A SAS2H/KENO-V.a METHODOLOGY FOR A COMBINED 1D/3D FULL CORE FUEL BURNUP ANALYSIS
by Miodrag MILOŠEVIĆ, Ehud GREENSPAN, Jasmina VUJIĆ

Abstract: An efficient methodology for 3D fuel burnup analysis of LWR reactors is described in this paper. This methodology is founded on coupling Monte Carlo method for 3D calculation of node power distribution, and transport method for depletion calculation in 1D Wigner-Seitz equivalent cell for each node independently. The proposed fuel burnup modeling, based on application of SCALE-4.4a control modules SAS2H and KENO-V.a is verified for the case of 2D x-y model of IRIS 15 x 15 fuel assembly (with reflective boundary condition) by using two well benchmarked code systems. The one is MOCUP, a coupled MCNP-4C and ORIGEN2.1 utility code, and the second is KENO-V.a/ORIGEN2.1 code system recently developed by authors of this paper. The proposed SAS2H/KENO-V.a methodology was applied for 3D burnup analysis of IRIS-1000 benchmark#44 core. Detailed K_eff and power density evolution with burnup are reported.

Key words: 3D Monte Carlo node power calculation, 1D fuel depletion calculation in each node, IRIS benchmark core, 3D burnup analysis

ERRORS ASSOCIATED WITH STANDARD NODAL DIFFUSION METHODS AS APPLIED TO MIXED OXIDE FUEL PROBLEMS
by Djordje I. TOMAŠEVIĆ, Patrick S. BRANTLEY, Edward W. LARSEN

Abstract: Cores loaded with mixed oxide (MOX) fuel assemblies have a very high thermal flux gradient at the interface between MOX and standard UO₂ loaded assemblies. It is known that flux reconstruction methods yield large errors in the presence of MOX assemblies. We have demonstrated that a large portion of that error is associated with quadratic leakage approximation (QLA) that is commonly used in standard nodal codes.

Key words: nodal diffusion methods, quadratic leakage approximation, flux reconstruction, mixed oxide (MOX) cores

FOURIER TRANSFORM METHOD: APPLICATION TO HALF-SPACE PARTICLE TRANSPORT
by Rodoljub SIMOVIĆ

Abstract: The energy independent transport equation written for a specific diffusion of particles consecutively scattered only into directions m < 0 until the last collision is exactly solved in the plane half-space geometry. The solving procedure is based on a lemma proved by Placzek and the Fourier analytic inversion technique. For the isotropic as well as the anisotropic scattering functions, the obtained mathematical expressions represent straightforward generalizations of the formula for once scattered particles.

Key words: transport equation, plane geometry, half-space problem, Fourier transform method, angular flux density, reflection coefficient

MONTE CARLO SIMULATION OF PROTON TRANSPORT AT THERAPEUTIC ENERGIES
by Ivan PETROVIĆ

Abstract: Physical and biological characteristics of protons as well as technical requirements on proton beams are reviewed in order to illustrate the need for accurate proton transport simulations for therapeutic applications. Certain Monte Carlo proton transport simulation codes that have been used at therapeutic energies are briefly discussed. A general insight into two proton transport simulation schemes is presented; one including the generation and transport of secondary protons and the other comprising the generation and transport of secondary electrons. Based on different experiences gained, an analysis of the role of secondary particles is given.

Key words: Monte Carlo simulation, proton transport codes, characteristics of protons, secondary particles, therapeutic energies, dosimetry, proton biomedical applications

DETERMINATION OF THE NEUTRON CURRENT AND DIAGNOSTIC APPLICATION IN AN EXPERIMENTAL SYSTEM
by Senada AVDIĆ, Per LINDÉN, Berit DAHL, Imre PÁZSIT

Abstract: This paper concerns experimental and numerical investigations of the applicability of a newly constructed detector for measuring neutron current components and for localizing a neutron source in an experimental system. The motivation for this work stems from a suggestion [Pázsit, Ann. Nucl. Energy, 24 (1997), 1257] that the performance of core monitoring methods could be enhanced if, in addition to the scalar neutron flux, the neutron current was also measured. To this end, a current detector was constructed, based on a scintillator mounted on a fibre and a Cd layer on one side of the detector. The measurements of the 2-D neutron current were performed in an experimental system by using this detector. The results of measurement and calculation show both the suitability of the detector construction for the measurement of the neutron current vector and the use of the current in diagnostics and monitoring.

Keywords: neutron current detector, reactor diagnostics, scintillation detector, optical fibre, localisation, neutron source

UNIVERSAL FUNCTIONS IN THE SINGLE COLLISION MODEL OF keV LIGHT ION REFLECTION
by Jovan VUKANIĆ, Rodoljub SIMOVIĆ

Abstract: Particle and energy reflection coefficients of light ions have been obtained in a single collision model as functions of the scaled transport cross section. These quantities have been calculated numerically by utilizing the exact scattering cross section for Kr-C potential and analytically with effective power cross section of the same potential. Our analysis has shown that the analytical formulae approximate very accurately the numerical results. It turns out that in the single collision energy region, the scaled transport cross section remains a convenient scaling parameter, as adopted previously in multiple collision theory.

Key words: light ions, reflection coefficients, single collision model, scaling parameter

QUALITY OF WATER FROM THE POOL, ORIGINAL CONTAINERS AND ALUMINUM DRUMS USED FOR STORAGE OF SPENT NUCLEAR FUEL
by Zoja IDJAKOVIĆ, Slobodan MILONJIĆ, Svetlana ČUPIĆ  

Abstract: Results of chemical analyses of water from the pool, including original containers and aluminium drums, for storage of spent nuclear fuel of the research reactor RA at the VINČA Institute and a short survey of the water properties from similar pools of other countries are presented in the paper.

Key words: wet spent nuclear fuel storage, water quality, chemical analyses

MICROCLIMATIC PARAMETERS AND INDOOR RADON CONCENTRATIONS OF THE VINČA REACTOR
by Zora S. ŽUNIĆ, Radmila M. LUČIĆ, James P. Mc LAUGHLIN

Abstract: The paper deals with the results of 2200 measurements of microclimatic parameters (temperature, relative humidity, air velocity) and 40 measurements of indoor radon concentrations performed within the working area of the reactor RA of the VINČA Institute of Nuclear Sciences, Belgrade, during the one-year period (1996/1997). Annual average indoor radon gas concentrations have been determined and an estimation of an annual effective dose record for individual workers arising from exposure to radon progeny at work has been made. Based on these measurements the comfort zones were assessed.

Key words: nuclear reactor, temperature, humidity, air velocity, indoor radon, comfort zone

MEDICAL TEAM EXPOSURE ASSESSMENT IN CONTRAST X - RAY DIAGNOSTICS
by Srpko MARKOVIĆ, Olivera CIRAJ

Abstract: An efficient analytic approach for the calculation of scattered radiation around a patient subjected to angiography, the contrast X-ray diagnostic technique, is presented here. Adopting the well justified physical and mathematical approximations, an expression for the space distribution of scattered radiation has been derived and the ANGIO computer code written. Calculated values were compared with the experimental data originally obtained. Based on this approach the collective dose assessment of a medical team operating in the scattered radiation field during the contrast diagnostic procedure was made.

Key words: ionizing radiation, photon energy flux density, Compton scattering, collective dose, X-ray diagnostics

MATHEMATICAL MODELING IN LEACHING STUDIES OF RADIOACTIVE WASTE
by Ilija PLEĆAŠ, Radojko PAVLOVIĆ, Snežana PAVLOVIĆ

Abstract: Transport phenomena involved in the leaching of a radioactive material from a composite matrix into surrounding water are investigated using three methods based on theoretical equations. These are: diffusion equation derived for a plane source model, rate equation for diffusion coupled with a first-order reaction and an empirical method employing a polynomial equation. The obtained results are compared with respect to their applicability to the ⁶⁰Co and ¹³⁷Cs leaching data.

Key words: radioactive waste, ion exchange resin, leached fraction, diffusion, cement

CHARACTERIZATION OF FISSILE MATERIALS IN WASTE PACKAGES FROM THE REPROCESSING PLANT KARLSRUHE
by Gerold G. SIMON, Marina ŠOKČIĆ-KOSTIĆ, Jasmina VUJIĆ

Abstract: The fissile material from a reprocessing plant must be analysed and quantified before conditioning and transportation to an interim or final storage. A high gamma radiation field must be considered when performing such measurements. New measuring components were developed for operation in such a high gamma field. FEMOS is a specially developed monitor devised to detect fissile materials for waste characterization and it is also, suitable to identify the main neutron emitters.

Key words: fissile materials, characterization, waste packages, neutron emitters, high gamma filed

RESEARCH REACTOR RECORDS IN THE INIS DATABASE
by Nada MARINKOVIĆ

Abstract: This report presents a statistical analysis of more than 13,000 records of publications concerned with research and technology in the field of research and experimental reactors which are included in the INIS Bibliographic Database for the period from 1970 to 2001. The main objectives of this bibliometric study were: to make an inventory of research reactor related records in the INIS Database; to provide statistics and scientific indicators for the INIS users, namely science managers, researchers, engineers, operators, scientific editors and publishers, decision-makers in the field of research reactors related subjects; to extract other useful information from the INIS Bibliographic Database about articles published in research reactors research and technology.

Key words: research reactor, experimental reactor bibliographic database, bibliometric study, INIS