Advanced Instrumentation, Information, and Control System Technologies: Nondestructive Examination Technologies - FY11 Report

Abstract

Licensees of commercial nuclear power plants in the United States are expected to submit license renewal applications for the period of operation of 60 to 80 years which has also been referred to as long term operation (LTO). The greatest challenges to LTO are associated with degradation of passive components as active components are routinely maintained and repaired or placed through maintenance programs. Some passive component degradation concerns include stress corrosion cracking of metal components, radiation induced embrittlement of the reactor pressure vessel, degradation of buried piping, degradation of concrete containment structures, and degradation of cables.Proactive management of passive component aging employs three important elements including online monitoring of degradation, early detection of degradation at precursor stages, and application of prognostics for the prediction of remaining useful life. This document assesses several nondestructive examination (NDE) measurement technologies for integration into proactive aging management programs. The assessment is performed by discussing the three elements of proactive aging management identified above, considering the current state of the industry with respect to adopting these key elements, and analyzing measurement technologies for monitoring large cracks in metal components, monitoring early degradation at precursor stages, monitoring the degradation of concrete containment structures, and monitoring the degradation of cables.Specific and general needs have been identified through this assessment. General needs identified include the need for environmentally rugged sensors that can operate reliably in an operating reactor environment, the need to identify parameters from precursor monitoring technologies that are unambiguously correlated with the level of pre-macro defect damage, and a methodology for identifying regions where precursor damage is most likely to initiate. v Summary Long-term operation (LTO) of the current fleet of nuclear power plants (NPPs) has been identified as high priority by the U.S. Department of Energy as part of an overall effort to meet rising demands for electricity and meet international obligations to lower greenhouse gas emissions. NPP operators are granted an initial license term of 40 years to operate and are eligible for multiple 20-year license extensions beyond the initial expiration. It is anticipated that most plants will apply for and be granted the initial 20-year license extension (21 initial license renewals have been approved thus far) but subsequent license extensions are less clear due to uncertainties regarding the performance of safety critical systems, structures and components (SSCs) beyond 60 years.Active SSCs (including pumps, valves, and rotating machinery) are well managed and undergo routine maintenance and repair/replacement activities through plant maintenance programs and are not expected to challenge LTO of NPPs. Passive SSCs (pipes, vessels, concrete, and cables) are managed by p...

Needs and opportunities: nondestructive evaluation for energy systems

“…Such plants typically undergo a major refurbishment before they are granted a license extension to enable them to operate for an additional 20 years. 44 and specifically from the NDE perspective there is significant interest in NDE for the detection and characterization of degradation precursors 45 . In looking at some cracking phenomena the various stages in degradation development present different challenges.…”

Prognostics and Health Management in Nuclear Power Plants: A Review of Technologies and Applications

“…Nondestructive measurement methods available for passive components include radiography, ultrasonic imaging, visual inspection, electromagnetic inspection (including eddy currents, potential drop methods, etc. ), and thermal imaging (Meyer et al 2010;Meyer et al 2011a). Almost all of these methods (with the exception of visual inspection) are focused on the detection of hidden damage in components, and rely on the interaction of applied energy with the material damage sites.…”

“…However, there are still no accepted measurement technologies for the detection and assessment of some degradation mechanisms unique to NPPs, such as void swelling. A recent review of monitoring techniques for passive systems is given in Meyer et al (2011a). Several key areas of effort have been identified for passive SSCs, including the reactor pressure vessel and Class 1 metal components, reactor vessel internals, concrete structures, cables, buried piping, and large transformers.…”

HTGR Measurements and Instrumentation Systems

“…[81][82][83] Material prognostics are especially important at HTGRs since at the higher temperatures the structural alloys have a greater tendency to creep under load, and careful monitoring and consequent adjustment of operating conditions can significantly extend the life of expensive, difficult-toreplace structural components.…”