Session: 17-01-01: Research Posters

Paper Number: 149252

149252 - Structural Design of Helical Tube Steam Generator for Smr 

Recently, Small Modular Reactors (SMRs) have attracted worldwide attention due to their advanced design features, such as structural safety improvements, simplification, and component modularization, which collectively enhance safety and economics. One of the most notable features of SMRs is that all the main components, such as the pressurizer, steam generators, and reactor coolant pumps, are installed inside the reactor pressure vessel. Helical tube steam generators are widely adopted in SMR design optimization to maximize the heat exchange area within the limited space of integral reactors.

In this presentation, we will explore the structural design considerations of helical tube steam generators used in SMRs, highlighting their unique attributes and challenges compared to the U-tube designs typically employed in large-scale nuclear power plants. The structural design features of helical tube steam generators differ significantly from those of typical U-tube steam generators. This presentation will address what should be considered in the structural design of helical tube steam generators.

Key issues addressed will include the springback phenomenon inherent to helical tubes, which affects the precise formation and placement of these tubes during manufacturing and installation. Given the limited space, the estimation of precise formation during the manufacturing process must be considered at the design stage. Additionally, we will delve into the problem of ovality during helical tube bending, where the cross-sectional shape of the tube becomes distorted, potentially leading to reduced flow efficiency and increased wear. Without considering ovality during the bending process, the structural integrity and wear of the tubes could be underestimated. The presentation will also cover the issue of density wave oscillations within helical tube steam generators. We will discuss structural considerations related to the density wave oscillation phenomenon that should be accounted for in the design of helical tube steam generators. Since phase changes occur inside the tube, unlike in U-tube steam generators, density wave oscillation is a crucial issue for helical tube steam generators. Many researchers focus on the system instability caused by density wave oscillation from a fluid system design perspective. We will discuss the effects of density wave oscillation on structural response. Additionally, we will introduce the development of an equivalent model of the helical type steam generator, including thousands of tubes, for seismic analysis.

By comprehensively examining these critical aspects, the presentation aims to provide a thorough understanding of the structural design of helical tube steam generators for SMRs, contributing to the advancement of reliable and efficient nuclear energy solutions.

Presenting Author: Kwanghyun Ahn Korea Atomic Energy Research Institute

Presenting Author Biography: - (2013) Ph.D. at KAIST (Korea Advanced Institute of Science and Technology)
- (2013~2016) Senior Researcher at Samsung Heavy Industries
- (2016~2022) Senior Researcher at Korea Atomic Energy Research Institute
- (2022~present) Principal Researcher at Korea Atomic Energy Research Institute
- (Current Position) Leader of mechanical design group for SMR at Korea Atomic Energy Research Institute

Authors:

Kwanghyun Ahn Korea Atomic Energy Research Institute
Gyogeun Youn Korea Atomic Energy Research Institute
Gyu Mahn Lee Korea Atomic Energy Research Institute