Overview: NuEST Lab
Research activities in the NuEST lab focus on understanding micro to macro scale transport of matter and radiation. The fundamental and applied research in the Nu-EST lab are conducted with the aide of novel experimental and computational tools.
I. High temperature thermal-hydraulics
Graphite-fuel matrix in VHTRs or HTGRs can come in direct contact with air at high temperature during air ingress as associated with severe accidents, which can affect their passive heat removal capabilities. Nuclear grade graphite material has been shown to undergo oxidation reaction during air ingress resulting in degradation of its thermal conductivity and emissivity. A new machine learning based technique is devised to characterize and classify thermographic images of graphite surfaces during transient heat transfer experiments.
II. Thermal Energy Storage
The serious economic challenge faced by the existing NPPs is their inability to follow the grid load demand. Due to this reason, they are economically less competitive as compared to their fossil counterparts which can supply peak-loads and thus generate far more revenue during those peak hours. The technical challenge behind this economic disposition is that reactor power cannot be allowed to follow the grid and fluctuate in order to avoid unsafe conditions inside the reactor. Thus, only way NPPs can accommodate grid demand is if the reactor thermal power or plant electrical power is stored in an integrated device when in surplus. We develop methods to store exergetically efficient thermal energy storage devices. The novel design of these methods is based on manipulating thermal anisotropies in materials at micro or macro-scale.
III. Passive Nuclear Safety
The performance of passive safety systems, in particular, passive heat removal systems is critical for advancing safe nuclear energy in the world. In several LWR designs including SMRs, natural circulation in two phase flow regime is a design feature essential for the short term or long term passive decay heat removal. In case of HTGRs, the decay heat is dissipated passively from the core by radiation/conduction/natural-convection heat transport to the surrounding environment either through conduction from the graphite core through the pressure vessel wall or through an engineered cooling system. Passive decay heat removal is one of the prime passive safety features of HTRs and the heat conduction through the internal core region to the periphery is one of the prime mechanisms of passive safety in HTGRs. The conduction and radiation heat transfer are designed to provide long-term heat removal.