MicroURANUS : Core design for long‐cycle lead‐bismuth‐cooled fast reactor for marine applications

Abstract

Summary A core design of MicroURANUS, a long‐cycle lead‐bismuth‐cooled fast nuclear reactor for marine applications, is presented. It aims to generate a power of 60MWth, which can be regulated during operation. MicroURANUS was designed to achieve a small burnup reactivity swing for 30 effective full‐power years of a lifetime without refueling. To attain these goals, a unit cell study with uranium oxide fuel was initiated to lay a solid foundation for core design, owing to size constraints. A reflector optimization was also performed to minimize neutron leakage. MicroURANUS adopts onion zoning constructed by two enrichment zones for flattening the power and lengthening the core lifetime. The coolant is driven by electromagnetic pumps to achieve inlet and outlet temperatures of 250°C and 350°C, respectively. MicroURANUS analyses were performed using the Argonne Reactor Computation suite and the Monte Carlo code MCS. Core performance features were analyzed for criticality, power profiles, fuel isotope mass inventory, reflector coefficients, reactivity feedback coefficients, and shutdown margin. Additional thermal‐hydraulic calculations were performed to confirm that the fuel and cladding temperatures were within the acceptable range. Furthermore, a load follow analysis using the quasi‐static reactivity balance method confirmed the feasibility of regulating power by adjusting the inlet coolant temperature.

Analysis of fuel performance under normal operation conditions of MicroURANUS: Micro long-life lead-bismuth-cooled fast reactor

“…The major fissile isotope is Pu-239. Furthermore, in the case of MicroURANUS, the production of approximately 465 kg during 30 EFPY was calculated in the core design process (as shown in Figure 1A) (Nguyen et al, 2021). Variations in the thermal conductivity, heat capacity, and thermal expansion of the fuel caused by plutonium generation were considered as variations during operation through the weight fraction and composition of Pu-239, Pu-240, and Pu-241.…”

“…In addition to the fuel material properties, the influence of the variations in fuel irradiation behavior caused by plutonium generation was investigated. It is reported that a fission gas release enhancement effect occurs in the case of a MOX with 20 wt% plutonium (which is operated in a fast reactor) it is reported that there is a fission gas release enhancement effect owing to inhomogeneity caused by the segregation of PuO 2 FIGURE 1 (A) Mass variation profiles of U and Pu isotopes and (B) composition profile of plutonium (Nguyen et al, 2021).…”

“…Among these, the leadcooled fast reactor (LFR) is considered the most potential Generation-Ⅳ (GenⅣ) innovative reactor concept. A nonrefueling ultra-long-life LFR called MicroURANUS is presently being developed in Korea as a nuclear propellant system for marine ships or icebreakers (Nguyen et al, 2021). MicroURANUS is a micro-reactor of 20 MWe.…”

Preliminary lightweight core design analysis of a micro‐transportable gas‐cooled thermal reactor

“…The MicroURANUS power reactor is also a lead-bismuth-cooled fast reactor designed for marine applications. 9 It provides an output power of 60 MWt, of which the core diameter and height are 200 and 155 cm, respectively. Coolant pumps and auxiliary systems can be eliminated by using heat pipe configurations.…”

“…Its core diameter and height are 192.2 cm and 100 cm with a weight of 34.86 metric tons. The MicroURANUS power reactor is also a lead‐bismuth‐cooled fast reactor designed for marine applications 9 . It provides an output power of 60 MWt, of which the core diameter and height are 200 and 155 cm, respectively.…”