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Title: Recent Heat Transfer Improvements to the RELAP5-3D Code

Abstract

The heat transfer section of the RELAP5-3D computer program has been recently improved. The improvements are as follows: (1) the general cladding rupture model was modified (more than one heat structure segment connected to the hydrodynamic volume and heat structure geometry’s internal gap pressure), (2) the cladding rupture model was modified for reflood, and (3) the heat transfer minor edits/plots were extended to include radiation/enclosure heat flux and generation (internal heat source).

Authors:
; ;
Publication Date:
Research Org.:
Idaho National Laboratory (INL)
Sponsoring Org.:
USDOE
OSTI Identifier:
911964
Report Number(s):
INL/CON-07-12083
TRN: US0800245
DOE Contract Number:
DE-AC07-99ID-13727
Resource Type:
Conference
Resource Relation:
Conference: ICAPP '07,Nice, France,05/13/2007,05/18/2007
Country of Publication:
United States
Language:
English
Subject:
22 - GENERAL STUDIES OF NUCLEAR REACTORS, 21 - SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; COMPUTER CODES; HEAT FLUX; HEAT TRANSFER; HYDRODYNAMICS; RUPTURES; heat transfer; reactor safety; RELAP5-3D

Citation Formats

Riemke, Richard A, Davis, Cliff B, and Oh, Chang. Recent Heat Transfer Improvements to the RELAP5-3D Code. United States: N. p., 2007. Web.
Riemke, Richard A, Davis, Cliff B, & Oh, Chang. Recent Heat Transfer Improvements to the RELAP5-3D Code. United States.
Riemke, Richard A, Davis, Cliff B, and Oh, Chang. Tue . "Recent Heat Transfer Improvements to the RELAP5-3D Code". United States. doi:. https://www.osti.gov/servlets/purl/911964.
@article{osti_911964,
title = {Recent Heat Transfer Improvements to the RELAP5-3D Code},
author = {Riemke, Richard A and Davis, Cliff B and Oh, Chang},
abstractNote = {The heat transfer section of the RELAP5-3D computer program has been recently improved. The improvements are as follows: (1) the general cladding rupture model was modified (more than one heat structure segment connected to the hydrodynamic volume and heat structure geometry’s internal gap pressure), (2) the cladding rupture model was modified for reflood, and (3) the heat transfer minor edits/plots were extended to include radiation/enclosure heat flux and generation (internal heat source).},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}

Conference:
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  • The RELAP5-3D computer program has been recently improved. Changes were made as follows: (1) heat structures are allowed to be decoupled from hydrodynamic components, (2) built-in material properties for heat structures have been made consistent with those in MATPRO and the Nuclear Systems Materials Handbook (they are now documented in the RELAP5-3D manual, (3) Schrock's flow quality correlation is now used for a downward oriented junction from a horizontal volume for the stratification entrainment/pullthrough model.
  • The hydrodynamics section of the RELAP5-3D computer program has been recently improved. Changes were made as follows: (1) improved turbine model, (2) spray model for the pressurizer model, (3) feedwater heater model, (4) radiological transport model, (5) improved pump model, and (6) compressor model.
  • The heat transfer boundary conditions used in the RELAP5-3D computer program have evolved over the years. Currently, RELAP5-3D has the following options for the heat transfer boundary conditions: (a) heat transfer correlation package option, (b) non-convective option (from radiation/conduction enclosure model or symmetry/insulated conditions), and (c) other options (setting the surface temperature to a volume fraction averaged fluid temperature of the boundary volume, obtaining the surface temperature from a control variable, obtaining the surface temperature from a time-dependent general table, obtaining the heat flux from a time-dependent general table, or obtaining heat transfer coefficients from either a time- or temperature-dependentmore » general table). These options will be discussed, including the more recent ones.« less
  • This paper summarizes (1) a recent application of the severe accident analysis code SCDAP/RELAP5/MOD3.1, and (2) development and assessment activities associated with the release of SACDAP/RELAP5/MOD3.2. The Nuclear Regulatory Commission (NRC) has been evaluating the integrity of steam generator tubes during severe accidents. MOD3.1 has been used to support that evaluation. Studies indicate that the pressurizer surge line will fail before any steam generator tubes are damaged. Thus, core decay energy would be released as steam through the surge line and the tube wall would be spared from exposure to prolonged flow of high temperature steam. The latest code version,more » MOD3.2, contains several improvements to models that address both the early phase and late phase of a severe accident. The impact of these improvements to the overall code capabilities has been assessed. Results of the assessment are summarized in this paper.« less
  • The presence of noncondensable gas in a condensing vapor significantly decreases the condensation heat transfer and thus noticeably affects the pressurizer response. The pressure response to pressurized water reactor transients is important in determining the timing of the safety system responses. In accidents, nitrogen gas can be discharged into the reactor system from the accumulator after the water inventory is exhausted. The purpose of this study is to model the Massachusetts Institute of Technology (MIT) pressurizer insurge transients, in which the vapor region contains steam mixed with nitrogen gas, using the RELAP5/MOD thermal-hydraulic code. The RELAP5/MOD2 predictions showed poor agreementmore » with the experimental data. A revised factor to account for the degradation of the condensation due to the presence of noncondensable gas was developed. Reasonable agreement of the revised code predictions with the data was achieved.« less