| 摘要 |
<p>1497297 Fuel elements CANADIAN GENERAL ELECTRIC CO Ltd 11 March 1975 [13 March 1974] 10011/75 Heading G6C An elongated nuclear fuel element comprises a plurality of close-fitting fuel pellets 14 stacked end-to-end in a locally flexible metallic sheath 12, the majority of the pellets 14 having provision at their ends, as by indenting, to accommodate individual axial expansion in operation and to substantially preclude differential axial expansion between the pellets 14 and the sheath 12. A low shear lining layer 16 of, e.g. graphite, siloxane or silicon, is interposed between the pellets 14 and the sheath 12 on their peripheral adjoining surfaces to facilitate peripheral distribution of stresses in the sheath to reduce the likelihood of rupture failure extending longitudinally of the sheath due to a concentration of peripheral expansion stresses. As shown in Fig. 2, the pellets 14 tend to change under reactor operating conditions from their original cylindrical form to an "hourglass" shape, while the sheath 12 formed of thin zirconium alloy conforms to the pellet shape under the coolant pressure (#1500 p.s.i.). The material to form the layer 16 is applied to the interior of the sheath 12 or the surface of the fuel pellets 14, either dry or in the form of a liquid or emulsion which is subsequently dried.</p> |
