Service Life Management System of Concrete Structures in Nuclear

projects, especially the O

ECD/NEA SCAP project (stress corrosion cracking and cable ageing),

the CIR-project (Co-operative IASCC Research) and in the Halden IASCC project. The project manager is steering committee member of the ICG-EAC (International co-operative group on environmentally assisted cracking) and in the scientific board for the 13th Symposium on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors.

Professor Roger Staehle visited VTT in September and gave three public lectures on steam generator corrosion related topics for more than 20 attendees.

6. Report archiving

The new task, report archiving, started in 2008 by collecting information on types, amounts

and diaries for nuclear materials reports, and continued with prosing a strategy for digital

report archiving.

• Developing the degradation and service life models by taking into account the material properties, structural details and environmental stresses specifically for each module.

• Developing and programming of the service life management system (SLMS).

• Developing the life cycle cost analysis and the life cycle assessment analysis (environmental impact analysis) and combining them with the condition analysis

Development and programming of structural degradation analyses and a system for serviceability limit state design

Developing and programming the design algorithm for serviceability state design in accordance with Eurocode 2 into the code of the design program “IVODIM” and conducting necessary tests for verification.

• Report on serviceability limit state and crack width analysis of concrete structures.

Risk analyses for the service life management system

• Pre-study on the risk analyses of steel liner and prestressing tendons in containment buildings..

• Report on the methods and outlines of the risk analyses for the corrosion of steel liner and prestressing tendons in containment buildings.

Participation in concrete technological research cooperation with other owners of infrastructure (BTS)

Partners in the BTS-research cooperation in 2008 were The Finnish Road Administration, The Finnish Rail Administration, Radiation and Nuclear Safety Authority (financing by National Nuclear Waste Management Fund), City of Helsinki, City of Tampere, and City of Turku. The research items in 2008 were the following:

1. Consulting on concrete technological topics

2. Correlation between shrinkage measurement methods and acceptance criteria (continued from 2007)

3. RH measurement method of the substrate for waterproofing and RH criteria 4. Electrochemical chloride extraction form reinforced concrete

5. Rapid, cheap and simple chloride content measurement method for site

In 2007 a field study DURAFIELD on durability of concrete materials and structures was started. In 2008 this project was enlarged international and the project name was changed to DURAINT. The results of this research can be utilised in the degradation models of NPP structures.

International cooperation (OECD/ NEA/IAGE and COST C25)

• Participation in OECD/NEA/CSNI/IAGE (Integrity and Aging) work group. IAGE

work group is divided into three subgroups: IAGE Seismic, IAGE Metal and IAGE

Concrete. The IAGE Concrete group deals with aging phenomenon and aging management of concrete structures in nuclear power plants.

• Participation in COST Action C25 “Sustainability of Constructions: Integrated Approach to Life-time Structural Engineering” meetings. and seminars

Deliverables in 2008

Development and programming of the service life management system

• The databases were finalised and connected to the framework of the service life management system. The databases of structures and structural modules include identification data, history data (dates of manufacturing and repairs), structural data, material data, measuring data, exposure data, observed damage data (inspection data) and specification data for the possible future maintenance and repair actions. The database for maintenance and repair systems includes data of optional materials (within the system), costs data, environmental impact data, data on degradation types and rates, data related to factors affecting the service life etc

• The degradation and service life models were finalised and integrated to the service life management system. The program was provided also with a calibration system of degradation models based on the observed degradation during in-service inspections and special inspections.

• The service life management tool was developed and tentatively programmed. Thus the first version of the program SERVICEMAN is ready. The outlines of the system are presented in the publication “Service life management system of concrete structures in nuclear power plants”. The system includes an automatically conducted condition analysis and a condition guarding system for each module of the system. The condition guarding system is able to trigger maintenance and repair actions every time when the preset condition limits are exceeded. The timings and specifications of the actions can be later changed manually.

•

Automatic LC cost analysis and the environmental impact analysis was developed and

combined with the condition analysis of the management system. The system produces

automatically life cycle action profiles (specification and timing of future maintenance

and repair actions) for all modules of the plant and the life cycle costs and

environmental impacts are counted both action based and life cycle based.

Figure 1. One of the results displays of the SLM Tool.

Development and programming of structural degradation analyses and a system for serviceability limit state design

• The development of serviceability limit state design for reinforced concrete structures was continued until the end of year 2008. The system is utilising the results of a FEM analysis and dimensioning is done through the in-house computer program according to the selected standard (National building code of Finland: B4, DIN 1045, SNiP-84). The system is applicable within structural analysis and limit state design especially in reinforced concrete structures of nuclear power plants. In 2008 the developed design algorithm was programmed into the in-house computer program developed for structural design and analysis of reinforced concrete structures. Also the design algorithm of ultimate limit state was developed and programmed and necessary verification tests were conducted. Reliability of the program was ensured by simple hand calculations for limited number of shell and beam elements and loading conditions.

• The report on serviceability limit state and crack width analysis of concrete structures according to Eurocode 2 was written. The report contains the algorithms and formulas of serviceability (and ultimate) limit state design. The report contains also a couple of calculation examples which demonstrates differences between design codes B4 and EC2.

Risk analyses for service life management system

• A report on the risk analysis methods and procedures with special reference to aging

effects on concrete structures in nuclear power plants was made. The report focuses on

risk analysis methods which can be used in studying the aging effects on prestressing

tendons and steel liners of containment buildings. At the end of the report a procedure

that can be used for a time variant risk assessment of pre-stressing tendons and steel liners is presented.

Participation in concrete technological research cooperation with other owners of infrastructure (BTS)

The following reports of the BTS-research cooperation were written in Finnish:

• Report on correlation between shrinkage measurement methods and acceptance criteria.

• Literature survey on RH measurement method of the substrate for waterproofing and RH criteria is under progress. Tests have been started.

• Report on electrochemical chloride extraction form reinforced concrete.

• Report on rapid, cheap and simple chloride content measurement method for site.

DuraInt reports:

• Effect of interacted deterioration parameters on service life of concrete structures in cold environments. State-of-the-art report.

• Field and laboratory testing and service life modelling in Finland. Paper for Nordic Miniseminar.

International cooperation (OECD/ NEA/IAGE and COST C25)

• Participation in the OECD/NEA IAGE WG Concrete subgroup meeting on 31st March in Paris. Memorandum in Finnish.

• Participation in the COST C25 Meeting in Belgrade 4th – 5th April. Participation in the

COST C25 Midterm seminar in Dresden 6th-7th Oct 2008. Several papers on service

life prediction and life cycle management tools were presented and published.

No documento SAFIR2010 Annual Report 2008 - VTT project pages server (páginas 76-80)