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  • Writer's pictureErez Gilad

Unveiling the Secrets of Reactor Core Power Peaking: A New Study

Introduction

In the world of nuclear science, understanding the behavior of reactor cores is paramount for optimizing design, ensuring safety, and maximizing performance. A recent groundbreaking study has delved into the complex details of power peaking factors within a reactor core, shedding light on how localized phenomena can have a profound impact. This high-fidelity investigation, utilizing a Monte Carlo model developed with the Serpent code, presents findings that have important implications for reactor design, operation, and safety assessment.


H. Abuzlf, C. Castagna, T. Makmal, O. Aviv, Z. Yungrais, G. Gabrieli, U. Steinitz, I. Neder, E. Gilad, High-fidelity Monte Carlo analysis of highly-localized fission power peaking near a flux trap in an MTR core, International Journal of Energy Research, 2023, 9727367.


The Power of Precision: Investigating Localized Power Peaking

The core of this study revolved around comprehending the behavior of the power peaking factor at a local scale within a reactor core. One key factor examined was the influence of water gaps, also known as flux traps, on local power peaking. We utilized a finely tuned spatial mesh to accurately represent the distribution of fission power and burnup.


Validation through Experimentation

To ensure the robustness of our findings, we compared the results obtained from the high-fidelity model with experimental data gathered from the IRR1 facility. This validation process added credibility to the study's outcomes, making them even more significant.


Model Fidelity Matters

One of the most eye-opening discoveries of the study was the significant impact of model fidelity. The power peaking factor was found to vary significantly when calculated at different scales. For instance, at the fuel assembly scale, the calculated power peaking factor was in close agreement with experimental measurements. However, the high-fidelity model predicted substantially higher power peaking factor values at other heights within the core, where measurements were unavailable. This observation emphasized the need to employ detailed fine-mesh models to account for localized behavior accurately, challenging traditional coarse-mesh or average approaches.


Safety and Performance Optimization

The study underlined the importance of understanding localized power peaking behavior for reactor safety and performance optimization. It demonstrated that the proximity of the fuel assembly to strong absorbers and neutron reflectors can significantly affect the local power peaking and power density. Moreover, it was shown that these effects can occur irrespective of the orientation of the fuel assembly. This highlights the need for careful consideration of core component placement in reactor design and operation to ensure safety and performance.


Broad Implications

The significance of this study extends beyond its immediate findings. It offers valuable insights into the behavior of power peaking near flux traps in various types of reactors. Furthermore, it enhances our understanding of experimental measurements, computational simulations, and mitigation strategies.


The Road Ahead

In conclusion, this study has illuminated the highly localized behavior of the power peaking factor within a reactor core. It emphasizes the need for high-fidelity models like the Monte Carlo model used in the study to make accurate predictions in such cases. By providing a deeper understanding of power peaking behavior, this research contributes to optimizing reactor design and operation and assessing safety margins. As we continue to explore the frontiers of nuclear science, studies like these pave the way for safer, more efficient, and more sustainable nuclear energy solutions.


The study was supported by the Pazy Foundation and was performed in collaboration with Soreq Nuclear Research Center.

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