Application of the method for uncertainty and sensitivity evaluation to results of PWR LBLOCA analysis calculated with the code ATHLET. Part 2: sensitivity analysis
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Y. Kozmenkov
Abstract
In the previously published part 1 of the paper the uncertainty analysis of the large break loss-of-coolant accident (LBLOCA) for German PWR Konvoi was performed using a statistical method, which is based on the Wilks' theory. The evaluated output parameter is the peak cladding temperature (PCT). The primary goal of this (second) part of the paper is a ranking of the input uncertainties, according to their contributions to the PCT uncertainty in the ATHLET simulation of PWR LBLOCA, by performing a sensitivity analysis. It was shown, that the first extended set of varied parameters used in part 1 can be considerably reduced without any statistically significant influence on the uncertainty analysis results. Thus, it can be shown that the input uncertainty vector based on the LBLOCA PIRT of AREVA GmbH was complete. To minimize the number of varied parameters the statistical t-test was used and, thus, a set of uncertainty parameters with significant impact on the uncertainty of the PCT was identified. The main contribution to the uncertainty of the first cladding temperature maximum during the blowdown phase of the accident is produced by the core parameters that affect the fuel's stored energy at the beginning of the accident. However, the major contributors to the uncertainty of the second PCT maximum are the uncertainties in the code models, and first of all the uncertainties in the heat transfer coefficients for dispersed and pure steam flows.
Kurzfassung
In einem bereits publizierten Teil 1 des Artikels wurden die Ergebnisse einer Unsicherheitsanalyse zu einem Störfall mit großem Leck (LBLOCA) für einen deutschen DWR vom Typ Konvoi vorgestellt, die auf der statistischen Methode von Wilks beruht. Der Zielparameter ist dabei die maximale Hüllrohrtemperatur (PCT). Das primäre Ziel der Arbeiten, die in diesem zweiten Teil des Artikels vorgestellt werden, besteht in einem Ranking der unsicheren Eingabeparameter für eine LBLOCA-Analyse mit dem Thermohydraulikcode ATHLET in Bezug auf ihren Beitrag zur Unsicherheit des Zielparameters mit Hilfe einer Sensitivitätsanalyse. Es konnte gezeigt werden, dass der ursprüngliche, erweiterte Parametersatz ohne statistisch relevanten Einfluss auf die Zielgröße erheblich reduziert werden kann. In diesem Sinne wurde die Vollständigkeit der Auswahl unsicherer Parameter bestätigt, die auf der Basis einer Phenomena Identification and Ranking Table (PIRT) für einen LBLOCA von der AREVA GmbH erstellt worden ist. Zur Minimierung der Anzahl von Unsicherheitsparametern wurde der statistische t-Test herangezogen. Dadurch wurde letztendlich ein Satz von Unsicherheitsparametern identifiziert, die von statistisch relevantem Einfluss auf die Unsicherheit des Zielparameters sind. Der Hauptbeitrag zur Unsicherheit des ersten Maximums der Hüllrohrtemperatur wird durch Parameter erbracht, welche die zu Beginn des Störfalls im Brennstoff gespeicherte Energie beeinflussen. Die Hautbeiträge zur Unsicherheit des zweiten Temperaturmaximums während der Auffüllphase sind allerdings durch Modellunsicherheiten bedingt, und zwar vor allem durch den Wärmeübergangskoeffizienten für disperse und reine Dampfströmung.
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© 2014, Carl Hanser Verlag, München
Artikel in diesem Heft
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Technical Contributions/Fachbeiträge
- A model-based approach to operational event groups ranking
- Application of the method for uncertainty and sensitivity evaluation to results of PWR LBLOCA analysis calculated with the code ATHLET. Part 2: sensitivity analysis
- Statistical Large-Break LOCA analysis for PWRs with combined ECC injection
- Analysis of the CSF model for simulated loss of coolant accident conditions
- Performance of two fluid model based numeric tool with pressure and enthalpy as independent variables for simulation of two phase flow in axial and radial direction
- Pre-decommissioning complex engineering and radiation inspection of the WWR-M reactor
- Analysis of the source term formation in a severe accident initiated by end fitting failure in CANDU type reactors
- Neutron flux investigation on certain alternative fluids in a hybrid system by using MCNPX Monte Carlo transport code
- Analytical investigation of lignite and its ash samples taken from the Afşin-Elbistan coal basin in Turkey
- Explicit formulation of a nodal transport method for discrete ordinates calculations in two-dimensional fixed-source problems
- T1 and U1 approximations to neutron transport equation in one-dimensional spherical geometry
Artikel in diesem Heft
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Technical Contributions/Fachbeiträge
- A model-based approach to operational event groups ranking
- Application of the method for uncertainty and sensitivity evaluation to results of PWR LBLOCA analysis calculated with the code ATHLET. Part 2: sensitivity analysis
- Statistical Large-Break LOCA analysis for PWRs with combined ECC injection
- Analysis of the CSF model for simulated loss of coolant accident conditions
- Performance of two fluid model based numeric tool with pressure and enthalpy as independent variables for simulation of two phase flow in axial and radial direction
- Pre-decommissioning complex engineering and radiation inspection of the WWR-M reactor
- Analysis of the source term formation in a severe accident initiated by end fitting failure in CANDU type reactors
- Neutron flux investigation on certain alternative fluids in a hybrid system by using MCNPX Monte Carlo transport code
- Analytical investigation of lignite and its ash samples taken from the Afşin-Elbistan coal basin in Turkey
- Explicit formulation of a nodal transport method for discrete ordinates calculations in two-dimensional fixed-source problems
- T1 and U1 approximations to neutron transport equation in one-dimensional spherical geometry
