EDN: SIGBNA
Authors & Affiliations
Blandinsky V.Yu., Lubina A.S.
National Research Center “Kurchatov Institute”, Moscow, Russia
Lubina A.S. – Researcher. Contacts: 1, pl. Akademika Kurchatova, Moscow, Russia, 123182. Tel.: +7 (499) 196-92-44; e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
Blandinsky V.Yu. – Deputy Head of the Complex for International Affairs, Scientific Secretary, Cand. Sci. (Tech.).
Abstract
A study of the hydrodynamics and heat exchange of the central fuel assembly of a fast sodium reactor with a relative step s/d=1.395 was carried out. In this arrangement of the core, a fairly high level of excess operating time of Pu-239 and Pu-241 is achieved — 504 kg/GW (el)/year, which significantly exceeds the target of 300 kg/GW (el)/year. In addition, this arrangement is characterized by a fairly high reactivity margin, which can be reduced by reducing the plutonium content, which will lead to a further increase in excess fuel consumption. Two variants of fuel assemblies were investigated: with a cover and without a cover. In a cover fuel assembly with a wide pitch (s/d=1,395) of 469 fuel rods (d=6.1 mm) spaced by grids, it is possible to achieve a fairly good equalization of the temperatures of the coolant and shells, with the exception of angular fuel rods. To reduce azimuthal temperature irregularities of the shells of angular fuel rods, it was proposed to increase the area of the angular fuel cell by either squeezing a groove in the corner of the cover, or a groove in the corner of the cover, 7 mm wide and no more than 0.4 mm deep. In such an optimized version of the fuel assembly design, the maximum temperatures of the outer surface of the shells of the angular, peripheral and central fuel elements turn out to be quite close and amount to 591, 587 and 586 °C, respectively. The wide step of the arrangement of fuel rods in the fuel assembly (s/d=1.395) allows the use of a shell-less cassette design. Since the periphery of a shell-less fuel assembly is not shielded from the inter-cassette gap by a cover, the temperature irregularities around the peripheral row of fuel elements in such a fuel assembly are noticeably higher than in the cover version of this cassette, however, the scale of temperature irregularities of the fuel element shells of the peripheral row can be considered acceptable. Thus, in the case of a 2-mm inter-cassette gap, the temperature irregularities of the shells of the angular and peripheral fuel rods reached 24 and 28 °C, respectively, and in the case of a 1-mm inter-cassette gap, they dropped to 13 and 14 °C, respectively.
Keywords
fast reactor, heat exchange, sodium coolant, secondary nuclear fuel, thermohydraulics, uncer-tainty factors
Article Text (PDF, in Russian)
References
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UDC 621.039.534.6
Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants, 2024, no. 2, 2:21
