An Advanced Sodium-Cooled Fast Reactor Core Concept Using Uranium-Free Metallic Fuels for Maximizing TRU Burning Rate

Wuseong You,Ser Hong

doi:10.3390/su9122225

Abstract

In this paper, we designed and analyzed advanced sodium-cooled fast reactor cores using uranium-free metallic fuels for maximizing burning rate of transuranics (TRU) nuclides from PWR spent fuels. It is well known that the removal of fertile nuclides such as 238U from fuels in liquid metal cooled fast reactor leads to the degradation of important safety parameters such as the Doppler coefficient, coolant void worth, and delayed neutron fraction. To resolve the degradation of the Doppler coefficient, we considered adding resonant nuclides to the uranium-free metallic fuels. The analysis results showed that the cores using uranium-free fuels loaded with tungsten instead of uranium have a significantly lower burnup reactivity swing and more negative Doppler coefficients than the core using uranium-free fuels without resonant nuclides. In addition, we considered the use of axially central B4C absorber region and moderator rods to further improve safety parameters such as sodium void worth, burnup reactivity swing, and the Doppler coefficient. The results of the analysis showed that the final design core can consume ~353 kg per cycle and satisfies self-controllability under unprotected accidents. The fuel cycle analysis showed that the PWR–SFR coupling fuel cycle option drastically reduces the amount of waste going to repository and the SFR burner can consume the amount of TRUs discharged from 3.72 PWRs generating the same electricity.

Highlights

20 PWRs (Pressurized Water Reactor) and four CANDU (CANadian Deuterium Uranium) reactors are operating in South Korea and their electric capacities are about 22.519 GWe
The analysis of the reference cores using different metallic fuels showed that, in spite of its high TRU burning rate, the reference burner core using the binary metallic fertile-free fuel (i.e., TRU-Zr) has a very small Doppler coefficient and large burnup reactivity swing, which can be problematic in terms of safety, while this core has the smallest sodium void worth, even smaller than that of the ternary metallic fertile fueled core (i.e., TRU-U-10Zr)
The reference core using TRU-W-10Zr fuel showed the most negative Doppler coefficient and smallest burnup reactivity swing, while it has the largest sodium void worth due to the large capture resonance cross sections of tungsten isotopes. This smallest burnup reactivity swing resulted from the large initial heavy metal inventory and the largest sodium void worth is due to the smallest negative contribution by leakage increase under sodium voiding

Summary

Introduction

20 PWRs (Pressurized Water Reactor) and four CANDU (CANadian Deuterium Uranium) reactors are operating in South Korea and their electric capacities are about 22.519 GWe. Of the fast spectrum reactors, SFR [7,8] has been considered a more realistic fission system that can burn the TRU feeds from the PWR spent fuel stocks with recycling of actinides than LFRs [9] due to their technical maturity because the other type fast reactors such as lead- and gas-cooled fast reactors have not been constructed and operated as commercial reactors It is shown from the operational experience records for the PHENIX, BN-600, and FBTR that SFRs are sufficiently reliable to be operated up to a comparable availability level of LWRs [10].

Computational Methods

Core Design Study and Performance Analysis

Advanced Uranium-Free Fueled Burner Cores

Fuel Cycle Analysis

Findings

Summary and Conclusions