Radiation Corrosion
Radiation corrosion, also known as “electrochemical corrosion,” is the deterioration of metal components due to the exposure of radiation. Radiation corrosion can occur both externally and internally and is not limited to metal components, as non-metal materials can also be affected. Radiation corrosion occurs when metal is exposed to the energy of radiation in the form of gamma rays, x-rays, or neutrons. This type of corrosion occurs when the metal is exposed to high levels of radiation and will cause the metal to become brittle and corroded over time.
The effects of radiation corrosion on metal depend largely on the type of radiation and the amount of exposure to which the metal is subjected. For example, gamma rays and x-rays, which have very high energy levels, have an ionizing effect on the metal that can create an electrochemical reaction between the metal and the environment. Neutrons, which have a lower energy level, will cause local heating of the metal surface which can lead to embrittlement and corrosion over time.
One of the most common forms of radiation corrosion is oxidation. Oxidation occurs when electrons are transferred from one metal atom to another. In this process, the metal being corroded will lose two or more electrons, which are then transferred to oxygen molecules present in the environment. As the metal loses electrons, the oxygen molecules form an oxide film on the metal surface, and this oxide film can act as a barrier, preventing further corrosion and reducing the rate of corrosion reaction. Depending on the severity of the radiation exposure, oxidation can eventually cause the metal to become brittle, lose strength, and break down.
In addition to oxidation, radiation corrosion can also cause chemical changes to the metal, as chemical bonds are sometimes broken and new ones are formed. Rapid bonds swapping causes the metal surface to become softer, weaker, and more porous, which can eventually accelerate corrosion. Neutron-induced changes to the metal’s chemical composition can also take place and can lead to deterioration of the metal’s performance and integrity.
Radiation corrosion is pervasive in areas such as nuclear power plants, where the exposure to radiation is higher than normal. Metal components used in these environments must be coated with protective layers such as Zirconium oxide or other corrosion-inhibiting materials in order to minimize the effects of radiation corrosion on the metal components. Additionally, proper design and use of the metal parts must be taken into account in order to ensure their stability and longevity.
Radiation corrosion is a real problem, and one that must be addressed if metal components are to stand up to the harsh environment of a nuclear power plant. With proper maintenance and design, radiation corrosion can be minimized and metal components can function as designed without fail, ensuring the safety of all those in the vicinity of the plant.
