LAUSR

Worldwide, the generation of electric power has several sources of energy that can be grouped as: (a) fossil fuels (coal, petroleum and natural gas), (b) nuclear and (c) renewable (wind, solar, hydroelectric, geothermal, biomass, etc.) sources. The Energy Information Administration of the USA predicts that by the year 2040 the world energy consumption by source will be dominated by fossil fuels, and nuclear energy will represent less than 10% of the total. However, 100% of the nuclear energy consumed is used to generate electricity, as compared, for example, with liquid fuels where only 1% of their consumption is used to generate electricity. As of mid-2017, the International Atomic Energy Agency reports that there are 449 nuclear power reactors in operation in the world, which generate approximately 20% of the electricity consumed. Most of these reactors use a uranium dioxide fuel encased in zirconium alloys cladding and are cooled by light water. In March 2011, a tsunami in northeast Japan caused plant blackouts at the Fukushima nuclear reactors. The lack of power to circulate the cooling water to remove the heat of fission caused the zirconium alloys on site to react rapidly with overheated water and steam producing zirconium oxide, hydrogen gas, and large amounts of heat due to the exothermic oxidation of the zirconium. Buildings exploding due to the ignition of the accumulated hydrogen were shown on the news worldwide. Due to the Fukushima accident, the international community has been working for the last quinquennium on the development of a nuclear fuel that will be resistant to events similar of those of Fukushima. This newer fuel has been called accident tolerant fuel (ATF) but currently some prefer to call it advanced technology fuel (ATF). Several ATF concepts are being developed worldwide to minimize the consequences of an accident. In general, the concepts can be grouped in three categories: (1) Use of iron-chrome-aluminum (FeCrAl) alloy for cladding of uranium dioxide fuel, (2) use of silicon carbide (SiC) as cladding material for either current fuel or uranium silicide fuel, and (3) use of coatings for the current zirconium alloys or molybdenum. Each of the three-broad concepts has its benefits and detriments. This special issue of Corrosion Reviews contains four contributions focusing on ATF materials interaction with the environment and encompassing the three concepts mentioned above. The first paper by Fumihisa Nagase et al. from Japan is a literature review of the degradation modes of the materials considered in several countries. The second contribution by Chongchong Tang et al. from Germany is also a review on the performance of surface modifications of zirconium (e.g. use of coatings) to minimize the reactivity of zirconium with water as the temperature increases. The third paper comes from Bruce A. Pint of the United States, where he describes the resistance of FeCrAl alloys to react with very high temperature (1400°C) steam by the formation of an alumina layer on their surface. The fourth and last paper by Raul B. Rebak et al. is an original research contribution on the resistance of FeCrAl alloys to oxidation in pure water at temperatures at near 300°C, which are the typical temperatures of normal operation conditions of the reactors. The studies at General Electric were performed for environments simulating the conditions of both pressurized water reactors containing excess hydrogen and boiling water reactors containing either oxygen or hydrogen. The subject of materials interaction with the environment for ATF is an ever-evolving field. The four offered manuscripts are intended to be a starting point on the current state of the art for many young professionals who may be joining this field of study in the next few years.