Symbio International Workshop 2012 on Advanced Condition Monitors for Nuclear Power And

Symbio International Workshop 2012 on Advanced Condition Monitors

for Nuclear Power and Other Process Systems,

September 3, 2012, Kyoto, Japan

Invited Lecture

On-line monitoring for passive structures in nuclear power plants

Leonard J. Bond、PhD

Director, Center for Nondestructive Evaluation (CNDE)

Professor of Aerospace Engineering,

Iowa State University, USA

ABSTRACT

As systems in a nuclear power plant (NPP) age there is in general material degradation, and the “life” of structures, systems, and components eventually consumed to the point where there is potential for loss of function and safety is impacted. The safe operating or remaining useful life of a nuclear power plant will therefore be ultimately limited by materials and their degradation issues. Active components (e.g. pumps, valves, motors, etc) can be monitored and in general they are well managed, and replaced as necessary, using condition based maintenance methods to determine and track condition and its degradation. It is the passive components, which include the reactor pressure vessel, primary piping, core internals, cables, buried piping and the concrete, both in terms of that which forms the nuclear island and that which comprises the containment, are now considered to be the items that will limit a plants life. Passive structure is currently managed under an aging management plan and the in-service inspections that are specified therein. The majority of US plants are expected to operate longer term operation (LTO) (40-60 years) and attention is now turning to extended longer term operation (eLTO), where plants would operate from 60-80 years. In terms of these second license extension a critical decision date is 2020, after which no decision, will in effect be a “NO” decision and alternate generating capacity will need to start to be built. It is most probably the management of the passive components in NPP, and the capital costs of upgrades and refurbishments, combined with the economics of monitoring, replacement and repair, which will determine the economic viability for plants after 60 years and if they will enter extended longer term operation (60-80 years). This seminar will provide an overview of online condition monitoring for the nuclear power industry for passive components. It will include the lessons learned from trials that demonstrated acoustic emission and discuss the opportunities for on-line monitoring technologies including guided waves and diffuse fields to give the assurance that an aging plant can maintain the ability to respond to a design basis event, even on the last day of operation.