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Science and Technology of Nuclear Installations
Volume 2016 (2016), Article ID 3071686, 10 pages
Research Article

Analysis of Density Wave Oscillations in Helically Coiled Tube Once-Through Steam Generator

1College of Energy, Xiamen University, Xiamen, China
2Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, China

Received 3 September 2016; Revised 1 November 2016; Accepted 6 November 2016

Academic Editor: Alejandro Clausse

Copyright © 2016 Junwei Hao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Helically coiled tube Once-Through Steam Generator (H-OTSG) is one of the key equipment types for small modular reactors. The flow instability of the secondary side of the H-OTSG is particularly serious, because the working condition is in the range of low and medium pressure. This paper presents research on density wave oscillations (DWO) in a typical countercurrent H-OTSG. Based on the steady-state calculation, the mathematical model of single-channel system was established, and the transfer function was derived. Using Nyquist stability criterion of the single variable, the stability cases were studied with an in-house computer program. According to the analyses, the impact law of the geometrical parameters to the system stability was obtained. RELAP5/MOD3.2 code was also used to simulate DWO in H-OTSG. The theoretical analyses of the in-house program were compared to the simulation results of RELAP5. A correction factor was introduced to reduce the error of RELAP5 when modeling helical geometry. The comparison results agreed well which showed that the correction is effective.