Recycling, aluminum-based alloys

Modern processing is based on the Hall-Heroult method, which makes inexpensive aluminum widely available. Aluminum is a remarkable metal. It does not corrode the way iron does, and we can recycle it easily — altiminum cans are continuously melted down and reused. One of the metal s most important properties is its low density. It s very light. That s why the Soviets used it to construct Sputnik, the world s first satellite. And the space shuttle is made primarily of aluminum as well. The huge fuel tank that dominates the vehicle is an aluminum alloy. Aluminum even gets the shuttle into outer space — it s the fuel used in the solid fuel boosters. That s because aluminum burns in the presence of an oxidizing agent, providing the thrust needed to get the shuttle into orbit so that it can meet up with the space station. 

A considerable amount of operating experience with U-Al fuels in aluminum and aluminum alloy cladding exists. This should be at least partially applicable to the Pu-Al fuels. The maximum bumup level expected with Pu-Al fuels without a recycle step is based on the performance of U-Al fuel plates irradiated in the Advanced Test Reactor. This bumup level (70% FIMA) is based on fuel element swelling and fission product release limitations in a thin plate geometry under conditions of high fission rates. More robust geometries might be fissioned to safe bumup levels in excess of 90%. Burnable poisons have been added to U-Al fuel plates with little difficulty, so burnable poisons could probably be added to a Pu-Al fuel form. 

The different alloying elements nsed in gold solders and brazes have implications for recycling that need to be considered. Many base metals can cause embrittlement in gold alloys, even at low concentrations, and the treatment of scrap would have to recognize this problem and implement suitable solutions, analogous to the handling of aluminum scrap. 

---