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Nuclear Safeguards Education Portal

Physical Signatures

There are several simple physical spent fuel signatures that can help verify a spent fuel assembly.  One common measure is to identify the assembly using the unique assembly ID tag.  Additionally, the appearance of the spent fuel can be an indication that the fuel was, in fact, irradiated in a reactor and was not replaced with a dummy assembly.  Often the appearance of the fuel changes after the assemblies experience degradation from irradiation in a nuclear reactor.  Reddish oxidation and/or scaling can occur on what were shiny surfaces of fresh fuel assemblies, or they can bend or warp during reactor operation.  

Spent _nuclear _fuel _hanford

Figure 10. These spent fuel assemblies at the Hanford Site clearly show the reddish oxidation and scaling characteristic of spent fuel. (Source: wikipedia)

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