Results 1 - 10 of 1867
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[en] The fuel for ship reactors has to comply with relatively strict technical specifications. These are briefly summarized in this paper which includes a description of the 'CARAMEL' type plate and uranium dioxide fuel designed for the C.A.S. type plants for merchant ship propulsion. The original features of this fuel are also of benefit to safety owing to the fact that this dispersed type of fuel is cold and partitioned. The in-pile and out-of-pile qualification tests already carried out and in hand at the CEA are reviewed
[fr]Le combustible des reacteurs navals doit satisfaire a des specifications techniques relativement severes. Celles-ci sont rappelees rapidement dans la communication. Suit une description du combustible a plaques et a dioxyde d'uranium dit 'Caramel', qui doit equiper les chaufferies type CAS utilisees pour la propulsion navale marchande. Les originalites de ce combustible sont autant d'avantages de SURETE dus au fait que ce combustible divise est froid et compartimente. On donne 'in fine' un apercu des essais de qualification en pile et hors pile qui ont deja eu lieu et qui se poursuivent au sein du Commissariat a l'Energie Atomique
[en] UMo-Al based fuel plates prepared with ground U8wt%Mo, ground U8wt%MoX (X = 1 wt%Pt, 1 wt%Ti, 1.5 wt%Nb or 3 wt%Nb) and atomized U7wt%Mo have been examined. The first finding is that that during the fuel plate production the metastable γ-UMo phases partly decomposed into two different γ-UMo phases, U2Mo and α′-U in ground powder or α″-U in atomized powder. Alloying small amounts of a third element to the UMo had no measurable effect on the stability of the γ-UMo phase. Second, the addition of some Si inside the Al matrix and the presence of oxide layers in ground and atomized samples is studied. In the case with at least 2 wt%Si inside the matrix a Silicon rich layer (SiRL) forms at the interface between the UMo and the Al during the fuel plate production. The SiRL forms more easily when an Al–Si alloy matrix – which is characterized by Si precipitates with a diameter ⩽1 μm – is used than when an Al–Si mixed powder matrix – which is characterized by Si particles with some μm diameter – is used. The presence of an oxide layer on the surface of the UMo particles hinders the formation of the SiRL
[en] A fuel element is described which includes a fuel nucleus constituted by the juxtaposition in a frame of a number of ceramic fuel material small plates each with a metal protection coat and clad between two metal plates. It is characterized in that the coating of each small plate is carried out laterally by a lattice of fine wires inserted in the frame, each mesh of this lattice has the shape and dimensions of a small plate so as to house one of them
[fr]On decrit un element combustible comportant un noyau combustible constitue par la juxtaposition dans un cadre d'une pluralite de plaquettes de materiau combustible ceramique revetues chacune d'une protection metallique et gainees entre deux plaques metalliques, caracterise en ce que le revetement de chaque plaquette est realise lateralement par une grille de fils minces encastree dans le cadre et dont chaque maille a la forme et les dimensions d'une plaquette pour servir de logement a l'une de celles-ci
[en] The Savannah River Site (SRS) has received some fast critical assembly (FCA) fuel from the Japan Atomic Energy Agency (JAEA) for disposition. Among the JAEA FCA fuel are approximately 7090 rectangular Stainless Steel clad fuel elements. Each element has an internal Pu-10.6Al alloy metal wafer. The thickness of each element is either 1/16 inch or 1/32 inch. The dimensions of each element ranges from 2 inches x 1 inch to 2 inches x 4 inches. This report discusses the potential chemical dissolution of the FCA clad material or stainless steel. This technology uses nitric acid-potassium fluoride (HNO3-KF) flowsheets of H-Canyon to dissolve the FCA elements from a rack of materials. Historically, dissolution flowsheets have aimed to maximize Pu dissolution rates while minimizing stainless steel dissolution (corrosion) rates. Because the FCA cladding is made of stainless steel, this work sought to accelerate stainless steel dissolution.
[en] A description is given of a fuel assembly for a nuclear reactor comprising a plurality of elongated plate-like fuel bearing elements of the same length and width, paired longer than they are wide and assembly spacer members having means defining opposed spaced notches for receiving the side edges of said elongated plate-like fuel bearing elements, and means for securing said plate-like fuel bearing elements to said paired assembly spacer members with the side edges of said plate-like elements engaged in opposite notches in said paired assembly spacer elements so as to secure said fuel bearing elements in side by side spaced relation in a staggered arrangement transversely so as to conform to a diamond shaped profile in which opposite sides are parallel and opposite angles are substantially 600 and substantially 1200
[en] Monolithic U-Mo fuel plates are rolled to final fuel element form from the original cast ingot, and thus any inhomogeneities in 235U distribution present in the cast ingot are maintained, and potentially exaggerated, in the final fuel foil. The tolerance for inhomogeneities in the 235U concentration in the final fuel element foil is very low. A near-real-time, nondestructive technique to evaluate the 235U distribution in the cast ingot is required in order to provide feedback to the casting process. Based on the technical analysis herein, gamma spectroscopy has been recommended to provide a near-real-time measure of the 235U distribution in U-Mo cast plates.
[en] A fuel assembly is described with two types of fuel rods, one is full-length, the other considerably shorter. The shorter rods are placed in the lower part of the assembly from the bottom plate to a spacer or between two spacers. In this way a smoother relation moderator/fuel is achieved in the axial direction