VINČA INSTITUTE OF NUCLEAR SCIENCES AND THE FUTURE OF NUCLEAR INVESTIGATIONS
by Miroslav KOPEČNI

Abstract: Ever since its foundation in 1948, the VINČA Institute of Nuclear Sciences was a nuclear-oriented scientific institution. Achieving valuable results in different fields of nuclear sciences and technologies, the VINČA Institute became, and still is, the largest scientific institution in the former and the today's Yugoslavia. Structure and intensity of nuclear activities varied with the time, following the pattern of domestic and international interest for this kind of knowledge. The nuclear part of the VINČA Institute had its rises and falls, it is a long history, but unquestionably there is a future, too. This paper presents a survey of the past and the present nuclear activities in Yugoslavia , with special attention paid to the future of nuclear sciences and technologies in the VINČA Institute.

Key words: nuclear investigations, nuclear sciences, nuclear technology, VINČA Institute, research reactors RA and RB, TESLA accelerator

FUTURE INDUSTRIALIZATION OF THE WORLD AND THE NECESSITY OF NUCLEAR POWER
HOW LIMITED ARE RESOURCES?
by Jovan JOVANOVIĆ

Abstract: Will the future world be forever divided into an industrial, developed and "rich" on one side, and primitive, undeveloped, and poor on the other? Is an industrial, affluent and sustainable world of 10-15 billion people owning 5-10 billion cars physically possible to exist? Can the world have enough food, minerals and energy to support such a widespread affluence in a sustainable manner? In previous papers I have argued that even without any major breakthroughs in science and technology, an industrialized, sustainable and affluent world can be created within the next half century, but only if breeder nuclear power is widely used throughout the world. In this paper I elaborate on the question of future availability of some basic natural resources.

Key words: industrialization, energy, food, resources, solar energy, nuclear energy, fission, fusion, breeders

Note: Full text published in Serbian

ELEMENTS OF THE PHYSICS OF FAST FISSION SYSTEMS FROM THE NUCLEAR MATERIALS MISUSE POINT OF VIEW
by Dušan STEFANOVIĆ

Abstract: Motive for writing this paper was the fact that frequent uncontrolled manipulation with nuclear fuel and even illegal trade has been noticed during last few years. Concept of critical mass, its meaning and materials which may form a critical mass are explained; some of the most reliable results from literature are shown. A review is given of the first basic compact critical systems which in fact represented experimental verification of computer codes needed for nuclear weapons design. Principle of nuclear weapons functioning and the energy release procedure are exposed. This is performed by an example of a fast fission system without control and regulation quite approximatively.

Key words: fast fission system, nuclear materials, critical mass, fission systems without control, compact systems, implosion, fission energy

Note: Full text published in Serbian

THE CHERNOBYL ACCIDENT - TEN YEARS AFTER
by Dušan SPASOJEVIĆ

Abstract: The general results and conclusions of the ten years analysis of causes, development and consequences of the accident on Chernobyl nuclear power plant unit-4 are presented. Besides the proved knowledge about that accident, the paper deals with some so far unresolved dilemmas. The state of art, as well as planned activity on the “sarcophagus” for destroyed reactor is discussed. Finally, the main conclusion of the analysis of the possibilities that the Chernobyl type accident can occur in nuclear power plants surrounding Yugoslavia , are discussed in a short form.

Key words: Chernobyl, nuclear power plant, nuclear safety, accident, sarcophagus

Note: Full text published in Serbian

DEVELOPMENT AND APPLICATION OF THE SPHERICAL HARMONICS METHOD FOR REACTOR CORE PARAMETERS DETERMINATION AND CRITICALITY SAFETY STUDIES
by Milena MATAUŠEK

Abstract: Exact solution of the stationary neutron transport Boltzmann equation, governing the space, angle, energy dependence of neutron flux in a multiplying medium, is only possible for extremely simple cases. To solve this equation taking into account complicated angle and energy variation of data representing neutron interactions with the nuclei of the surrounding material, as well as the geometrical arrangement of different materials in systems encountered in practice, numerous approximate methods have been developed and applied by a large number of authors. Comprehensive work has also been performed by the author of the present paper, and valuable results have been obtained in development, improvement and application of methods to treat energy and space variation in spherical harmonics approximation of neutron transport equation. These are reviewed in the following paragraphs.

Key words: neutron transport, reactor theory, Boltzmann equation, spherical harmonics method, multi-group method, reactor core parameters, nuclear criticality safety

FLUX DECOMPOSITION METHOD: APPLICATION TO ENERGY DEPENDENT PARTICLE REFLECTION
by Rodoljub SIMOVIĆ

Abstract: In this paper an analytical approximate method for solving Boltzmann transport equation is developed and its efficiency for treating energy dependent particle reflection is investigated. Procedure is based on particle flux decomposition in two parts. The first one is derived exactly and the second one is determined approximately by ordinary DPN method. Transport equation for a semi-infinite planar medium is rederived by assuming that slowing down of particles is described by energy independent total cross section and by four different models of synthetic scattering kernel. Energy reflection coefficients are computed for monodirectional and isotropic incident flux and the accuracy of the flux decomposition method is assessed by comparison with exact solution, variational method and ordinary DPN approximations.

Key words: transport equation, synthetic scattering kernel, DPN method, energy reflection coefficient

STUDY OF MULTIPARTICLE BREAK-UP OF CARBON NUCLEUS INDUCED BY NEUTRONS
by Biljana RADOJEVIĆ

Abstract: The four-body break-up of the n + ¹²C system induced by neutrons of about 14 MeV has been studied in a kinematically complete experiment and in a calculation by optical model. The theory provides a fairly good understanding of the measured neutron cross sections, which are in very good agreement with calculation results obtained by adequate optical parametric set.

Key words: multiparticle break-up, sequential reaction mechanism, quasifree scattering, tissue- equivalent materials, carbon nuclei, optical model

CALIBRATION OF NEUTRON DOSIMETERS AT THE VINČA INSTITUTE STANDARD DOSIMETRY LABORATORY
by Milan PETROVIĆ, Marko NINKOVIĆ, Mirjana PROKIĆ, Srboljub STANKOVIĆ, Milojko KOVAČEVIĆ

Abstract: Calibration technique for area and personal dosimeters is postulated in this paper. Data for neutron sources at the Secondary Standard Dosimetry Laboratory are systematized. An example of an area monitoring dosimeter calibration is described. Results of specific measurements that additionally characterize neutron fields are presented.

Key words: calibration, californium, dose equivalent, dose-meter, neutron, room return, radiation dosimetry