Simulation of an hypothetical out-of-phase instability case in boiling water reactor by RELAP5/PARCS coupled codes

Costa, Antonella Lombardi; Pereira, Cláubia; Ambrosini, Walter; D'Auria, Francesco Saverio

doi:10.1016/j.anucene.2007.08.019

Cited by 22 publications

(3 citation statements)

References 12 publications

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“…In this way, the TH mapping is independent on each half of the core permitting to verify the independent behavior of each one during the transient. The obtained new results for the control rod banks movement can be seen in the currently published work [38].…”

Section: Control Rod Bank Movementmentioning

confidence: 51%

Analyses of Instability Events in the Peach Bottom-2 BWR Using Thermal-Hydraulic and 3D Neutron Kinetic Coupled Codes Technique

Costa

Petruzzi

D'Auria

et al. 2008

Science and Technology of Nuclear Installations

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Boiling water reactor (BWR) instabilities may occur when, starting from a stable operating condition, changes in system parameters bring the reactor towards an unstable region. In order to design more stable and safer core configurations, experimental and theoretical studies about BWR stability have been performed to characterise the phenomenon and to predict the conditions for its occurrence. In this work, contributions to the study of BWR instability phenomena are presented. The RELAP5/MOD3.3 thermalhydraulic (TH) system code and the PARCS-2.4 3D neutron kinetic (NK) code were coupled to simulate BWR transients. Different algorithms were used to calculate the decay ratio (DR) and the natural frequency (NF) from the power oscillation predicted by the transient calculations as two typical parameters used to provide a quantitative description of instabilities. The validation of the code model set up for the Peach Bottom Unit 2 BWR plant is performed against low-flow stability tests (LFSTs). The four series of LFST have been performed during the first quarter of 1977 at the end of cycle 2 in Pennsylvania. The tests were intended to measure the reactor core stability margins at the limiting conditions used in design and safety analyses.

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Section: Control Rod Bank Movementmentioning

confidence: 51%

Analyses of Instability Events in the Peach Bottom-2 BWR Using Thermal-Hydraulic and 3D Neutron Kinetic Coupled Codes Technique

Costa

Petruzzi

D'Auria

et al. 2008

Science and Technology of Nuclear Installations

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“…The fact that the large number of parallel channels of a BWR has common lower and upper plena imposes the same pressure drop to all the reactor fuel channel assemblies [8]. This fact was verified also in a preceding work were it was analyzed two halves of the core [9].…”

Section: Resultsmentioning

confidence: 69%

Valuation of Power Oscillations in a BWR After Control Rod Banks Withdrawal Events

Costa

Pereira

Silva

et al. 2010

IEEE Trans. Nucl. Sci.

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The out-of-phase mode of oscillation is a very challenging type of instability occurring in BWR (Boiling Water Reactor) and its study is relevant because of the safety implications related to the capability to promptly detect any such inadvertent occurrence by in-core neutron detectors, thus triggering the necessary countermeasures in terms of selected rod insertion or even reactor shutdown. In this work, control rod banks withdrawal transient was considered to study the power instability occurring in a BWR. To simulate this transient, the control rod banks were continuously removed from the BWR core in different cases. The simulation resulted in a very large increase in the power. To perform the instability simulations, the RELAP5/MOD3.3 thermal hydraulic system code was coupled with the PARCS/2.4 3-D neutron kinetic code. Data from a real BWR, the Peach Bottom, have been used as reference conditions and reactor parameters. The trend of the mass flow rate, pressure, coolant temperature and the void fraction to four thermal hydraulic channels symmetrically located in the core with respect to the core centre, were taken. The behavior of the thermal hydraulic parameters investigated presented out-of-phase evolution comparing the channels that represents each half of the core.

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“…Inherent feedback mechanisms in reactors necessitate a multi-physics approach, particularly between neutronics and thermal-hydraulics [9,10]. Numerous neutronics and thermal-hydraulics coupling research studies have been done with simplified physical models, such as nodal diffusion theory and subchannel or single-channel thermal hydraulic codes [11][12][13][14]. Although such models are effective, the assumptions made in their formulation limit the accuracy of solution.…”

Section: Introductionmentioning

confidence: 99%

An Efficient Scheme for Coupling OpenMC and FLUENT with Adaptive Load Balancing

Zhang

Peng

Zhang

et al. 2021

Science and Technology of Nuclear Installations

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This paper develops a multi-physics interface code MC-FLUENT to couple the Monte Carlo code OpenMC with the commercial computational fluid dynamics code ANSYS FLUENT. The implementations and parallel performances of block Gauss–Seidel-type and block Jacobi-type Picard iterative algorithms have been investigated. In addition, this paper introduces two adaptive load-balancing algorithms into the neutronics and thermal-hydraulics coupled simulation to reduce the time cost of computation. Considering that the different scalability of OpenMC and FLUENT limits the performance of block Gauss–Seidel algorithm, an adaptive load-balancing algorithm that can increase the number of nodes dynamically is proposed to improve its efficiency. Moreover, with the natural parallelism of block Jacobi algorithm, another adaptive load-balancing algorithm is proposed to improve its performance. A 3 x 3 PWR fuel pin model and a 1000 MWt ABR metallic benchmark core were used to compare the performances of the two algorithms and verify the effectiveness of the two adaptive load-balancing algorithms. The results show that the adaptive load-balancing algorithms proposed in this paper can greatly improve the computing efficiency of block Jacobi algorithm and improve the performance of block Gauss–Seidel algorithm when the number of nodes is large. In addition, the adaptive load-balancing algorithms are especially effective when a case demands different computational power of OpenMC and FLUENT.

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Simulation of an hypothetical out-of-phase instability case in boiling water reactor by RELAP5/PARCS coupled codes

Cited by 22 publications

References 12 publications

Analyses of Instability Events in the Peach Bottom-2 BWR Using Thermal-Hydraulic and 3D Neutron Kinetic Coupled Codes Technique

Analyses of Instability Events in the Peach Bottom-2 BWR Using Thermal-Hydraulic and 3D Neutron Kinetic Coupled Codes Technique

Valuation of Power Oscillations in a BWR After Control Rod Banks Withdrawal Events

An Efficient Scheme for Coupling OpenMC and FLUENT with Adaptive Load Balancing

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