Best-Estimate Model Calibration and Prediction through Experimental Data Assimilation—II: Application to a Blowdown Benchmark Experiment

2010 ◽  
Vol 165 (1) ◽  
pp. 45-100 ◽  
Author(s):  
Alessandro Petruzzi ◽  
Dan G. Cacuci ◽  
Francesco D’Auria
Keyword(s):  
Experimental Data ◽  
Data Assimilation ◽  
Model Calibration ◽  
Benchmark Experiment ◽  
Best Estimate

scholarly journals The predictability of the "Voyager" accident

2008 ◽  
Vol 8 (3) ◽  
pp. 533-537 ◽  
Author(s):  
L. Bertotti ◽  
L. Cavaleri
Keyword(s):  
Experimental Data ◽  
Measured Data ◽  
Balearic Islands ◽  
Local Conditions ◽  
Best Estimate ◽  
Non Linear ◽  
Local Wave ◽  
Wave Heights ◽  
Wave Conditions

Abstract. On 14 February 2005 a severe mistral storm caused substantial damage to the passenger cruiser "Voyager" between Balearic Islands and Sardinia. The storm had been well predicted. However, the ship was hit by one or more, apparently unexpected, large waves. Our aim was to understand if this was a freak event or it was within the expectable probability. At this aim we use our best estimate of the local wave conditions, obtained combining modelling and measured data. Starting from these we derive the probability of large waves, considering both linear and non-linear cases. Notwithstanding a correction towards the worse of the, otherwise inconsistent, available reports, on the basis of the data at disposal we conclude that, given the local conditions, the event was within the range of the potentially expectable wave heights. This turns out to be even more the case on the basis of recent results based on theoretical and experimental data.

Quantification of the RELAP5 Model Uncertainty for Application to the Loss-of-RHR Event During the Mid-Loop Operation

2009 ◽  
Author(s):  
Ikuo Kinoshita ◽  
Hiroichi Nagumo ◽  
Minoru Yamada ◽  
Yasuhiro Sasaki ◽  
Yoshitaka Yoshida
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Model Uncertainty ◽  
Stratified Flow ◽  
Condensation Heat Transfer ◽  
Analysis Method ◽  
Gas Distribution ◽  
Two Phase ◽  
Model Parameter ◽  
Best Estimate

Best estimate analysis method for the loss of Residual Heat Removal (loss-of-RHR) event during the mid-loop operation is being conducted along the Code Scaling, Applicability and Uncertainty (CSAU) evaluation methodology. The analysis method uses RELAP5/MOD3.2 as a best estimate analysis code. One of the important processes in the CSAU methodology is the development of the Phenomena Identification and Ranking Table (PIRT) which identifies thermal-hydraulic phenomena during the event and ranks the identified phenomena from the view point of influence on the safety evaluation parameters. The safety parameters for evaluation are Reactor Coolant System (RCS) pressure and reactor vessel water level. The PIRT for the reflux cooling of the loss-of-RHR event during the mid-loop operation was developed based on existing integral test results, plant analysis results and related papers considering influence on coolant distribution, non-condensible gas distribution and heat transfer. Referenced integral tests are ROSA-IV/LSTF, BETHSY, PKL and IIST. Uncertainty of RELAP5/MOD3.2 physical models related to high ranked phenomena identified in the PIRT for the reflux cooling is quantified using the related experimental data for application to PWR plant statistical analysis based on the developed verification matrix. Uncertainty quantified models are void model, horizontal stratified flow criteria and SG condensation heat transfer. These models are related to the following phenomena respectively. Void model (interfacial friction factor in bubbly and slug flow regimes): - Two phase expansion in core and upper plenum due to core boiling. - Two phase flow to Steam Generator (SG) inlet plenum and U-tubes. Horizontal stratified flow criterion: - Stratification of flow in hot leg. - Water transportation from hot leg to SG by steam flow. SG condensation heat transfer model: - Heat transfer in SG U-tube under presence of non-condensable gas. Distribution of model parameter multiplier which represents model uncertainty was obtained by either experiment analysis by RELAP5 or comparison of separate RELAP5 model prediction to experimental data. Mean value and standard deviation are calculated for distribution of model parameter multiplier.

Modeling of Thermal Hydraulics Features of Top Water Reflood Experiment PARAMETER-SF3 Using SOCRAT/V2 Code

2009 ◽  
Author(s):  
Arcadii E. Kisselev ◽  
Valerii F. Strizhov ◽  
Alexander D. Vasiliev ◽  
Vladimir I. Nalivayev ◽  
Nikolay Ya. Parshin
Keyword(s):  
Experimental Data ◽  
Nuclear Power ◽  
Cooling System ◽  
Severe Accident ◽  
Numerical Code ◽  
Thermal Hydraulics ◽  
Vver Fuel ◽  
Design Basis ◽  
Best Estimate ◽  
Core Cooling

The PARAMETER-SF3 test conditions simulated a severe LOCA (Loss of Coolant Accident) nuclear power plant sequence in which the overheated up to 1700÷2300K core would be reflooded from the top and the bottom in occasion of ECCS (Emergency Core Cooling System) recovery. The test was successfully conducted at the NPO “LUTCH”, Podolsk, Russia, in October 31, 2008, and was the third of four experiments of series PARAMETER-SF. PARAMETER facility of NPO “LUTCH”, Podolsk, is designed for studies of the VVER fuel assemblies behavior under conditions simulating design basis, beyond design basis and severe accidents. The test bundle was made up of 19 fuel rod simulators with a length of approximately 3.12 m (heated rod simulators) and 2.92 m (unheated rod simulator). Heating was carried out electrically using 4-mm-diameter tantalum heating elements installed in the center of the rods and surrounded by annular UO2 pellets. The rod cladding was identical to that used in VVERs: Zr1%Nb, 9.13 mm outside diameter, 0.7 mm wall thickness. After the maximum cladding temperature of about 1900K was reached in the bundle during PARAMETER-SF3 test, the top flooding was initiated. The thermal hydraulic and SFD (Severe Fuel Damage) best estimate numerical complex SOCRAT/V2 was used for the calculation of PARAMETER-SF3 experiment. The counter-current flow limitation (CCFL) model was implemented to best estimate numerical code SOCRAT/V2 developed for modeling thermal hydraulics and severe accident phenomena in a reactor. Thermal hydraulics in PARAMETER-SF3 experiment played very important role and its adequate modeling is important for the thermal analysis. The results obtained by the complex SOCRAT/V2 were compared with experimental data concerning different aspects of thermal hydraulics behavior including the CCFL phenomenon during the reflood. The temperature experimental data were found to be in a good agreement with calculated results. It is indicative of the adequacy of modeling the complicated thermo-hydraulic behavior in the PARAMETER-SF3 test.

Validation of the Deterministic Realistic Method Applied to CATHARE on LB LOCA Experiments

2002 ◽  
Author(s):  
Jean-Yves Sauvage ◽  
Ste´phane Laroche
Keyword(s):  
Experimental Data ◽  
Statistical Analysis ◽  
Deterministic Model ◽  
Evaluation Model ◽  
Flexible Tool ◽  
Model Based ◽  
Design Basis ◽  
Best Estimate ◽  
Design Basis Accident

Framatome-ANP and EDF have defined a generic approach for using a best-estimate code in design basis accident studies called Deterministic Realistic Method (DRM). It has been applied to elaborate a LB LOCA ECCS evaluation model based on the CATHARE code. From a prior statistical analysis of uncertainties, the DRM derives a conservative deterministic model, preserving the realistic nature of the simulation, to be used in the further applications. The conservatism of the penalized model is demonstrated comparing penalized calculations with relevant experimental data. The DRM proved to be a highly flexible tool and has been applied successfully to meet the specific French and specific Belgian requirements of Safety Authorities.

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