Analyse du transfert de chaleur et de la perte de pression pour des écoulements supercritiques dans le réacteur CANDU-SCWR
Bibliographic record
Abstract
Le reacteur refroidi a eau supercritique est l'un des six concepts retenus par le Forum International Generation IV. Le Canada a choisi de mener des recherches avancees sur ce type de reacteur. Pour la conception et l'analyse de surete de ce reacteur, le developpement des codes de simulations numeriques est necessaire. Le code ARTHUR est un code de calcul thermohydraulique developpe par Fassi-Fehri (2008), a l'Ecole Polytechnique de Montreal, pour l'analyse du reacteur CANDU-6. Le but de ce projet est de modifier ce code de calcul afin qu'on puisse l'utiliser pour traiter les reacteurs du type CANDU-SCWR. Dans le but de calculer les proprietes thermohydrauliques du caloporteur dans le canal de combustible d'un reacteur CANDU-SCWR, on a suppose que l'ecoulement de l'eau dans des conditions supercritiques est monophasique. Ainsi a l'interieur de ce code, on a developpe les equations de conservation monophasique. La perte de pression par frottement et le transfert de chaleur par convection forcee sont deux aspects importants dont il faut tenir compte dans la modelisation d'un canal de combustible d'un reacteur nucleaire. Pour le choix de la correlation utilisee dans le calcul du coefficient de la perte de pression par frottement, on a compare des calculs numeriques, utilisant differentes correlations trouvees dans la litterature, a des donnees experimentales. On a conclu que la correlation de Garimella (2008) est la plus coherente pour l'incorporer par la suite dans le code ARTHUR_SCWR. Ainsi, on a demontre que le choix de correlation pour l'estimation de la perte de pression par frottement a une faible influence sur le comportement des differentes proprietes thermohydrauliques dans le canal de combustible. Dans les conditions supercritiques, l'eau est caracterisee par des variations importantes des proprietes thermophysiques dans la region pseudocritique. Cette variation influence le phenomene du transfert de chaleur par convection forcee. Dans le cadre de determination de la correlation qui a ete utilisee afin de calculer le coefficient de transfert de chaleur par convection forcee, on a compare des calculs numeriques avec les valeurs experimentales et on a deduit que la correlation de Mokry et al. (2010) donne l'ecart type le plus faible sur l'ensemble des experiences.----------Abstract The supercritical water reactor is one of the six concepts of generation IV nuclear reactors that has been selected by the International Generation IV Forum (GIF). Canada has chosen to conduct advanced research on this type of reactor. For the design and safety analysis of the reactor concept, the development of numerical simulation codes is needed. The ARTHUR code is a thermal-hydraulic computer code developed by Fassi-Fehri (2008), at the Ecole Polytechnique de Montreal, to analyse the CANDU-6 reactor. The purpose of this project is to modify this numerical code so that it can be used to treat the CANDU-SCWR. To calculate the coolant thermal-hydraulics properties in the fuel channel of a CANDU-SCWR, it was assumed that the water flows under supercritical conditions is a one-phase flow. Thus within this code, we developed the conservation equations for one-phase flow. Hydraulic resistance and heat transfer at supercritical pressure are two important aspects to be considered in the modeling of a fuel channel in a nuclear reactor. To choose the accurate correlation to predict the pressure friction factor, we compared numerical calculations, using different correlations found in literature, to experimental data. We concluded that the Garimella (2008) correlation is the most consistent, to be incorporated in the ARTHUR_SCWR code. We proved that the choice of the friction factor correlation affects slightly the distribution of thermal-hydraulic properties in the fuel channel. Under supercritical conditions, water thermal-physical properties are characterized by significant variations in the pseudo-critical region. This behavior influences the forced convection heat transfer phenomena. To choose the adequate correlation to calculate the forced convection heat transfer coefficient, we compared numerical results to experimental data, and we found that the standard deviation given by Mokry et al. (2010) correlation is the lowest. In order to model the fuel channel, some geometrical simplifications are made. In fact, we assumed that the coolant flow in the fuel channel is represented by the flow around the fuel rod, bounded by the first crown. This simplified model was used for neutronic/thermal-hydraulic coupled calculation performed with neutronic codes DRAGON/DONJON (Varin et al., 2005), to analyse the thermal-hydraulic behavior of the fuel channel in CANDU-SCWR.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".