Mechanical Testing of Zirconium Alloys – Vol. I
(ZIRAT18/IZNA13 STR)
This report covers separate effects testing of Zr alloys
Pellet-Cladding Interaction
(ZIRAT11/IZNA6 STR)
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
(ZIRAT6/IZNA1 STR)
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.
Charged Particle Bombardment of Zirconium Alloys
(ZIRAT19/IZNA14 STR)
The ability of reactor engineers to predict changes in the dimensions of the reactor core components during service is crucial to the safety and efficiency of reactor operation. Successful core design anticipates dimensional changes due to thermal expansion, stress-induced elastic deformation and, to some extent, large stress plastic deformation of core components. Of greater difficulty is predicting dimensional changes due to the effects of the intense irradiation environment, mainly due to high energy neutrons produced by the fission process. Fuel rods, spacers/grids, channels, guide tubes, tie rods, other structural components, etc. – all undergo irradiation-induced dimensional changes due to irradiation growth, irradiation creep, irradiation-altered plastic deformation, and irradiation-influenced corrosion and hydriding of the zirconium alloy components. These topics and process are routinely covered by the ZIRAT Programmes. This Report reviews the effect of ion irradiation (or ion bombardment, used interchangeably in this report) on not only the standard dimensional stability topics but also the full range of properties that can be influenced by ion irradiation. The primary questions addressed are: What properties of zirconium alloys can ion irradiated simulate (emulate or substitute for) neutron irradiation? How, or to what extent, can ion bombardment complement neutron irradiation?
BWR Fuel Channel Distortion
(ZIRAT16/IZNA11 STR)
In the past ten years approximately half of the 35 BWRs in the United States have reported Control Blade interference due to channel distortion, primarily channel bow. Channels fabricated by all vendors have been affected. This Report is primarily focused on channel distortion; that is, change of shape during in-reactor service: length, bow, bulge and twist. This Report addresses a broad range of channel features which can contribute to normal and problematic performance. In particular, the so-called “shadow corrosioninduced” channel bow phenomena are analyzed.
In-Reactor Creep of Zirconium Alloys
(ZIRAT14/IZNA9 STR)
In this Report we have attempted to summarize data and mechanisms by addressing the variables that are known to affect irradiation creep. A number of conclusions are reached which give insight into the uses of creep data, mechanisms and models to assess in-service performance of reactor components.
Structural Behaviour of Fuel Components
(ZIRAT10/IZNA5 STR)
The objective of this Report is to provide a better understanding of the mechanisms behind the dimensional changes of structural materials in LWRs and CANDUs. Such improved understanding may improve both fuel reliability and reactor safety.
Dimensional Stability of Zirconium Alloys
(ZIRAT7/IZNA2 STR)
This report provides the understanding of the mechanisms of dimensional instability (including irradiation creep and growth) in the aggressive environment of the nuclear core and the potential effects on fuel performance.
Effect of Hydrogen on Zirconium Alloy Performance (Normal Operaton, LOCA/RIA and Dry Storage) – Vol. II
(ZIRAT13/IZNA8 STR)
The intent of these two reports is to discuss the basics of hydrogen, hydrides and their effect on the zirconium alloy properties in Volume I and in-pile performance during normal and accident conditions as well as dry storage in Volume II. A better understanding of the mechanisms by which hydrogen/ hydrides impacts zirconium alloy properties and in-pile performance may enable the nuclear industry to find means to reduce the harmful effects of hydrogen/hydrides on the material in-pile performance.
Effect of Hydrogen on Zirconium Alloy Properties – Vol. I
(ZIRAT5/IZNA1 STR)
The objective of this report is to provide the basic understanding of the hydrogen pickup and redistribution mechanisms involved and the impact of hydriding on fuel performance.