Issue 2/2010

ABSTRACTS:

UDK 621.039.51
EXPERIMENTAL RESEARCHES OF PROMPT NEUTRONS KINETICS IN ASSEMBLIES WITH A CORE OF PLUTONIUM / V. P. Gorelov, V. I. Il’in, A. A. Kaigorodov, M. I. Kuvshinov, A. V. Panin, D. P. Peshekhonov // P. 3
There have being defined kinetic properties (constant Rossi-α₀, effective fraction of delayed neutrons ß_ef and lifetime of prompt neutrons т₀) for bare critical assembly of ²³⁹Pu (98 %) in δ-phase. The experiments were performed on a critical test bench FKBN-2M. The results obtained at different times in VNIIEF for a bare assembly of ²³⁹Pu (98 %) using various equipment types were compared to the data for a similar American bare assembly Jezebel of  239Pu (95,5 %) (LANL). The results of all measurements considered in VNIIEF are not contradictory but differ from the American results. Basing on the analysis of experiments performed on assembly Jezebel there was made a conclusion that the obtained values of α₀ and τ₀ for Jezebel are mistaken. There is proposed a new interpretation of LANL results that ensures the possibility of mistake elimination at definition the values of α₀, τ₀  and ß_ef for Jezebel.
Key words: metal plutonium-239, test bench FKBN-2M, critical assembly, reactivity, constant Rossi- α₀, lifetime of prompt neutrons, effective fraction of delayed neutrons.

UDK 621.039.514
EQUATIONS OF REACTOR AND BOOSTER POINT KINETICS IN TERMS OF FISSION INTENSITY / V. Kh. Khoruzhy // P. 14
There is presented a derivation of differential point kinetics equations for reactor or booster at the availability of external source as related to a neutron multiplying system.
Key words: reactor, booster, core, external source, point kinetics.

UDK 519.212.3
SOME CHАRACTERISTICS OF RADIATION DISTRIBUTION IN THE SPHERICAL ACTIVE SYSTEM / E. F. Fomushkin // P. 17
With the aid of geometrical probabilities method there were made calculations of space distribution of interaction events in the volume of radiation spherical source.
Key words: geometrical probabilities method, nuclear interaction, radiation sources.

UDK 621.039.55
IMPROVED EQUATIONS OF BIGR PULSED REACTOR DYNAMICS / V. F. Kolesov, E. V. Intyapina // P. 22
The paper presents results of a theoretical study performed for the purposes of finding reasons for unsatisfactory reproduction (in calculations of BIGR reactor) of so-called «plateau» (or a «tail») of fission pulses, particularly, distinct oscillations of reactor power on the plateau. It is shown that in all probability the reason is manifestation of instability of fuel rings radial displacement or deterministic deformation of their cross-section form. Solutions of modified equations of BIGR reactor dynamics, recorded taking into account these phenomena, satisfactorily agree with the experiment.
Key words: BIGR reactor, core, fuel rings, fission pulse, pulse plateau, reactor dynamic equation, reactivity changes, displacement instability of fuel rings.

UDK 621.039.53
CALCULATED MODELS OF BRAKE SYSTEMS (DAMPERS) FOR ACTUATING UNITS OF PULSE NUCLEAR REACTOR CONTROL ELEMENTS I. A. Nikitin // P. 43
There are described brake systems (dampers) applied in executive mechanisms of pulsed nuclear reactors to reduce shock loads on the members of reactivity regulation and moving system elements. The types and design peculiarities of pneumatic and hydraulic dampers are considered. The calculated models are presented. It is demonstrated that calculated models can be used for designing of brake mechanisms.
Key words: pulse nuclear reactor, brake mechanism, damper, calculated models, executive mechanism, work member.

UDK 539.074.8+621.039
THERMAL NEUTRON SOURCE EhI-T-22 OF REACTOR BR-1M / A. S. Koshelev, M. V. Mochkaev, A. V. Arapov, V. A. Bogdanov, V. D. Sevastianov // P. 52
There is described a design, the experimental data used at subsequent certification are presented, and considered the forms of practical application of EhI-T-22 thermal neutron source of a second grade working standard at its joint operation with BR-1M reactor of FSUE «RFNC-VNIIEF».
Key words: thermal neutron source, BR-1M reactor, neutron fluence, single fluence spectrum, neutron gas temperature.

UDK 621.039.571;539.1.084
SPACE, SPECTRAL AND TIME CHARACTERISTICS OF A SPECIALIZED GAMMA-SOURCE OF BR-K1 REACTOR / A. S. Koshelev, V. Kh. Khoruzhy // P. 61
There are presented space, spectral and time characteristics of a specialized gamma-source of BR-K1 reactor required at calibration of dose detectors and detectors of gamma-radiation dose rate intended to be used in radiation fields of RFNC-VNIIEF reactor facilities.    
Key words: reactor BR-K1, specialized gamma-source, dose, dose rate, prompt gamma-quanta, delayed gamma-quanta.

UDK 539.1.03:621.039.514
TO THE CHOICE OF THE MEASURE OF COMPARATIVE NEUTRON SENSITIVITY / A. S. Koshelev, V. Kh. Khoruzhy // P. 69
There is discussed the possibility of using complete absorbed neutron dose in detector material as a measure of neutron spectra comparability by the effect to gamma-radiation detectors. There are presented group functionals of neutron effect for eight dosimetric materials.
Key words: neutron spectrum, gamma-dosimeter, measure of comparability, complete absorbed dose, neutron effect functional.

UDK 621.039.562
MODERNIZED AUTOMATED SYSTEM OF CONTROL, GOVERNING AND PROTECTION OF PULSED WATER-SOLUTION REACTOR / O. A. Mingazov // P. 83
Issues of building a structure of YAGUAR modernized pulse nuclear reactor and its technical implementation are discussed. Measuring channels and software are described.
Key words: system of reactor governing and protection, YAGUAR reactor, software, measurement channels.

UDK 621.039
TEST EXAMPLE OF CHECK OF THE SOFTWARE FOR CALCULATION OF PROBABILITY OF DESTRUCTION (ПН-1.1) WITH USE OF A. RZHANITSYN’S METHODOLOGY / А. Yu. Kuz’michevskiy, A. F. Getman // P. 89
The method of the resource estimation of equipment and pipelines of nuclear power plants in probability aspect is described.
The method is development of the classical approach of A. Rzhanitsyn to definition of probability of destruction of a design at static loadings.
The method allows to consider quality of designs, the equipment and pipelines by criterion of their faultiness, inclu-ding after carrying out of non-destroying test and repair of the revealed defects.
Based on the method developed by one of modules of the computer complex based on the Maple 12 to carry out the calculation of the probability of destruction, leaks and defects in equipment and pipelines of nuclear power plant, optimization of non-destructive testing and maintenance during operation.
There are examples of resource assessment and the probability of destruction of nuclear power plant equipment.
Key words: equipment resource of atomic power plant, resource evaluation method, destruction probability, cyclical loading.

UDK 621.039.51
NEUTRON CHARACTERISTICS OF CRITICAL ASSEMBLIES MADE OF ²³⁵U (89.6 %) AND ²³⁹Pu WITHOUT REFLECTORS / A. A. Malinkin, V. A. Davidenko, V. F. Kolesov, M. I. Kuvshinov, B. D. Stciborski // P. 95
The article presents results of studying of energy-spatial neutron distributions and total reaction numbers for spherical critical assemblies made of ²³⁵U (89.6 %) and ²³⁹Рu without reflectors. The study was performed on the basis of measurement of densities and efficient cross-sections of different energy-sensitive reactions for which a dependence of cross-sections on energy of monochromatic neutrons is known with good precision. There were used fission reactions of ²³⁵U, ²³³U, ²³⁸U, ²³⁹Рu, ²⁴⁰Рu, ²³⁷Np, ²³²Th and reactions of ³²S(np), ²³⁸U(n2n), ²³²Th(n2n), ²³⁸U(n-γ), ¹⁹⁷Au(n-γ), ⁶Li(n-α), ¹⁰В(n-α). Some local and average (for the entire core) integral spectral neutron characteristics are also reported.
Key words: critical assemblies, neutron characteristics of critical assemblies, uranium-235, plutonium-239, nuclear reactions cross-sections, neutron spectrum, energy sensitive reactions, spectrum recovery method.

UDK 621.039.51
NEUTRON CHARACTERISTICS OF CRITICAL ASSEMBLIES MADE OF ²³⁵U (36 %), ²³⁵U (89.6 %), ²³⁹Pu AND ²³³U WITH URANIUM REFLECTOR / A. A. Malinkin, V. A. Davidenko, V. F. Kolesov, M. I. Kuvshinov, B. D. Stciborski // P. 102
The article presents results of a study of energy-spatial neutron distributions and total reaction numbers for spherical critical assemblies made of ²³⁵U (36 %), ²³⁵U (89,6 %), ²³³U and ²³⁹Рu  and for those with thick reflectors made of uranium of natural isotopic composition. The study was performed on the basis of measurement of densities and efficient cross-sections of different reactions for which a dependence of cross-sections on energy of monochromatic neutrons is known with good precision. There were used fission reactions of ²³⁵U, ²³³U, ²³⁸U, ²³⁹Рu, ²³⁷Np, ²³²Тh and ²⁴⁰Рu and reactions ³²S(np), ²³⁸U(n2n), ²³²Тh(n2n), ²³⁸U(nγ), 197Au(nγ), ⁶Li(nα), ¹⁰B(nα). Also presented are some local and average (over the assemblies’ volume) integral spectral neutron characteristics, as well as multiplication and reproduction factors for a restricted and infinite uranium reflector.
Key words: critical assemblies, neutron characteristics of critical assemblies, uranium-235, plutonium-239, nuclear reactions cross-sections, neutron spectrum, energy sensitive reactions, spectrum recovery method.

UDK 621.039.51
INVESTIGATION OF REACTIVITY PERTURBATIONS IN SIMPLE CRITICAL ASSEMBLIES / A. A. Malinkin, V. A. Davidenko, V. F. Kolesov // P. 113
The article reports results of perturbation measurements of reactivity of small samples of different matters in spherical assemblies made of ²³⁵U (89.6 %) without a reflector (KS-1) and those of ²³⁹Pu without reflector (KS-2) and ²³⁹Pu with reflector made of natural uranium (KS-5). Interpretation of experiences basing on one-group perturbation theory is presented. Values of one-group parameters (ν-1)σ_f-σ_с, σ_tr, νσ_f+σ_str of studied perturbation matters for assemblies’ cores are given. Here are also given relations of coupling between reactivity perturbation of an absorbing or fission sample and lifetime of prompt neutrons. Lifetimes of prompt neutrons for KS-1 and KS-2 are estimated with their aid.
Key words: critical assemblies, reactivity disturbances, small samples, uranium-235, plutonium-239, natural uranium, one-group perturbation theory.