Rapid cooling of a high-temperature block by the attachment of a honeycomb porous plate on a nanoparticle-deposited surface

One strategy for dealing with severe accidents is in-vessel retention (IVR) of corium debris. In-vessel retention consists of external cooling of the reactor vessel in order to remove decay heat from the molten core by lower head of the vessel. In this system, it is important to establish techniques to (1) cool the high-temperature reactor vessel in order to change the boiling regime from film boiling to nucleate boiling as soon as possible, because the heat transfer coefficient for film boiling is very low, and (2) enhance the critical heat flux (CHF), because heat removal is limited by the occurrence of the CHF condition at the outer surface of the reactor vessel. Furthermore, approaches for increasing the IVR capability must be simple and installable at low cost. Regarding (2) CHF enhancement, we have demonstrated CHF enhancement of a large heated surface by a honeycomb porous plate (HPP) in saturated pool boiling of distilled water. In the present paper, we focus on the quenching behavior of a honeycomb porous plate on a nanoparticle-deposited surface. As a result, the quenching period was significantly reduced by approximately 22% as compared to the case of bare surface (without surface modification) due to the combination of nanoparticle deposition and a honeycomb porous plate.