- Physical Review Journals
All JournalsPhysics Magazine

PRX Energy

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Open Access

High-Resolution Multiphysics Analysis of CRUD Effects in Reactor Assemblies

Chaoyuan Zhang, Han Yin, Yan Liu, Hui He, Xiaojing Liu, and Tengfei Zhang*

Sicheng Wang

  • *Contact author: zhangtengfei@sjtu.edu.cn
PDF

PRX Energy 4, 033016 – Published 16 September, 2025

DOI: https://doi.org/10.1103/nqhj-dppn

Abstract

This study develops a high-fidelity multiphysics coupling framework to systematically investigate the impact of Chalk River unidentified deposits (CRUD) on pressurized-water-reactor (PWR) assemblies, integrating neutronics, thermal hydraulics, and chemical kinetics modeling. CRUD, formed via subcooled nucleate boiling (SNB) and corrosion-product deposition, alters local boron concentrations, thereby inducing a power shift (CIPS) due to CRUD and generating asymmetric axial power distributions. The proposed framework adopts an internally coupled approach, utilizing Picard iteration and a background-mesh technique to resolve multiscale computational challenges while maintaining numerical accuracy and efficiency. Numerical simulations of a 17×17 PWR fuel assembly reveal that CRUD deposition reduces the eigenvalue by 293 percent mille (pcm) and shifts the axial power peak downward by 21 cm, corresponding to a 6.27% axial offset. Radially, the effect of CRUD on power distribution remains minimal (approximately 0.04%). A critical observation is the dominant influence of surface heat flux on CRUD growth, with thicker deposits and elevated boron concentrations observed in high-power regions. CRUD-induced perturbations also exhibit a “neighboring phenomenon,” wherein CRUD-free fuel rods experience comparable axial power shifts due to neutron-flux disturbances. These findings underscore the intricate coupling between power distribution, SNB, and CRUD chemistry, providing valuable insights for enhancing reactor performance and safety.

View figure in article

Physics Subject Headings (PhySH)

Popular Summary

In nuclear power plants, layers of mineral deposits - known as Chalk River Unidentified Deposites (CRUD) - can form on rector fuel rods during operation. CRUD can trap boron and alter how neutrons behave inside the reactor, leading to shifts in power distribution that affect both performance and safety. This study introduces a hig-fidelity modeling framework that integrates neurtronics, thermal-hydraulics, and chemical kinetics modeling. Simulations of a pressurized water reactor fuel assembly show that CRUD deposits can cause measurable shifts in the reactor’s power profile, including a downward shift of the axial power peak, while leaving radial variations mostly unchanged. The results also reveal that regions with higher surface heat flux foster thicker deposits and elevated boron concentration, and that power shifts can influence even neighboring rods without deposits. These insights can inform improved reactor behavior prediction, operation strategies and safety assessments.

Article Text

References (48)

  1. S. Chu and A. Majumdar, Opportunities and challenges for a sustainable energy future, Nature 488, 294 (2012).
  2. C. Karakosta, C. Pappas, V. Marinakis, and J. Psarras, Renewable energy and nuclear power towards sustainable development: Characteristics and prospects, Renewable Sustainable Energy Rev. 22, 187 (2013).
  3. J. R. Lovering, A. Yip, and T. Nordhaus, Historical construction costs of global nuclear power reactors, Energy Policy 91, 371 (2016).
  4. E. Severnini, Impacts of nuclear plant shutdown on coal-fired power generation and infant health in the Tennessee Valley in the 1980s, Nat. Energy 2, 1 (2017).
  5. L. M. Freese, G. P. Chossière, S. D. Eastham, A. Jenn, and N. E. Selin, Nuclear power generation phase-outs redistribute US air quality and climate-related mortality risk, Nat. Energy 8, 492 (2023).
  6. P. Fernández-Arias, D. Vergara, and J. A. Orosa, A global review of PWR nuclear power plants, Appl. Sci. 10, 4434 (2020).
  7. S. Chen, T. Wang, Z. Zhang, R. Li, S. Yuan, R. Zhang, C. Yuan, C. Zhang, and J. Zhu, Linear regression and machine learning for nuclear forensics of spent fuel from six types of nuclear reactors, Phys. Rev. Appl. 19, 034028 (2023).
  8. J. de Dios Sánchez, Key Emerging Issues and Recent Progress Related to Plant Chemistry/Corrosion (PWR, CANDU, and BWR Nuclear Power Plants), Tech. Rep. (Advanced Nuclear Technology International, 2024).
  9. F. Cattant, D. Crusset, and D. Féron, Corrosion issues in nuclear industry today, Mater. Today 11, 32 (2008).
  10. P. M. Scott and P. Combrade, in Corrosion: Environments and Industries, edited by S. D. Cramer and B. S. Covino, Jr. (ASM International, Materials Park, OH, 2006), Vol. 13C, p. 0.
  11. J. Buongiorno, Can corrosion and CRUD actually improve safety margins in LWRs? Ann. Nucl. Energy 63, 9 (2014).
  12. J. Deshon, D. Hussey, B. Kendrick, J. McGurk, J. Secker, and M. Short, Pressurized water reactor fuel crud and corrosion modeling, JOM 63, 64 (2011).
  13. R. Riess, Chemistry experience in the primary heat transport circuits of Kraftwerk Union pressurized water reactors, Nucl. Technol. 29, 153 (1976).
  14. H. Fenech, Heat Transfer and Fluid Flow in Nuclear Systems (Pergamon Press Inc., Oxford, U.K, 1981).
  15. J. Breitenbach, I. V. Roisman, and C. Tropea, Drop collision with a hot, dry solid substrate: Heat transfer during nucleate boiling, Phys. Rev. Fluids 2, 074301 (2017).
  16. Y. Hao, Y. Zhang, and A. Prosperetti, Mechanics of gas-vapor bubbles, Phys. Rev. Fluids 2, 034303 (2017).
  17. Y. Liu, X. Liu, T. Zhang, and H. He, Understanding flow fouling deposition and solute hideout–return behavior at the phase change interface, ACS Appl. Mater. Interfaces 16, 4719 (2024).
  18. F. D. Nicholson and J. V. Sarbutt, The effect of boiling on the mass transfer of corrosion products in high temperature, high pressure water circuits, Corrosion 36, 1 (1980).
  19. J. Yang, J. Wang, J. Liu, S. Wang, D. Yun, D. Ma, Y. Li, and D. Xu, Microstructural understanding on the fouling behavior of crud on PWR fuel cladding surface, J. Nucl. Mater. 582, 154500 (2023).
  20. W. A. Byers, G. Wang, M. Y. Young, and J. Deshon, Simulation of PWR CRUD, in International Conference on Nuclear Engineering (2014), Vol. 1, p. V001T02A029.
  21. R. A. Castelli, Nuclear Corrosion Modeling: The Nature of CRUD (Butterworth-Heinemann, Oxford, U.K, 2010).
  22. M. Barton, M. R. Conqueror, K. Garbett, M. A. Mantell, M. E. Phillips, M. V. Polley, and W. A. Westall, in Water Chemistry of Nuclear Reactor Systems 8 (Thomas Telford Publishing, London, England, 2001), pp. 2: 391–398.
  23. Y. Liu, H. He, T. Zhang, and X. Liu, Pressurized water reactor fuel corrosion-related unidentified deposit and its related safety issues—I. Corrosion product deposition and heat transfer, Ann. Nucl. Energy 208, 110758 (2024).
  24. M. P. Short, D. Hussey, B. K. Kendrick, T. M. Besmann, C. R. Stanek, and S. Yip, Multiphysics modeling of porous CRUD deposits in nuclear reactors, J. Nucl. Mater. 443, 579 (2013).
  25. J. Pongpuak, Ph.D. thesis, Department of Chemical Engineering, University of New Brunswick, 2006.
  26. P. Cohen, Heat and mass transfer for boiling in porous deposits with chimneys, AIChE Symp. Ser. 70, 71 (1974).
  27. J. Deshon, PWR axial offset anomaly (AOA) guidelines, revision 1, EPRI (Palo Alto, CA, 2004), https://www.epri.com/research/products/000000000001008102.
  28. L. Zou, H. Zhang, J. Gehin, and B. Kochunas, Coupled thermal-hydraulic/neutronics/CRUD framework in prediction of CRUD-induced power shift phenomenon, Nucl. Technol. 183, 535 (2013).
  29. EPRI, Boron-Induced Offset Anomaly (Palo Alto, CA, 2017), Software No. 3002012131, https://www.epri.com/research/products/000000003002012131.
  30. G. Wang, P. Sapienza, R. J. Fetterman, M. Y. Young, J. R. Secker, S. W. Nelson, R. L. Oelrich, and Y. Sung, in Volume 3: Thermal-Hydraulics; Turbines, Generators, and Auxiliaries (American Society of Mechanical Engineers, Anaheim, California, 2012), pp. 93–101.
  31. B. Collins, J. Galloway, R. Salko, Jr., K. Clarno, A. Wysocki, B. Okhuysen, and A. D. Andersson, Whole core CRUD-induced power shift simulations using vera, Tech. Rep. (Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee, 2018).
  32. D. J. Walter, B. K. Kendrick, V. Petrov, A. Manera, B. Collins, and T. Downar, Proof-of-principle of high-fidelity coupled CRUD deposition and cycle depletion simulation, Ann. Nucl. Energy 85, 1152 (2015).
  33. M. Jin and M. Short, Multiphysics modeling of two-phase film boiling within porous corrosion deposits, J. Comput. Phys. 316, 504 (2016).
  34. S. Seo, B. Park, S. J. Kim, H. C. Shin, S. J. Lee, M. Lee, and S. Choi, botani: High-fidelity multiphysics model for boron chemistry in CRUD deposits, Nucl. Eng. Technol. 53, 1676 (2021).
  35. Y. Liu, J. Chen, G. Wang, H. He, T. Zhang, and X. Liu, Pressurized water reactor fuel corrosion-related unidentified deposit and its related safety issues—II. Corrosion product deposition and heat transfer modeling, Ann. Nucl. Energy 211, 110932 (2025).
  36. H. G. Joo, J. Y. Cho, K. S. Kim, C. C. Lee, and S. Q. Zee, Methods and Performance of a Three-Dimensional Whole-Core Transport Code DeCART (American Nuclear Society, Chicago, Illinois, 2004).
  37. T. Zhang, W. Xiao, H. Yin, Q. Sun, and X. Liu, vitas: A multi-purpose simulation code for the solution of neutron transport problems based on variational nodal methods, Ann. Nucl. Energy 178, 109335 (2022).
  38. T.-l. Hu, H.-c. Wu, L.-z. Cao, Y.-q. Zheng, and K. Zhuang, Neutronics and thermal-hydraulics coupling analysis of molten salt reactor at steady state, At. Energy Sci. Technol. 10, 1823 (2016).
  39. J. Tang, M. Huang, Y. Zhao, X. Ouyang, and J. Huang, A new procedure for solving steady-state and transient-state nonlinear radial conduction problems of nuclear fuel rods, Ann. Nucl. Energy 110, 492 (2017).
  40. W. Jens and P. Lottes, Analysis of Heat Transfer, Burnout, Pressure Drop and Density Data for High-Pressure Water (Naval Reactor Division, Argonne National Laboratory, Lemont, IL, 1955).
  41. C. Pan, B. G. Jones, and A. J. Machiels, Concentration levels of solutes in porous deposits with chimneys under Wick boiling conditions, Nucl. Eng. Des. 99, 317 (1987).
  42. C. B. Lee, Ph.D. thesis, Modeling of corrosion product transport in PWR primary coolant, Department of Nuclear Engineering, Massachusetts Institute of Technology, 1990.
  43. C. Y. Tai and C.-H. Lin, Crystal growth kinetics of the two-step model, J. Cryst. Growth 82, 377 (1987).
  44. B. G. Park, S. Seo, S. J. Kim, J. H. Kim, and S. Choi, Meso-scale multi-physics full coupling within porous CRUD deposits on nuclear fuel, J. Nucl. Mater. 512, 100 (2018).
  45. R. Macfarlane, D. W. Muir, R. M. Boicourt, A. C. Kahler, and J. L. Conlin, The njoy nuclear data processing system, version 2016. Los Alamos National Lab. (LANL), Los Alamos, NM (United States, 2017).
  46. J. A. Turner, K. Clarno, M. Sieger, R. Bartlett, B. Collins, R. Pawlowski, R. Schmidt, and R. Summers, The virtual environment for reactor applications (vera): Design and architecture, J. Comput. Phys. 326, 544 (2016).
  47. Y. Liu, G. Wang, H. He, T. Zhang, and X. Liu, Pressurized water reactor fuel corrosion-related unidentified deposit and its related safety issues—III. N-TH-M coupled CIPS prediction, Ann. Nucl. Energy 208, 110800 (2024).
  48. S. H. Baek, H.-S. Shim, J. G. Kim, and D. H. Hur, Effects of heat flux on fuel crud deposition and sub-cooled nucleate boiling in simulated PWR primary water at 13 MPa, Ann. Nucl. Energy 133, 178 (2019).

Outline

Information

PRX Energy 4, 033016– Published 16 September, 2025
  • Received 12 May 2025
  • Revised 22 July 2025
  • Accepted 19 August 2025
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation