The Passive Heat Removal Facility: Testing and Demonstrating an Innovative Decay Heat Removal System

Innovative reactor concepts are being studied by several research institutions and private entities for their role against climate change and energy poverty. The Generation IV International Forum, committed for more than 20 years in support of advanced reactors, has drawn up a series of objectives for the new class of nuclear plants, among which is an improvement in safety and economy through passive safety systems for the removal of decay heat. One of the most studied technologies is the lead fast reactor (LFR), whose coolant has a high boiling point, excellent shielding capabilities, and good heat transfer in forced and natural circulation, as well as neutron properties suitable for a hard spectrum. These allow for designing systems with high simplification and wide safety margins. On the other hand, opacity, corrosion, and innovative design choices require demonstration of the technology in experimental campaigns before using it in the industrial field.

In recent years, Westinghouse Electric Company has begun the conceptual study of an intermediate size LFR [~460 MW(electric)] which, by exploiting the opportunities of the technology, aims at marketability over the next decade. One of the features is a passive heat removal system that allows, through different heat exchange mechanisms including conduction, convection, and radiation, for the transfer of decay heat from the reactor block to a pool of water inside the containment. The system is designed for indefinite heat removal thanks to channels that allow outside air to replace water following complete boiling. For the geometry of the system, the size, the materials, and the heat transfer mechanisms, an experimental activity is required to validate the prediction of the calculation codes and potentially support design optimization.

The UK Department for Business, Energy & Industrial Strategy has recently subsidized the design, procurement, installation, and operation of the Passive Heat Removal Facility, an experimental facility to study the innovative safety system. This paper presents the activities of scaling, design, pretesting, and installation of that facility.