Abstract: Cladding tube for a fuel rod for a boiling water reactor fuel element, and its production. The cladding tube is composed practically homogeneously of the constituents of zircaloy and, with the ductility parameter &ggr;=3{square root over ((kd))}/(fr)2≦3.5 (&ggr;=ductility parameter, KD=mean grain diameter; fr=Kearns factor), has an elongation at break of at least 20%, set by low-temperature treatment of an extruded tube blank. The starting body used for the extrusion has a defined distribution of precipitated secondary particles which is produced by &bgr;-quenching and differs in the areas which form the inner surface and outer surface of the extruded tube. At the inner surface, the particles have a greater diameter and are at a greater average distance apart, this distribution being described by the “spacing”.

Abstract: In order to avoid uncontrolled secondary damage to a fuel rod, in particular a fuel rod being formed of Zircaloy and having a liner on the inside, in which the secondary damage may be generated by coolant that enters the fuel rod in the event of primary damage, a nucleus is deliberately provided in a cladding tube. The nucleus, although passivated in an undamaged fuel rod and not impeding the serviceability of the fuel rod, is activated by coolant which enters the fuel rod in the event of primary damage or by hydrogen or other reaction products produced in reactions of the coolant in the interior of the fuel rod and results in a small-area perforation. This prevents an aggressive atmosphere, which may result in unintentional large-area secondary damage at other points, from accumulating in the cladding tube after primary damage.

Abstract: Zircaloy 2 and zircaloy 4 are zirconium alloys which are permitted and tried and tested in nuclear engineering and which have constituents with fixed concentration ranges. The properties, especially corrosion resistance, mechanical stability and sensitivity to pellet-cladding interaction of those alloys are subject to pronounced spreads of unknown origin. According to the invention, the tin content is between 1.4 and 1.8% by weight, the Fe content between 0.1 and 0.25% by weight, the Cr content between 0.1 and 0.3% by weight, the Si content between 0.05 and 0.02% by weight, the O content between 0.05 and 0.11% by weight, the C content below 0.02% by weight and the Ni content below 0.08% by weight. This restriction of the permissible concentration ranges ensures that the material properties are spread only within a narrow favorable range. A liner made from zirconium with an iron constituent of between 0.2 and 0.8% by weight is proposed for the inner lining of a fuel-rod sheathing tube.

Abstract: A fuel rod has a cladding including a thicker inner layer and a thin outer layer being metallurgically bound thereto. In view of the conditions prevailing on the inside of the cladding tube and the mechanical properties of the entire cladding tube, the inner layer is formed of zircaloy having a comparatively high Sn content and a low Fe and Fe+Cr content. The outer layer also contains virtually only zircaloy constituents, but in view of corrosion, H2 take-up and sensitivity to Li dissolved in the cooling water, the Fe and Fe+Cr content is greater than or at most equal to that of the inner layer, the chosen Sn content is less than 1.3% and the chosen Sn+Fe+Cr content is more than 1.0%. Low failure rates of the cladding tube are thereby achieved even for long service lives.

Abstract: A structural part for a nuclear reactor fuel assembly includes a zirconium alloy material having at least one alloy ingredient selected from the group consisting of oxygen and silicon, a tin alloy ingredient, at least one alloy ingredient selected from the group consisting of iron, chromium and nickel, and a remainder of zirconium and unavoidable contaminants. The zirconium alloy material has a content of the oxygen in a range of substantially from 700 to 2000 ppm, a content of the silicon of substantially up to 150 ppm, a content of the iron in a range of substantially from 0.07 to 0.5% by weight, a content of the chromium in a range of substantially from 0.05 to 0.35% by weight, a content of the nickel of substantially up to 0.1% by weight, and a content of the tin in a range of substantially from 0.8 to 1.7% by weight.

Abstract: A structural part for a nuclear reactor fuel assembly includes a zirconium alloy material having at least one alloy ingredient selected from the group consisting of oxygen and silicon, a tin alloy ingredient, at least one alloy ingredient selected from the group consisting of iron, chromium and nickel, and a remainder of zirconium and unavoidable contaminants. The zirconium alloy material has a content of the oxygen in a range of substantially from 700 to 2000 ppm, a content of the silicon of substantially up to 150 ppm, a content of the iron in a range of substantially from 0.07 to 0.5% by weight, a content of the chromium in a range of substantially from 0.05 to 0.35% by weight, a content of the nickel of substantially up to 0.1% by weight, and a content of the tin in a range of substantially from 0.8 to 1.7% by weight.

Abstract: A fuel rod for a nuclear reactor fuel assembly includes a cladding tube having an outer surface and a given total wall thickness. Nuclear fuel is disposed in the cladding tube. The cladding tube is formed of a first zirconium alloy which may have alloy components of from 1.2 to 2% by weight of tin, 0.07 to 0.2% by weight of iron, 0.05 to 0.15% by weight of chromium, 0.03 to 0.08% by weight of nickel, 0.07 to 0.15% by weight of oxygen, and a total percent by weight for the alloy components of iron, chromium and nickel in a range of from 0.18 to 0.38% by weight. The first zirconium alloy may also have alloy components of from 1.2 to 2% by weight of tin, 0.18 to 0.24% by weight of iron, 0.07 to 0.13% by weight of chromium, 0.10 to 0.16% by weight of oxygen, and a total percentage by weight for the components of iron and chromium in a range of from 0.28 to 0.37% by weight.

Abstract: A nuclear reactor fuel assembly includes a fuel rod containing nuclear fuel in a cladding tube formed of an iron-containing zirconium alloy. A fuel assembly skeleton to which the fuel rod is attached has a structural part formed of the iron-containing zirconium alloy. The iron-containing zirconium alloy has an oxygen content of from 0.1 to 0.16% by weight and contains alloy components of from 0 to 1% by weight of niobium, 0 to 0.8% by weight of tin, at least two metals from the group consisting of iron, chromium and vanadium having from 0.2 to 0.8% by weight of iron, 0 to 0.4% by weight of chromium and 0 to 0.3% by weight of vanadium, a total percent by weight of iron, chromium and vanadium of from 0.25 to 1% by weight, and a total percent by weight for niobium and tin in the range from 0 to 1% by weight.

Abstract: Fuel rod cladding tube having an inner tubular layer of a zirconium alloy with alloying components of 1.2 to 1.7% tin, 0.07 to 0.2% iron, 0.05 to 0.15% chromium, 0.03 to 0.08% nickel, 0.07 to 0.15% oxygen, with the sum of percentages of iron, chromium and nickel in the range of 0.18 to 0.38%; or with the alloying components 1.2 to 1.7% tin, 0.18 to 0.24% iron, 0.07 to 0.13% chromium, 0.10 to 0.16% oxygen, with the sum of percentages of iron and chromium in the range of 0.28 to 0.37%; and with the inner tubular layer having an outside surface layer of another zirconium alloy with a layer thickness of 5 to 20% of the cladding tube as well as with 0 to 1% iron as an alloying component and with at least one alloying component from the group of: vanadium with 0.1 to 1% by weight, platinum with 0.1 to 1% by weight, and copper with 1 to 3% by weight.

Abstract: Cladding tube of a zirconium alloy especially for a nuclear reactor fuel rod, characterized by the feature that the geometric mean of the grain diameters in the zirconium alloy is smaller than or equal to 3 .mu.m.

Abstract: A method for treating the surface of finished parts formed of zirconium alloys for nuclear reactor fuel assemblies with an oxidizing agent, includes heating the finished parts in an autoclave and subjecting the finished parts to an oxidizing agent sufficient to generate oxygen in atomic form and to form a substantially hydrogen-impervious surface layer of oxide at least on the surface portions of the finished parts which are subjected to water or steam in the nuclear reactor.

Abstract: Method for manufacturing a cladding tube of a zirconium alloy for the nuclear reactor fuel of a nuclear reactor fuel assembly by deformation of a starting tube and subsequent post-treatment of the deformed starting tube. The deformed starting tube is first ground on the outside surface for the post-treatment and is then subjected to a final annealing treatment.

Abstract: Method of protecting a zirconium-alloy cladding tube of a nuclear-reactor fuel rod against attack by radioactive fission products, such as iodine especially, which includes applying an internal pressure to the cladding tube at a temperature of from 300.degree. to 500.degree. C. so as to deform the cladding tube, depending upon the geometric dimensioning thereof, in the elastic range and up to nearly the yield point thereof and, while this condition exists, reacting a medium previously introduced into the interior of the cladding tube, with the inner surface of the cladding tube to form a protective layer.