NUCLEAR POWER - AN INEVITABLE COMPONENT OF A SUSTAINABLE ENERGY MIX
by Miodrag MESAROVIĆ

Abstract: Nuclear power plants already add consequential amounts of energy to the global energy supply and continue to offer advantages for large additions of capacity. If increased, the nuclear share in world's energy mix would reduce the environmental damages as well as the climate change threats caused by the use of fossil fuels, thus providing an essential element of sustainable development. Such a potential contribution of nuclear power on large scale in a sustainable energy mix is considered, with its actual burdens and challenges discussed. Sustainable energy development with or without nuclear power is presented, with public acceptance of nuclear energy and global warming issues discussed in more details.

Key words: nuclear power, sustainable development, energy mix, environmental impact, global warming, public acceptance, deregulation, economics

NATURAL CIRCULATION LIMITS ACHIEVABLE IN A PWR
by Francesco D'AURIA, Monica FROGHERI

Abstract: The present paper deals with the Natural Circulation (NC) phenomenon in Pressurized Water nuclear Reactors (PWR). In the first part, data gathered from relevant experiments in PWR simulators are considered. These allowed the establishment of a flow map that has been used for evaluating the NC performance of various reactor concepts. In the second part, a theoretical study has been completed to assess the power removal capability by NC from the core of a PWR having the current geometric configuration. Taking as reference a PWR equipped with U-tubes steam generators, two-phase conditions occur in the core at power levels less than 20% nominal power. Therefore, for core power larger than this value the reactor cannot be classified any more as a PWR. The study shows that from a thermohydraulic point of view, the core can operate at power levels close to the current nominal value without experiencing thermal crisis. Limited consideration has been given to the neutronic design of the core.

Key words: natural circulation, PWR, PWR simulator, natural circulation flow map, core power

DETERMINATION OF NEUTRON-MECHANICAL SCALE FACTORS IN A PWR NUCLEAR POWER PLANT
by Ljiljana KOSTIĆ, Joachim RUNKEL, Peter HEIDEMANN

Abstract: In order to determine the vibration amplitudes of pressurized water reactors core internals by use of in-core neutron signals, one miniature biaxial accelerometer is installed inside one of the instrument tubes. It is shown that the neutron-mechanical scale factors and the amplitudes of displacements can be estimated from the normalized auto power spectral densities of in-core self power neutron detector signals and auto power spectral densities of the acceleration signal.

Key words: in-core neutron noise, acceleration, self power neutron detector, biaxial accelerometer, vibration amplitude, neutron-mechanical scale factor, power spectral density, root mean squared value

ANALYTIC SOLUTIONS OF SOME SPECIFIC TRANSPORT EQUATIONS
by Rodoljub SIMOVIĆ

Abstract: An analytic procedure for solving the Fourier transformed transport equation with a common anisotropic scattering function is presented here. In infinite plane geometry the close solutions are derived for particles consecutively scattered only in the directions m  < 0 or in the directions m  > 0. The angle integrated flux calculated for different values of the multiplication factor c and the distance x is compared with the flux of once scattered particles. It is concluded from the investigation that the obtained exact solutions are the authentic generalizations of the expressions for once scattered particles acquired by the classical iterative method.

Key words: transport equation, plane geometry, Fourier transform method, iterative method, particle flux

INTERNATIONAL INTERCOMPARISON ON GLASS IMPLANTED ²¹⁰Po IN YUGOSLAVIAN HOUSES
by Z. S. ŽUNIĆ, F. TROTTI, A. BIROVLJEV, F. BISSOLO, R. FALK, J. P. Mc LAUGHLIN, A. TANFERI, C. WALSH

Abstract: Measurements of ²¹⁰Po embedded in glass have been performed with passive detectors in houses of three rural communities of Yugoslavia. Field work has been initiated and carried out by the VINČA Institute of Nuclear Sciences, Belgrade, and analyses have been conducted by SSI (Sweden), UCD (Ireland), NRPA (Norway) and CRR (Italy). Based on ²¹⁰Po concentration assessments, radon retrospective estimates have been produced. Fairly good agreement amongst laboratories resulted both for polonium and radon determinations. Comparison of radon retrospective estimates with contemporary levels has identified a small number of contemporary concentrations which are certainly not representative of the past. Retrospective measurements give clear indication of higher levels for one of the three communities (Gornja Stubla). From the analysis of retrospective and contemporary levels in different rooms of a high concentration house in Gornja Stubla, less data dispersion has come out for retrospective estimates, indicating a sort of better spatial stability of these estimates.

Key words: ²¹⁰Po , surface traps, retrospective radon estimates, Yugoslavia, intercomparison

ARCHITECTURE OF THE MODERN ACCELERATOR CONTROL SYSTEM
by Branko SAMARDŽIĆ, Vujo DRNDAREVIĆ

Abstract: Well defined concept of the system and construction plan are the important conditions for the successful realization of the accelerator control system. In this paper the modern concept of accelerator control system as well as guidelines for its efficient development have been presented. Described concept could be applied for the design of control systems for other types of facilities for experimental physics and for industrial process control.

Key words: accelerator, control system, system architecture

Note: Full text published in Serbian