Pellet-Cladding Interaction (PCI and PCMI): progress in nuclear industry


Pellet-Cladding Interaction (PCI) and Pellet-Cladding Mechanical Interaction (PCMI) remains an important phenomenon in the modern nuclear reactor fuel engineering. This topic was addressed in detail in ZIRAT-11 Special topical report on PCI issued in 2006. Since then, a substantial development has taken place, such as introduction of new cladding materials and additive fuel pellets. In addition to this, flexible power operation is being considered by many utilities worldwide. This introduces new challenges to the safe and reliable operation of the nuclear fuel. The report discusses up-to-date developments in the above mentioned areas and summarizes the main outcomes of the R&D work performed since 2006.


Pellet-Cladding Interaction

PCI has historically resulted in a large number of fuel failures in BWRs but also to some extent in PWRs. The introduction of various remedies such as power change operation restrictions and liner/barriers in BWRs has reduced the number of PCI failures. However, there are some recent fuel failures in both BWRs and PWRs that has put the PCI failure mode in focus again. The objective of this report is to give a better understanding of the PCI mechanisms, pertinent methods to test PCI performance and PCI remedy technology may improve fuel reliability and reactor safety.


Mechanical Properties of Zirconium Alloys

Adequate mechanical properties are crucial for satisfactory fuel assembly performance: 1) in-pile under normal operation, anticipated operational occurrences and accident conditions as well as, 2) under intermediate storage conditions. The objective of this report is to provide the basic understanding of the mechanical properties of the fuel components that are crucial for the fuel in-pile performance.