EDN: HEREQE
Authors & Affiliations
Bednyakov S.M., Bezborodov A.A., Mikhailov G.M., Yazvinsky N.Yu., Yarovoy M.V.
A.I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Russia
Bednyakov S.M. – Leading Researcher, Cand. Sci. (Tech.).
Bezborodov А.А. – Senior Researcher.
Doolin V.A. – Chief Researcher, Professor, Dr. Sci. (Phys.-Math.).
Izotov V.V. – Senior Researcher.
Mikhailov G.M. – Head of the Laboratory, Cand. Sci. (Tech.).
Yazvinsky N.Yu. – Research Engineer.
Yarovoy М.V. – Researcher, A.I. Leypunsky Institute for Physics and Power Engineering. Contacts: 1, pl. Bondarenko, Obninsk, Kaluga region, Russia, 249033. Tel.: +7 (484) 399-84-73; e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
Abstract
The article discusses the matrix exponential method (MEXP) employed for the processing of the measured curve N(t) – count rate or current of the neutron detector – to get the time dependence of the reactivity ρ(t) under conditions of the neutron-multiplying system perturbation. The results of the reactivity calculations made using the new method are compared with the results obtained by the conventional point approximation IKES method. It has been shown that discrepancies in the experimental data on the neutron-multiplying system subcriticality, which were obtained by point approximation processing of the readings taken from flux detectors geometrically located in different places near the system, can reach 60 %. The scheme that takes into account the spatial energy effects (SEE) in determining the reactivity is considered. This scheme has not been used before. The example considered in the article shows how the proposed scheme is used in the experiments of the “runaway – rod drop” type reduces scattering of the detector readings relative to the subcriticality of the studied system by about five times compared to the point approximation processing. The contribution of the delayed neutron data inaccuracy to the reactivity uncertainty is assessed using a probabilistic approach. The results of the calculated assessment reveal that in calculating the system subcriticality a random change in all the values of λi and βi within ± 5 % limit leads to its deviation within ± 3 % limit with a probability of about 80 %.
Keywords
neutron-multiplying medium, reactivity, differential system, matrix exponential method, spatial energy effects, delayed neutrons, fractional error
Article Text (PDF, in Russian)
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UDC 621.039.51
Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants, 2024, no. 4, 4:4
