Speaker
Description
The Water-Cooled Ceramic Breeder (WCCB) Test Blanket System (TBS), a fusion blanket test module for ITER, employs high-temperature, high-pressure water cooling and requires safety assessments based on numerical simulations of thermal-hydraulic and accident phenomena. Because the accuracy of such assessments depends on modeling assumptions and input data, experimental validation is essential to establish confidence in safety analyses. This need to validate simulation tools against representative experimental data is a common issue in both fusion safety studies and accelerator reliability assessments.
To support validation of simulation tools used in ITER safety assessments, QST Rokkasho has developed a series of dedicated safety test benches that reproduce key phenomena under representative operating conditions. These facilities provide benchmark data for assessing analytical models and reducing uncertainties in safety evaluations.
Particular emphasis has been placed on two facilities that directly support simulation validation. A High Heat Flux Test Facility has been used to evaluate heat removal performance and thermal response of first-wall components under ITER-relevant heat loads. Experimental temperature and cooling-performance data are compared with analytical predictions to confirm thermal design margins and improve confidence in thermal-hydraulic models.
An In-Box Water Eruption and Leakage Test Facility has been developed to investigate loss-of-coolant accident (LOCA) scenarios inside the TBM box. Measurements of coolant release behavior and pressure transients provide benchmark data for validation of accident analysis methodologies and contribute to improved understanding of accident progression mechanisms.
In addition, a Flow Assisted Corrosion Test Loop is being operated to obtain material degradation data for future model development and long-term reliability assessments, while a Beryllium-Steam Reaction Test Facility provides experimental information on hydrogen generation and reaction heat associated with beryllium-water interactions.
This paper presents the objectives and capabilities of these safety test benches, with particular focus on the comparison between simulation results and experimental observations obtained in high heat flux and LOCA studies. The experience demonstrates how dedicated test facilities can improve model credibility, reduce uncertainties, and strengthen confidence in the safety and reliability of fusion blanket systems.