamos critical assemblies that range from having average energies causing Fission of 400–600 keV (BIG TEN and the outer regions of the Flattop-25 assembly) to higher energies (1.4–1.9 MeV) in the Jezebel, and in the central regions of the Flattop-25 and Flattop-Pu, critical assemblies. From these data we determine ratios of Fission Product yields in different fuel and neutron environments (Q-values) and Fission Product yields in Fission spectrum neutron environments for 99Mo, 95Zr, 137Cs, 140Ba, 141,143Ce, and 147Nd. Modest incident-energy dependence exists for the 147Nd Fission Product yield; this is discussed in the context of models for Fission that include thermal and dynamical effects. The Fission Product data agree with measurements by Maeck and other authors using mass-spectrometry methods, and with the ILRR collaboration results that used gamma spectroscopy for quantifying Fission Products. We note that the measurements also contradict earlier 1950s historical Los Alamos estimates by ∼5–7%, most likely owing to self-shielding corrections not made in the early thermal measurements. Our experimental results provide a confirmation of the England-Rider ENDF/B-VI evaluated Fission-spectrum Fission Product yields that were carried over to the ENDF/B-VII.0 library, except for 99Mo where the present results are about 4%-relative higher for neutrons incident on 239Pu and 235U. Additionally, our results illustrate the importance of representing the incident energy dependence of Fission Product yields over the fast neutron energy range for high-accuracy work, for example the 147Nd from neutron reactions on plutonium. An upgrade to the ENDF library, for ENDF/B-VII.1, based on these and other data, is described in a companion paper to this work.
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Fission Product yields from Fission spectrum n 239pu for endf b vii 1
Nuclear Data Sheets, 2010Co-Authors: M B Chadwick, H D Selby, M Mac R Innes, D W Barr, C J Burns, T Kawano, A C Kahler, Todd L Graves, W C Inkret, A L KeksisAbstract:We describe a new cumulated Fission Product yield (FPY) evaluation for Fission spectrum neutrons on plutonium that updates the ENDF/B-VI evaluation by England and Rider, for the forthcoming ENDF/B-VII.1 database release. We focus on FPs that are needed for high accuracy burnup assessments; that is, for inferring the number of Fissions in a neutron environment. Los Alamos conducted an experiment in the 1970s in the Bigten fast critical assembly to determine Fission Product yields as part of the Interlaboratory Reaction Rate (ILRR) collaboration, and this has defined the Laboratory's Fission standard to this day. Our evaluation includes use of the LANL-ILRR measurements (not previously available to evaluators) as well as other Laboratory FPY measurements published in the literature, especially the high-accuracy mass spectrometry data from Maeck and others. Because the measurement database for some of the FPs is small - especially for {sup 99}Mo - we use a meta-analysis that incorporates insights from other accurately-measured benchmark FP data, using R-value ratio measurements. The meta-analysis supports the FP measurements from the LANL-ILRR experiment. Differences between our new evaluations and ENDF/B-VI are small for some FPs (less than 1-2%-relative for {sup 95}Zr, {sup 140}Ba, {sup 144}Ce), but are larger for {sup 99}Momore » (4%-relative) and {sup 147}Nd (5%-relative, at 1.5 MeV) respectively. We present evidence for an incident neutron energy dependence to the {sup 147}Nd Fission Product yield that accounts for observed differences in the FPY at a few-hundred keV average energy in fast reactors versus measurements made at higher average neutron energies in Los Alamos' fast critical assemblies. Accounting for such FPY neutron energy dependencies is important if one wants to reach a goal of determining the number of Fissions to accuracies of 1-2%. An evaluation of the energy-dependence of Fission Product yields is given for all A values based on systematical trends in the measured data, with a focus on the energy dependence over the fast neutron energy range from 0.2-2 MeV. Based on these trends, we present an evaluation of the FPY data at 0.5 and 2.0 MeV average incident neutron energies. This new set of ENDF/B-VII data will enable users to linearly interpolate between the pooled FPY data at {approx}0.5 MeV and our new data at 2 MeV to obtain FPYs at other energies.« less
C J Burns - One of the best experts on this subject based on the ideXlab platform.
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Fission Product data measured at los alamos for Fission spectrum and thermal neutrons on 239pu 235u 238u
Nuclear Data Sheets, 2010Co-Authors: H D Selby, M B Chadwick, M Mac R Innes, D W Barr, A L Keksis, R A Meade, C J Burns, T C WallstromAbstract:Abstract We describe measurements of Fission Product data at Los Alamos that are important for determining the number of Fissions that have occurred when neutrons are incident on plutonium and uranium isotopes. The Fission-spectrum measurements were made using a Fission chamber designed by the National Institute for Standards and Technology (NIST) in the BIG TEN critical assembly, as part of the Inter-laboratory Liquid Metal Fast Breeder Reactor (LMFBR) Reaction Rate (ILRR) collaboration. The thermal measurements were made at Los Alamos' Omega West Reactor. A related set of measurements were made of Fission-Product ratios (so-called R-values) in neutron environments provided by a number of Los Alamos critical assemblies that range from having average energies causing Fission of 400–600 keV (BIG TEN and the outer regions of the Flattop-25 assembly) to higher energies (1.4–1.9 MeV) in the Jezebel, and in the central regions of the Flattop-25 and Flattop-Pu, critical assemblies. From these data we determine ratios of Fission Product yields in different fuel and neutron environments (Q-values) and Fission Product yields in Fission spectrum neutron environments for 99Mo, 95Zr, 137Cs, 140Ba, 141,143Ce, and 147Nd. Modest incident-energy dependence exists for the 147Nd Fission Product yield; this is discussed in the context of models for Fission that include thermal and dynamical effects. The Fission Product data agree with measurements by Maeck and other authors using mass-spectrometry methods, and with the ILRR collaboration results that used gamma spectroscopy for quantifying Fission Products. We note that the measurements also contradict earlier 1950s historical Los Alamos estimates by ∼5–7%, most likely owing to self-shielding corrections not made in the early thermal measurements. Our experimental results provide a confirmation of the England-Rider ENDF/B-VI evaluated Fission-spectrum Fission Product yields that were carried over to the ENDF/B-VII.0 library, except for 99Mo where the present results are about 4%-relative higher for neutrons incident on 239Pu and 235U. Additionally, our results illustrate the importance of representing the incident energy dependence of Fission Product yields over the fast neutron energy range for high-accuracy work, for example the 147Nd from neutron reactions on plutonium. An upgrade to the ENDF library, for ENDF/B-VII.1, based on these and other data, is described in a companion paper to this work.
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Fission Product yields from Fission spectrum n 239pu for endf b vii 1
Nuclear Data Sheets, 2010Co-Authors: M B Chadwick, H D Selby, M Mac R Innes, D W Barr, C J Burns, T Kawano, A C Kahler, Todd L Graves, W C Inkret, A L KeksisAbstract:We describe a new cumulated Fission Product yield (FPY) evaluation for Fission spectrum neutrons on plutonium that updates the ENDF/B-VI evaluation by England and Rider, for the forthcoming ENDF/B-VII.1 database release. We focus on FPs that are needed for high accuracy burnup assessments; that is, for inferring the number of Fissions in a neutron environment. Los Alamos conducted an experiment in the 1970s in the Bigten fast critical assembly to determine Fission Product yields as part of the Interlaboratory Reaction Rate (ILRR) collaboration, and this has defined the Laboratory's Fission standard to this day. Our evaluation includes use of the LANL-ILRR measurements (not previously available to evaluators) as well as other Laboratory FPY measurements published in the literature, especially the high-accuracy mass spectrometry data from Maeck and others. Because the measurement database for some of the FPs is small - especially for {sup 99}Mo - we use a meta-analysis that incorporates insights from other accurately-measured benchmark FP data, using R-value ratio measurements. The meta-analysis supports the FP measurements from the LANL-ILRR experiment. Differences between our new evaluations and ENDF/B-VI are small for some FPs (less than 1-2%-relative for {sup 95}Zr, {sup 140}Ba, {sup 144}Ce), but are larger for {sup 99}Momore » (4%-relative) and {sup 147}Nd (5%-relative, at 1.5 MeV) respectively. We present evidence for an incident neutron energy dependence to the {sup 147}Nd Fission Product yield that accounts for observed differences in the FPY at a few-hundred keV average energy in fast reactors versus measurements made at higher average neutron energies in Los Alamos' fast critical assemblies. Accounting for such FPY neutron energy dependencies is important if one wants to reach a goal of determining the number of Fissions to accuracies of 1-2%. An evaluation of the energy-dependence of Fission Product yields is given for all A values based on systematical trends in the measured data, with a focus on the energy dependence over the fast neutron energy range from 0.2-2 MeV. Based on these trends, we present an evaluation of the FPY data at 0.5 and 2.0 MeV average incident neutron energies. This new set of ENDF/B-VII data will enable users to linearly interpolate between the pooled FPY data at {approx}0.5 MeV and our new data at 2 MeV to obtain FPYs at other energies.« less