[en] Possibility of the justified risk concept application when determining the optimal, from economic point of view, accuracy of WWER reactor in-vessel component fabrication is discussed. It is shown, that the minimal damage is reached at standard values of tolerance for the diameter, equal to 0.2 mm. That is why, the present-day standards, providing for 2 mm tolerance should be reconsidered. Otherwise, the economic damage due to inadequate accuracy of WWER-440 reactor in-vessel component fabrication may constitute about 300 thousand rubles (reactor x year)

[en] Applicability of inductive-resonance radiationless transition theory as a method for describing the effect of temperature and aggregate state change on the activaor luminescence is demonstrated on Er³⁺-, Ho³⁺- and Nd³⁺-ion-activated YLiF₄, BaY₂F₈, SrY₂F₈, CaF₂ crystals

[en] Influence of steel layer thickness decrease , resulting from the existing technological allowances, on fabrication accuracy of in-vessel component shells and on the efficiency of the WWER reactor vessel iron-water shield is considered. Using the WWER-440 reactor as an example it is shown, that the most probable total thickness of steel shell walls is approximately by 0.25 cm smaller, than the nominal thickness. Besides local wall thickness decreases by 0.2-0.5 cm are considered allowable, though such defects may result in local overirradiation of reactor vessel inner surface and in reduction of the vessel service life, respectively. Conclusion is made about the necessity the reconsider and optimaze the existing allowances for fabrication of reactor in-vessel component shells

[en] On the example of one of typical shield compositions (cylindrical two-section channel in water bent at a right angle) the possibility is studied of using differential quasialbedo conception for solving problems on radiation propagation in heterogeneous shields by the Monte Carlo. Calculation of neutron fields and secondary γ radiation is performed by means of a PH3 program complex. The results obtained confirmed the importance of account of secondary γ radiation contribution to the full radiation field characteristics in shield heterogeneities and the possibility of using for this purpose two-group semiempirical model of quasialbedo calculation together with the Monte Carlo parametric method

[en] Problem of errors and uncertainties of important indexes in nuclear facility safety ground has been considered. The problem is analyzed at different hierarchies and subject directions. An idea on the necessity of coordinated system creation for the determination of error and uncertainty at all levels and for all subject directions is realized

[en] The ''spectrum tracking'' method is described, that permits to calculate differential characteristics of the scattered gamma field from sources with arbitrary energy and angular distributions behind barriers with the thickness up to 5-6 mean free paths. The characteristics being calculated correspond to the maximum energy of tracking a particle pack trajectory. Comparison of the calculations of the γ-spectra behind iron barriers of different thickness, with those obtained by the ROZ-5 code, exhibits, as a whole, a satisfactory agreement. Analysis of the calculations of the gamma dose rates behind a concerete barrier with the thickness up to 1 m for gamma sources with the spectrum in the range from 0.04 to 8 MeV has shown, . that the maximum error does not exceed 40%. The ''spectrum tracking'' method is pointed out to be especially efficient for homogeneous barriers. Meanwhile it can be generalized for heterogeneous barriers by application of the delta-scattering method

[en] Spectra, quantum yields and luminescence attenuation curves as well as V⁴⁺ ion luminescence excitation spectra are measured in the following glasses: fluorine-phosphate, barium metaphosphate, lithium metaphosphate and boron-phosphate. It is detected that in these systems the differences in the D_q value characterizing the crystal field intensity, is not large. The limiting times of luminescence attenuation coincide for glasses of different composition. However, there are notable differences in the value of V⁴⁺ ion surrounding inhomogeneity, which are manifested in different half-widths of ion absorption spectra, in a three-time difference of shift value between luminescence absorption and excitation spectra, in notably different levels of luminescence attenuation non-exposure and consequently in luminescence quantum yields differing by more than an order. The V⁴⁺ luminescence spectra in different glasses differ much weaker. A possibility of a substantial activator ion effect on luminescence parameters by means of changing cation-modifier and transition to mixed glass forming agents is discussed

[en] The sensitivity of calculational differential and integral neutron albedo and quasialbedo characteristics in different media to cross section errors and (in the case of quasialbedo) to the medium composition has been studied. Main results are presented. Variations of the total neutron cross sections for a semi-infinite iron reflector by +-10% have not changed the integral albedo characteristics. In the case the errors that might be caused by uncertainties in the differential cross sections are negligible. Analytical relationships are presented that describe the sensitivity of the current integral dose (energy, numerical) quasialbedo to variations of the partial neutron cross sections for light media, neutron source characterisitics and concentration of different nuclides in the media

[en] The problem of creation of the problem-oriented constant systems designed to calculate characteristics of radiation fields in shields of a certain type facilities (BN and WWER-type reactor of the thermonuclear reactors), is discussed. A number of methodical calculations for different functionals of radiation field in the BN-600 reactor one-dimensional spherical test model shield using different group approximations was carried out with different averaging spectra and different initial constant systems, to evaluate errors and volume of wide-group calculational operations. The calculations are conducted by the ANISN program in the p₃S₁₆-approximation of scattering cross-section angular dependence radiation flux density and rather high 191-internal approximation by spatial variable. It is shown , that the less is the number of groups within constant system, and the less it is oriented to the given class of problems, the higher are the calculation errors. Transfer from 171-group to 49- and 28-group approximation gives 10- and 20-fold gain in time, respectively

No abstract available