Nonuniform Steam Generator U-Tube Flow Distribution during Natural Circulation Tests in ROSA-IV Large Scale Test Facility

1988 ◽  
Vol 99 (4) ◽  
pp. 289-298 ◽  
Author(s):  
Y. Kukita ◽  
H. Nakamura ◽  
K. Tasaka ◽  
C. Chauliac
Keyword(s):  
Steam Generator ◽  
Large Scale ◽  
Natural Circulation ◽  
Flow Distribution ◽  
Test Facility ◽  
Tube Flow ◽  
Scale Test

Feasibility Study on the Natural Circulation Cooling Procedure at the Loop Unbalanced Condition

2017 ◽  
Author(s):  
Wataru Sakuma ◽  
Shinya Miyata ◽  
Manabu Maruyama ◽  
Junto Ogawa
Keyword(s):  
Large Scale ◽  
Natural Circulation ◽  
Test Facility ◽  
Coolant Temperature ◽  
Pressurized Water Reactor ◽  
Primary Coolant ◽  
Pressurized Water ◽  
Coolant Pump ◽  
Scale Test ◽  
Safety Enhancement

In typical pressurized water reactor (PWR) plant, in case that one steam generator (SG) is dried out and cannot be credited for the primary cooldown, at least one reactor coolant pump (RCP) has to be operated in order to homogenize the primary coolant temperature distribution among loops when the plant is cooled down to the cold shutdown state. For example, an accident such as steam line break (SLB) and feedwater line break (FLB) leads to this situation. If the natural circulation condition is established due to unavailability of all the RCPs, the natural circulation in the primary loop connected to the affected SG would be interrupted in the plant cooldown phase. In this situation, the continuous cooldown disturbs the smooth depressurization because it leads to void generation at the top of the affected SG tube where the high temperature coolant is left. In addition, there is a possibility that all RCPs cannot be operated in case of the earthquake or the fire if the RCPs are not earthquake-proof and fire-resistant. Therefore the establishment of the cooldown procedure without RCPs operation under the temperature unbalanced condition among the primary loops can contribute to the safety enhancement for typical PWR plants. The several experiments have been already performed to observe the natural circulation phenomena under the temperature unbalanced condition. It has been reported that the plant can be continuously cooled down with smooth depressurization by stepwise cooling manner using MSRVs of the intact SGs. In this study, Mitsubishi Heavy Industries, Ltd. (MHI) performed the transient analyses to simulate the natural circulation cooldown test under the temperature unbalanced condition among loops performed by Large Scale Test Facility (JAEA ROSA/LSTF) using M-RELAP5, which was a modified plant system transient code by MHI based on RELAP5-3D. Based on the analysis results, the thermal hydraulic phenomena of natural circulation cooldown under the temperature unbalanced condition were investigated. As a result, the mechanism of natural circulation interruption was clarified, and this paper shows the outline of the cooldown procedure under the temperature unbalanced condition which could be applied to the PWR plants.

Analysis of the Core Exit Temperature and the Peak Cladding Temperature During a SBLOCA: Application to a Scaled-Up Model

2016 ◽  
Vol 2 (2) ◽  
Author(s):  
Andrea Querol ◽  
Sergio Gallardo ◽  
Gumersindo Verdú
Keyword(s):  
Time Delay ◽  
Large Scale ◽  
Test Facility ◽  
The Core ◽  
Accident Management ◽  
Loss Of Coolant ◽  
Exit Temperature ◽  
Scale Test ◽  
Versus Peak ◽  
Physical Phenomena

During loss-of-coolant accidents (LOCAs), operators may start accident management (AM) actions when the core exit temperature (CET) measured by thermocouples exceeds a certain value. However, a significant time delay and temperature discrepancy in the superheat detection were observed in several facilities. This work is focused on clarifying CET thermocouple responses versus peak cladding temperature (PCT) and studying if the same physical phenomena are reproduced in two TRACE5 models with different geometry (a large-scale test facility (LSTF) and a scaled-up LSTF) during a pressure vessel (PV) upper head small break LOCA (SBLOCA). Results obtained show that the delay between the core uncover and the CET excursion is reproduced in both cases.

scholarly journals Experimental Investigation of a Leading Edge Cooling System With Optimized Inclined Racetrack Holes

2014 ◽  
Author(s):  
Carlo Carcasci ◽  
Bruno Facchini ◽  
Lorenzo Tarchi ◽  
Nils Ohlendorf
Keyword(s):  
Film Cooling ◽  
Large Scale ◽  
Cooling System ◽  
Leading Edge ◽  
Test Facility ◽  
Cooling Flow ◽  
Nusselt Numbers ◽  
Nusselt Number Distribution ◽  
Scale Test ◽  
Film Cooling Holes

An experimental survey of a leading edge cooling scheme was performed to measure the Nusselt number distribution on a large scale test facility simulating the leading edge cavity of an high pressure turbine blade. Test section is composed by two adjacent cavities, a rectangular supply channel and the leading edge cavity. The cooling flow impinges on the concave leading edge internal walls, by means of an impingement array located between the two cavities, and it is extracted through showerhead and film cooling holes. The impingement geometry is composed by a double array of circular or shaped holes. The aim of the present study is to investigate the heat transfer performance of two optimized impingement schemes in comparison with a standard one with circular and orthogonal holes. Both the optimized arrays have inclined racetrack shaped holes and one of them has also a converging shape. Measurements were performed by means of a transient technique using narrow band Thermo-chromic Liquid Crystals (TLC). Jet Reynolds number was varied in order to cover the typical engine conditions of these cooling systems (Rej = 15000–45000). Results are reported in terms of detailed 2D maps, radial and tangential averaged Nusselt numbers.

Sampling Based Uncertainty Analysis of 10% Hot Leg Break LOCA in LSTF

2010 ◽  
Author(s):  
Samiran Sengupta ◽  
S. K. Dubey ◽  
R. S. Rao ◽  
S. K. Gupta ◽  
V. K. Raina
Keyword(s):  
Sensitivity Analysis ◽  
Uncertainty Analysis ◽  
Large Scale ◽  
Latin Hypercube Sampling ◽  
Test Facility ◽  
Accident Analysis ◽  
Design Matrix ◽  
Best Estimate ◽  
Scale Test ◽  
Screening Sensitivity

This paper describes the uncertainty analysis carried out for 10% Hot leg break LOCA of Large Scale Test Facility as a part of IAEA Coordinated Research Project on “Evaluation of Uncertainty in Best Estimate Accident Analysis”. The best estimate code used for this analysis is RELAP5/MOD3.2. Initially the nodalisation of the test facility for carrying out the analysis is qualified for both steady state and transient level by systematically applying the procedures lead by Uncertainty Methodology based on Accuracy Extrapolation developed at University of Pisa. Subsequently the uncertainty analysis is carried out using sampling based Monte Carlo approach, which involves the generation and extrapolation of a mapping from uncertain inputs to the uncertain analysis results. The major steps followed in this methodology mainly includes screening sensitivity analysis for input parameters, design matrix generation using Latin Hypercube Sampling, representation of uncertainty analysis results based on best estimate thermal hydraulic code runs and importance /sensitivity analysis using regression analysis. The steps followed have been described in details in this paper.

RELAP5 Code Analysis of LSTF Small Break LOCA Tests With Steam Generator Intentional Depressurization as an Accident Management Procedure: Investigation on Base Case Result Appropriate for the Best Estimate Plus Uncertainty (BEPU) Application

2014 ◽  
Author(s):  
Ikuo Kinoshita ◽  
Toshihide Torige ◽  
Michio Murase ◽  
Yoshitaka Yoshida ◽  
Takeshi Takeda ◽  
...  
Keyword(s):  
Steam Generator ◽  
Large Scale ◽  
Model Simulation ◽  
Test Facility ◽  
Base Case ◽  
Best Estimate ◽  
Management Procedure ◽  
Accident Management ◽  
Characteristic Features ◽  
Secondary Side

The application of the Best Estimate Plus Uncertainty (BEPU) method is made to analysis of the “Intentional depressurization of steam generator secondary side” which is an accident management procedure in a small-break loss-of-coolant accident (SBLOCA) with high pressure injection (HPI) system failure. RELAP5/MOD3.2 is used as the analysis code. By applying the BEPU method, the uncertainties of the analysis results can be estimated quantitatively. However, the accuracy of the analysis results depends primarily on the base case result predicted by the best estimate code. In this study, in order to investigate the appropriate base case model, simulation analyses using the RELAP5/MOD3.2 were carried out for the ROSA Large Scale Test Facility (ROSA/LSTF) secondary-side depressurization tests. It was found that the code predicted well the major event progressions such as pressure responses, core liquid level responses, and rod surface temperatures, as well as important phenomena such as formation and clearing of loop seals, accumulation of water from condensation, and countercurrent flow limitation (CCFL) at the inlet of the U-tubes, which are characteristic features of this accident scenario.

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