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Title: TRACE/PARCS Core Modeling of a BWR/5 for Accident Analysis of ATWS Events

Abstract

The TRACE/PARCS computational package [1, 2] isdesigned to be applicable to the analysis of light water reactor operational transients and accidents where the coupling between the neutron kinetics (PARCS) and the thermal-hydraulics and thermal-mechanics (TRACE) is important. TRACE/PARCS has been assessed for itsapplicability to anticipated transients without scram(ATWS) [3]. The challenge, addressed in this study, is to develop a sufficiently rigorous input model that would be acceptable for use in ATWS analysis. Two types of ATWS events were of interest, a turbine trip and a closure of main steam isolation valves (MSIVs). In the first type, initiated by turbine trip, the concern is that the core will become unstable and large power oscillations will occur. In the second type,initiated by MSIV closure,, the concern is the amount of energy being placed into containment and the resulting emergency depressurization. Two separate TRACE/PARCS models of a BWR/5 were developed to analyze these ATWS events at MELLLA+ (maximum extended load line limit plus)operating conditions. One model [4] was used for analysis of ATWS events leading to instability (ATWS-I);the other [5] for ATWS events leading to emergency depressurization (ATWS-ED). Both models included a large portion of the nuclear steam supply system and controls, andmore » a detailed core model, presented henceforth.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL)
Sponsoring Org.:
AMERICAN NUCLEAR SOCIETY
OSTI Identifier:
1108563
Report Number(s):
BNL-101128-2013-CP
R&D Project: 15451/15830; 401001060
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Conference
Resource Relation:
Conference: 2013 ANS Winter Meeting and Nuclear Technology Expo; Washington, D.C; 20131110 through 20131114
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; ATWS-ED; TRACE/PARCS; MATLAB; BWR/5

Citation Formats

Cuadra A., Baek J., Cheng, L., Aronson, A., Diamond, D., and Yarsky, P.. TRACE/PARCS Core Modeling of a BWR/5 for Accident Analysis of ATWS Events. United States: N. p., 2013. Web.
Cuadra A., Baek J., Cheng, L., Aronson, A., Diamond, D., & Yarsky, P.. TRACE/PARCS Core Modeling of a BWR/5 for Accident Analysis of ATWS Events. United States.
Cuadra A., Baek J., Cheng, L., Aronson, A., Diamond, D., and Yarsky, P.. 2013. "TRACE/PARCS Core Modeling of a BWR/5 for Accident Analysis of ATWS Events". United States. doi:. https://www.osti.gov/servlets/purl/1108563.
@article{osti_1108563,
title = {TRACE/PARCS Core Modeling of a BWR/5 for Accident Analysis of ATWS Events},
author = {Cuadra A. and Baek J. and Cheng, L. and Aronson, A. and Diamond, D. and Yarsky, P.},
abstractNote = {The TRACE/PARCS computational package [1, 2] isdesigned to be applicable to the analysis of light water reactor operational transients and accidents where the coupling between the neutron kinetics (PARCS) and the thermal-hydraulics and thermal-mechanics (TRACE) is important. TRACE/PARCS has been assessed for itsapplicability to anticipated transients without scram(ATWS) [3]. The challenge, addressed in this study, is to develop a sufficiently rigorous input model that would be acceptable for use in ATWS analysis. Two types of ATWS events were of interest, a turbine trip and a closure of main steam isolation valves (MSIVs). In the first type, initiated by turbine trip, the concern is that the core will become unstable and large power oscillations will occur. In the second type,initiated by MSIV closure,, the concern is the amount of energy being placed into containment and the resulting emergency depressurization. Two separate TRACE/PARCS models of a BWR/5 were developed to analyze these ATWS events at MELLLA+ (maximum extended load line limit plus)operating conditions. One model [4] was used for analysis of ATWS events leading to instability (ATWS-I);the other [5] for ATWS events leading to emergency depressurization (ATWS-ED). Both models included a large portion of the nuclear steam supply system and controls, and a detailed core model, presented henceforth.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2013,
month =
}

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  • The control rod withdrawal accident at hot zero power (HZP) is characterized by a single rod withdrawal from a core position with high reactivity worth, starting at criticality with a very low power level. The evolution consists basically of a continuous reactivity insertion. The main factor limiting the consequences of the accident is a mixed void-Doppler feedback in BWR. The peak power occurs while important power distribution changes take place in the core and also the rod extraction continues. To check the performance of the coupled codes TRAC-BF1/VALKIN and TRACE/PARCS against complex 3D neutronic transients, a rod withdrawal accident inmore » COFRENTES NPP is simulated. This transient is a dynamically complex event, where neutron kinetics is coupled with thermal hydraulics in the reactor primary system, and reactor variables change very rapidly. TRAC-BF1/VALKIN code uses the best estimate TRAC-BF1 code to give account of the heat transfer and thermalhydraulic processes, and a 3D neutronic module. This module has two options, MODKIN that makes use of a modal method based on the assumption that the neutronic flux can be approximately expanded in terms of the dominant lambda modes associated with a static configuration of the core, and the NOKIN option that uses a one-step backward discretization of the neutron diffusion equation. TRACE is a code to study also transients in LWR reactors. This code used as a neutronic module the PARCS code. (authors)« less
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