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).
Reactor neutron irradiation dramatically affects the properties and performance of all the materials in the reactor core. This report focuses on the behaviour of zirconium alloys used for the main structural components in the fuel bundle and should provide a solid understanding of the role that irradiation plays in component performance. This report is a complementary companion to the Structural Behaviour of Fuel Components (ZIRAT10/IZNA5 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.
To meet the current situation with more aggressive reactor environments, a large number of zirconium alloys have been and are being developed. The objective of this Report is to ensure that the new Zirconium Alloys performs satisfactory during normal operation, Anticipated Operational Occurrences (AOOs), postulated accidents and intermediate dry storage.
This Report is a comprehensive review and evaluation of the high strength nickel alloys (625, 718, X-750 and A286) used for PWR/VVER and BWR fuel assembly components. These alloys have been used for spacer grids, bolts and springs since the start of the LWR industry. The report concentrates on the good performance record as well as a description of the reported failures, their causes and remedies. The relationship of various heat treatments to the microstructures and their corrosion resistance are discussed.
One of the major present challenges to nuclear energy lies in its commercial competitiveness. To stay competitive, the industry needs to maximize the availability and capacity factors of nuclear power plants while reducing maintenance and fuel cycle costs and enhancing safety. Extended burnup is one of the methods applied to meet these objectives. There are a number of issues related to normal operation, anticipated operation occurrences, design basis accidents and dry storage that need resolution to be able to successfully implement extended burnup. This special topic reviews the potential consequences of increased burnup on fuel. Recommendations are also given on how to remedy the high burnup issues.
This Fuel Design Review Handbook intends to provide a guide to the items that have the greatest influence on fuel performance and prioritize the audits that are recommended. A review of all aspects of the fuel design is not feasible or necessary within the time constraints of the utility and the vendor. The objective is to do the most effective audit in the shortest time period. The Handbook provides the “what, why and how” for the audits by describing the design criteria, their influence on performance and the approach to reviewing the associated design features for the three distinct technical areas of nuclear, thermalhydraulic, and mechanical/materials design, each written by experts in their field. A guide for design tool verification is included as well as a guide to auditing the vendor design QA system.
This first volume of the Fuel Material Technology Report covers short general outlines of the designs of PWR, BWR, CANDU, VVER and RBMK reactors but with focus on the corresponding fuel assembly and supporting structure designs together with the rational for the selection of the materials used in the different applications. This volume also gives an overview of the in-reactor fuel performance, of fuel performance codes and the manufacturing process of the fuel assembly.
In this second volume of the Fuel Material Technology Report, the following topics for different water cooled type reactors are covered:
- Effect of radiation on the various fuel assembly materials as well as the interaction between materials and cooling water chemistry in this radioactive environment.
- Water chemistries in different reactor types
- Fuel design criteria and operating limits
- Fuel performance during Loss Of Coolant Accidents and Reactivity Initiated Accidents
- Fuel performance during intermediate storage
- Trends and potential burnup limitations
The primary objective of this volume of the Fuel Material Technology Report, FMTR Vol. IV, is to provide guidance in improving fuel reliability. To reach this objective, various Poolside and Hot Cell Examinations techniques may be used. A good knowledge of the pros- and cons- of the different techniques can guide the utility or fuel vendor to select the most cost efficient techniques for their specific goals. A second objective of this Report is to document this knowledge in a form which can be updated as new information, and methods become available.