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Kerr M.,Queens University | Daymond M.R.,Queens University | Holt R.A.,Queens University | Almer J.D.,Argonne National Laboratory | Stafford S.,Kinectrics Inc.
Scripta Materialia | Year: 2010

This paper reports X-ray diffraction results obtained during in situ precipitate growth studies. A Zr-2.5Nb specimen containing 60 wt. ppm hydrogen was subject to a thermomechanical cycle in order to precipitate hydrides preferentially at a 15 μm root radius notch. Diffraction patterns were collected as a function of time, during growth of a large (∼100 μm long) notch-tip hydride. The results indicate that hydride precipitation relaxes the crack tip strain field and confirm differences in overload behavior observed at room temperature and 250 °C. © 2009 Acta Materialia Inc. Source

Hasegawa K.,Japan Nuclear Energy Safety Organization | Meshii T.,University of Fukui | Scarth D.A.,Kinectrics Inc.
Journal of Pressure Vessel Technology, Transactions of the ASME | Year: 2011

One of the more common modes of degradation in power plant piping has been wall thinning due to erosion-corrosion or flow-accelerated corrosion. Extensive work has been performed to understand flow-accelerated corrosion mechanisms and develop fracture criteria of locally thinned pipes since the tragic events at Surry Unit 2 and Mihama Unit 3. A large number of tests have been performed on carbon steel pipes, elbows, and tees with local wall thinning. In addition, the American Society of Mechanical Engineers Boiler and Pressure Vessel Code provides procedures in Code Case N-597-2 for the evaluation of wall thinning in pipes. This paper provides validation of the evaluation procedures in Code Case N-597-2 by comparing with the field rupture data and pipe burst test data. The allowable wall thinning from the Code Case N-597-2 procedures is shown to maintain adequate margins against rupture. © 2011 American Society of Mechanical Engineers. Source

In any reactor physics analysis, the instantaneous power distribution in the reactor core of any power reactor, including CANDU-type reactor, can be calculated when the actual bundle-wise burnup distribution is known. Considering the fact that CANDU utilizes the on-power refuelling to compensate for the reduction in reactivity due to fuel burnup, in the CANDU fuel management analysis, snapshots of power and burnup distributions can be obtained by simulating and tracking reactor operation over an extended period using various tools such as the∗SIMULATE module of the reactor fuelling simulation program (RFSP) code. However, for some studies, such as an evaluation of a conceptual design of a next generation CANDU reactor, the preferred approach to obtain a snapshot of the power distribution in the core is based on the patterned-channel-age model implemented in the∗INSTANTAN module of the RFSP code. The objective of this approach is to obtain a representative snapshot of core conditions quickly. Presently such patterns could be generated by a program called RANDIS which is implemented within the∗INSTANTAN module. Presented in this paper is an alternative approach to derive the patterned-channel-age model where an optimization algorithm is utilized to find patterns which produce representative power distributions in the core. In the present analysis, the genetic algorithm (GA) technique has been successfully utilized to find a quasi-optimal patterned-channel-age. This paper is Part I of a two-part paper which highlights the development of this alternative method for generating patterned-channel-ages. © 2016 Elsevier Ltd. All rights reserved. Source

Chisholm W.A.,Kinectrics Inc. | Chisholm W.A.,University of Quebec at Chicoutimi
IEEE Electrical Insulation Magazine | Year: 2010

Lightning overvoltages were causing problems on overhead lines well before Tesla and Edison argued over the merits of ac and dc. Many of the overvoltage protection methods for distribution lines follow the same philosophy as that used for telegraph and telephone lines. For example, early surge protective devices on single-phase power lines used single or multiple air gaps (Figure 1) that followed telegraph line protection measures closely. © 2006 IEEE. Source

El-Hag A.H.,American University of Sharjah | Meyer L.H.,Regional University of Blumenau | Naderian A.,Kinectrics Inc.
IEEE Electrical Insulation Magazine | Year: 2010

Aging, under contaminated conditions, manifests itself by tracking and/or erosion of polymer materials and insulators and usually leads to failure of insulators. Aging is still one of the main causes of the registered failures of polymer insulators in the field. Consequently, to improve both materials and insulator designs, it is important to understand the mechanisms of aging, as well as the factors surrounding aging, and the best way to do this is through actual field experience. However, the problem with field experience is that it often requires a very long time before any noticeable changes become evident. For this reason, several laboratory accelerated tests have been developed to evaluate aging of polymer materials and insulators. Laboratory aging tests are of 2 types: one for polymer materials and another for polymer insulators. Salt-fog and rotatingwheel tests are examples of tests for insulators, and the inclinedplane tracking and erosion of insulating materials test is an example of a test for materials. Using both tests to either design or evaluate insulators requires exhaustive work, but regardless of the aging test, the main challenge is to correlate accelerated aging in the laboratory to the natural aging process to correctly evaluate the insulator design or material. The 2 most important characteristics of polymer materials are their hydrophobicity, which prevents the development of leakage current (LC), and their resistance to the degradation process that can ensue when hydrophobicity is lost, either temporarily as in the case of silicone and silicone co-polymers or permanently as for other polymer materials. These 2 characteristics are also interrelated with the profile of the insulator. As a result, it is important to evaluate the performance of polymer insulators and materials based on these 2 characteristics using accelerated aging tests. This article briefly describes the experiences of using both the IEC 61109 salt-fog test and the IEC 60587 inclined-plane test, with some emphasis on the practical difficulties of using these tests and what can be measured by each test. © 2006 IEEE. Source

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