Dynamic HRA in outage from literature and outage personnel interview perspectives

In 2021, the goal of the SAFIR2022 project NAPRA task T3.2 was to provide an overview of an outage of a nuclear power plant from the perspective of human reliability analysis (HRA). The general features of the outage as well as the specific matters related to human reliability and dynamism in the outage context were studied from literature and outage personnel interview perspectives.The safety-critical nature of an outage is well recognized, and there is a wealth of literature on the specifics of outage and the challenges associated with the successful completion of work. HRA methods have mostly been developed for full power conditions where the operator’s actions are well trained and laid down in procedures, in time frames typically less than 60 minutes. In the planned shutdown the work concentrates outside the control room, is less in procedures and less trained and the time frames may be much longer. The environment is continuously changing, there are huge number of workers, large variety of work activities, tight schedule and the requirements are high concerning both safety and productivity. The key issues that should be considered in the HRA are errors of commission (EOCs), dependencies between human actions and the dynamism of the operating environment.One practical objective of this report was to identify a scenario to focus on in further work related to dynamic modelling. Based on interviews, heavy loads were identified as critical but also mentally and physically loaded. They also include features identified safety critical in scientific literature. This scenario will be studied in more detail in 2022. Work analysis will be performed with special emphasis on applying a combination of methods to elicit the key dynamic features from the HRA perspective

Human operator trust in autonomic functionalities

Justice Antonin Scalia titled his 1989 Oliver Wendell Holmes Lecture at Harvard Law School The Rule of Law as a Law of Rules. The lecture posed the sort of dichotomy that has become a familiar feature of Justice Scalia\u27s jurisprudence and of his general approach to judging. On one hand are judges who recognize that the only legitimate means by which they may adjudicate cases in a democracy is to seek to do so through rules of general application. On the other hand are those judges who generally prefer to adopt an all-things considered balancing approach to adjudication. This latter species of judge is akin, he says, to King Solomon, deciding difficult constitutional questions based on some judge-empowering intuition. This dichotomy is familiar in both the literature and the case law. In her 1991 Harvard Law Review foreword, Kathleen Sullivan memorably distinguished between a [j]ustice of rules and a [j]ustice of standards. A justice of rules prefers to issue legal directives that bind[] a decisionmaker to respond in a determinate way to the presence of delimited triggering facts. The key word in this formulation is delimited – as Sullivan writes, the rule\u27s force as a rule is that decisionmakers follow it, even when direct application of the background principle or policy [that the rule captures] to the facts would produce a different result. A justice of standards prefers to collapse decisionmaking back into the direct application of the background principle or policy to a fact situation. Sullivan notes that the distinction in constitutional law between categorical approaches and balancing approaches is a version of the rules/standards distinction

Improving design processes in the nuclear domain–Insights on organisational challenges from safety culture and resilience engineering perspectives

Design flaws have been contributing to major industrial accidents. However, design activities are understudied in human and organisational factors studies. In the nuclear power domain, both pre-operational design and design of modifications depend on a network of organizations, and aim at developing solutions which meet different criteria. Nuclear power companies often outsource the design work to organisations, which might not be hitherto familiar with the safety requirements of nuclear industry. The final phase of SADE project focused on testing and evaluating the results of the first two phases through in depth analysis of case studies conducted in Finland and Sweden. The study aimed at providing insights on the inter-organizational challenges related to design activities, which could potentially affect safety of the Nordic nuclear power plants. In 2013 we carried out 14 semi-structured interviews with representatives of power plant organisations, design organisations and regulators. Interviews of the Finnish case studies were complemented by one group interview each. The study indicated that design-related challenges in the nuclear domain are mainly inter-organizational. This implies that safety management and safety culture approaches should take better into account the inter-organisational nature of work processes. For some of the challenges (e.g. coordination) many coping practices exist throughout the network, whereas for others (e.g. shared understanding) just a few were mentioned. This signifies that design organisations have learned the consequences of insufficient coordination in previous projects, while reaching a shared understanding proves to be challenging. The design process involves both rational and creative approaches to deal with real-life problems. In nuclear industry, designers face the need to balance between fulfilling requirements and doing an extensive amount of paperwork, and creating new, safe and functional solutions. To better manage safety culture in design activities in a networked context, nuclear power companies and design supply chains need to reach a shared understanding on achieving this balance. Finally, the study provides a set of recommendations to support and improve the design process and to help anticipate emerging risks in the nuclear industry

Análise de Chuvas Orográficas no Centro do Estado do Rio Grande do Sul

http://dx.doi.org/10.5902/2179460X11244In the state of Rio Grande do Sul (RS) the rainfall is not homogeneous, showing spatial and temporal variability conditioned by interactions of different climatic mechanisms. Those features give rise to different behaviors of rainfall, including orographic rainfall. The aim of this paper is to analyze the probable existence of the orographic effect on rainfall in the central region of the RS. The study was conducted at Silveira Martins, situate on the edge of the Central Depression and Southern Plateau Riograndense. To achieve the goal was performed the rainfall monitoring with the installation of ten rain gauge stations. Stations were installed six upwind and four downwind of Silveira Martins, and statistically compared the average total at each position. In addition, we have characterized the events from satellite images of the digital database of the National Institute for Space Research. The monitoring totalized 30 events and, at the significance level of 5%, the statistical analysis suggests the occurrence of orographic effect. From the analysis of satellite images can be evidenced that the orographic effect of the region intensifies frontal rainfalls due to movements of the masses of polar air.http://dx.doi.org/10.5902/2179460X11244No Estado do Rio Grande do Sul (RS) o regime pluviométrico não é homogêneo, apresentando variabilidade espacial e temporal condicionadas às interações de diferentes mecanismos climáticos. Estas particularidades fazem surgir diferentes comportamentos da chuva, incluindo as chuvas orográficas. O objetivo deste artigo é analisar a provável existência do efeito orográfico nas chuvas da região central do RS. O estudo foi realizado no município de Silveira Martins, situado no limite da Depressão Central e o Planalto Meridional Riograndense. Para atingir o objetivo foi realizado o monitoramento das chuvas com a instalação de dez postos pluviométricos. Foram instalados quatro postos a barlavento e seis a sotavento de Silveira Martins, sendo comparados estatisticamente os totais médios precipitados nas duas posições. Além disso, caracterizaram-se os eventos de chuva a partir de imagens de satélite do banco de dados digital do Instituto Nacional de Pesquisas Espaciais. O monitoramento totalizou 30 eventos de chuva e, ao nível de significância de 5%, a análise estatística sugere a ocorrência de efeito orográfico. A partir da análise das imagens de satélite pode-se evidenciar que o efeito orográfico da região intensifica as chuvas frontais decorrentes do movimento das massas de ar polares