No abstract available

[en] The fuel element assembly (FA) of fast reactor comprising fuel elements with enriched fuel and fuel elements with fossil material is described. With the purpose of increasing the power rating without deterioration of coolant temperature parameters at the core outlet in each FA elementary cell there are fuel elements of both types

No abstract available

No abstract available

[en] The construction of the cell grid provides a large number of tubular clamps or twin clamps, which are suitable for accommodating fuel rods or sprinkler pipes. They consist of a closed metal strip, which is divided into two similar openings by a bridge piece. Bowspring or leaf springs (Nimonic from RTH) are used to fix the rods and pipes, the former are supported on bridge supports. There is always a pair of coplanar hollows or bumps in the surface of the metal strip or the clamp opposite the springs. (RW)

No abstract available

[en] CONIFERS is a neutronics code for nuclear reactors whose fuel is in channels that are separated from each other by several neutron mean-free-path lengths of moderator. It can treat accurately situations in which the usual homogenized-cell diffusion equation becomes inaccurate, but is more economical than other advanced methods such as response-matrix and source-sink formalisms. CONIFERS uses exact solutions of the neutron diffusion equation within each cell. It allows for the breakdown of this equation near a channel by means of data that almost any cell code can supply. It uses the results of these cell analyses in a reactor equations set that is as readily solvable as the familiar finite-difference equations set. CONIFERS can model almost any configuration of channels and other structures in two or three dimensions. It can use any number of energy groups and any reactivity scales, including scales based on control operations. It is also flexible from a programming point of view, and has convenient input and output provisions. (author)

[en] The kinetics of glass alteration is studied in a reactor cell containing parallel glass plates with a small gap, representing an ideal crack geometry. The calibrated aperture of the crack is varied from a few tens to a few hundred micrometers. The glass coupons are immersed in a highly alkaline solution to obtain fast alteration. Although the cell is closed and isothermal, it is observed that vertical or horizontal configurations lead to very different alteration gel thickness profiles. This effect results from gravity-driven flow taking place in the vertical geometry due to glass leaching as opposed to essentially diffusive transport in the horizontal case. The advection velocity is estimated from a one-dimensional model of the coupled reaction/transport mechanism, based on a zero or first order reaction. The coupling between reaction and transport has a clear influence on the apparent alteration kinetics, a phenomenon generally ignored.

[en] Some imprecisions are pointed out in the derivation by a previous author of a correction for the neutron flux in a heterogeneous lattice cell. In particular, the equation which is basic to the mathematical formulation does not properly take into account the lethargy and energy variables. It is shown that this and other errors in the derivation lead to an overestimation of the proposed correction. (UK)

[en] The diffusion equation for the fluidized bed nuclear reactor concept (FBNR) is derived. It is shown that existing neutronic codes can be applied for the cell calculation. (orig.)