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Papers by Andrzej Wojciechowski

Research paper thumbnail of Irradiation history and resulting isotope decay scheme influence on yttrium gamma activity

Proceedings of XXI International Baldin Seminar on High Energy Physics Problems — PoS(Baldin ISHEPP XXI), 2013

Spallation neutrons produced during QUINTA setup irradiation react with 89 Y samples producing a ... more Spallation neutrons produced during QUINTA setup irradiation react with 89 Y samples producing a set of gamma active yttrium isotopes. These reactions are used to determine neutron fields inside setup. The measured gamma activity used for isotope production determination is influenced by several phenomena. This work is focused on two of them-on irradiation history (IH) and decay scheme. After introductory explanation of the both effects some QUINTA experiment results are shown as the illustrative examples.

Research paper thumbnail of On results of Y-89 irradiation with deuteron beam on QUINTA-assembly «E+T - RAW» using Nuclotron (JINR Dubna)

Proceedings of XXI International Baldin Seminar on High Energy Physics Problems — PoS(Baldin ISHEPP XXI), 2013

Experimental values of high energy neutron flux in three energy ranges (11.5-20.8, 20.8-32.7, 32.... more Experimental values of high energy neutron flux in three energy ranges (11.5-20.8, 20.8-32.7, 32.7-100 MeV) and spatial distributions of 88 Y, 87 Y, 86 Y and 85 Y isotope production are presented for a QUINTA assembly. Deuteron beam energy range was from 2.0 to 6.0 GeV. Monte Carlo simulation using MCNPX 2.6 code of the neutron flux density is roughly in agreement with the obtained experimental data.

Research paper thumbnail of Recent results of the study of ads with 500kg natural uranium target assembly QUINTA irradiated by deuterons with energies from 1 TO 8 GeV at JINR NUCLOTRON

Proceedings of XXI International Baldin Seminar on High Energy Physics Problems — PoS(Baldin ISHEPP XXI), 2013

Research paper thumbnail of Międzynarodowa konferencja naukowa z okazji 90-lecia Rumuńskiego Instytutu Geologicznego - Bukareszt, Rumunia, 12-19.06.1996

Research paper thumbnail of The U-232 production in thorium cycle

Progress in Nuclear Energy

Research paper thumbnail of Analysis of potential advanced thorium based fuel for EPR reactor

Proceedings of XXI International Baldin Seminar on High Energy Physics Problems — PoS(Baldin ISHEPP XXI)

As thorium based fuels have benefits in terms of radio-toxicity there are however challenges in t... more As thorium based fuels have benefits in terms of radio-toxicity there are however challenges in terms of reprocessing the spent thorium based fuel. The database and experience of thorium fuels and thorium fuel cycles are very limited , as compared to UO 2 and (U,Pu)O 2 fuels, and need to be augmented before large investments are made for commercial utilization of thorium fuels and fuel cycles. That is why, as the first step of studying the thorium application feasibility, once through thorium based fuel cycle analysis for energy production and radioactive waste transmutation was undertaken, which does not require the technically difficult reprocessing of the spent fuel. The idea is to analyze the thorium based fuel application in the open cycle feasibility study in the existing light water reactors with minimal modifications in order to exploit them. Preliminary analysis of thorium based fuel application in the EPR reactor have shown that once through thorium fuel cycle can be reached with difficulty. It is inferred that the 233 U concentration tends to saturation value which does not depend on power density while the kinetics of reaching the saturation value depends on it. Monte Carlo methodology calculations for the contribution to the analysis of thorium based fuel application in the EPR reactor and in the accelerated driven systems (ADS) were used.

Research paper thumbnail of Evolution of intranuclear collisions at intermediate energies

Physics of Particles and Nuclei Letters

The experimental data on energy and multiplicity distributions of protons and momentum spectra of... more The experimental data on energy and multiplicity distributions of protons and momentum spectra of deuterons emitted in the reactions of pions and protons of energy ranging from 2.5 to 200 GeV with several nuclei are compared to the calculations based upon two different model approaches: DCM Monte Carlo [3] code and the tube-ˇreball (TF) model [4]. The results of this confrontation are discussed within the framework of the intranuclear interaction mechanism assumed. A detailed study of the intranuclear scenario presented by the DCM Monte Carlo program gives grounds to build simpliˇed analytic models like the TF which may turn out very useful in many practical problems as being of predictive nature.

Research paper thumbnail of (n,xn) cross section measurements for Y-89 foils used as detectors for high energy neutron measurements in the deeply subcritical assembly “QUINTA”

EPJ Web of Conferences

Study of the deep subcritical systems (QUINTA) using relativistic beams is performed within the p... more Study of the deep subcritical systems (QUINTA) using relativistic beams is performed within the project "Energy and Transmutation of Radioactive Wastes" (E&T-RAW). The experiment assembly was irradiated by deuteron/proton beam (Dubna NUCLOTRON). We calculated the neutron energy spectrum inside the whole assembly by using threshold energy (n,xn) reactions in yttrium (Y-89) foils. There are almost no experimental cross section data for those reactions. New Y-89(n,xn) cross section measurements were carried out at The Svedberg laboratory (TSL) in Uppsala, Sweden in 2015. In this paper we present preliminary results of those experiments.

Research paper thumbnail of A Method of Spallation Neutron Energy Spectrum Reconstruction with Yttrium Sample Activation

Research paper thumbnail of Measurements of High Energy Neutron Spectrum (> 10 MeV) by Using Yttrium Foils in a U/Pb Assembly

Nuclear Data Sheets, 2014

ABSTRACT Study of deep subcritical electronuclear systems and radioactive waste transmutation usi... more ABSTRACT Study of deep subcritical electronuclear systems and radioactive waste transmutation using relativistic beams were performed. This work is a preliminary step toward the study of the physical properties of Accelerator Driven Systems, in which a deeply subcritical active core is irradiated by a pulsed beam of relativistic ions. The long-range goal of the project is to study the capabilities of such systems with a hard neutron spectrum, for transmutation of radioactive nuclear wastes. Two experimental assemblies, “Energy plus Transmutation” (2006-2009) and “Quinta” (2011-), were irradiated by 1 to 6 GeV deuteron beams using the JINR NUCLOTRON accelerator. The main difference between the two experimental setups is the spallation target - lead or natural uranium. We attempt to obtain neutron energy spectra inside the volume of these assemblies using threshold reactions in natural yttrium (89Y) foils. Some results from three different experiments are presented.

Research paper thumbnail of Influence of moderator to fuel ratio (MFR) on burning thorium in a subcritical assembly

Nuclear Engineering and Design, 2014

Abstract The conversion ratio (CR) of Th-232 to U-233 calculation results for a subcritical react... more Abstract The conversion ratio (CR) of Th-232 to U-233 calculation results for a subcritical reactor assembly is presented as a function of MFR, burnup, power density (PD) and fissile concentration. The calculated model is based on subcritical assembly which makes configuration of fuel rods and volumes of moderator and coolant changes possible. This comfortable assembly enables investigation of CR in a thorium cycle for different value of MFR. Additionally, the calculation results of U-233 saturation concentration are explained by mathematical model. The value of MFR main influences the saturation concentration of U-233 and fissile and the fissile concentration dependence of CR. The saturation value of CR is included in the range CR ∈ (0.911, 0.966) and is a slowly increasing function of MFR. The calculations were done with a MCNPX 2.7 code.

Research paper thumbnail of Yttrium as a New Threshold Detector for Fast Neutron Energy Spectrum (>10 MeV) Measurement

Journal of the Korean Physical Society, 2011

Results of two experiments with Yttrium 89 probe are presented. The experiment assembly (U/Pb mod... more Results of two experiments with Yttrium 89 probe are presented. The experiment assembly (U/Pb model) was irradiated with Dubna NUCLOTRON for 1.6 and 2.52 GeV deuteron beam and we obtain Neutron Energy Spectrum inside whole 3D model by using threshold energy reaction. Normally in experiment like this one uses neutron activation detectors made from gold (197 Au), cobalt (59 Co), bismuth (209 Bi) etc. Detector, yttrium (89 Y) was proposed. Yttrium detectors give quite good results for neutron energy spectrum from 10 MeV to about 50 MeV

Research paper thumbnail of Influence of the power density on a conversion ratio in Accelerated Driven System (ADS)

Annals of Nuclear Energy, 2012

The U-233 Conversion Ratio (CR) calculation results for Yalina Thermal assembly are presented as ... more The U-233 Conversion Ratio (CR) calculation results for Yalina Thermal assembly are presented as a function of burnup, power density, irradiation history and U-233 concentration. The Yalina Thermal assembly is an ADS which makes configuration changes possible. These various configurations enable investigation and comparison of CR in a Thorium cycle (Th cycle) and a mixed Uranium-Thorium cycle (U-Th cycle) of burning. The power density has no influence on the U-233 concentration dependence of CR and on the burnup dependence of CR. The calculations were done with a MCNPX code.

Research paper thumbnail of Irradiation history and resulting isotope decay scheme influence on yttrium gamma activity

Proceedings of XXI International Baldin Seminar on High Energy Physics Problems — PoS(Baldin ISHEPP XXI), 2013

Spallation neutrons produced during QUINTA setup irradiation react with 89 Y samples producing a ... more Spallation neutrons produced during QUINTA setup irradiation react with 89 Y samples producing a set of gamma active yttrium isotopes. These reactions are used to determine neutron fields inside setup. The measured gamma activity used for isotope production determination is influenced by several phenomena. This work is focused on two of them-on irradiation history (IH) and decay scheme. After introductory explanation of the both effects some QUINTA experiment results are shown as the illustrative examples.

Research paper thumbnail of On results of Y-89 irradiation with deuteron beam on QUINTA-assembly «E+T - RAW» using Nuclotron (JINR Dubna)

Proceedings of XXI International Baldin Seminar on High Energy Physics Problems — PoS(Baldin ISHEPP XXI), 2013

Experimental values of high energy neutron flux in three energy ranges (11.5-20.8, 20.8-32.7, 32.... more Experimental values of high energy neutron flux in three energy ranges (11.5-20.8, 20.8-32.7, 32.7-100 MeV) and spatial distributions of 88 Y, 87 Y, 86 Y and 85 Y isotope production are presented for a QUINTA assembly. Deuteron beam energy range was from 2.0 to 6.0 GeV. Monte Carlo simulation using MCNPX 2.6 code of the neutron flux density is roughly in agreement with the obtained experimental data.

Research paper thumbnail of Recent results of the study of ads with 500kg natural uranium target assembly QUINTA irradiated by deuterons with energies from 1 TO 8 GeV at JINR NUCLOTRON

Proceedings of XXI International Baldin Seminar on High Energy Physics Problems — PoS(Baldin ISHEPP XXI), 2013

Research paper thumbnail of Międzynarodowa konferencja naukowa z okazji 90-lecia Rumuńskiego Instytutu Geologicznego - Bukareszt, Rumunia, 12-19.06.1996

Research paper thumbnail of The U-232 production in thorium cycle

Progress in Nuclear Energy

Research paper thumbnail of Analysis of potential advanced thorium based fuel for EPR reactor

Proceedings of XXI International Baldin Seminar on High Energy Physics Problems — PoS(Baldin ISHEPP XXI)

As thorium based fuels have benefits in terms of radio-toxicity there are however challenges in t... more As thorium based fuels have benefits in terms of radio-toxicity there are however challenges in terms of reprocessing the spent thorium based fuel. The database and experience of thorium fuels and thorium fuel cycles are very limited , as compared to UO 2 and (U,Pu)O 2 fuels, and need to be augmented before large investments are made for commercial utilization of thorium fuels and fuel cycles. That is why, as the first step of studying the thorium application feasibility, once through thorium based fuel cycle analysis for energy production and radioactive waste transmutation was undertaken, which does not require the technically difficult reprocessing of the spent fuel. The idea is to analyze the thorium based fuel application in the open cycle feasibility study in the existing light water reactors with minimal modifications in order to exploit them. Preliminary analysis of thorium based fuel application in the EPR reactor have shown that once through thorium fuel cycle can be reached with difficulty. It is inferred that the 233 U concentration tends to saturation value which does not depend on power density while the kinetics of reaching the saturation value depends on it. Monte Carlo methodology calculations for the contribution to the analysis of thorium based fuel application in the EPR reactor and in the accelerated driven systems (ADS) were used.

Research paper thumbnail of Evolution of intranuclear collisions at intermediate energies

Physics of Particles and Nuclei Letters

The experimental data on energy and multiplicity distributions of protons and momentum spectra of... more The experimental data on energy and multiplicity distributions of protons and momentum spectra of deuterons emitted in the reactions of pions and protons of energy ranging from 2.5 to 200 GeV with several nuclei are compared to the calculations based upon two different model approaches: DCM Monte Carlo [3] code and the tube-ˇreball (TF) model [4]. The results of this confrontation are discussed within the framework of the intranuclear interaction mechanism assumed. A detailed study of the intranuclear scenario presented by the DCM Monte Carlo program gives grounds to build simpliˇed analytic models like the TF which may turn out very useful in many practical problems as being of predictive nature.

Research paper thumbnail of (n,xn) cross section measurements for Y-89 foils used as detectors for high energy neutron measurements in the deeply subcritical assembly “QUINTA”

EPJ Web of Conferences

Study of the deep subcritical systems (QUINTA) using relativistic beams is performed within the p... more Study of the deep subcritical systems (QUINTA) using relativistic beams is performed within the project "Energy and Transmutation of Radioactive Wastes" (E&T-RAW). The experiment assembly was irradiated by deuteron/proton beam (Dubna NUCLOTRON). We calculated the neutron energy spectrum inside the whole assembly by using threshold energy (n,xn) reactions in yttrium (Y-89) foils. There are almost no experimental cross section data for those reactions. New Y-89(n,xn) cross section measurements were carried out at The Svedberg laboratory (TSL) in Uppsala, Sweden in 2015. In this paper we present preliminary results of those experiments.

Research paper thumbnail of A Method of Spallation Neutron Energy Spectrum Reconstruction with Yttrium Sample Activation

Research paper thumbnail of Measurements of High Energy Neutron Spectrum (> 10 MeV) by Using Yttrium Foils in a U/Pb Assembly

Nuclear Data Sheets, 2014

ABSTRACT Study of deep subcritical electronuclear systems and radioactive waste transmutation usi... more ABSTRACT Study of deep subcritical electronuclear systems and radioactive waste transmutation using relativistic beams were performed. This work is a preliminary step toward the study of the physical properties of Accelerator Driven Systems, in which a deeply subcritical active core is irradiated by a pulsed beam of relativistic ions. The long-range goal of the project is to study the capabilities of such systems with a hard neutron spectrum, for transmutation of radioactive nuclear wastes. Two experimental assemblies, “Energy plus Transmutation” (2006-2009) and “Quinta” (2011-), were irradiated by 1 to 6 GeV deuteron beams using the JINR NUCLOTRON accelerator. The main difference between the two experimental setups is the spallation target - lead or natural uranium. We attempt to obtain neutron energy spectra inside the volume of these assemblies using threshold reactions in natural yttrium (89Y) foils. Some results from three different experiments are presented.

Research paper thumbnail of Influence of moderator to fuel ratio (MFR) on burning thorium in a subcritical assembly

Nuclear Engineering and Design, 2014

Abstract The conversion ratio (CR) of Th-232 to U-233 calculation results for a subcritical react... more Abstract The conversion ratio (CR) of Th-232 to U-233 calculation results for a subcritical reactor assembly is presented as a function of MFR, burnup, power density (PD) and fissile concentration. The calculated model is based on subcritical assembly which makes configuration of fuel rods and volumes of moderator and coolant changes possible. This comfortable assembly enables investigation of CR in a thorium cycle for different value of MFR. Additionally, the calculation results of U-233 saturation concentration are explained by mathematical model. The value of MFR main influences the saturation concentration of U-233 and fissile and the fissile concentration dependence of CR. The saturation value of CR is included in the range CR ∈ (0.911, 0.966) and is a slowly increasing function of MFR. The calculations were done with a MCNPX 2.7 code.

Research paper thumbnail of Yttrium as a New Threshold Detector for Fast Neutron Energy Spectrum (>10 MeV) Measurement

Journal of the Korean Physical Society, 2011

Results of two experiments with Yttrium 89 probe are presented. The experiment assembly (U/Pb mod... more Results of two experiments with Yttrium 89 probe are presented. The experiment assembly (U/Pb model) was irradiated with Dubna NUCLOTRON for 1.6 and 2.52 GeV deuteron beam and we obtain Neutron Energy Spectrum inside whole 3D model by using threshold energy reaction. Normally in experiment like this one uses neutron activation detectors made from gold (197 Au), cobalt (59 Co), bismuth (209 Bi) etc. Detector, yttrium (89 Y) was proposed. Yttrium detectors give quite good results for neutron energy spectrum from 10 MeV to about 50 MeV

Research paper thumbnail of Influence of the power density on a conversion ratio in Accelerated Driven System (ADS)

Annals of Nuclear Energy, 2012

The U-233 Conversion Ratio (CR) calculation results for Yalina Thermal assembly are presented as ... more The U-233 Conversion Ratio (CR) calculation results for Yalina Thermal assembly are presented as a function of burnup, power density, irradiation history and U-233 concentration. The Yalina Thermal assembly is an ADS which makes configuration changes possible. These various configurations enable investigation and comparison of CR in a Thorium cycle (Th cycle) and a mixed Uranium-Thorium cycle (U-Th cycle) of burning. The power density has no influence on the U-233 concentration dependence of CR and on the burnup dependence of CR. The calculations were done with a MCNPX code.