Welcome
Ian Kolaja is a nuclear engineer focused on advanced reactor operation and fuel measurement. He earned his PhD in Nuclear Engineering from UC Berkeley, with a designated emphasis in Computational and Data Science and Engineering. He also completed his undergraduate degree at Berkeley after transferring from Fullerton College. Ian is a strong advocate for transfer students and for those impacted by the foster youth system.
Research
Ian's dissertation addressed key challenges in operating and monitoring pebble bed reactors (PBRs), with extensions to molten salt reactors (MSRs). His work combined high-fidelity modeling, bent crystal diffraction (BCD) spectroscopy, and machine learning.
Fuel pebbles discharged from PBRs must be measured quickly under intense radiation, conditions where conventional gamma spectroscopy struggles. Ian designed BCD spectrometers—devices widely used in astrophysics but never before applied to PBRs—that act as energy filters for gamma rays. Coupled with machine learning, these spectrometers enabled accurate prediction of pebble properties such as burnup, residence time, and fluence
He also developed long-short term memory (LSTM) models to connect these measurements with operation history, predicting reactivity and flux/power distributions over time. This approach allows operators to forecast reactor behavior and optimize startup sequences, reducing the time to equilibrium.
For MSRs, Ian demonstrated that the same BCD spectroscopy methods could isolate key isotopes like Np-239, enabling real-time tracking of plutonium production for safeguards applications.
Ian's dissertation will be available on ProQuest on September 30th, 2026.
Industry Experience
Before his PhD, Ian worked at Kairos Power, where he was the first developer of the Kairos Power Advanced Core Simulator (KPACS). This tool supported equilibrium core studies for the company’s generic fluoride-salt-cooled high temperature reactor (gFHR) benchmark and contributed to the early design of KP-Hermes 1.
Outside of Nuclear
Ian has a wide range of creative pursuits including music production and filmmaking. Before pursuing science in community college, he wanted to be a film director. He participated and won awards at a handful of student film festivals in Southern California. He also recently has released his first EP, a collection of indie pop songs.
Publications
"Machine Learning Prediction of Pebble History in Pebble Bed Reactors"
I. Kolaja et al., in
Proceedings of the International Conference on Physics of Reactors (PHYSOR 2024), Apr. 2024, pp.
1437-1446.
doi: 10.13182/PHYSOR24-43890.
"Neutronics, thermal-hydraulics, and multi-physics benchmark models for a generic pebble-bed fluoride-salt-cooled high temperature reactor (FHR)"
N. Satvat et al., Nuclear Engineering and Design, vol. 384, no. C, Nov. 2021
doi: 10.1016/j.nucengdes.2021.111461.
"First Direct Measurements of Superheavy-Element Mass Numbers,"
J. M. Gates et al., Phys. Rev. Lett., vol. 121, no. 22, p. 222501, Nov. 2018,
doi: 10.1103/PhysRevLett.121.222501.
Curriculum Vitae
You can download a PDF copy of my CV here.
Presentations
PhD Qualifying Examination
I. Kolaja, UC Berkeley, May 2024
Slides
Machine Learning Prediction of Pebble History and Nuclide Concentration in PBRs
I. Kolaja et al., International Conference on Physics of Reactors (PHYSOR 2024), Apr. 2024
Session: Machine Learning and Artificial Intelligence for Reactor Physics: I
Slides
Resources
NE150/215M: Introduction to Nuclear Reactor Theory
UC Berkeley Nuclear Engineering Department, Spring 2022
GSI Discussion Slides by Ian Kolaja
Note: I joined the course a few weeks in, so weeks 1-3 are missing. These slides have not been edited since the course, so if you see any mistakes please let me know!
Discussion 4: Criticality
Discussion 5: Neutron Transport
Midterm 1 Review: Slides
Midterm 1 Review: Worksheet
Midterm 1 Review: Solutions
Discussion 6: Diffusion Equation Pt. 1
Discussion 7: Diffusion Equation Pt. 2
Discussion 8: Diffusion Equation Pt. 3
Discussion 9: Multigroup Diffusion
Discussion 10: Reactor Kinetics and Long-Term Core Behavior
Midterm 2 Review: Slides
Midterm 2 Review: Worksheet
Midterm 2 Review: Solutions
Media
[Video] ARCO: Making Advanced Reactors Smarter
By Ian Kolaja, Laura Shi, and Eddie Bird
Vimeo, June 2019
[Article] How UC Berkeley researchers are making nuclear reactors smarter
By Laura Shi, Ian Kolaja, and Eddie Bird
Fung Institute for Engineering Leadership, August 2019
[Video] Nuclear Values
By Ian Kolaja
Vimeo, March 2018