Jiwon Choe

Optimal Control Rod for Boron-Free Small Modular PWR

This paper proposes a new control rod material for a boron-free small modular pressurized water reactor (SMPWR) to compensate the loss of the soluble boron. To design control rod for SMPWR is difficult due to the large amount of reactivity control necessity and the multiple roles of control rod, i.e., the excess reactivity control, the coarse/fine power control, and the axial shape control and shutdown. This paper presents a study of various control rod materials: B4C, Ag-In-Cd, and HfB2. The rod worth and the excess reactivity control capability will be assessed for the SMPWR using Studsvik’s reactor core design code system, CASMO-4E/SIMULATE-3.

Cutback sensitivity test for boron-free small modular PWR

A soluble boron-free small modular pressurized water reactor (SMPWR) uses burnable absorbers (BA) instead of soluble boron to reduce excess reactivity. As a consequence, the fuel cycle length can be shortened by the residual penalty of BA. This paper performs cutback sensitivity tests to extend the cycle length. The influence of the height of the cutback, of the 235U enrichment rate, and of the BA material on the power peaking factor (Fq), the axial offset (AO) and the fuel cycle length is analyzed with the reactor core design system, CASMO-4E/SIMULATE-3 code system.

Study for requirement of advanced long life small modular fast reactor

To develop an advanced long-life SMR core concept, the feasibility of the long-life breed-and-burn core concept has been assessed and the preliminary selection on the reactor design requirement such as fuel form, coolant material has been performed. With the simplified cigar-type geometry of 8m-tall CANDLE reactor concept, it has demonstrated the strengths of breed-and-burn strategy. There is a saturation region in the graph for the multiplication factors, which means that a steady breeding is being proceeded along the axial direction. The propagation behavior of the CANDLE core can be also confirmed through the evolution of the axial power profile. Coolant material is expected to have low melting point, density, viscosity and absorption cross section and a high boiling point, specific heat, and thermal conductivity. In this respect, sodium is preferable material for a coolant of this nuclear power plant system. The metallic fuel has harder spectrum compared to the oxide and carbide fuel, which is favorable to increase the breeding and extend the cycle length.