Patent Number: 
Section: claims

1. A fuel rod assembly, comprising:a fuel rod;wherein the fuel rod includes a cladding;wherein the cladding includes a weldless, solid-rolled tubular element with spiraled ribs located on an outer surface of the fuel rod and is made of chrome silicon steel with a ferrite grain size of less than 0.0336 mm;wherein an opening angle of each rib is between 30° and 40° and a cross-sectional shape of the rib is a trapezoid with rounded corners at a top portion of the trapezoid and with smoothed corners at a base portion of the trapezoid;wherein the fuel rod is sealed at ends thereof and nuclear fuel is placed inside the cladding;wherein each rib has a height of at least 0.75 mm and a wall thickness of a maximum of 0.6 mm;wherein the trapezoid has a curvature radius of 0.2-0.35 mm;wherein the trapezoid has a fillet radius of 0.55-0.9 mm;wherein the fuel rod assembly is operable to be used in a reactor with a heavy liquid metal coolant, wherein the heavy liquid metal coolant includes lead or a lead-bismuth mixture. 2. The fuel rod assembly according to claim 1, wherein the cladding is made of steel with a chromium content between 10 wt % and 12 wt % and a silicon content between 1.0 wt % and 1.3 wt %. 3. The fuel rod assembly according to claim 1, wherein the cladding has four spiraled ribs that are equally spaced apart.