[en] Considerable potential for improvement is felt to exist in the maintenance of nuclear installations with a view to further reducing the residual risk and the costs of maintenance. The development of adequate concepts is suggested on the basis of representative studies yet to be conducted in nuclear plants. An important tool in remedying present weak spots and omissions is experience-oriented preventive maintenance. This concept is characterized by its definition of specific maintenance measures on the basis of past experience. In this way, it helps to avoid, by prophylaxis, disturbances and uneconomic approaches resulting from necessary measures either not being taken at all or taken too late, while unnecessary measures are prevented altogether. Each and every maintenance measure which is superfluous not only represents a cost factor but, as a consequence of potential mistakes or deteriorations of plant conditions, even impairs plant safety. (orig.)

[en] The nine discussion papers presented at the meeting use theoretical models and practice-based examples to show that apart from the technical aspects always playing an important role, facts and aspects of the fields such as law, economics, and insurance systems do have significance. For three papers a separate subject analysis has been made for the database. (HP)

[en] Very High Resolution (VHR) satellite images are used to verify the correctness and completeness of declarations provided by member States, and to generate preparatory information for on-site inspections and technical visits. VHR satellite images are also used for collect data for nuclear monitoring in inaccessible areas of interest. Most satellites acquire image in the morning, and the better resolution requires higher costs. This presentation is focused on introduction of alternative VHR satellite images: KOMPSAT (KOrean Multi-Purpose SATellite) constellation. KOMPSAT-2 (1.0 m resolution) and KOMPSAT-3(0.7 m resolution) provides VHR optical images and KOMPSAT-5 (1.0 m resolution) provides VHR SAR images as well and those make it possible to look into the situation more accurately and promptly. KOMPSAT-3 has highest quantization with 14 bits per pixel, which contains more information than any other optical satellite. SI Imaging Services offers further VHR optical satellite data such as DubaiSat-2 and Deimos-2 which provide 1m resolution optical image. Shorter revisit time on a specific target can be achieved by combination of KOMPSAT-2, -3, -5, DubaiSat-2, and Deimos-2. KOMPSAT constellation provides not only unique combination of optical and SAR but also unique imaging time combination, namely 06:00, 10:50, 13:30, and 18:00. Using this constellation, event related monitoring over a specific target can be achieved and change detection within one day can be performed. Data continuity for both optical and SAR data is guaranteed by long-term government commitment followed by KOMPSAT-3A (Optical and IR) and KOMPSAT-6 (SAR). This unique combination can provide advanced data sets to analysts by enhancing collection capability and enabling integrated analysis for important assignments. (author)

[en] In this paper we describe the round robin tests that have been designed and are being conducted in the international program. Participants in the PINC have offered more than 30 test blocks for use in round-robin tests of NDE effectiveness. The test blocks have more than 130 flaws in nickel-base weld metal that are intended to simulate PWSCC in a variety of component geometries. NDE techniques representative of current in-service inspections are being applied, along with emerging NDE approaches

[en] Surveillance techniques are based on the detection of changes. These changes can be caused by moving objects or people, or by modifications made to the environment itself. Visual surveillance uses optical means, e.g., the analysis of an image acquired by a surveillance camera. These techniques are effective in detecting objects moving within the surveyed area. There are situations, however, where optical surveillance may prove to be unreliable. In some cases, the changes in the image are too small to be properly detected with scene change detectors. In other cases, alarms are generated without objects (or people) moving. These false alarms may be caused by changes in illumination, e.g., a faulty lamp or spurious reflections in places near water pools. Further, the absence of illumination during a blackout (whether it is caused by accident or on purpose) prevents cameras from their surveillance operation. There are high security installations for which it is necessary to introduce reliable, independent and effective sensors that can keep the surveillance work even during a blackout. Laser range scanners are electronic instruments measuring the distance from the instrument itself to the outside world along a specific direction. The type of the instrument to use depends on the range of distances to measure. Indeed, whereas for large distances (e.g. between 1 and 200m) it is possible to use time-of-flight instruments, for short distances (e.g., from a few centimetres to about 1.5m) a triangulation laser striping system is used. The deflection of the laser beam (e.g., using rotating mirrors) enables the acquisition of the distance profiles (or matrices) of the surrounding premises in a very short time

[en] Safety of nuclear power plants is one of the most important conditions for their acceptance. Safety is being acheived by numerous methods and techniques in phase of design, manufacturing and maintenance of the nuclear power plants. In-service Inspection (ISI) has a significant role in avoidances of failure in components of nuclear power plants just the same as in assurance of their integrity. Non-destructive examinations are performed periodically in accordance with 10 CFR 50 50.55a and ASME Boiler and Pressure Vessel Code section XI which is referenced by 10 CFR 50.55a. Nondestructive examinations provide information about a current condition of equipment at nuclear power plants and about any damage, defect or degradation mechanism. A lot of effort is often spent in situations in which the probability of failure and their effects on safety have a very low impact. Practical experience shows that failures can often occur at locations where the inspection has never been performed. Costs and expenses of in-service inspections are very high. Therefore, the accent has to be on locations with significant risk to safety. Many years of nuclear power plants' operation and maintenance have resulted in a more broad knowledge of degradation mechanism and the most susceptible locations and huge databases of different nuclear power plants' components. U.S. Nuclear Regulatory Commission (NRC) and the nuclear industry have recognized that probabilistic risk assessment (PRA) has developed and changed to be more useful in improvement of traditional engineering approaches in nuclear power plants regulation. After the publication of its policy statement on the use of PRA in nuclear regulatory activities, the Commission ordered the NRC staff to develop a regulatory framework that incorporated risk insights. The American Society of Mechanical Engineers (ASME) initiated Code Case N-560, N-577, and N-578 that address the importance of categorization and inspection of piping using risk insights. It is expected that licensees will ask for modifications of plant's design, operation, and other activities that require NRC approval to incorporate risk insights into their ISI programs. In-service inspection program in which is incorporated risk insights is known as risk-informed in-service inspection programs, RI-ISI. Until the RI-ISI is approved for generic use, the staff expects that licensees will ask for modifications of ISI programs by requesting NRC to approve alternative inspection programs. Alternative inspection programs must meet 10 CFR 50.55a (a)(3)(i) which says that 'the applicant shall demonstrate that the proposed alternatives would provide an acceptable level of quality and safety'. As always, licensees should identify how the chosen approach, methods, data, and criteria are appropriate for the decisions that have to be made. RI-ISI can provide reduction of scope and frequency of inspections that may lead to higher risk. The higher risk means that a probability of failure or consequences are higher and shutdown of nuclear power plants is more likely to occur. RI-ISI can also provide extensive scope of inspection or increased frequency of inspection. (author)

[en] Burn-in is an effective tool to improve product reliability and reduce field failure costs before a product is sold to customers. As many products are becoming highly reliable, traditional burn-in that tests a batch of a product until most weak units fail requires an unaffordable testing duration. If the product failure can be associated with an underlying degradation process and a weak unit degrades faster than a normal one, then degradation-based burn-in can be implemented. Due to such various factors as human errors and limited precision of the measurement device, measurement errors are often inevitable. Ignoring measurement errors in the degradation observations would lead to inferior burn-in decisions. This study uses the Wiener process to model the underlying degradation and considers Gaussian measurement errors in the observations. Two burn-in models with different cost structures are studied and the optimal cutoff level for each model is obtained analytically. The relation between the two models is discussed, leading to a new cost model. - Highlights: • Degradation-based burn-in considering measurement errors is studied. • Optimal burn-in strategies are proposed under different cost models. • Impacts of measurement errors on the burn-in strategies are investigated. • A new cost model is proposed for burn-in test.

[en] This patent describes a method of inspecting a fuel assembly to determine the orientation of externally-projecting mated bulges connecting a grid sleeve to a guide thimble of the assembly, the method comprising the steps of: (a) inserting a radially-expandable tubular member within the guide thimble, the tubular member having externally-projecting embossments thereon spaced circumferentially from one another about the tubular member, the embossments being the same in number as the bulges of the guide thimble and configured to fit therewithin; (b) axially moving an elongated expansion member, which extends through and rotatably mounts the tubular member, relative to the tubular member from a first position in which the expansion member permits inward contraction of the tubular member and displacement of embossments thereon away from the interior of the guide thimble bulges for removing the embossments from registry therewith and a second position in which the expansion member produces radial expansion of the tubular member and displacement of the embossments thereon toward the interior of the guide thimble bulges for placing the embossments in registry therewith; (c) rotating the tubular member relative to the expansion member so as to bring the embossments on the tubular member into alignment with the guide thimble bulges as the embossments on the tubular member are being displaced toward and into registry with the interior of the bulges; and (d) responsive to rotation of the tubular member away from a reference position, providing an indication of the orientation of the guide thimble bulges relative to a reference point upon displacement of the embossments into registry therewith

[en] The purpose of this presentation is to educate the audience on best practices that have been identified for analysis, inspection, cleaning and maintenance of power plant bus duct systems. Many plant managers ignore bus duct, forgetting it is the only system critical component in the power plant that does not have redundancy. The presentation will provide first-hand insight into forty years of experience and field findings of the Nation's premier high voltage power conductor experts. Presentation topics will include case studies detailing inspection options (both online and offline), the ramifications of poorly and/or inadequately maintained bus duct systems, current trends in predictive maintenance programs, and best practices for bus duct inspection and cleaning (including insight into the newest technologies available). (author)

[en] The main objectives of this project are to enhance the national radiation protection infrastructure through the strengthening of the analytical capabilities in the field of radiation monitoring, and to improve the performance to respond to the increasing load of service samples and to comply with the latest legislation concerning the radioactivity content in consumable goods. Also this project will enhance the capabilities to develop researches applied to elemental analysis and their applications in environmental radioactivity studies, and will perform the skills in this field. (author)