Preliminar mechanical evaluation of the structure of a nuclear plate-type fuel element

Abstract

The improvement in the efficiency and safety aspects of compact nuclear reactors is directly linked to innovations in fuels and in the geometry of fuel elements (F.E), as is the case of plate-type fuel elements. From the mechanical viewpoint, to ensure that the structure of a fuel element is safe to operate in a compact PWR reactor is important to confirm that it meets the functional design requirements for structures of this type and application, present in ANSI/ANS-57.5-1996 and, also, that the stresses resulting from the loads imposed are less than the permissible mechanical limits for their structural materials, in accordance with ASME III, division 1, subsection NB. In order to develop a methodology of mechanical analysis to verify compliance with the criteria of the cited standards, a numerical model of a plate-type fuel element was developed, taking into consideration the main active loads admitted from the full power operation event belonging to the normal operating condition of a compact PWR type nuclear reactor. The results of the analyses demonstrated that the fuel element designed did not show signs of mechanical failure with respect to the modes of plastic collapse and excess of mechanical deformation.