Law - Interaction Diagrams for Ambient and Heatec Concrete Sections, Engineering Structures.pdf
IN USE: CONCRETE STRUCTURE CHARACTERIZATION AND...
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Nondestructive Evaluation August 2016 ISSUE STATEMENT Materials aging in nuclear power plants has predominantly focused on the metals used in reactor internals, piping, sup- port structures, and welds. Concrete structures have received comparatively less attention, but recent field experience indi- cates that these structures may be beginning to show their age. While the performance of post- tensioned and rein- forced concrete structures in the nuclear power industry has been good, greater understanding of degradation mecha- nisms in a nuclear environment is essential. Adequate tools do not exist to characterize the integrity of existing and new concrete structures and to predict their remaining life. Improved nondestructive evaluation (NDE) techniques are needed to confidently assess structural integ- rity, as are certification processes and protocols to ensure their reliability. DRIVERS Asset Management Many utilities will need to budget for major repairs or replacements of large concrete structures. orough inspec- tion will be required to diagnose an estimated remaining life and allow utilities to optimize their approach to aging management. Long-Term Operation e economic basis for long-term operation requires techni- cal information regarding the structural soundness of plant systems and components, including concrete facilities. Structures such as concrete containment, basements and spent fuel pools cannot be replaced and can limit the service life of the plants. Regulatory Requirements Regulatory bodies may increase scrutiny of concrete struc- tures in defining requirements for life extension or license renewal. New Construction Technology gaps related to new infrastructure have already delayed construction activities at some new plant projects. ese gaps should be addressed to inform technical decisions for subsequent waves of new plant deployment. Limitations of Inspection Technology e NDE methods and structural assessment methods cur- rently available cannot provide the level of reliability required for existing and new nuclear plants and demanded by regu- latory requirements. A system to accommodate rapid NDE test deployment, identification of degradation, and imple- mentation of repair techniques would enhance the assess- ment of emerging issues in older plants. RESULTS IMPLEMENTATION Upon completion of this work, it is expected that: • All sectors of the electricity industry (nuclear, generation, transmission and distribution) will have access to best practices related to infrastructure asset management and inspections for concrete infrastructure. • Utilities will be able to deploy improved and reliable NDE tests to assess emergent and routine degradation of con- crete infrastructure. • Utilities will have an asset management platform for con- crete infrastructure where the rate of degradation can be predicted; and repairs, maintenance and replacement needs can be identified early and planned in advance. PROJECT PLAN Research on concrete degradation and inspection at EPRI started in 2008 and focused on fundamental degradation of concrete structures and its related inspection techniques. is roadmap builds upon that effort. is roadmap has four basic components: Enhanced NDE inspection, Aging Management Programs for Concrete Structures, Repairs and Mitigation, and Best Practices. Enhanced NDE inspection EPRI’s recent research in this area has shown that the reli- ability of NDE inspections is poor, especially when large and thick concrete structures are tested. is area will focus on improving the reliability of existing inspections and develop- ing new inspection techniques in areas where none are available. Infrastructure is changing and new designs of structures are constantly being introduced to decrease construction times. Inspection of these new designs is challenging and the inspection technologies used in conventional concrete struc- tures cannot always be used. is area will focus on inspec- tion of composite structures (steel-concrete) that are used in new nuclear plants and dry cask storage overpacks. IN USE: CONCRETE STRUCTURE CHARACTERIZATION AND NONDESTRUCTIVE EVALUATION
Transcript of IN USE: CONCRETE STRUCTURE CHARACTERIZATION AND...
Nondestructive Evaluation August 2016
ISSUE STATEMENT
Materials aging in nuclear power plants has predominantly focused on the metals used in reactor internals, piping, sup-port structures, and welds. Concrete structures have received comparatively less attention, but recent field experience indi-cates that these structures may be beginning to show their age. While the performance of post- tensioned and rein-forced concrete structures in the nuclear power industry has been good, greater understanding of degradation mecha-nisms in a nuclear environment is essential.
Adequate tools do not exist to characterize the integrity of existing and new concrete structures and to predict their remaining life. Improved nondestructive evaluation (NDE) techniques are needed to confidently assess structural integ-rity, as are certification processes and protocols to ensure their reliability.
DRIVERS
Asset ManagementMany utilities will need to budget for major repairs or replacements of large concrete structures. Thorough inspec-tion will be required to diagnose an estimated remaining life and allow utilities to optimize their approach to aging management.
Long-Term OperationThe economic basis for long-term operation requires techni-cal information regarding the structural soundness of plant systems and components, including concrete facilities. Structures such as concrete containment, basements and spent fuel pools cannot be replaced and can limit the service life of the plants.
Regulatory RequirementsRegulatory bodies may increase scrutiny of concrete struc-tures in defining requirements for life extension or license renewal.
New ConstructionTechnology gaps related to new infrastructure have already delayed construction activities at some new plant projects. These gaps should be addressed to inform technical decisions for subsequent waves of new plant deployment.
Limitations of Inspection TechnologyThe NDE methods and structural assessment methods cur-rently available cannot provide the level of reliability required for existing and new nuclear plants and demanded by regu-latory requirements. A system to accommodate rapid NDE test deployment, identification of degradation, and imple-mentation of repair techniques would enhance the assess-ment of emerging issues in older plants.
RESULTS IMPLEMENTATION
Upon completion of this work, it is expected that:• All sectors of the electricity industry (nuclear, generation,
transmission and distribution) will have access to best practices related to infrastructure asset management and inspections for concrete infrastructure.
• Utilities will be able to deploy improved and reliable NDE tests to assess emergent and routine degradation of con-crete infrastructure.
• Utilities will have an asset management platform for con-crete infrastructure where the rate of degradation can be predicted; and repairs, maintenance and replacement needs can be identified early and planned in advance.
PROJECT PLAN
Research on concrete degradation and inspection at EPRI started in 2008 and focused on fundamental degradation of concrete structures and its related inspection techniques. This roadmap builds upon that effort. This roadmap has four basic components: Enhanced NDE inspection, Aging Management Programs for Concrete Structures, Repairs and Mitigation, and Best Practices.
Enhanced NDE inspectionEPRI’s recent research in this area has shown that the reli-ability of NDE inspections is poor, especially when large and thick concrete structures are tested. This area will focus on improving the reliability of existing inspections and develop-ing new inspection techniques in areas where none are available.
Infrastructure is changing and new designs of structures are constantly being introduced to decrease construction times. Inspection of these new designs is challenging and the inspection technologies used in conventional concrete struc-tures cannot always be used. This area will focus on inspec-tion of composite structures (steel-concrete) that are used in new nuclear plants and dry cask storage overpacks.
IN USE: CONCRETE STRUCTURE CHARACTERIZATION AND NONDESTRUCTIVE EVALUATION
EPRI | Nuclear Sector Roadmaps August 2016
Aging Management of Concrete StructuresPrior studies on concrete degradation at EPRI and the DoE showed that the concrete degradation mechanisms of con-cern to the durability and structural integrity of concrete structures are: alkali-silica reaction, reinforcement corro-sion, boric acid attack and delaminations/cracking. Aging management programs for concrete irradiation, thermal damage and creep will be developed as the potential implica-tion of these degradation mechanisms on the structural integrity of concrete structures is determined.
Therefore, this area will focus on providing technical basis for aging management of concrete subjected to alkali-silica reaction, reinforcement corrosion, boric acid attack and delaminations/cracking. The approach will be based on the aging management program implemented within the mate-rials group at EPRI. This area will be heavily influenced by the long term operation needs of existing plants.
Repairs and MitigationThe objective of this work is to develop repair and mitigation techniques applicable to large concrete structures in nuclear facilities. The approach will be to address each degradation mechanism separately. This area has already started in 2014 with the development of guidance for mitigation of rein-forcement corrosion of concrete structures.
Best PracticesA significant body of work has been developed in this area reinforced by utility support in cases of severe degradation. This area will capitalize on best practices for durability of structures against common degradation mechanisms such as alkali-silica reaction, reinforcement corrosion, boric acid attack and delaminations/cracking.
The synergy between different energy sectors will be used to benefit this program. For example, the existence of similar concrete structures in hydroelectric plants, but with a differ-ent regulatory environment, may make it easier to start implementing new inspection techniques in that industry prior to their implementation in nuclear plants.
RISKS
• Cooperation: Utilities may be reluctant to test or imple-ment new inspection techniques unless required by a reg-ulatory agency or they can see immediate benefits with manageable risk. This risk can be managed by a) showing the benefits of inspection by using concrete structures in sectors that have less regulatory load and similar concrete structures; b) building awareness of the financial risk of not inspecting and maintaining concrete structures; c) using new inspection techniques in severely damaged structures that must be tested; d) testing decommissioned plants; and e) defining acceptance criteria.
• Awareness: Many utilities are not yet fully cognizant of the breadth of problems with concrete structures. This risk can be managed by making utilities aware of the deg-radation of concrete structures and the need to maintain those structures in acceptable conditions.
RECORD OF REVISION
This record of revision will provide a high level summary of the major changes in the document and identify the Road-map Owner.
revision description of change
0 Original Issue: August 2011 Roadmap Owner: Maria Guimaraes
1 Revision Issue: August 2012 Roadmap Owner: Maria Guimaraes
Changes: Within flowchart: Recorded completion of first milestone – Addition of all other milestones – Adjustment to timelines to reflect earlier starting of tasks
2 Revision Issue: August 2013 Roadmap Owner: Maria Guimaraes
Changes: Within flowchart – Recorded completion of milestone #2. Updated to accurately reflect funding of projects through the end of 2013.
3 Revision Issue: January 2014 Roadmap Owner: Maria Guimaraes
Changes: Within flowchart – Recorded completion of milestone #5. Updated to accurately reflect funding of projects and new deadlines.
4 Revision Issue: December 2014 Roadmap Owner: Maria Guimaraes
Changes: Within flowchart – Recorded completion of milestones. Updated to accurately reflect funding of projects and new deadlines.
5 Revision Issue: August 2015 Roadmap Owner: Maria Guimaraes
Changes: New roadmap to reflect the lessons learned from the past 5 years. Some areas have been sunset. The program is evolving towards an aging management program.
6 Revision Issue: August 2016 Roadmap Owner: Maria Guimaraes
Changes: Within Flowchart – Updated to accurately reflect funding.
Nondestructive Evaluation August 2016
EPRI | Nuclear Sector Roadmaps August 2016
