Igor Remec

• Oak Ridge National Laboratory

The European Spallation Source, currently under construction in Lund, Sweden, is a multidisciplinary international laboratory. Once completed to full specifications, it will operate the world’s most powerful pulsed neutron source. Supported by a 3 million Euro Research and Innovation Action within the EU Horizon 2020 program, a design study (HighNE...

A key aim of the HighNESS project for the European Spallation Source is to enable cutting-edge particle physics experiments. This volume presents a conceptual design report for the NNBAR experiment. NNBAR would exploit a new cold lower moderator to make the first search in over thirty years for free neutrons converting to anti-neutrons. The observa...

The Second Target Station project at Oak Ridge National Laboratory will develop a cold neutron source to meet growing experimental needs. This paper describes calculations of the residual dose rates associated with the monolith shield plug and the beamline bunker, two key conventional operations and radiation safety features. While neutron producti...

At the U.S. Department of Energy’s Oak Ridge National Laboratory, the Second Target Station (STS) beamline sources for preliminary design have been used to perform a shielding analysis of the bunker. Prompt total effective dose rates (i.e., neutron plus photon effective dose rates when the proton beam is on) were calculated on top of the bunker roo...

Liquid hydrogen filled tubes arranged in a triangular shape surrounded by light-water premoderators were investigated as cold moderators coupled to a neutron production zone of a tungsten target fed by a 1.3 GeV proton beam in a short-pulse mode. A moderator concept optimized for the tube length, premoderator thickness, and target position was foun...

The Spallation Neutron Source, in operation at the Oak Ridge National Laboratory since 2006, was designed to allow the addition of a second target station and an upgrade of the accelerator proton power. Both upgrades are now underway. This paper describes the evolution of the design of the target of the second target station with the emphasis on th...

The automatic conversion of the computer aided design (CAD) models into models suitable for radiation transport simulations has been receiving a lot of attention in the last decade or so. The main drivers are the need to reduce the time that neutronics analysts invest in development and verification of models and the need to develop larger and more...

Description Get the latest information on databases, benchmark studies, techniques, and standardization of radiation metrology and regulatory information related to reactor dosimetry. Learn more about modern technologies used in radiation imaging and the development of radiation instrumentation. Plus you’ll get over 50 peer-reviewed papers covering...

Liquid ammonia is an attractive intermediate temperature moderating material, offering a high hydrogen density, low tendency toward radiation-initiated polymerization, and broad accessible temperature range. The LENS collaboration has characterized decoupled poisoned liquid ammonia moderators in an attempt to validate scattering kernels we are gene...

This paper presents an update of the status of the neutronics analyses performed for the Second Target Station (STS). The target station is driven with short (less than 1 micro second long) proton pulses at 15 Hz repetition rate and 700 kW proton beam power. The target will be optimized for high intensity and high resolution long wavelength neutron...

Simulation work is underway to identify a very cold neutron source solution that would provide an order of magnitude higher neutron output than the conventional moderator suite. Moderator candidates such as water ice, beryllium, ortho-D2, CH4, and neon all solid at temperatures of 4-6 K were investigated. At present no moderator option was able to...

Life extensions of nuclear power plants (NPPs) to 60 years of operation and the possibility of subsequent license renewal to 80 years have renewed interest in long-term material degradation in NPPs. Large irreplaceable sections of most nuclear generating stations are constructed from concrete, including safety-related structures such as biological...

A review of the current state of knowledge on the effects of radiation on concrete in nuclear power production applications is presented. Emphasis is placed on the effects of radiation damage, as reflected by changes in engineering properties of concrete, in the evaluation of the long-term operation and for plant life or aging management of nuclear...

License renewal up to 60 years and the possibility of subsequent license renewal to 80 years has resulted in a renewed focus on long-term aging of materials at nuclear power plants (NPPs) including concrete. Large irreplaceable sections of most nuclear generating stations include concrete. The Expanded Materials Degradation Analysis, jointly perfor...

Dommages d’irradiation du béton des puits de cuve des réacteurs T.M. Rosseel1, J.J. Wall2, K.G. Field1, Y. Le Pape1*, D.J. Naus1, I. Remec1, J.T. Busby1, P. Bruck3 1 Oak Ridge National Laboratory 2 Electric Power Research Institute 3 LPI, Inc. Le prolongement de la durée de fonctionnement des réacteurs au-delà de 60 ans et l’amélioration de leur p...

A complete evaluation of the experimental uncertainties of the KRITZ-2 series of critical and relative fission rate experiments was performed within the International Reactor Physics Experiment Evaluation Project. The uncertainties in the benchmark model keg are mainly due to uranium enrichment, plutonium content [mixed oxide (MOX) fuel], pitch, an...

The need to understand and characterize the effects of neutron irradiation on concrete has become urgent because of the possible extension of service life of many nuclear power generating stations. Current knowledge is primarily based on a collection of data obtained in test reactors. These data are inherently difficult to interpret because materia...

A large fraction of light water reactor (LWR) construction utilizes concrete, including safety-related structures such as the biological shielding and containment building. Concrete is an inherently complex material, with the properties of concrete structures changing over their lifetime due to the intrinsic nature of concrete and influences from l...

Life extensions of nuclear power plants to 60 and potentially 80 years of operation have renewed interest in long-term material degradation. One material being considered is concrete, with a particular focus on radiation-induced effects. Based on the projected neutron fluence values (E > 0.1 MeV) in the concrete biological shields of the US pressur...

Radiation Damage In Reactor Cavity Concrete T.M. Rosseel1, J.J. Wall2, K.G. Field1, Y. Le Pape1*, D.J. Naus1, I. Remec1, J.T. Busby1, and P. Bruck3 1 Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831-6148 2 Electric Power Research Institute, 1300 W W.T. Harris Blvd, Charlotte, NC 28262 3LPI, Inc. 36 Main Street, Amesbury,...

Description Fifty-seven peer-reviewed papers provide an extensive examination of timely topics in the field of Reactor Dosimetry. Also, two keynote papers address: the energy future and structural materials for innovative nuclear systems. Topics cover

Releases of short-lived species from ISOL targets are simulated with computer codes. Analytic solutions to the diffusion equation are compared with those obtained from a finite-difference code for radioactive isotope diffusion release from simple geometry targets. The Monte Carlo technique as a practical means for vapor transport system design is d...

A prototype detector based on the inclined boron layer principle is introduced. For typical measurement conditions at the Liquids Reflectometer at the Spallation Neutron Source, its count rate capability is shown to be superior to that of the current detector by nearly two orders of magnitude.

Computational simulation studies with state-of-the-art codes offer cost effective means for designing ISOL targets with optimized diffusion release properties and vapor transport systems with short effusion path lengths. To demonstrate the power of the technique for designing optimum thickness targets, analytic solutions to the diffusion equation a...

The purpose of the study is to obtain estimates of limits on uncontrolled beam losses of heavy ions for allowing hands-on maintenance at a heavy-ion linacfor a rare isotope beam facility. Semiempirical formulas are used to estimate dose equivalent rates from activated accelerator components for 1 W/m uncontrolled losses of protons up to 1 GeV. The...

At the High Flux Isotope Reactor, in operation since 1966 at the Oak Ridge National Laboratory, a larger HB-2 beam tube was installed to enhance capabilities for neutron science research. Neutronic analyses, including dosimetry measurements, radiation transport simulations, and simultaneous neutron and gamma spectrum adjustment calculations, perfor...

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory reached 180 kW in August 2007, becoming the brightest pulsed neutron source in the world. At its full power of 1.4 MW, SNS will have thermal neutron fluxes approximately an order of magnitude greater than any existing pulsed spallation source. It thus brings a serious challenge to...

Calculations have been carried out to evaluate the effectiveness of a range of carbon- and hydrogen-rich materials for shielding against energetic heavy ions relevant to the galactic cosmic ray spectrum. Experimental work integrated with the calculations included both preparation and characterization of physical properties of candidate materials an...

Measurements and simulations of the proton beam interaction with the mercury target were performed to support Spallation Neutron Source design. Due to the abundance of isotopes produced in mercury, the long delay between the irradiation and the measurements, and the self-shielding of the mercury sample, the measurements were difficult to perform an...

The High Flux Isotope Reactor (HFIR) has been in operation at Oak Ridge National Laboratory since 1966. To upgrade and enhance capabilities for neutron science research at the reactor, a larger HB-2 beam tube was installed in April of 2002. To assess, experimentally, the impact of this larger beam tube on radiation damage rates [i.e., displacement-...

In supporting pre-conceptual research and development of the Rare-Isotope Accelerator (RIA) facility or similar next-generation exotic beam facilities, one critical focus area is to estimate the level of activation and radiation in the linear accelerator second stripping region and to determine if remote handling is necessary in this area. A basic...

Next-generation exotic beam facilities will offer several approaches to produce rare isotopes far from stability. One approach is Isotope Separation On-line, ISOL, which is the isotope production by interactions of light ion beams with heavy nuclei of targets. A pre-conceptual design of an ISOL target station was done as part of the research and de...

Calculations have been carried out to evaluate the effectiveness of a range of carbon and hydrogen rich materials for shielding against energetic heavy-ions relevant to the galactic cosmic ray (GCR) spectrum. Experimental work integrated with the calculations included both preparation and characterization of physical properties of candidate materia...

The characterization of the neutron environment in a reusable facility for irradiation of metal-lurgical specimens, located at the Ford Nuclear reactor in Michigan, was performed with a combination of transport calculations, extensive dosimeter measurements, and neutron spectrum adjustment. The average difference between the calculated and "measure...

Measurements and simulations of the proton beam interaction with the mercury target were performed to support Spallation Neutron Source design. Due to the abundance of isotopes produced in mercury, the long delay between the irradiation and the measurements, and the self-shielding of the mercury sample, the measurements were difficult to perform an...

The Rare Isotope Accelerator (RIA) facility, planned to be built in the USA, will be capable of delivering diverse beams, from protons to uranium ions, with energies from 1 GeV to at least 400 MeV per nucleon to rare isotope-producing targets. High beam power—400 kW—will allow RIA to become the most powerful rare isotope beam facility in the world;...

Fragmentation of energetic 16O ions in carbon- and hydrogen-rich materials was simulated with the Quantum Molecular Dynamic-based Monte Carlo code PHITS [1]. The simulation results are compared with measurements recently conducted at the NASA Space Radiation Laboratory at Brookhaven National Laboratory [2]. The experimental layout is shown schemati...

The planned Rare Isotope Accelerator (RIA) facility in the US would become the most powerful radioactive beam facility in the world. Beam energies of up to 1 GeV for protons and up to 500 MeV per nucleon for heavy ions are foreseen with beam powers up to 400 kW. The magnitude of the prompt radiation generated at the target stations and characteriza...

The Department of Energy’s Office of Nuclear Physics, within the Office of Science (SC), has given high priority to consider and analyze design concepts for the target areas for the production of rare isotopes via the ISOL technique at the Rare-Isotope Accelerator (RIA) Facility. Key criteria are the maximum primary beam power of 400 kW, minimizing...

The development of high-power beam dumps and catchers, and pre-separator layouts for proposed fragment separators of the Rare-Isotope Accelerator (RIA) Facility are important in realizing how to handle the 400 kW in the primary beam. Examples of pre-conceptual designs of the pre-separator area and components, along with examples of ongoing radiatio...

The Inner Plug, and the Proton Beam Window Insert, central components of the SNS target monolith are exposed to high-level radiation fields during routine operation. The inner plug houses the SNS target, and the proton beam window insert contains the proton beam window located about 2 meters upstream from the target. Both the plug and the insert ne...

Description Fifty-seven papers provide a diverse and highly technical discussion of the influence of radiation on the microstructure and mechanical properties of structural materials. Nine sections cover: reactor pressure vessel (RPV) steels, austenitic and ferritic/martensitic alloys, proton and spallation neutron sources, radiation damage fundame...

Description One hundred papers provide an extensive overview of latest advances in reactor dosimetry. An additional nine summaries provide the status of technical workshops held at the Tenth International Symposium on Reactor Dosimetry and three keynote papers address: why we need dosimetry; the role of ASTM Committee E10 on Nuclear Technology, and...

The Charpy impact response of reirradiated Heavy-Section Steel Irradiation (HSSI) Program Weld 73W has been determined at three fluence levels. The Charpy specimens had previously been irradiated at 288°C to 1.8 × 1019 cm-2 (E > 1 MeV) and annealed at 454°C for 168 h. The results show that the change in the 41-J Charpy energy level transition tempe...

The impact is discussed of the differences in fission spectra from the SAILOR and BUGLE-96 cross-section libraries on reactor pressure vessel (RPV) flux determination. The fission spectra from the SAILOR library (ENDF/B-IV) and BUGLE-96 library (ENDF/B-VI) are compared. The SAILOR ²³⁹Pu spectrum was collapsed from the VITAMIN-C library, which w...

This report discusses the impact of the change from the SAILOR cross-section library, based on the ENDF/B-IV data, to the BUGLE-96 cross-section library, based on the ENDF/B-VI data, on the neutron flux prediction in the H. B. Robinson-2 pressure vessel, in the surveillance capsule, and in the cavity. The fast flux (E > 1 MeV) from the transport ca...

The study of the neutron flux and dpa attenuation in the reactor pressure vessel (PV) wall presented in this work was performed with state-of-the art methods currently used to determine PV fluxes, the BUGLE-96 cross-section library, and the iron displacement cross sections derived from ENDF/B-VI data. The calculations showed that the RG 1.99, Rev....

The atom displacement (dpa) cross sections for iron given in the ASTM Standard Practice E6 693 are based on the data from ENDF/B-IV the cross sections have been changed considerably. In particular for iron, ENDF/B-VI gives cross-section evaluations for the individual isotopes with more forward-directed inelastic scattering, and reduced magnitude of...

The gamma field accompanying neutrons may, in certain circumstances, play an important role in the analysis of neutron dosimetry and even in the interpretation of radiation induced steel embrittlement. At the High Flux Isotope Reactor pressure vessel the gamma induced reactions dominate the responses of {sup 237}Np and {sup 238}U dosimeters, and {s...

Two benchmarks for the qualification of the pressure vessel fluence calculational methodology were formulated and are briefly described. The Pool Critical Assembly (PCA) benchmark is based on the experiments performed at the PCA in Oak Ridge. The measured quantities to be compared against the calculated values are the equivalent fission fluxes at s...

The U.S. Nuclear Regulatory Commission Draft Regulatory Guide DG-1053, {open_quotes}Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence,{close_quotes} requires qualification of the methodology for nuclear reactor pressure vessel fluence calculations. One step of the qualification is the analysis of benchmarks. To pro...

The H. B. Robinson Unit 2 Pressure Vessel Benchmark (HBR-2 benchmark) is described and analyzed in this report. Analysis of the HBR-2 benchmark can be used as partial fulfillment of the requirements for the qualification of the methodology for calculating neutron fluence in pressure vessels, as required by the U.S. Nuclear Regulatory Commission Reg...

This pool critical assembly (PCA) pressure vessel wall facility benchmark (PCA benchmark) is described and analyzed in this report. Analysis of the PCA benchmark can be used for partial fulfillment of the requirements for the qualification of the methodology for pressure vessel neutron fluence calculations, as required by the US Nuclear Regulatory...

One of the primary concerns of the aging nuclear power plants is the radiation-induced embrittlement of the reactor pressure vessels (PVs). In the current methodology, the PV material embrittlement is determined from the prescribed (regulatory) or plant-specific trend curves, which give the increase of reference nil-ductility transition (NDT) tempe...

Recent comprehensive dosimetry experiments revealed the presence of an intense gamma field at the High Flux Isotope Reactor (HFIR) surveillance locations near the pressure vessel. Measured responses of fission dosimeters 238U and 237Np, as well as 9Be helium accumulation fluence monitors were placed in accordance with responses of threshold and the...

The spectrum adjustment procedure was extended to simultaneous neutron and gamma spectrum adjustment, and the feasibility of this technique is demonstrated in the analysis of HFIR dosimetry experiments. Conditions in which gamma rays may contribute considerably to radiation damage in steels are discussed. Beryllium helium accumulation fluence monit...

Description STP 1270 features the latest information from the world's leading experts on how radiation impacts a wide range of metals. This extensive volume includes 68 peer-reviewed papers organized into 8 comprehensive categories: Modeling of Controlling Mechanisms -- 8 papers explore mechanisms controlling the behavior and process of radiation e...

Accelerated radiation-induced embrittlement of the High Flux Isotope Reactor (HFIR) surveillance materials has been investigated since its discovery in 1986. Recent comprehensive dosimetry experiments revealed the presence of an intense gamma field at the HFIR surveillance locations near the pressure vessel. Gamma-induced reactions were found to do...

This project addresses the potential problem of radiation embrittlement of reactor pressure vessel (RPV) supports. Surveillance specimens irradiated at the High Flux Isotope Reactor (HFIR) at relatively low neutron flux levels (about 1.5E + 8 cm{sup {minus}2}.s{sup {minus}1}) and low temperatures (about 50{degrees}C) showed embrittlement more rapid...

Description 31 peer-reviewed papers cover: • National Perspectives • Surveillance Programs and Their Results • Fracture Approaches • Applied Research • Fundamental Research • Amelioration of Effects.

A set-up for irradiation of biological samples in the TRIGA Mark II research reactor in Ljubljana is described. Threshold activation detectors were used for characterisation of the neutron flux, and the accompanying gamma dose was measured by TLDs. Human peripheral blood samples were irradiated "in vitro" and biological effects evaluated according...

A search for neutrons, protons, tritons, 3He ions, γ- and X-rays emitted from D + D fusion in a Pd tube charged electrochemically with deuterium was carried out with a radiation detection system using mainly passive detectors. The system was composed of: (i) an array of six 3He neutron detectors (total efficiency 0.14%); (ii) a bubble damage polyme...

Description Included are papers on applications to reactor pressure vessel surveillance; measurements to provide basic nuclear data and benchmarks for measurement standardization; calculational methods; and research on breeder and fusion environment. Section headings: LWR Pressure Vessel Surveillance Programs; Nuclear Data; Benchmarks and Standards...

A series of calculations has been completed to compute dosimeter activation in the Oak Ridge Research Reactor (ORR) HSST Simulator Experiment. Comparison of calculated and experimental results shows that calculations underpredict dosimeter activities on the average of about 15%. The C/E values indicated the now familiar tendency to become lower as...

Neutron flux, neutron exposure rate and iron displacement cross-section averaged over the neutron spectrum in a two-loop, 632 MWe PWR were calculated. The transport code DOT 3.5 was used. Calculations were performed separately for the reactor and the surveillance capsule. Presented are spatial distributions as well as absolute values at most import...

The capability of the sparking technique for the enhancement of track-etch image in neutron radiography and autoradiography using LR-115 film was experimentally investigated. The optimum residual foil thicknesses and sparking/presparking voltage were determined. With the technique developed it is possible to reduce exposure by a factor of 100.

The capability of the sparking technique for the enhancement of track-etch image in neutron radiography and autoradiography using LR-115 film was experimentally investigated. The optimum residual foil thicknesses and sparking/presparking voltage were determined. With the technique developed it is possible to reduce exposure by a factor of 100.

The international Expert Group on Reactor-Based Plutonium Disposition (TFRPD) has been established at the OECD/NEA to facilitate the sharing of existing information and experience in the physics and fuel behavior of MOX fuel as it relates to the disposition of weapons-grade plutonium. One of the many recent activities of this Experts Group is the a...

The calculations with the broad-group cross-section library Bugle-96, and atom displacement (dpa) cross sections for iron, both derived from ENDF/B-VI data, result in higher calculated fast neutron fluxes, better agreement of calculations with radiometric dosimeter measurements, and significantly slower dpa rate attenuation through pressure vessel...

SUMMARY The total activity, decay heat, and DOE-STD-1027 hazard classification category 3 threshold quantity ratio were calculated for simple tungsten and iron- clad mercury spallation targets using MCNPX and the two radionuclide inventory codes CINDER'90 and the Activation Analysis System, based on ORIHET. In addition, the effect of an updated nuc...

Dose rates from accelerator components activated by 1 W/m beam losses are obtained semiempirically for a 1 GeV proton beam and by use of Monte Carlo transport codes for the proton beam and for 777 MeV/u 3He, 500 MeV/u 48Ca, 86Kr, 136Xe, and 400 MeV/u 238U ions. The dose rate obtained by the semi-empirical method, 0.99 mSv/h (99 mrem/h) at 30 cm, 4...

The objective of this program is to develop, maintain, and upgrade computerized data bases, calculational procedures, and standards relating to reactor pressure vessel fluence spectra determinations and embrittlement assessments. As part of this program, the information from radiation embrittlement research on nuclear reactor pressure vessel steels...