Thermally resistant linings for nuclear - reactor fuel element sheaths

摘要

To prevent the loss of efficiency due to overcooling of the fuel material in Na cooled reactors, an effective thermal insulation layer is formed between the outer surface of the core material and the sheath. This is formed by a statistical contact system between the two using ribbing or surface roughening or by partial coating of the fule on its outer faces with a bad thermal conductor. The gaps between the individual points of contact are filled with a bad thermally conductive gas, e.g. Ar instead of the usual He.