The Safety Challenges of Nuclear Energy Nuclear energy plays a key role by providing 13% of the world's energy, but is one of the more controversial energy sources out there. Although the carbon footprint of nuclear energy is virtually zero, the political and safety risks associated with it cause people to have strong opinions on whether or not it should be used. A major part of the materials challenge of nuclear energy is improving safety through focusing on material degradation issues. Because the materials in nuclear power plants are exposed to extreme conditions, corrosion and cracking of structural parts is a large safety problem. Austentic stainless steels are the primary structural material used, while nickel-based alloys are used for higher-strength needs such as springs, tubes, and fasteners. The reason such materials are used is that they have good aqueous corrosion resistance at high temperatures. Finding alloys that are better suited for such conditions and alloys that are suited to the specific conditions in the new generation of power plants being created seems to be an important piece of improving the safety of nuclear power. Not only is it important for materials to be noncorrosive and capable of withstanding high pressures and temperatures, but they must also have low friction and be radiation insulating. To ensure resistance to high pressures the grain boundaries are carefully planned in the metal, and metals with strong intermolecular forces are used to keep them from breaking. Any friction can create air cavities, cause the wearing away of the pipes and decrease the flow rate through the system. All of this leads to less profitability, as pipes must be changed more frequently and a less efficient transfer of energy With some power plants having several decades of operation, even the best materials develop irregularities and require part replacements from time to time. To determine which pipes are at risk of bursting or developing cracks, 'eddy current testing' is performed, whereby an electromagnetic force is measured through the pipe and any irregularities in the lattice structure are detected by a weakening of the magnetic force. The lifetime of a nuclear power plant comes down to how long its materials will last and so materials improvements will provide economic benefits in addition to safety ones. Sources: Dexter, Stephen C., "Materials for containment of low-level nuclear waste in the deep ocean", US Office of Radiation Programs, pages 1-5, 1983 Gentry, Robert V., "Differential Lead Retention in Zircons: Implications for nuclear waste containment", Science, Vol. 216, p.296-299, 1982 Hrma, P. R., "Impact of Particle Size and Agglomeration on Settling of Solids in Continuous Melters Processing Radioactive Waste Glass", US Department of Energy, 2008 Schaible, Micah J. & Matyas, Josef, "Physical Modeling of Spinel Crystals Settling at Low Reynolds Numbers", 2009

• published: 06 May 2014
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