[en] In this paper, the main problems encountered in the design of fuel elements for fast breeder reactors are reviewed. The following problems are studied: oxide behavior (chemical and structural evolution, fission gas release); cladding and pin behavior (swelling, irradiation creep); bundle and wrapper tube behavior; failed fuel problems

No abstract available

[en] The most important problems in fast reactor fuel element come from the excessive swelling of the structural materials used. The limitations of irradiation time for a given reactor result from the cladding or hexagonal wrapper deformations. Irradiation creep plays a major role, either in inducing additional deformations, or in providing possible ways of accommodation of bending stresses. Progress has been made in designing swelling resistant and/or low irradiation creep modulus materials. For instance in FRANCE, annealed 316 SS has been eliminated from pin and subassembly, and replaced by cold worked 316; we are now considering introduction of stabilizing elements in 316 SS as a further improvement and studying different alloys (nickel alloys, or ferritic steels). It has to be checked that the improvement of irradiation characteristic is not counterbalanced by losses on other properties (embrittlement for instance). Considering that pushing off or eliminating a limit may lead to the onset of a new one, it is porposed to make a review of the consequences of substantial improvement of structural material behavior

No abstract available

[en] For Super-Phenix fuel assemblies, Phenix technological arrangements will be used again, but they will be simplified as far as possible. The maximum fuel can temperature has been lowered in order to obtain a good behavior of hexagonal tubes and cans at high irradiation levels. An important experimental programme and the experience gained from Phenix operation will confirm the merits of the options retained. The fuel element fabrication is envisaged to take place in the plutonium workshop at Cadarache. Usual procedures will be employed and both reliability and automation will be increased

No abstract available

[en] Because of the promised shutdown and decommissioning of the French Superphenix fast breeder reactor, the French research programs on transmutation will be reoriented towards the smaller Phenix reactor. This issue of 'DRN Actualites' brochure reports on the works carried out by the operator with the help of the Direction of Nuclear Reactors (DRN) of the CEA and Novatome company to satisfy the nuclear safety authorities requirements for the start-up of the Phenix reactor. Three aspects are developed: the 'Service life' project which concerns the non-destructive control of the reactor core and primary circuit, the seismic behaviour of the installation (diagnostic and reinforcement), and the renewal of the secondary circuit and steam generators. (J.S.)

[en] From the first reactor start up, up to the end of 1980, about 80.000 standard fuel pins have been or are being irradiated in experimental French fast breeder reactor PHENIX. On the begining of the commercial power operation the nominal burn up was 60.000 MWd/t. Later, in 1979 it has been increased of 10%. In the near future the material improvement and the better in pile behaviour knowledge will allow higher burn up to be reached: 90.000 MWd/t in the internal core and 110.000 MWd/t in the external core. The following of the breeder core is important to get and increase our knowledge. In other respects, in addition to the favorable consequences for the operation of this reactor, the continue performances improvement give us the hope of good commercial power reactors operation

[en] This paper shows the experience we have on the actual problem associated with sodium cooling, and summarises the R and D we carry out, in France, to alleviate these problems. (J.P.N.)

No abstract available