Experimental Investigation of a Helium-Cooled Breeding Blanket First Wall under LOFA Conditions and Pre-Test and Post-Test Numerical Analysis

Abstract

The experimental investigation of a prototypical set-up simulating a loss of flow accident in a helium-cooled breeding blanket first wall mock-up under typical heat load conditions is presented. The experimental campaign reproduces the expected DEMO thermal-hydraulics conditions during normal and off-normal situations and aims at providing some insight into the fast transients associated with the loss of flow in the blanket first wall. The experimental set-up and the definition of the experimental matrix are discussed, including pre-test analysis performed in support of these activities. The major experimental results are discussed, and a procedure of using the acquired data for validating and calibrating the RELAP-3D model of the mock-up is introduced. All these activities contributed to the creation of a relevant theoretical and practical experience that can be used in further studies concerning incidental transients in real-plant scenarios in the framework of DEMO plant fusion safety activities.

Post-Test Numerical Analysis of a Helium-Cooled Breeding Blanket First Wall under LOFA Conditions with the MELCOR Fusion Code

“…The FWMU was originally manufactured to test different manufacturing techniques, and then it was repurposed for the LOFA experimental campaign [4]. To evaluate the manufacturing quality, and to get an understanding of the flow behavior through each channel, the FWMU was subjected to several pressure drop characterization tests [10].…”

“…The LOFA experimental campaign was performed with the purpose of evaluating the response of the FW under accidental conditions [4]. The tests were carried out keeping a constant heat flux on top of the FWMU central zone (Channels 3, 4, 7 and 8), while reducing the helium flow through Channels 1-5.…”

“…In recent years, the Karlsruhe Institute of Technology (KIT) has performed several experimental campaigns to qualify the HCPB design and to provide experimental data for code validation studies [1,3]. One of these campaigns involved is a First Wall Mock-Up (FWMU) under different Loss Of Flow Accident (LOFA) conditions [4].…”

“…The approach to perform this study is the same adopted for the RELAP5-3D code [4]: mean tests are depicted from the experimental tests carried out, and a best-estimate methodology is used to ease the distinction between user's effects and code limitations. The adopted best-estimate methodology is the "Best-Estimate Model Calibration and Prediction through Experimental Data Assimilation" methodology [7].…”

“…This rigorous methodology is based on the information theory and the Bayes' theorem, and it requires an accurate model-oriented choice of parameters and responses to provide best-estimated evaluations of the selected parameters and responses. The theoretical details of this methodology can be found in [7], while the Best-estimate for SYstem Codes software (BeSYC) used to apply it is described in [8] (References [4,8] are published in the same Applied Sciences issue. The reader is advised to look at the two papers for further information concerning the LOFA experimental campaign and the software used to apply the best-estimate methodology).…”