**5. Conclusions**

We end this paper with a list of the most important conclusions:


**Author Contributions:** J.M. designed the research; Q.Y. performed the S.C.D. calculations and made all the figures; M.R. developed the early version of the hydrogen diffusion code; N.S. assisted with some of the calculations and figures; J.M. and Q.Y. discussed the data and participated in writing the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the Consortium for Advanced Simulation of Light Water Reactors (CASL), an Energy Innovation Hub for Modeling and Simulation of Nuclear Reactors under U.S. Department of Energy Contract No. DE-AC05-00OR22725.

**Acknowledgments:** This work was done using computer time allocations at UCLA's IDRE Hoffman2 supercomputer. Helpful discussions with A. Couet, A. Motta, B. D. Wirth, and A. Van der Ven are gratefully acknowledged.

**Conflicts of Interest:** The authors declare no conflict of interest.
