Computational modelling for nuclear reactor thermal hydraulics

为了完成政府提高核能在未来低碳英国能源部门中的作用的计划，将在未来几十年内建造新的反应堆，以增加总体核能发电能力。尽管这听起来很明显，但对这些新反应堆来说，达到尽可能高的安全标准至关重要。拟议的这项工作旨在为两个可能是最重要的安全相关研究领域做出贡献，同时与活跃在该领域的两个受人尊敬的海外研究小组建立强有力的研究联系：-正如最近福岛事件所表明的那样，即使在没有任何有功电源的情况下，能够为核电站提供必要的冷却也有巨大的好处。这可以通过依靠被动冷却方法来实现，这种方法是自然现象的结果，不需要任何有源电源干预。在核电站中，被动冷却可以通过自然对流安全有效地提供。然而，自然对流的有效性和可靠性是难以准确预测的。提出的研究旨在提高我们用来预测被动冷却有效性的方法的准确性和可靠性。这部分工作将通过与意大利米兰理工大学核反应堆小组的研究人员积极合作来完成。几乎所有的水冷反应堆都采用沸腾作为一种非常有效的冷却方法。沸腾是一种非常有效的传热机制，只要受热表面保持水的湿润。否则，传热会急剧恶化，最终危及燃料棒的完整性和电站的安全。这部分工作涉及我们的理解和预测沸腾流动最相关的方面之一的能力，这是大部分流动中的气泡的行为。主要目标是进一步发展可用的计算方法，并验证其对气泡流的预测，作为提高我们预测沸腾流能力的基本步骤。研究将通过与德国Helmholtz-Zentrum dresden - rosendorf流体动力学研究所的研究人员积极合作来完成。

To accomplish government's plan of increasing the role of nuclear energy in the future low-carbon United Kingdom's energy sector, new reactors that increase the overall nuclear generating capacity will be built in the forthcoming decades. As obvious as it might sounds, it is of uttermost importance for these new reactors to reach the highest possible safety standards. The proposed piece of work aims at contributing to two of perhaps the most important safety-related areas of research while establishing strong research links with two esteemed overseas research groups active in the areas: - As the recent events in Fukushima have demonstrated, there is an enormous benefit in being able to provide the necessary cooling of the plant even in absence of any active power. This can be achieved by relying on passive cooling methods that happens as a consequence of natural-occurring phenomena and does not require any active power intervention. In a nuclear plant, passive cooling can be safely and efficiently provided by natural convection. However, effectiveness and reliability of natural convection is significantly difficult to be predicted with accuracy. The research proposed aims at advancing accuracy and reliability of the methods we use to predict the effectiveness of passive cooling. This part of the work will be accomplished by actively collaborating with researchers from the Nuclear Reactors Group of Politecnico di Milano, in Italy.- Almost all water cooled reactors exploit boiling as a very efficient cooling method. Boiling is a very efficient heat transfer mechanism as long as the heated surface remains wetted by water. Otherwise heat transfer deteriorates dramatically, eventually compromising the integrity of the fuel rods and the safety of the plant. This part of the work deals with our understanding and ability to predict one of the most relevant aspect of boiling flows, which is the behaviour of the bubbles in the bulk of the flow. Main objective is to further develop computational methods available and validate their predictions against bubbly flows as a fundamental step to increase our ability to predict boiling flows. Research will be accomplished by actively collaborating with researchers from the Institute of Fluid Dynamics at Helmholtz-Zentrum Dresden-Rossendorf, in Germany.