Assessment of RELAP5/MOD3.3 for subcooled boiling, flashing and condensation in a vertical annulus

Caleb Brooks, William D. Fullmer, Clayton D. Lietwiler

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Continued development of system analysis codes has resulted in the recovery of conservatisms originally imposed on nuclear power reactors, allowing for an increase in the capacity of the nuclear power fleet. These codes also play an instrumental role in the design and certification of new reactor systems. With the increased demand for passive natural circulation and gravity driven cooling options, these codes are met with the new challenge of simulating low pressure, low flow conditions. The objective of this work is to demonstrate the effectiveness of the widely used RELAP5/MOD3.3 code to simulate boiling, condensing and flashing flows under such conditions. Several conditions of significance were selected from a published database of two-phase flow data in a vertical annulus with inner diameter of 19.1mm and outer diameter of 38.1mm. The code calculation of pressure, temperature, void fraction, interfacial area concentration, and void weighted gas velocity along the 4.5 m test section is compared with data at five axial locations. In the 2.8 m heated section of the channel the code predictions compare favorably in general, although the error does increase at low system pressure. Beyond the heated length, code predictions of condensation and flashing show more noticeable disagreement along the 1.7m unheated section. Condensation appears to be consistently under-predicted. Flashing varies from relatively good agreement to complete failure, depending on the conditions at the exit of the heated section.

Original languageEnglish (US)
Title of host publicationInternational Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015
PublisherAmerican Nuclear Society
Pages7261-7271
Number of pages11
ISBN (Electronic)9781510811843
StatePublished - Jan 1 2015
Event16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2015 - Chicago, United States
Duration: Aug 30 2015Sep 4 2015

Publication series

NameInternational Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015
Volume9

Other

Other16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2015
CountryUnited States
CityChicago
Period8/30/159/4/15

Keywords

  • Condensation
  • Flashing
  • RELAP5
  • Subcooled boiling
  • Validation

ASJC Scopus subject areas

  • Instrumentation
  • Nuclear Energy and Engineering

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  • Cite this

    Brooks, C., Fullmer, W. D., & Lietwiler, C. D. (2015). Assessment of RELAP5/MOD3.3 for subcooled boiling, flashing and condensation in a vertical annulus. In International Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015 (pp. 7261-7271). (International Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015; Vol. 9). American Nuclear Society.