Reliability Prediction of Acrylonitrile O-Ring for Nuclear Power Applications Based on Shore Hardness Measurements

The degradation of polymeric components is of considerable interest to the nuclear industry and its regulatory bodies. The objective of this work was the development of a methodology to determine the useful life—based on the storage temperature—of acrylonitrile O-rings used as mechanical sealing elements to prevent leakages in nuclear equipment. To this aim, a reliability-based approach that allows prediction of the use-suitability of different storage scenarios (that involve different storage times and temperatures) considering the further required in-service performance, is presented. Thus, experimental measurements of Shore A hardness have been correlated with storage variables (temperature and storage time). The storage (and its associated hardening) was proved to have a direct effect on in-service durability, reducing this by up to 60.40%. Based on this model, the in-service performance was predicted; after the first three years of operation the increase in probability of failure (POF) was practically insignificant. Nevertheless, from this point on, and especially, from 5 years of operation, the POF increased from 10% to 20% at approximately 6 years (for new and stored). From the study, it was verified that for any of the analysis scenarios, the limit established criterion was above that of the storage time premise considered in usual nuclear industry practices. The novelty of this work is that from a non-destructive test, like a Shore A hardness measurement, the useful life and reliability of O-rings can be estimated and be, accordingly, a decision tool that allows for improvement in the management of maintenance of safety-related equipment. Finally, it was proved that the storage strategies of our nuclear power plants are successful, perfectly meeting the expectations of suitability and functionality of the components when they are installed after storage.

Elaboration of standards and quality of railway rails

Russian national standards for rails establish technical requirements, acceptance rules and quality control methods. These are very important to ensure the quality and service durability of rails. Requirements for rail production variation within a period from 1960 to the present considered, peculiarities of their accounting in the standards shown. It was demonstrated that stricter requirements to rails resulted in the development of new steel compositions, the creation and introduction of new technological processes in steel production, rail rolling and heat treatment, as well as new methods of production quality control. Basic technical requirements for rails produced according to the national standard of theRussian Federationand to the European Norm presented. It was pointed out that the current national standard GOST R 51685‒2013 was elaborated accounting the requirements of the latest foreign standard EN 3674-1:2011+A1:2017. However, the former is not equivalent to the latter because it pertains to Russian rail types and contains requirements corresponding to the Russian climatic and geographical conditions, as well as the track facilities system used by OJSC RZD. It was shown that rails, meeting the current standard requirements, in terms of operational resistivity exceed the resistivity level of best foreign analogues. At present, a new standard is being elaborated accounting the need of increasing the service life of railway rails under conditions of high load, low climatic temperatures, higher-speed combined train operation and high-speed running, and high working capacity. The list of key issues presented, that are mirrored in the new standard draft, which accounts for the goal of mastering new rail categories and the increased requirements of OJSC RZD to rails quality.

The Evaluation of Short- and Long-Term Performance of Cold-Mix Asphalt Patching Materials

Potholes, one of the major types of distress on pavement surfaces, damage vehicles and are a safety hazard for the travelling public. In order to mitigate the effect of potholes, cold-mix asphalt (CMA) patching materials are commonly used for urgent repair of pavement surfaces before resurfacing can be undertaken. Therefore, the short-term (initial stability) and long-term (in-service durability) performance evaluation of CMA patching materials is necessary. This study conducted several curing conditions in the laboratory to investigate short-term, long-term, and moisture effects on pavement surfaces. Moreover, this study compared the Marshall stability of samples prepared under various compaction conditions. Marshall stability, Cantabro abrasion, and UK wheel tracking tests were conducted to evaluate the performance of CMA patching materials. The results indicated that the Marshall stability of dense-gradation (DG) CMA patching materials was higher than that of open-graded (OG) CMA patching materials and the Marshall stability of OG CMA patching materials was highly influenced by the coarse aggregate proportion. The DG and OG CMA patching materials exhibited comparable abrasion resistance, and the Cantabro abrasion ratio was highly correlated to the estimated asphalt film thickness for the OG CMA patching materials. A moisture indicator (MI) was proposed, and the effect of moisture damage on Marshall stability and Cantabro abrasion ratio was related to the proposed MI. The rutting resistance of the DG CMA patching materials was higher than that of the OG CMA patching materials, which is consistent with the Marshall stability result.

Natural Weathering of Bio-Based Façade Materials

Although there is a global awareness that the exploitation of non-renewable materials is unsustainable, there has been limited interest in fully utilizing natural, renewable resources like wood and its products because of the service durability concerns. One such issue is the aesthetical degradation of wooden facades due to the impact of weathering. This research was carried out as an international cooperation project to ascertain the weathering resistance of bio-based façade materials under the Estonian climate. In total, 120 bio-based façade materials obtained from 31 different companies, universities and research institutions from 17 countries were investigated. The specimens were placed on an exposure rack, inclined at an angle of 45° located at 59°23′50.6″ N 24°39′24.0″ E and then subjected to accelerated natural weathering for 2 years. Parameters such as precipitation, UV index, temperature and relative humidity were measured during the period of the natural weathering. The influence of the weathering on the colour change and cracks on the surface of test specimens was evaluated using Minolta Chroma Meter CR-121 (Konica Minolta INC., Tokyo, Japan) and Avongard Check Width Gauge (Avongard Ltd., Gloucestershire, UK), respectively. The results showed that the untreated natural wood façade materials presented the least resistance to weathering, while 63 of the tested materials developed checks. The outcome of this study is essential to the optimization of software-simulating changes in the appearance of façade materials in outdoor conditions.

Impact of Brand Loyalty on Consumers Packaged Milk Products in Chennai

Brand loyalty is refers to positive feeling towards the brand and the continuous purchase of particular brand products..It various from place to place depending on quality, reliability, service, durability etc. The main objectives of this study is to study the factors influencing brand impact of milk among rural and urban consumers and to analyse the problems faced by rural and urban consumers in the usage of different brands of milk and to find out the reasons for switchover from one brand to other brand of milk. Descriptive research is used with convenient sampling method, in this study. The research was conducted in Chennai with 1450 respondents .Primary data is collected through questionnaire schedule and secondary data was selected from journals. The research found that brand loyalty have a positive association among the people. The study concludes that impact of brand loyalty among people on packaged milk products differs from person to person.

Graphene Decorated with Hierarchical CuS Nanoplates: Enhanced Photocatalytic Performance

Graphene decorated with hierarchical CuS nanoplates (CuS NP-G) was synthesized using a microwave method to be used as a photocatalytic material. The incorporation of graphene into hierarchical CuS nanoplates was confirmed by structural, morphological and optical characterizations. The photocatalytic performance of the nanocomposite was evaluated. This study confirmed that the introduction of graphene was an effective way not only to improve the structural stability and service durability of the composite, but also to improve its solar photocatalytic activity by promoting the electron transfer and charge separation of hierarchical CuS nanoplates.