Conceptual design and feasibility analysis of a megawatt level low enriched uranium heat pipe cooled reactor core

•Design concept for a multi-purpose micro heat pipe cooled reactor is presented.•Low-enriched uranium and a new ATF are applied.•Burnable poison Gd2O3 is used to reduce initial excess reactivity. Micro reactors are gaining popularity due to their lower cost, increased safety, and flexibility as compared to normal commercial nuclear power plants. This paper presents a design concept for a multi-purpose heat pipe cooled micro-reactor with enrichment of 19.75 %, which can operate for more than 5 years at 2 MWt without refueling. A new Accident Tolerant Fuel called Fuel-in-Fibers is used and in addition, both control drums and control rods are applied for safety consideration. Besides, graphite is used as the core matrix material to reduce uranium enrichment because it can reduce the parasitic absorption of neutrons and moderate neutrons. For longer burnup and more stable operation, Integral Fuel Burnable Absorber (IFBA) pin with burnable poison Gd2O3 is used to reduce initial excess reactivity. Monte Carlo simulation is performed to calculate the reactivity, burnup, power distribution, temperature coefficient and other parameters on normal and accident conditions. According to the neutron physics results, the preliminary design satisfies the economy and safety requirements. This work may provide a reference for the design of multi-purpose heat pipe cooled reactor core using low enriched uranium fuel.