Session: 04-07: SMRs, Advanced Reactors and Fusion

Paper Number: 136201

136201 - The Neutronics Analysis of Heat Pipe Cooled Traveling Wave Reactor Designs With High-Assay Low-Enrichment Uranium and Natural Uranium 

Abstract: 

The heat pipe cooled traveling wave reactor (HPTWR) is a novel design. This paper firstly presented a heat pipe cooled traveling wave reactor design featured with a traditional traveling wave reactor core, which consists of high-assay low-enrichment uranium (HALEU) section (20%) and natural uranium section (0.725%), or ignitor section and breeder section. The core was a hexagonal prism and assembled with more than a thousand of separated UN fuel elements. Each fuel element was a smaller hexagonal prism with a heat pipe channel in the center. A lithium and Mo/Re heat pipe was used in the current design. The axial ratio of the ignitor section to the breeder section was 1:2, and the total axial length of the core was 2 meter. And the radius of the core was less than 0.8 meter. The neutronics calculations were performed using Monte Carlo code RMC. The continuous-energy cross section based on the ENDF/B-VII library was used for the RMC calculations in this study. Each depletion calculation in the reactor had 50 inactive cycles and 250 active cycles with 30,000 particle history per cycle. The corresponding statistic error of keff was less than 17pcm. All the HPs, cladding and UN fuel had a same operational temperature (1700 K) in the neutronics calculations. The core was equally divided into 20 smaller zones in the axial direction to simulate the axial neutron breeding wave of the reactor in the depletion calculation. The neutronics analysis showed that at the beginning of the cycle reactivity is high, and K_eff has reached 1.35, and power is concentrated in the ignitor section with nearly zero power in the far end of breeding section. Then an improved heat pipe cooled traveling wave reactor design is proposed to limit the swing of k_eff in 1%, and distribute the power more evenly by reducing the enrichment difference between ignitor section and breeder section with similar core geometry but 1 meter in axial length. With the operating temperature as 1700K of the Li/Mo heat pipe, both designs can reach more than 50MWth of power and 20 years of refueling cycle. And more detail results of burnup analysis and power peak propagation were presented. The current design was a small modular reactor (SMR), which could be delivered by truck and airplane for its light weight and could be a competitive option for decentralized electricity markets for its high power，long-term refueling cycle and passive safety.

Presenting Author: Po Hu Shanghai Jiao Tong University

Presenting Author Biography: Po Hu
Ph.D in Nuclear Engineering
Specialized in advanced nuclear reactor design, passive safety technology, hydrogen safety

Authors:

Po Hu Shanghai Jiao Tong University
Kunfeng Ma Shanghai Jiao Tong University