Thermal Effects of an Advanced Wire Mesh Packaging Material

In order to be certified for transportation of radioactive materials, a container must be able to withstand a series of rigorous structural and thermal tests. Typical materials used in the construction of radioactive material transportation containers include stainless steel, mild steel, Cellotex and organic foams. This paper presents the thermal characteristics of an advanced composite material for use in radioactive material transportation containers. Experimental and analytical methods were used to characterize the advanced packaging material. The composite material is made up of layers of aluminum wire mesh and insulating material. Laboratory results indicate that the wire mesh thermal conductivity is highly anisotropic. In- and out-of-plane wire mesh thermal conductivity differ by an order of magnitude, with the in-plane thermal conductivity higher than the out-of-plane thermal conductivity. A test package was built consisting of a stainless steel outer shell, an overpack made of the advanced composite packaging material and a stainless steel containment vessel. The package was 99 em (39 inches) long and had a diameter of 46 em (18 inches). A steady state experiment and a transient experiment performed at the Sandia National Laboratories Radiant Heat Test Facility were conducted to characterize the packaging material. A heat source of 20 watts was included in the package to simulate the payload. The package was instrumented with type K thermocouples, and temperatures were recorded during the test.