1st Nuclear Knowledge Preservation & Consolidation (NKP&C) Workshop

Nuclear knowledge had been build up continuously since the middle of the last century. After Chernobyl in 1986 the public opinion changed leading to a gradual phasing out process of nuclear energy in several Member States. During that time a trend at universities and in industry was observed of a decrease in students choosing nuclear related studies. Now the generation of senior nuclear experts is retiring. On the other hand, due to security supply and climate change issues (green house mitigation measures) receiving more importance lately, a renaissance of nuclear power is ongoing. In order to avoid a possible loss of capability and knowledge in the EU action is taken now preserving and disseminating it to the new generation. There is a huge amount of information and knowledge available, either published or easily available, but also publications difficult to trace. Especially those are at risk of being dispersed or lost due to a series of factors, including: ¿ retirement of Senior Experts who were present at the time when most Nuclear Power Plants were designed and put into operation, ¿ generational gap (due to years of decline in new constructions, only a limited number of people started their career in that area) ¿ non-electronic publishing in the past ¿ limited dissemination possibilities ¿ language (many non-English publications from Eastern countries) Therefore, the Institute for Energy of the Directorate General Joint Research Centre has developed a method for consolidation of nuclear knowledge Several reviewers received between 7 and 21 papers in their field of expertise, in order to review the content and present it for discussion and consolidation to the WWER Reactor Pressure Vessel embrittlement experts during the workshop. The reports and presentations were requested to follow the below structure: o per paper ¿ paper title, author(s), reference ¿ reviewers summary/abstract ¿ comments on "up-to-date-ness" of the papers/material o conclusion on the complete review: ¿ more reference papers in the area known to the reviewer ¿ open issues in the area known to the reviewer The short-term scope is to reach a consolidated conclusion for the individual reviews, after the discussion and consolidation process during the workshop. The medium-term scope is a consolidated review in the individual expert fields. The long-term scope is to prepare a State-of-the-Art report for the complete WWER RPV Irradiation Embrittlement expert field, incl. the history and reasons of the choices made (material, composition, etc.). The last general document was produced more than 26 years ago by Nikolaev, Amaev and Alechenko, which is in Russian and needs upgrading.JRC.F.4-Safety of future nuclear reactor

Peer Review Report 2006

This document is reporting findings from the research peer reviews held February 7-9, 2006 for PHMSA’s Pipeline Safety Research and Development Program. The findings and recommendations in this report derive from the scoring and comments collected from the peer review panelists. Department of Transportation (DOT) Operating Agencies (OA) are required to begin a systematic process for peer review planning for all influential and highly influential information that the OA plans to disseminate in the “foreseeable” future. Through the Information Quality Act, Congress directed Office of Management and Budget (OMB) to “provide policy and procedural guidance to Federal agencies for ensuring and maximizing the quality, objectivity, utility, and integrity of information, (including statistical information) disseminated by Federal agencies.” A resulting OMB Bulletin entitled, “Final Information Quality Bulletin for Peer Review” was issued prescribing required procedures for Federal programs. The Office of the Secretary of Transportation (OST) produced procedures governing modal implementation of this OMB Bulletin. These procedures as well as the OMB Bulletin serve as the basis and justification for the PHMSA Pipeline Safety R&D Program peer reviews. Peer reviews are intended to uncover any technical problems or unsolved issues in a scientific work product through the use of technically competent and independent (objective) experts. Peer review of a major scientific work product that will have the imprimatur of the Federal Government needs to be incorporated into the upfront planning of any action based in the work product. This includes obtaining the proper resources commitments (reviewers and funds) then establishing realistic schedules

Peer Review Report 2006

This document is reporting findings from the research peer reviews held February 7-9, 2006 for PHMSA’s Pipeline Safety Research and Development Program. The findings and recommendations in this report derive from the scoring and comments collected from the peer review panelists. Department of Transportation (DOT) Operating Agencies (OA) are required to begin a systematic process for peer review planning for all influential and highly influential information that the OA plans to disseminate in the “foreseeable” future. Through the Information Quality Act, Congress directed Office of Management and Budget (OMB) to “provide policy and procedural guidance to Federal agencies for ensuring and maximizing the quality, objectivity, utility, and integrity of information, (including statistical information) disseminated by Federal agencies.” A resulting OMB Bulletin entitled, “Final Information Quality Bulletin for Peer Review” was issued prescribing required procedures for Federal programs. The Office of the Secretary of Transportation (OST) produced procedures governing modal implementation of this OMB Bulletin. These procedures as well as the OMB Bulletin serve as the basis and justification for the PHMSA Pipeline Safety R&D Program peer reviews. Peer reviews are intended to uncover any technical problems or unsolved issues in a scientific work product through the use of technically competent and independent (objective) experts. Peer review of a major scientific work product that will have the imprimatur of the Federal Government needs to be incorporated into the upfront planning of any action based in the work product. This includes obtaining the proper resources commitments (reviewers and funds) then establishing realistic schedules

Machine Learning Approach for Risk-Based Inspection Screening Assessment

Risk-based inspection (RBI) screening assessment is used to identify equipment that makes a significant contribution to the system's total risk of failure (RoF), so that the RBI detailed assessment can focus on analyzing higher-risk equipment. Due to its qualitative nature and high dependency on sound engineering judgment, screening assessment is vulnerable to human biases and errors, and thus subject to output variability and threatens the integrity of the assets. This paper attempts to tackle these challenges by utilizing a machine learning approach to conduct screening assessment. A case study using a dataset of RBI assessment for oil and gas production and processing units is provided, to illustrate the development of an intelligent system, based on a machine learning model for performing RBI screening assessment. The best performing model achieves accuracy and precision of 92.33% and 84.58%, respectively. A comparative analysis between the performance of the intelligent system and the conventional assessment is performed to examine the benefits of applying the machine learning approach in the RBI screening assessment. The result shows that the application of the machine learning approach potentially improves the quality of the conventional RBI screening assessment output by reducing output variability and increasing accuracy and precision.acceptedVersio

Meeting the challenges related to material issues in chemical industries

Reliable performance and profitability are two important requirements for any chemical industry. In order to achieve high level of reliability and excellent performance, several issues related to design, materials selection, fabrication, quality assurance, transport, storage, inputs from condition monitoring, failure analysis etc. have to be adequately addressed and implemented. Technology related to nondestructive testing and monitoring of the plant is also essential for precise identification of defect sites and to take appropriate remedial decision regarding repair, replacement or modification of process conditions. The interdisciplinary holistic approach enhances the life of critical engineering components in chemical plants. Further, understanding the failure modes of the components through the analysis of failed components throws light on the choice of appropriate preventive measures to be taken well in advance, to have a control over the overall health of the plant. The failure analysis also leads to better design modification and condition monitoring methodologies, for the next generation components and plants. At the Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, a unique combination of the expertise in design, materials selection, fabrication, NDT development, condition monitoring, life prediction and failure analysis exists to obtain desired results for achieving high levels of reliability and performance assessment of critical engineering components in chemical industries. Case studies related to design, materials selection and fabrication aspects of critical components in nuclear fuel reprocessing plants, NDT development and condition monitoring of various components of nuclear power plants, and important failure investigations on critical engineering components in chemical and allied industries are discussed in this paper. Future directions are identified and planned approaches are briefly described

The Effect of Corrosion Defects on the Failure of Oil and Gas Transmission Pipelines: A Finite Element Modeling Study

The transportation of oil and gas and their products through the pipelines is a safe and economically efficient way, when compared with other methods of transportation, such as tankers, railroad, trucks, etc. Although pipelines are usually well-designed, during construction and later in service, pipelines are subjected to a variety of risks. Eventually, some sections may experience corrosion which can affect the integrity of pipeline, which poses a risk in high-pressure operations. Specifically, in pipelines with long history of operation, the size and location of the corrosion defects need to be determined so that pressure levels can be kept at safe levels, or alternatively, a decision to repair or replace the pipe section can be made. To make this decision, there are several assessment techniques available to engineers, such as ASME B31G, MB31G, DNV-RP, software code called RSTRENG. These assessment techniques help engineers predict the remaining strength of the wall in a pipe section with a corrosion defect. The corrosion assessment codes in the United States, Canada and Europe are based on ASME-B31G criterion for the evaluation of corrosion defects, established based on full-scale burst experiments on pipes containing longitudinal machined grooves, initially conducted in 1960s. Because actual corrosion defects have more complex geometries than machined grooves, an in-depth study to validate the effectiveness of these techniques is necessary. This study is motivated by this need. The current study was conducted in several stages, starting with the deformation behavior of pipe steels. In Phase 1, true-stress-true plastic strain data from the literature for X42 and X60 steel specimens were used to evaluate how well four commonly used constitutive equations, namely, those developed by Hollomon, Swift, Ludwik and Voce, fit the experimental data. Results showed that all equations provided acceptable fits. For simplicity, the Hollomon equation was selected to be used in the rest of the study. In Phase 2, a preliminary finite element modeling (FEM) study was conducted to compare two failure criteria, stress-based or strain-based, performed better. By using data from the literature for X42 and X60 pipe steels, experimental burst pressure data were compared with predicted burst pressure data, estimated based on the two failure criteria. Based on this preliminary analysis, the stress-based criterion was chosen for further FEM studies. In Phase 3, failure data from real corrosion pits in X52 pipe steels with detailed profiles were used to develop a FEM scheme, which included a simplified representation of the defect. Comparison of actual and predicted burst pressures indicated a good fit, with a coefficient of determination (R2) level of 0.959. In Phase 4, burst pressure levels were estimated for real corrosion pits for the experiments from the same study as in Phase 3, but only with corrosion pit depths and length and without corrosion widths. Widths were estimated from the data used in Phase 3, by using an empirical equation as a function of pit length. There was significant error between experimental and predicted burst pressure. Errors in Phases 3 and 4 were compared statistically. Results showed that there is a statistically significant difference in the error when the width of the corrosion pit is unknown. This finding is significant because none of the assessment techniques in the literature takes width into consideration. Subsequently, a parametric study was performed on three defect geometries from the same study in Phase 3. The pit depths and lengths were held constant but widths were changed systematically. In all cases, the effect of the pit width on burst pressure was confirmed. In Phase 5, the three assessment techniques, ASME B31G, MB31-G and DNV-RP were evaluated by using experimental test results for X52 pipe. Synthetic data for deeper pits were developed by FEM and used along with experimental data in this phase. Two types of the error were distinguished to classify defects. Type I errors (α) and Type II errors (β) were defined using Level 0 evaluation method. Results showed that although ASME B31G is the most conservative technique, it is more reliable for short defects than MB31G and DNV-RP. The least conservative technique was DNV-RP but it yielded β error, i.e., the method predicted a safe operating pressure and pipe section would fail. Therefore, DNV-RP is not recommended for assessment of steel pipes, specifically for X52 pipes

Weld Residual Stress Profiles for Structural Integrity Assessment

Economic and safe management of operating nuclear power plants can be highly dependent on the structural integrity assessments for safety critical pressure vessels and piping components. In engineering fracture assessment procedures the full (3-D) residual stress field at a welded joint is usually simplified by considering a representative onedimensional profile through the wall-thickness of the stress tensor component acting normal to the crack face. The stress intensity factor, calculated from this estimated through-thickness stress profile, is used directly in the fracture assessment. Therefore, assessments of defects in welds can be highly sensitive to the through-thickness residual stress profiles assumed in the calculations. There is a need for reliable characterisation of residual stresses in welded structures such as in stainless steel girth welded pipes as there are a lot of discrepancies in the current methodologies used. For example, bounding residual profiles found in fitness for service assessment procedures have been based on examination of residual stress measurements, finite element weld simulation and expert judgment. This approach suffers from the drawback that the upper bound curve can increase as more measurements and data scatter are obtained. The consequence of this is that structural integrity assessments of defective plant can be over-conservative by a large margin, and may lead to unnecessary and costly repair or inspection. This thesis illustrates how a neural network model, can be developed and applied to predict through-thickness residual stress profiles in austenitic stainless steel pipe girth welds for simplified fracture assessments. The model is validated by comparing predictions with new experimental measurements made using neutron diffraction and contour method. The new measurements were undertaken by fabricating six pipe girth welds with a range of wall-thickness, weld heat input and weld groove geometries. The robustness of the developed artificial neural network (ANN) approach is demonstrated by sensitivity studies in input variables and training data. The performance and suitability of the ANN approach is discussed by comparison with stress profiles recommended in defect assessment procedures. This is followed by an evaluation of whether the use of neural network bounding profiles can lead to non-conservative estimates of stress intensity factor in fracture assessments. The neural network approach shows sufficient potential to be developed into an alternative prediction tool for use in fracture assessment of welded components

Institute for Energy Annual Report 2006

Report on Activities, accomplishment and resources related to the JRC's Institute for Energy work carried out in 2006. An overview is given of the organisational changes, the mission and its implementation, the scientific activities and relations with customers and partners.JRC.C.7-Knowledge for the Energy Unio