Abstract
A conceptual design for a horizontal split table to perform critical experiments is being explored as a collaborative effort between Oak Ridge National Laboratory and Lawrence Livermore National Laboratory. The design’s main goal is to provide nuclear data testing and validation capabilities for advanced reactors such as pebble-bed high-temperature gas cooled reactor, molten salt reactor and heat pipe microreactors. The first concept explored for the horizontal split table is a pebble-bed design based on the HTR-10 reactor and is described in this paper. A critical configuration corresponding to a footprint of about 4.5 m2 was determined with SCALE/KENO-VI, fitting on the planned dimensions of the horizontal split table. The pebble-bed design and the HTR-10 reactor application similarity was assessed with SCALE/TSUNAMI, and a similarity coefficient ck of 0.9982 was obtained, proving the concept would be useful for nuclear data validation of pebble-bed type advanced reactor. The materials with the highest keff sensitivity in this design are graphite and uranium, demonstrating that a particular care must be given to carbon related cross-section data. The effect of mechanical uncertainties between the fixed and moving tables was also assessed by calculating the reactivity change due to vertical and horizontal gaps, angular and torsion offsets between the two sides of the horizontal split table concept. The highest relative changes on the concept’s reactivity were due to angular perturbations. The same process is currently being used to create a molten salt advanced reactor type horizontal split table concept based on the Molten Salt Reactor Experiment (MSRE).
KEYWORDS: Critical experiment design, Graphite, Pebble-bed, Nuclear data
