Results 1 - 10 of 115
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[en] We describe analytical formalism for estimating neutron radiative capture and elastic scattering cross section covariances in the resolved resonance region. We use capture and scattering kernels as the starting point and show how to get average cross sections in broader energy bins, derive analytical expressions for cross section sensitivities, and deduce cross section covariances from the resonance parameter uncertainties in the recently published Atlas of Neutron Resonances. The formalism elucidates the role of resonance parameter correlations which become important if several strong resonances are located in one energy group. Importance of potential scattering uncertainty as well as correlation between potential scattering and resonance scattering is also examined. Practical application of the formalism is illustrated on 55Mn(n,γ) and 55Mn(n,el).
[en] We evaluated covariances for neutron capture and elastic scattering cross sections on major structural materials, 52Cr, 56Fe and 58Ni, in the resonance region which extends beyond 800 keV for each of them. Use was made of the recently developed covariance formalism based on kernel approximation along with data in the Atlas of Neutron Resonances. The data of most interest for AFCI applications, elastic scattering cross section uncertainties at energies above about few hundred keV, are on the level of about 12% for 52Cr, 7-8% for 56Fe and 5-6% for 58Ni.
[en] We evaluated covariances in the neutron resonance region for capture and elastic scattering cross sections on minor structural materials, 50,53Cr, 54,57Fe and 60Ni. Use was made of the recently developed covariance formalism based on kernel approximation along with data in the Atlas of Neutron Resonances. Our results of most interest for advanced fuel cycle applications, elastic scattering cross section uncertainties at energies around 100 keV, are on the level of about 7-10%.
[en] MCNP4C, WIMSD-5, HELIOS libraries are constantly being updated and upgraded by responding users' demands, such as adding new nuclides and burnup chains. Libraries for SFR and VHTR are also being upgraded, and the structure of the group constant is being revised according to the users' needs. Neutron data of 32 fission products were fully evaluated and registered in the ENDF/B-VII.0 which was officially released December 2006 by the Cross Section Evaluation Working Group(CSEWG), USA. Neutron-induced gamma spectra, which are essential in the fields of nuclear industry and space engineering, are newly evaluated for 9Y, 93Nb, 127I, 133Cs, 141Pr, 197Au, natTl and 209Bi by introducing improved gamma strength function to describe irregular bumps. Various libraries such as for MCNP4C code, WIMSD-5 code, fast reactor, shielding, fission product burnup, and reactor benchmark were generated based on the ENDF/B-VII.0 and JEFF-3.1. Various sensitivity calculations for U-235 and U-238 based on the ENDF/B-VII.0 were carried out and their impacts on the criticalities of a number of international benchmark problems. Neutron capture cross sections of four isotopes, 155,156,157,158Gd were measured using Pelletron accelerator in the TIT of Japan. Upgrade was made on PAL facilities, and measurements were performed for neutron total cross sections for energies from thermal to hundreds eV for Pr
[en] The system for detecting existence and position the explosive using accelerator is being developed. The gamma is produced by 1.75 MeV proton through the Proton-Gamma reaction in 13C target, and the scattered gamma with 14N in explosive is detected by gamma detector. The system consists of accelerator, target and detector. The required proton beam current is 10mA, which is determined by calculation. The large current proton beam can be accelerated in tandem proton accelerator, which is designed with negative ion source, accelerating column, high voltage power supply, and stripper. The accelerator system design with optics design, vacuum design, and accelerating column design are reported in this paper and the vacuum test of the accelerating column are described
[en] Growing interest in the proton accelerator and accelerator-driven system (ADS) is accompanied with evaluation of nuclear data and development of a code system to simulate the elementary production of particles in spallation reactions and transport of these particles in the target. Up to now, three kinds of evaluations for high energy region have been released or in the preliminary stage. These evaluations include LA150, KAERI and JENDL HE Files. Total neutron yields for several targets bombarded by protons were calculated by particle transport codes such as MCNPX and KASKAD-S using the latest evaluations and then compared with the measured data
[en] Various research collaborations with foreign organizations such as IAEA, OECD, ORNL, BNL, etc. have been performed and strengthened. By actively participating in meetings that are sponsored by IAEA and OECD, we could make a decision on the research directions for nuclear data and offer our nuclear data to the international community without difficulty. The evaluation and validation of Np-237, Pu-240, and Cm isotopes have been carried out in collaboration with ORNL and the evaluation of Fe-56 were performed in collaboration with BNL. The resonance region uncertainty analysis code has been improved and the uncertainty analyses for the structural materials and Np-237 have been carried out. The revision of the evaluated library for minor actinides has been carried out and the evaluated files for 11 Curium isotopes have been adopted into new JEFF-3.2 Library released in March 2014. New evaluation of the resolved and unresolved resonance region for U-238 capture cross sections has been carried out with EC-JRC-IRMM at Belgium. The evaluation methodology for the structural materials is being developed and the new evaluated files for future nuclear fusion reactors will be produced. The electron-impact ionization (EII) cross sections for Wq+ and the electron-impact recombination cross section for W17+ have also been calculated. The validation system of nuclear reaction/covariance data for Np-237, Pu-240 and Cm-isotopes was established, comparative analysis of recent covariance data and validation of the data through nuclear data sensitivity/uncertainty analysis for some criticality benchmark problems was performed, and contribution to validation of COMMARA-2.0 covariance data through some fast reactor benchmark analyses under International Nuclear Data Evaluation Co-operation managed by OECD/NEA was made. Research for building time-of-flight facility has been performed. The shielding analysis and architectural design for the building have been performed, and the heat and structural analysis and manufacture of main part for the liquid lead target have been done. The nuclear reaction cross sections were measured at various domestic and overseas facilities including KIRAMS, KOMAC, Pohang electron accelerator, HZDR, IRMM and IMAC.
[en] Establishment of Nuclear Data Validation System Research collaboration was carried out with IAEA, OECD/NEA, ORNL and BNL for the update of FENDL, the production of group constant libraries, the uncertainty analysis and the development of the resonance module, respectively. The covariance evaluation system was established based on JENDL-3.3 library for the one-dimensional criticality analysis, which uses the codes NJOY, ERRORJ, ANISN and SUSD3D. The benchmark calculations on a fast power reactor core were carried out to validate the new evaluation system. The newly evaluated nuclear data for W-182, -183, -184, -186 were processed and tested in the various benchmark studies. Establishment of Precise Nuclear Data Evaluation System The resonance module has been developed and improved for the evaluation of the nuclear data in the resolved and unresolved resonance region under collaboration with BNL. The module will produce the resonance parameters, their uncertainties and covariances in the final version. The nuclear data for W-182, -183, -184, -186 were newly evaluated up to the neutron energy of 20 MeV by introducing and applying the evaluation system called 'Global Evaluation of Nuclear Data'. The proton-induced nuclear cross sections were measured and evaluated for natW, natSn, natCd, 27Al, natZr, natAg, natPd and natTi using the 40 MeV proton beam of MC50 cyclotron at KIRAMS. Nuclear Data Measurements BGO detector module was constructed by coupling the BGO crystal and PMT, and tested by using the radiation sources. The photo-nuclear reaction was studied for In, Zr, Mo, W, Ta, Bi, Pb, Nb by using the Bremsstrahlung radiation induced by the electron beam with energies of 50, 60, 70 MeV. A feasibility study for the construction of neutron generator for nuclear fusion applications was performed. The use of the domestic accelerator for the neutron generation was also studied
[en] Youngkwang Unit 3,4 and Ulchin Unit 3 and 4 have had problem of the KSNP Steam Generator due to a severe fretting wear on the tube. In particular, the wears were localized and concentrated in the upper part of U-bend of the Central Cavity region. At the upper tube bundle Central Cavity, the fluid flow velocities and void fraction are very high, because the steam is made by high heat transfer at secondary region. Also, this region is affected easily by fretting wear due to it's unsupported span is longer than another regions. The fretting wear is assumed to be result of Flow-Induced Vibration (F. I. V), which can occur by many mechanisms. EFDP was added to UCN 5,6 for prevent fretting wear by the SEC LCC and DSHIC, a company of design and manufacture of the steam generator, respectively. In order to evaluate the efficacy of EFDP, ANSYS and ATHOS-3 Code were used. From sensitivity analysis and calculation results, Density and Velocity into the Central Cavity are reduced after the EFDPs are installed. Also, a calculation result was plotted in the Fluid Elastic Instability criteria-diagram by Pettigrew. The plotted result shows that Fluid Elastic Instability is considerable. Finally, installing EFDP is considerable for preventing fretting wear by FIV in the KSNP Steam Generators
[en] The linac and beam lines were developed through PEFP (Proton Engineering Frontier Project), the first phase of KOMAC, from 2002 to 2012. Currently, the accelerator is commissioned with the average proton beam power of about 10 kW. The beam power will be increased gradually up to 96 kW for 20 MeV beam and 160 kW for 100 MeV beam. Two beam lines are operational at present for user service and the number of available beam lines will be augmented to ten, five of which will be dedicated to 20-MeV beam lines and the others to 100 MeV proton beam. Reflecting the increasing demands of radioisotopes for the medical and industrial applications, we are constructing a beam lines for RI production. The status of KOMAC accelerator and beam lines will be presented in this work. The original design of the KOMAC facility includes ten beam lines and just two of them are currently operational. We are going to increase the number of the available beam lines step by step. As a short-term plan, a beam line for RI production is under construction. High-power proton accelerator like KOMAC can be used for new medical radio-isotope production, such as Sr-82, Cu-67, Ge-68 and Na-22. For Sr-82, it has been commercialized already because of rising demands in the market and the successful development of radiopharmaceuticals. The beam commissioning of the proton linac up to higher beam power is still continuing in parallel with the beam service. An upgrade plan of the 100-MeV linac to a 1-GeV, 2-MW linac with pulsed spallation neutron sources is included in the National Facility Roadmap. When all of these plans are realized, the KOMAC will be a unique research complex at which high quality beams of proton, neutron and possibly other particles are available for the exploration of the frontiers of science and technology