Characteristics of type-i density wave oscillations in a natural circulation bwr at relatively high pressure

Masahiro Furuya, Fumio Inada, Tim H.J.J. Van Der Hagen

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Experiments were conducted to investigate two-phase flow instabilities in a boiling natural circulation loop with a chimney at high pressure. The SIRIUS-N facility was designed to have non-dimensional values which are nearly equal to those of a typical natural circulation BWR. The observed oscillations are found to be density wave oscillations, since the void fractions in the chimney inlet and exit are out of phase. They belong to the Type-I category, since they occur at low flow qualities, according to the Fukuda—Kobori's classification. Moreover, the oscillation period correlates well with the passing time of bubbles in the chimney section regardless of the system pressure, the heat flux, and the inlet subcooling. Two distinct phenomena are found in relation between the oscillation period and liquid passing time in the chimney, indicating that the driving mechanisms of the instabilities are different between low and high pressures. Stability maps were obtained in reference to the inlet subcooling and the heat flux at the system pressures of 1, 2, 4, and 7.2 MPa. The flow became stable below a certain heat flux regardless of the channel inlet subcooling. The stable region enlarges with increasing system pressure. Thus, the stability margin becomes larger in a startup process of a reactor by pressurizing the reactor sufficiently before withdrawing the control rods. The obtained stability map demonstrates that the nominal operating condition of the ESBWR has a significant stability margin to the unstable region.

Original languageEnglish
Pages (from-to)191-200
Number of pages10
JournalJournal of Nuclear Science and Technology
Volume42
Issue number2
DOIs
Publication statusPublished - 2005 Jan 1
Externally publishedYes

Fingerprint

chimneys
Chimneys
oscillations
Heat flux
heat flux
margins
reactors
pressurizing
control rods
Control rods
Pressurization
Void fraction
two phase flow
Two phase flow
boiling
Boiling liquids
voids
bubbles
low pressure
Liquids

Keywords

  • Boling two-phase flow
  • BWR type reactors
  • Density wave oscillations
  • Natural circulation
  • Stability

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering

Cite this

Characteristics of type-i density wave oscillations in a natural circulation bwr at relatively high pressure. / Furuya, Masahiro; Inada, Fumio; Van Der Hagen, Tim H.J.J.

In: Journal of Nuclear Science and Technology, Vol. 42, No. 2, 01.01.2005, p. 191-200.

Research output: Contribution to journalArticle

@article{3f135ed7cb0c4a0a8dc558777ccf2366,
title = "Characteristics of type-i density wave oscillations in a natural circulation bwr at relatively high pressure",
abstract = "Experiments were conducted to investigate two-phase flow instabilities in a boiling natural circulation loop with a chimney at high pressure. The SIRIUS-N facility was designed to have non-dimensional values which are nearly equal to those of a typical natural circulation BWR. The observed oscillations are found to be density wave oscillations, since the void fractions in the chimney inlet and exit are out of phase. They belong to the Type-I category, since they occur at low flow qualities, according to the Fukuda—Kobori's classification. Moreover, the oscillation period correlates well with the passing time of bubbles in the chimney section regardless of the system pressure, the heat flux, and the inlet subcooling. Two distinct phenomena are found in relation between the oscillation period and liquid passing time in the chimney, indicating that the driving mechanisms of the instabilities are different between low and high pressures. Stability maps were obtained in reference to the inlet subcooling and the heat flux at the system pressures of 1, 2, 4, and 7.2 MPa. The flow became stable below a certain heat flux regardless of the channel inlet subcooling. The stable region enlarges with increasing system pressure. Thus, the stability margin becomes larger in a startup process of a reactor by pressurizing the reactor sufficiently before withdrawing the control rods. The obtained stability map demonstrates that the nominal operating condition of the ESBWR has a significant stability margin to the unstable region.",
keywords = "Boling two-phase flow, BWR type reactors, Density wave oscillations, Natural circulation, Stability",
author = "Masahiro Furuya and Fumio Inada and {Van Der Hagen}, {Tim H.J.J.}",
year = "2005",
month = "1",
day = "1",
doi = "10.1080/18811248.2005.9726379",
language = "English",
volume = "42",
pages = "191--200",
journal = "Journal of Nuclear Science and Technology",
issn = "0022-3131",
publisher = "Atomic Energy Society of Japan",
number = "2",

}

TY - JOUR

T1 - Characteristics of type-i density wave oscillations in a natural circulation bwr at relatively high pressure

AU - Furuya, Masahiro

AU - Inada, Fumio

AU - Van Der Hagen, Tim H.J.J.

PY - 2005/1/1

Y1 - 2005/1/1

N2 - Experiments were conducted to investigate two-phase flow instabilities in a boiling natural circulation loop with a chimney at high pressure. The SIRIUS-N facility was designed to have non-dimensional values which are nearly equal to those of a typical natural circulation BWR. The observed oscillations are found to be density wave oscillations, since the void fractions in the chimney inlet and exit are out of phase. They belong to the Type-I category, since they occur at low flow qualities, according to the Fukuda—Kobori's classification. Moreover, the oscillation period correlates well with the passing time of bubbles in the chimney section regardless of the system pressure, the heat flux, and the inlet subcooling. Two distinct phenomena are found in relation between the oscillation period and liquid passing time in the chimney, indicating that the driving mechanisms of the instabilities are different between low and high pressures. Stability maps were obtained in reference to the inlet subcooling and the heat flux at the system pressures of 1, 2, 4, and 7.2 MPa. The flow became stable below a certain heat flux regardless of the channel inlet subcooling. The stable region enlarges with increasing system pressure. Thus, the stability margin becomes larger in a startup process of a reactor by pressurizing the reactor sufficiently before withdrawing the control rods. The obtained stability map demonstrates that the nominal operating condition of the ESBWR has a significant stability margin to the unstable region.

AB - Experiments were conducted to investigate two-phase flow instabilities in a boiling natural circulation loop with a chimney at high pressure. The SIRIUS-N facility was designed to have non-dimensional values which are nearly equal to those of a typical natural circulation BWR. The observed oscillations are found to be density wave oscillations, since the void fractions in the chimney inlet and exit are out of phase. They belong to the Type-I category, since they occur at low flow qualities, according to the Fukuda—Kobori's classification. Moreover, the oscillation period correlates well with the passing time of bubbles in the chimney section regardless of the system pressure, the heat flux, and the inlet subcooling. Two distinct phenomena are found in relation between the oscillation period and liquid passing time in the chimney, indicating that the driving mechanisms of the instabilities are different between low and high pressures. Stability maps were obtained in reference to the inlet subcooling and the heat flux at the system pressures of 1, 2, 4, and 7.2 MPa. The flow became stable below a certain heat flux regardless of the channel inlet subcooling. The stable region enlarges with increasing system pressure. Thus, the stability margin becomes larger in a startup process of a reactor by pressurizing the reactor sufficiently before withdrawing the control rods. The obtained stability map demonstrates that the nominal operating condition of the ESBWR has a significant stability margin to the unstable region.

KW - Boling two-phase flow

KW - BWR type reactors

KW - Density wave oscillations

KW - Natural circulation

KW - Stability

UR - http://www.scopus.com/inward/record.url?scp=17444410793&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=17444410793&partnerID=8YFLogxK

U2 - 10.1080/18811248.2005.9726379

DO - 10.1080/18811248.2005.9726379

M3 - Article

VL - 42

SP - 191

EP - 200

JO - Journal of Nuclear Science and Technology

JF - Journal of Nuclear Science and Technology

SN - 0022-3131

IS - 2

ER -