Small modular high temperature reactor optimisation - Part 1: A comparison between beryllium oxide and nuclear graphite in a small scale high temperature reactor

摘要

The small modular reactor market is starting to take shape for the future global energy challenges, with several major players emerging with new technologies. To maximise the potential in this market, the most appealing designs will have to be financially favourable and low risk for investors. Due to its perceived lower risk, this article investigates a high temperature reactor conceptual design proposal, the U-Battery. One of the challenges which high temperature reactors face, is the material selection due to the high temperature in the core and the temperature gradients across the core in addition to the mechanical effects which graphite faces as it ages. The original design is based on using a novel Beryllium oxide reflector. This article investigates the consequences of replacing this novel approach with the more common approach of a graphite reflector.This article aims to provide a comparison between Beryllium oxide and nuclear graphite as a neutron reflector for high temperature reactor. The article emphasises on at what additional costs Beryllium oxide create and if graphite could meet the same performance at lower cost. To deduce a comparison between the materials, a model based around the U-Battery was produced. A neutronic analysis implied that to obtain a similar performance the core would be require 23% larger radial reflectors and 75% larger axial reflectors made if graphite rather than that of Beryllium. However, the cost of the graphite reflected core would be nearly half of that of a Beryllium design. The neutronic analysis demonstrates that the graphite design can be an efficient alternative to the Beryllium reflector creating even slightly better power distributions.