Development and Validation of Thermal-Hydraulic ... in BWR's and PWR's: Can modern CFD models reliably predict DNB for nuclear power applications?

The United Kingdom government has decided that continued use of nuclear power should be made to contribute to a low-carbon electricity generating system in the United Kingdom. It is important that new nuclear plants are designed to be as safe as possible, and this research will contribute to this.

Broadly, when a water-cooled nuclear reactor remains cooled by water, it is essentially impossible for it to overheat and suffer damage. Conversely, when the water coolant turns inadvertently to steam this possibility does arise. This project is aimed at developing better predictive tools to understand when the change of coolant from liquid water to steam occurs. Better predictive capability here will allow new plants to be designed with even more confidence as to their safety.

This project will be undertaken in collaboration with our colleagues in the Indian civil nuclear power industry, specifically at the Bhaba Atomic Research Centre in Mumbai. Here our Indian colleagues, supported by the United Kingdom team, will engage in complex measurements of the boiling process, and of the turning of the liquid water coolant into steam. Alongside these measurements, we and they will develop sophisticated computational predictive tools for this change from liquid water to steam. These predictive tools will study the fundamental physics of the boiling process, right down at a scale of a few microns, and will extend to the construction and validation of predictive tools applied to the scale of whole portions of the nuclear core.

The quality and effectiveness of the predictive tools to be developed will be able to be assessed by comparing their predictions with the observed occurrence of this water-steam transition.

This project evolved from discussions between UK and Indian researchers. The Indian researchers concerned are directly involved in design and analysis of new reactors, and their enthusiasm to conduct this project is a measure of how direct its impact will be when it is able to be applied to the design and analysis of new nuclear plants.

In addition, the measurements that will be made of the characteristics of boiling systems, at the various length scales proposed, will form a valuable addition to the literature in this area, which is needed for the development and validation of models of boiling. This impact will be achieved by the wide dissemination of our results, via international and national conferences, and via publication in peer reviewed technical journals.

All the team of researchers have good contacts throughout the nuclear industry, and these contacts will allow the significance of the work to be appreciated more directly by nuclear engineer practitioners, which will facilitate the adoption of these new methods in new nuclear plant design, analysis and regulation.