Recent activities carried out under auspices of the WPEC Subgroup 24, or those closely related to... more Recent activities carried out under auspices of the WPEC Subgroup 24, or those closely related to the subgroup, are summarized. The major efforts were addressing formal studies and implementation of the newly proposed Unified Monte Carlo method, comparison of existing approaches (KALMAN, Monte Carlo, Backward-Forward Monte Carlo, and GANDR), establishing practical procedures for determination of covariances, and production of new covariance files. Although substantial progress has been achieved in all these directions further studies are needed to understand differences among various approaches and reach consensus on the methodology. 1
This paper deals with a divertor coil currents optimized procedure to design High Flux Expansion ... more This paper deals with a divertor coil currents optimized procedure to design High Flux Expansion (HFE) configurations in the JET tokamak aimed to study the effects of flux expansion variation on the radiation fraction and radiated power redistribution. A number of benefits of HFE configuration have been experimentally demonstrated on TCV, EAST, NSTX and DIII-D tokamaks and are under investigation for next generation devices, as DEMO and DTT. The procedure proposed here exploits the linearized relation between the plasma-wall gaps and the Poloidal Field (PF) coil currents. Once the linearized model is provided by means of CREATE-NL code, the divertor coils currents are calculated using a constrained quadratic programming optimization procedure, in order to achieve HFE configuration. HFE configurations have been experimentally realized both in ohmic and heated plasma with and without nitrogen seeding. Preliminary results on the effects of the flux expansion variation on total power radiation increase will be also briefly discussed.
Two series of measurements were performed in the JSI TRIGA research reactor in 2014 and 2017 to v... more Two series of measurements were performed in the JSI TRIGA research reactor in 2014 and 2017 to validate the 55Mn(n,γ)56Mn cross-sections and experimentally investigate the relationship between the 55Mn(n,γ)56Mn reaction and the rate of tritium production through the 6Li(n,t)4He reaction. Indeed, previously observed similarities between the sensitivity profiles of the neutron reaction of tritium production on lithium, 6Li(n,t)4He, and those of the 55Mn(n,γ)56Mn reaction in tritium breeder modules indicated that the latter reaction could be used as an effective monitor of tritium production, at least for short-term monitoring (the half-life of 56Mn being 2.579 h). However, experimental verification, improvements and validation of the 55Mn(n,γ)56Mn cross-sections are needed in order to meet the required accuracy. Foils of certified reference material Al–1%Mn, as well as LiF thermoluminescent detectors and Li2O samples were irradiated, both bare and under cadmium, to study the potentia...
The effect of fast ions on turbulent particle transport, driven by ion temperature gradient (ITG)... more The effect of fast ions on turbulent particle transport, driven by ion temperature gradient (ITG)/trapped electron mode turbulence, is studied. Two neutral beam injection (NBI) heated JET discharges in different regimes are analyzed at the radial position ρ t = 0.6, one of them an L-mode and the other one an H-mode discharge. Results obtained from the computationally efficient fluid model EDWM and the gyro-fluid model TGLF are compared to linear and nonlinear gyrokinetic GENE simulations as well as the experimentally obtained density peaking. In these models, the fast ions are treated as a dynamic species with a Maxwellian background distribution. The dependence of the zero particle flux density gradient (peaking factor) on fast ion density, temperature and corresponding gradients, is investigated. The simulations show that the inclusion of a fast ion species has a stabilizing influence on the ITG mode and reduces the peaking of the main ion and electron density profiles in the abs...
The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact ... more The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear technologies-235,238 U, 239 Pu, 56 Fe, 16 O and 1 H-with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform
An evaluation of the criticality and relative fission rate radial distribution experiments in an ... more An evaluation of the criticality and relative fission rate radial distribution experiments in an 69.2-cm diameter aluminium sphere filled with intermediately enriched UO 2 F 2 aqueous solution is presented. An evaluation of the total experimental uncertainty has been performed within the framework of the International Criticality Benchmark Evaluation Project (ICSBEP) and International Reactor Physics Benchmark Evaluation Project (IRPhEP). In addition, the uncertainty due to the uncertainties in the nuclear data is evaluated in this paper. It has been determined that the highest contribution to the overall uncertainty in the effective multiplication factor k eff is due to the uncertainty in the uranium enrichment (550 pcm in k eff due to the 4% uncertainty in 235 U enrichment). The highest experimental uncertainties in the relative fission rate profile in terms of the relative standard uncertainty (Lrs) are 0.032, 0.016, and 0.020 due to the uncertainty in guide tube diameter, filling tubes position, and detector position, respectively. It is estimated that the uncertainty in the nuclear data contributes approximately 400 pcm-1200 pcm to the uncertainty in k eff depending on the covariance data library used. k eff and radial fission rates have been calculated with MCNP and COG Monte Carlo neutron transport codes and have been compared to the experimental benchmark values. In general, the various Monte Carlo codes have given similar results with deviations within uncertainties.
We review the methods employed in the GANDR system to perform a global assessment of nuclear data... more We review the methods employed in the GANDR system to perform a global assessment of nuclear data. We then describe the integration of the International Standards Evaluation into a recently initiated global data assessment.
The SINBAD project started in the early 1990's as a collaboration between the Organization for Ec... more The SINBAD project started in the early 1990's as a collaboration between the Organization for Economic Cooperation and Development's Nuclear Energy Agency Data Bank (OECD/NEADB) and the Radiation Safety Information Computational Center (RSICC) at the Oak Ridge National Laboratory (ORNL) with the goal to preserve the information on the performed radiation shielding benchmarks and make them available in a standardised form to the international community. The SINBAD database comprises now 100 shielding benchmarks, covering fission reactor shielding, fusion blanket neutronics, and accelerator shielding. A thorough revision of the SINBAD benchmark experiments was undertaken recently in order to verify the completeness and consistency of the benchmark information, in particular concerning the evaluation of the experimental sources of uncertainty. New improved computer code models were prepared. This review process is expected to provide users with an easier choice and help them make better use of the experimental information. The OECD NEA Working Party on Scientific Issues of Reactor Systems (WPRS) Expert Group on Radiation Transport and Shielding (EGRTS) was started in 2011 with the mandate among others, to monitor, steer and support the continued development of the SINBAD database. SINBAD is available from RSICC and from the NEA Data Bank.
'QUADOS', a concerted action of the European Commission, has promoted an intercom... more 'QUADOS', a concerted action of the European Commission, has promoted an intercomparison aimed at evaluating the use of computational codes for dosimetry in radiation protection and medical physics. This intercomparison was open to all users of radiation transport codes. Eight problems were selected for their relevance to the radiation dosimetry community, five of which involved photon and proton transport. This paper focuses on a discussion of lessons learned from the participation in solving the photon and charged particle problems. The lessons learned from the participation in solving the neutron problems are presented in a companion paper (in this issue).
In support of the breeder blanket development program, the EU is conducting a dedicated neutronic... more In support of the breeder blanket development program, the EU is conducting a dedicated neutronics R&D effort to provide the basis for the design of nuclear tests to be performed in ITER on the Test Blanket Modules (TBMs). It includes the development of computational tools comprising both Monte-Carlo and deterministic transport, sensitivity and uncertainty codes, the generation of high quality neutron crosssection and covariance data libraries. These are validated experimentally in view of their application in the ITER TBM and the DEMO design. To this purpose, two neutronics experiments have been carried out on mock-ups of both the Helium Cooled Pebble Bed (HCPB) and the Helium Cooled Lithium Lead (HCLL) variants of ITER TBMs, at 14-MeV neutron sources. Redundant experimental techniques have been used to measure the resulting tritium production rate and the neutron and gamma ray spectra which are needed to predict the blanket shielding performance, nuclear power production and all nuclear loads. The comparison of experiment and corresponding calculation is obtained with the associated uncertainty margin based on experimental as well as calculational uncertainties. At the same time, suitable nuclear measuring techniques for TBMs in ITER, in particular for the tritium production, are being developed, optimised, and tested in the mock-up experiments. In particular, the present paper summarizes the preliminary results of the latest of such experiments, i.e. the one conducted on a mock-up of the HCLL blanket. It describes also the dedicated neutronics R&D activities, including the efforts to specify the neutronics tests and objectives in TBMs in ITER, considering the various design concepts.
The status of the Joint Evaluated Fission and Fusion file (JEFF) is described. JEFF-3.1 comprises... more The status of the Joint Evaluated Fission and Fusion file (JEFF) is described. JEFF-3.1 comprises a significant update of actinide evaluations, materials evaluations that have emerged from various European nuclear data projects, the activation library JEFF-3.1/A, the decay data and fission yield sub-libraries, and fusion-related data files from the EFF project. The revisions were motivated by the availability of new measurements, modelling capabilities and trends from integral experiments. Validations have been performed, mainly for criticality, reactivity temperature coefficients, fuel inventory and shielding of thermal and fast systems. Compared with earlier releases, JEFF-3.1 provides improved performance with respect to a variety of scientific and industrial applications. Following on from the public release of JEFF-3.1, the French nuclear power industry has selected this suite of nuclear applications libraries for inclusion in their production codes.
The ongoing OECD Light Water Reactor (LWR) Uncertainty Analysis in Modeling (UAM) benchmark activ... more The ongoing OECD Light Water Reactor (LWR) Uncertainty Analysis in Modeling (UAM) benchmark activity contributes to establishing unified framework to determine the uncertainty in LWR system calculations at all stages of a coupled reactor physics/thermal hydraulics calculation. This benchmark sequence started in 2007, and integrates the expertise in reactor physics, thermalhydraulics and reactor system modeling as well as uncertainty and sensitivity analysis. Such an effort has been undertaken within the framework of a program of international co-operation that benefits from the coordination of the NEA Nuclear Science Committee (NSC), and from interfacing with the Committee of Safety of Nuclear Installations (CSNI). Reference LWR systems and scenarios for coupled code analysis are defined. Three main LWR types are selected, based on previous benchmark experiences and available data – BWR, PWR and VVER-1000. The full chain of uncertainty propagation from basic data, engineering uncert...
In order to validate new nuclear cross-section evaluations and computational methods, a large num... more In order to validate new nuclear cross-section evaluations and computational methods, a large number of benchmarks experiments were performed in the past. OECD/NEA launched several projects aiming to collect, preserve and disseminate the benchmark data in a userfriendly format. Reactor physics benchmarks are covered by the IRPhE project. The information on experiments available in this database can be found from http://www.nea.fr/html/dbprog/. This paper presents the preparation of the IRPhE compilation for the KRITZ-2 critical experiments. Altogether six configurations, both UO2 and MOX, were measured at 2 different temperatures at Studsvik. These configurations were analysed in the scope of an international exercise using Monte Carlo and deterministic methods (MCNP, MVP, MCU, THREEDANT, HELIOS). Cross section sensitivity and uncertainty analysis were also performed using the SUSD3D code to check the consistency among the C/E (calculation to experiment) discrepancy observed by the ...
The shielding integral benchmark archive and database (SINBAD) collection of experiments descript... more The shielding integral benchmark archive and database (SINBAD) collection of experiments descriptions was initiated in the early 1990s. SINBAD is an international collaboration between the Organization for Economic Cooperation and Development's Nuclear Energy Agency Data Bank (OECD/NEADB) and the Radiation Safety Information Computational Center (RSICC) at Oak Ridge National Laboratory (ORNL). SINBAD was designed to compile experiments and corresponding computational models with the goal of preserving institutional knowledge and expertise that need to be handed down to future scientists. SINBAD can serve as a learning tool for university students and scientists who need to design experiments or gain expertise in modeling and simulation. The SINBAD database is currently divided into three categories - fission, fusion, and accelerator experiments. Many experiments are described and analyzed using deterministic or stochastic (Monte Carlo) radiation transport software. The nuclear c...
Recent activities carried out under auspices of the WPEC Subgroup 24, or those closely related to... more Recent activities carried out under auspices of the WPEC Subgroup 24, or those closely related to the subgroup, are summarized. The major efforts were addressing formal studies and implementation of the newly proposed Unified Monte Carlo method, comparison of existing approaches (KALMAN, Monte Carlo, Backward-Forward Monte Carlo, and GANDR), establishing practical procedures for determination of covariances, and production of new covariance files. Although substantial progress has been achieved in all these directions further studies are needed to understand differences among various approaches and reach consensus on the methodology. 1
This paper deals with a divertor coil currents optimized procedure to design High Flux Expansion ... more This paper deals with a divertor coil currents optimized procedure to design High Flux Expansion (HFE) configurations in the JET tokamak aimed to study the effects of flux expansion variation on the radiation fraction and radiated power redistribution. A number of benefits of HFE configuration have been experimentally demonstrated on TCV, EAST, NSTX and DIII-D tokamaks and are under investigation for next generation devices, as DEMO and DTT. The procedure proposed here exploits the linearized relation between the plasma-wall gaps and the Poloidal Field (PF) coil currents. Once the linearized model is provided by means of CREATE-NL code, the divertor coils currents are calculated using a constrained quadratic programming optimization procedure, in order to achieve HFE configuration. HFE configurations have been experimentally realized both in ohmic and heated plasma with and without nitrogen seeding. Preliminary results on the effects of the flux expansion variation on total power radiation increase will be also briefly discussed.
Two series of measurements were performed in the JSI TRIGA research reactor in 2014 and 2017 to v... more Two series of measurements were performed in the JSI TRIGA research reactor in 2014 and 2017 to validate the 55Mn(n,γ)56Mn cross-sections and experimentally investigate the relationship between the 55Mn(n,γ)56Mn reaction and the rate of tritium production through the 6Li(n,t)4He reaction. Indeed, previously observed similarities between the sensitivity profiles of the neutron reaction of tritium production on lithium, 6Li(n,t)4He, and those of the 55Mn(n,γ)56Mn reaction in tritium breeder modules indicated that the latter reaction could be used as an effective monitor of tritium production, at least for short-term monitoring (the half-life of 56Mn being 2.579 h). However, experimental verification, improvements and validation of the 55Mn(n,γ)56Mn cross-sections are needed in order to meet the required accuracy. Foils of certified reference material Al–1%Mn, as well as LiF thermoluminescent detectors and Li2O samples were irradiated, both bare and under cadmium, to study the potentia...
The effect of fast ions on turbulent particle transport, driven by ion temperature gradient (ITG)... more The effect of fast ions on turbulent particle transport, driven by ion temperature gradient (ITG)/trapped electron mode turbulence, is studied. Two neutral beam injection (NBI) heated JET discharges in different regimes are analyzed at the radial position ρ t = 0.6, one of them an L-mode and the other one an H-mode discharge. Results obtained from the computationally efficient fluid model EDWM and the gyro-fluid model TGLF are compared to linear and nonlinear gyrokinetic GENE simulations as well as the experimentally obtained density peaking. In these models, the fast ions are treated as a dynamic species with a Maxwellian background distribution. The dependence of the zero particle flux density gradient (peaking factor) on fast ion density, temperature and corresponding gradients, is investigated. The simulations show that the inclusion of a fast ion species has a stabilizing influence on the ITG mode and reduces the peaking of the main ion and electron density profiles in the abs...
The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact ... more The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear technologies-235,238 U, 239 Pu, 56 Fe, 16 O and 1 H-with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform
An evaluation of the criticality and relative fission rate radial distribution experiments in an ... more An evaluation of the criticality and relative fission rate radial distribution experiments in an 69.2-cm diameter aluminium sphere filled with intermediately enriched UO 2 F 2 aqueous solution is presented. An evaluation of the total experimental uncertainty has been performed within the framework of the International Criticality Benchmark Evaluation Project (ICSBEP) and International Reactor Physics Benchmark Evaluation Project (IRPhEP). In addition, the uncertainty due to the uncertainties in the nuclear data is evaluated in this paper. It has been determined that the highest contribution to the overall uncertainty in the effective multiplication factor k eff is due to the uncertainty in the uranium enrichment (550 pcm in k eff due to the 4% uncertainty in 235 U enrichment). The highest experimental uncertainties in the relative fission rate profile in terms of the relative standard uncertainty (Lrs) are 0.032, 0.016, and 0.020 due to the uncertainty in guide tube diameter, filling tubes position, and detector position, respectively. It is estimated that the uncertainty in the nuclear data contributes approximately 400 pcm-1200 pcm to the uncertainty in k eff depending on the covariance data library used. k eff and radial fission rates have been calculated with MCNP and COG Monte Carlo neutron transport codes and have been compared to the experimental benchmark values. In general, the various Monte Carlo codes have given similar results with deviations within uncertainties.
We review the methods employed in the GANDR system to perform a global assessment of nuclear data... more We review the methods employed in the GANDR system to perform a global assessment of nuclear data. We then describe the integration of the International Standards Evaluation into a recently initiated global data assessment.
The SINBAD project started in the early 1990's as a collaboration between the Organization for Ec... more The SINBAD project started in the early 1990's as a collaboration between the Organization for Economic Cooperation and Development's Nuclear Energy Agency Data Bank (OECD/NEADB) and the Radiation Safety Information Computational Center (RSICC) at the Oak Ridge National Laboratory (ORNL) with the goal to preserve the information on the performed radiation shielding benchmarks and make them available in a standardised form to the international community. The SINBAD database comprises now 100 shielding benchmarks, covering fission reactor shielding, fusion blanket neutronics, and accelerator shielding. A thorough revision of the SINBAD benchmark experiments was undertaken recently in order to verify the completeness and consistency of the benchmark information, in particular concerning the evaluation of the experimental sources of uncertainty. New improved computer code models were prepared. This review process is expected to provide users with an easier choice and help them make better use of the experimental information. The OECD NEA Working Party on Scientific Issues of Reactor Systems (WPRS) Expert Group on Radiation Transport and Shielding (EGRTS) was started in 2011 with the mandate among others, to monitor, steer and support the continued development of the SINBAD database. SINBAD is available from RSICC and from the NEA Data Bank.
'QUADOS', a concerted action of the European Commission, has promoted an intercom... more 'QUADOS', a concerted action of the European Commission, has promoted an intercomparison aimed at evaluating the use of computational codes for dosimetry in radiation protection and medical physics. This intercomparison was open to all users of radiation transport codes. Eight problems were selected for their relevance to the radiation dosimetry community, five of which involved photon and proton transport. This paper focuses on a discussion of lessons learned from the participation in solving the photon and charged particle problems. The lessons learned from the participation in solving the neutron problems are presented in a companion paper (in this issue).
In support of the breeder blanket development program, the EU is conducting a dedicated neutronic... more In support of the breeder blanket development program, the EU is conducting a dedicated neutronics R&D effort to provide the basis for the design of nuclear tests to be performed in ITER on the Test Blanket Modules (TBMs). It includes the development of computational tools comprising both Monte-Carlo and deterministic transport, sensitivity and uncertainty codes, the generation of high quality neutron crosssection and covariance data libraries. These are validated experimentally in view of their application in the ITER TBM and the DEMO design. To this purpose, two neutronics experiments have been carried out on mock-ups of both the Helium Cooled Pebble Bed (HCPB) and the Helium Cooled Lithium Lead (HCLL) variants of ITER TBMs, at 14-MeV neutron sources. Redundant experimental techniques have been used to measure the resulting tritium production rate and the neutron and gamma ray spectra which are needed to predict the blanket shielding performance, nuclear power production and all nuclear loads. The comparison of experiment and corresponding calculation is obtained with the associated uncertainty margin based on experimental as well as calculational uncertainties. At the same time, suitable nuclear measuring techniques for TBMs in ITER, in particular for the tritium production, are being developed, optimised, and tested in the mock-up experiments. In particular, the present paper summarizes the preliminary results of the latest of such experiments, i.e. the one conducted on a mock-up of the HCLL blanket. It describes also the dedicated neutronics R&D activities, including the efforts to specify the neutronics tests and objectives in TBMs in ITER, considering the various design concepts.
The status of the Joint Evaluated Fission and Fusion file (JEFF) is described. JEFF-3.1 comprises... more The status of the Joint Evaluated Fission and Fusion file (JEFF) is described. JEFF-3.1 comprises a significant update of actinide evaluations, materials evaluations that have emerged from various European nuclear data projects, the activation library JEFF-3.1/A, the decay data and fission yield sub-libraries, and fusion-related data files from the EFF project. The revisions were motivated by the availability of new measurements, modelling capabilities and trends from integral experiments. Validations have been performed, mainly for criticality, reactivity temperature coefficients, fuel inventory and shielding of thermal and fast systems. Compared with earlier releases, JEFF-3.1 provides improved performance with respect to a variety of scientific and industrial applications. Following on from the public release of JEFF-3.1, the French nuclear power industry has selected this suite of nuclear applications libraries for inclusion in their production codes.
The ongoing OECD Light Water Reactor (LWR) Uncertainty Analysis in Modeling (UAM) benchmark activ... more The ongoing OECD Light Water Reactor (LWR) Uncertainty Analysis in Modeling (UAM) benchmark activity contributes to establishing unified framework to determine the uncertainty in LWR system calculations at all stages of a coupled reactor physics/thermal hydraulics calculation. This benchmark sequence started in 2007, and integrates the expertise in reactor physics, thermalhydraulics and reactor system modeling as well as uncertainty and sensitivity analysis. Such an effort has been undertaken within the framework of a program of international co-operation that benefits from the coordination of the NEA Nuclear Science Committee (NSC), and from interfacing with the Committee of Safety of Nuclear Installations (CSNI). Reference LWR systems and scenarios for coupled code analysis are defined. Three main LWR types are selected, based on previous benchmark experiences and available data – BWR, PWR and VVER-1000. The full chain of uncertainty propagation from basic data, engineering uncert...
In order to validate new nuclear cross-section evaluations and computational methods, a large num... more In order to validate new nuclear cross-section evaluations and computational methods, a large number of benchmarks experiments were performed in the past. OECD/NEA launched several projects aiming to collect, preserve and disseminate the benchmark data in a userfriendly format. Reactor physics benchmarks are covered by the IRPhE project. The information on experiments available in this database can be found from http://www.nea.fr/html/dbprog/. This paper presents the preparation of the IRPhE compilation for the KRITZ-2 critical experiments. Altogether six configurations, both UO2 and MOX, were measured at 2 different temperatures at Studsvik. These configurations were analysed in the scope of an international exercise using Monte Carlo and deterministic methods (MCNP, MVP, MCU, THREEDANT, HELIOS). Cross section sensitivity and uncertainty analysis were also performed using the SUSD3D code to check the consistency among the C/E (calculation to experiment) discrepancy observed by the ...
The shielding integral benchmark archive and database (SINBAD) collection of experiments descript... more The shielding integral benchmark archive and database (SINBAD) collection of experiments descriptions was initiated in the early 1990s. SINBAD is an international collaboration between the Organization for Economic Cooperation and Development's Nuclear Energy Agency Data Bank (OECD/NEADB) and the Radiation Safety Information Computational Center (RSICC) at Oak Ridge National Laboratory (ORNL). SINBAD was designed to compile experiments and corresponding computational models with the goal of preserving institutional knowledge and expertise that need to be handed down to future scientists. SINBAD can serve as a learning tool for university students and scientists who need to design experiments or gain expertise in modeling and simulation. The SINBAD database is currently divided into three categories - fission, fusion, and accelerator experiments. Many experiments are described and analyzed using deterministic or stochastic (Monte Carlo) radiation transport software. The nuclear c...
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