The detection of failed fuel in LWRs [light water reactors] - a historical review

The light water reactor (LWR) industry has progressed significantly from the early homogeneous reactors and the lack of fuel rods to its current state. With the development of fuel rods, a need for failure detection emerged. The basic visual inspection used in the early days of the industry has evolved to present-day ultrasonic, sipping, and computer analysis of isotopes. The first detection methods concentrated on the detection of assemblies that contained an unknown number of failed fuel rods. Recent techniques have developed too such a point that the detection of failed assemblies during normal operations, and then the timely location of failed fuel rods during scheduled outages, can be accomplished. This paper reviews the historical development of fuel rod detection, the major trend changes, and the resulting present-day methods utilized by the LWR industry. The ultimate goal, exact failed fuel rod detection during operations, has not been reached but continues to improve. The trend has been, and largely still is, to identify the presence of failed fuel rods during operation and then to locate the specific failed rods during operation and then to locate the specific failed rods during scheduled outage periods. Detection during operation must be developed further, and location methods must be enhanced while maintaining the current excore detection methods