2010 Technology Innovation Strategic Programs TI Strategic Program: Advanced Nondestructive Evaluation Overview Nondestructive Evaluation (NDE) tech- nologies are critical for determining structural integrity, estimating remaining lifetime, avoiding failure, and demon- strating safety and reliability for in-ser- vice power plant components. To address critical capability gaps, EPRI is develop- ing advanced techniques for ultrasonic testing (UT) of buried piping, assessment of aging concrete structures, and early detection of creep and cracking. In addi- tion, NDE methods are being devised for inspection of cast stainless steel compo- nents and examination of piping weld- ments during—rather than after—the welding process. Progress and Plans In 2009, EPRI established feasibility for hand-held “acoustic mouse” technology offering equivalent or improved accuracy, lower costs, and greater applicability than today’s leading automated UT inspection methods. For several other areas of ongo- ing strategic research, achievements to date and next steps are highlighted below. Additional details are available from the EPRI project managers and recent publications. Buried Piping. Although leaks of tritium- contaminated water from underground piping and related systems at nuclear plants pose no health threats, public con- cern has created operations and relicensing challenges and made new inspection requirements for buried components likely. To develop methods for avoiding expen- sive and time-consuming excavations, two underground inspection test mock-ups were constructed in 2009, one at EPRI’s offices in Charlotte, NC, and the second at its nearby storage yard. Currently, guided-wave (GW) UT equipment is being applied in combination with finite element analysis to examine and model underground piping mockups at both sites. New understanding of GW propaga- tion will support refinement of UT probes and analytics for enhanced detection, sizing, and characterization of inside diam- eter, outside diameter, and weld flaws. By 2012, improved “minimal dig” inspection technology—incorporating advanced data processing and analysis algorithms—is expected to be ready for field demonstra- tion and qualification testing at nuclear plant sites. Value. Commercial NDE technology capable of accurately assessing the integrity of buried components will help meet regulatory mandates, inform run-repair- replace decision-making, and support long-term plant operation. Minimizing the need for excavation alone could provide huge savings, as individual plants host miles of piping and the cost associated with individual inspection points ranges Advanced NDE techniques for assessing the integrity of buried piping could substantially reduce inspection costs by minimizing the need for excavation while supporting long-term operation of nuclear plants and other generating facilities. Strategic Connections New Plant Build • Component Degredation • Long-Term Operations • Safety •
Transcript
2010 Technology Innovation Strategic Programs
TI Strategic Program: Advanced Nondestructive Evaluation
Overview
Nondestructive Evaluation (NDE) tech-nologies are critical for determining structural integrity, estimating remaining lifetime, avoiding failure, and demon-strating safety and reliability for in-ser-vice power plant components. To address critical capability gaps, EPRI is develop-ing advanced techniques for ultrasonic testing (UT) of buried piping, assessment of aging concrete structures, and early detection of creep and cracking. In addi-tion, NDE methods are being devised for inspection of cast stainless steel compo-nents and examination of piping weld-ments during—rather than after—the welding process.
Progress and Plans
In 2009, EPRI established feasibility for hand-held “acoustic mouse” technology offering equivalent or improved accuracy, lower costs, and greater applicability than today’s leading automated UT inspection methods. For several other areas of ongo-ing strategic research, achievements to date and next steps are highlighted below. Additional details are available from the EPRI project managers and recent publications.
Buried Piping. Although leaks of tritium-contaminated water from underground piping and related systems at nuclear
plants pose no health threats, public con-cern has created operations and relicensing challenges and made new inspection requirements for buried components likely. To develop methods for avoiding expen-sive and time-consuming excavations, two underground inspection test mock-ups were constructed in 2009, one at EPRI’s offices in Charlotte, NC, and the second at its nearby storage yard. Currently, guided-wave (GW) UT equipment is being applied in combination with finite element analysis to examine and model underground piping mockups at both sites. New understanding of GW propaga-tion will support refinement of UT probes and analytics for enhanced detection, sizing, and characterization of inside diam-eter, outside diameter, and weld flaws. By 2012, improved “minimal dig” inspection technology—incorporating advanced data processing and analysis algorithms—is
expected to be ready for field demonstra-tion and qualification testing at nuclear plant sites.
Value. Commercial NDE technology capable of accurately assessing the integrity of buried components will help meet regulatory mandates, inform run-repair-replace decision-making, and support long-term plant operation. Minimizing the need for excavation alone could provide huge savings, as individual plants host miles of piping and the cost associated with individual inspection points ranges
Advanced NDE techniques for assessing the integrity of buried piping could substantially reduce inspection costs by minimizing the need for excavation while supporting long-term operation of nuclear plants and other generating facilities.
Strategic Connections
New Plant Build•
Component Degredation•
Long-Term Operations•
Safety•
from about $100,000 to $500,000. Improved inspection, detection, and char-acterization capabilities also can lower the risk of leaks and structural damage and the possible loss of public confidence.
Aging Concrete. Current inspection prac-tices for aging concrete structures at nuclear plants rely heavily on visual tech-niques. To advance the industry’s NDE capabilities, a state-of-knowledge assess-ment was initiated in 2009 in collabora-tion with the Material Aging Institute, EdF, and Oak Ridge National Laboratory. A new EPRI reference manual introduces materials degradation mechanisms, opera-tional considerations, and assessment protocols for spent fuel pool, cooling tower, containment, and other structures. Ongoing modeling focuses on long-term reactions involving ordinary Portland cement and water containing boric acid, and laboratory evaluation of aging in post-tensioned concrete containment structures is planned. In addition, com-mercial NDE methods are being evaluated
for imaging of voids, cracks, and other internal features within concrete, and instrumentation suitable for spent fuel pool leakage and structural monitoring is being explored. Field demonstration and testing of promising techniques specific to problems and degradation mechanisms in concrete structures at nuclear plants are expected to begin within the next few years.
Value. New knowledge and technologies supporting inspection, condition assess-ment, and repair of aging concrete infra-structure are critical not only for meeting anticipated regulatory requirements relat-ing to continued safe plant operation for lifetimes of 60 years and beyond but also for informing near-term asset management decisions. For example, advanced NDE capabilities would allow faster diagnosis, analysis, and mitigation of delamination or extensive voiding due to construction or operational events, leading to significant savings. At one U.S. plant, accelerated degradation detected in a containment
wall has resulted in downtime, diagnosis, and repair costs on the order of $100 million.
Early Creep and Cracking. Mechanical damage generally cannot be detected until it has progressed for several years and entered the final, rapid phase of crack growth. For reliability and safety purposes, frequent inspection of critical components is required, even shorter intervals are nec-essary once a crack is detected, and unscheduled interventions are sometimes needed. To support detection and moni-toring of incipient damage, EPRI has completed a state-of-knowledge assessment and developed a dedicated laboratory set-up for in situ evaluation of test sam-ples. Preliminary experiments using acous-tic emission and digital emission correlation capabilities are under way, to be followed by investigation of these and other advanced NDE methods for inspec-tion and monitoring of samples exposed to conditions associated with creep and intergranular stress corrosion cracking. Field demonstration and qualification testing of promising techniques are expected to begin within the next few years.
Value. NDE technology capable of detect-ing cracking at initiation, monitoring propagation of incipient damage during operation, and informing intervention would help optimize maintenance and repair activities at nuclear and fossil plants, producing significant savings while reduc-ing the likelihood of component failure. Demonstrating crack arrest in a single 14-inch-diameter dissimilar metal weld at a nuclear plant would yield savings on the order of $1 million, giving a sense of the scale of potential economic benefits.
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Images of the welded pipe sample instrumented with fiber optic strain gages oriented transverse
to the weld.
1021581 September 2010
Electric Power Research Institute 3420 Hillview Avenue, Palo Alto, California 94304-1338 • PO Box 10412, Palo Alto, California 94303-0813 USA 800.313.3774 • 650.855.2121 • [email protected] • www.epri.com
For more information, contact the EPRI Customer Assistance Center at 800.313.3774 ([email protected])
C O N TA C T S
Program Value
Improved NDE capabilities are critical to address emerging regulatory issues and safety concerns and support long-term operation of nuclear power plants, as well as to reduce costs and inform run/repair/replace decision-making for fossil capac-ity. Innovative technologies, more accu-rate flaw detection and characterization techniques, and lower-cost inspection methods will provide substantial savings across the existing generation fleet, for new assets, and in other industries.
Resources
Concrete Civil Infrastructure in United States Commercial Nuclear Power Plants (1020932)
The Electric Power Research Institute, Inc. (EPRI, www.epri.com) conducts research and development relating to the generation,
delivery and use of electricity for the benefit of the public. An independent, nonprofit organization, EPRI brings together its scientists and
engineers as well as experts from academia and industry to help address challenges in electricity, including reliability, efficiency, health, safety
and the environment. EPRI also provides technology, policy and economic analyses to drive long-range research and development planning,
and supports research in emerging technologies. EPRI’s members represent more than 90 percent of the electricity generated and delivered
in the United States, and international participation extends to 40 countries. EPRI’s principal offices and laboratories are located in Palo Alto,
Calif.; Charlotte, N.C.; Knoxville, Tenn.; and lenox, Mass
