(ZIRAT24/IZNA19 STR)
The overall objective of this Special Topic Report (STR) is to provide the knowledge of how the reactor environment (fast neutron flux, temperature, water chemistry, etc.) and the Zr-alloy microstructure, which is a function of material chemistry and manufacturing process, impacts fuel performance during normal operations, transients, design basis accidents and interim dry storage.
(ZIRAT12/IZNA7 STR)
The welding of Zirconium Alloy components is one of the most critical manufacturing processes of Nuclear Reactor fuel. Small amounts of contamination resulting from inadequate cleanliness or from poor atmospheric control during welding may lead to diminished corrosion resistance of the weld and in severe cases to weld failure. Other weld defects such as piping, pore formation or insufficient weld penetration may also result in costly fuel failures. This Report describes the different welding processes used for the various fuel assembly components. A comprehensive discussion of welding Quality Management is included.
(ZIRAT6/IZNA1 STR)
The purpose of the report is to describe the fundamentals in crud formation, transport, and deposition, in order to provide a solid basis for evaluating and analysing any fuel operational problem due to crud deposits. The ultimate purpose is to provide knowledge and insight for staff involved in the operation and materials selection in nuclear power plants, in order to prevent the occurrence of any crud-related fuel problems.
(ZIRAT8/IZNA3 STR)
This report reviews the experience of the impact of Zn-injection (in PWRs and BWRs) and Nobel Metal Chemical Addition (NMCA) in BWRs on fuel integrity. The report also discusses fundamentals in crud formation related to Zn-injection and NMCA.
Hydride orientation has an important effect on fracture toughness of hydride-containing zirconium alloys because hydrides form as approximately linear arrays of platelet-shaped microscopic precipitates with habits on or near the basal planes of the α–Zr matrix in which they form.
This Stand Alone Report (SAR) addresses a key aspect of the issues raised in the foregoing by providing a comprehensive, self-contained and up-to-date review and analyses of the results of studies carried out on the conditions governing hydride orientation in zirconium alloy pressure and fuel cladding tubes used in nuclear reactors. The report combines a detailed theoretical and experimental overview of this subject with the author’s own analyses of these results. These analyses make use of theoretical advances documented in the author’s 2012 book dealing with the effects of hydrogen and hydrides on the integrity of zirconium alloy components. In the author’s 2012 book, emphasis is placed on delayed hydride cracking, which is a localised failure mechanism.
(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.
Except for a few countries (Finland, Sweden, France, and possibly Canada), the timing for establishing a geologic repository has been shown to be unpredictable. Therefore, spent fuel storage will remain the last backend operation for the foreseeable future in many countries. With proper attention, the radiological impact of storage is very low, but regulatory agencies have placed a heavy burden on licensees because of concerns related to the highly negative public perception related to the presence of spent fuel storage facilities in our biological environment. Therefore, locations where spent nuclear fuel (SNF) is or will be stored and their chosen storage technologies are the subjects of much scrutiny.
The focus of this review is on the spent nuclear fuel rods, and not on the storage system components such as the casks or the canisters and their internal hardware elements. More specifically, the following topics are treated in the report:
The Report discusses the different parameters impacting PWR fuel corrosion and provides a computer code which allows an equivalent comparison of new alloys irradiated in different reactors at different conditions. The computer code may also assist in identifying the mechanism why the corrosion rate starts to accelerate under certain conditions.
(ZIRAT15/IZNA10 STR)
With increased burnup, processes going on inside a nonfailed fuel rod decrease pellet density, lower the fuel melting temperature and thermal conductivity, increase the fission gas release. Also, a high burnup structure is formed at pellet average burnups in excess of about 50 MWd/kgU This volume I of the report describes the processes going on inside a nonfailed fuel rod during normal operation. The associated volume II of the report describes the corresponding information during accident conditions (RIA and LOCA).
(ZIRAT15/IZNA10 STR)
Processes going on inside a nonfailed fuel rod may have dramatic impact on fuel performance during normal operation and during accident conditions such as Loss Of Coolant Accident (LOCA) and Reactivity Initiated Accident (RIA) This volume II of the report describes the above information during accident conditions (RIA and LOCA). The associated volume I of the report describes the processes going on inside a nonfailed fuel rod during normal operation.