专利名称：Fabrication of nuclear reactor fuel elements 发明人：JONES HERBERT NOEL,CAMPSIE IAN
COCHRAN
申请号：US8759961
申请日：19610207
公开号：US3153280A
公开日：
19641020
专利内容由知识产权出版社提供
摘要：957,605. Nuclear fuel elements. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Jan. 26,1961 [Feb. 10, 1960; June 2, 1960], Nos. 4788/60 and 19526/60. Heading G6C. In the manufacture of fuel elements comprising fissile material enclosed in a protective sheath, in which the sheath is subject to external pressurisation at an elevated temperature in order to form it into intimate contact with the fissile material, a longitudinal compressive stress is applied to the sheath by a clamp made of two or more materials in composite form so as to be matched in thermal expansion with the fissile material, the sheath thus being allowed to elongate by approximately only the same amount as the fissile material on heating during pressurisation. In the embodiment shown in Fig. 1, a fuel element 1 comprising a cylindrical uranium rod 2 enclosed in a magnesium alloy sheath 3 having external helical fins 4 is held in a clamp 8 formed of two tubular sections 9, 10 joined by a circumferential butt weld 11. Section 9 is of mild steel and is three times the length of section 10 which is of stainless steel. A screwed end cap 12 is fitted at the lower end of the clamp 8 and a quick-release end cap 13 at the upper end, the latter carrying a clamping screw 18 having an end flange 20 with an integral skirt 21. The fuel element 1 is clamped between rings 22, 23 which bear against the ends of the
reactor thenfins 4, clamping pressure being applied by turning down the screw 18 to finger tightness. The body of the clamp 8 is perforated by longitudinal slots 24 while the end caps 12,13 are perforated by holes 25, 26 respectively. Pressurisation may be carried out hydraulically by preheating in oil at 250‹C. and 100 psi for 15 min., the pressure then being increased to 12,000 psi and maintained for 30 min. Strain due to the clamp initially cooling faster than the fuel element on withdrawal from the oil is avoided by releasing the end cap 13 before cooling starts. When gas pressurising at 500‹C. is employed, the clamp should consist of half mild steel and half stainless steel. Where the sheath has circumferential fins, multistart helical fins of short pitch or a single start helical fin of short pitch, the loading cannot be applied in the above manner because it would then be localised on one fin at each end of the sheath. In such a case end fitments for applying the load to several fins at each end of the sheath where these are circumferential, or to several turns of the fin or fins where these are helical are used, an end fitment 6 formed in two complementary halves 7, 8 for use with a single start helical fin 10 being illustrated in Fig. 4.
申请人：UNITED KINGDOM ATOMIC ENERGY AUTHORITY
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