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# Junior Core Design Engineer

- **Company:** Pacific Northwest National Laboratory
- **Location:** Chattanooga, TN, United States
- **Experience:** Starter
- **Salary:** $100,100.0
- **Contract:** Temporary contract
- **Skills:** C++ (Programming Language), Cyber Security, Computer Programming, Linux, Fortran (Programming Language), Python (Programming Language), Scripting, High Performance Computing, Git, Software Version Control
- **Published:** September 2, 2026
- **Apply:** https://www.techcareers.com/job.asp?id=3373868785&tx=KJ2929FFP&pt=1&aff=0B19D771-A501-4A5E-8338-2A822B784D54&utm_source=Job%20Feed&utm_medium=textkernel&utm_campaign=DE&utm_term=0B19D771-A501-4A5E-8338-2A822B784D54

## About the Role

* BS/BA and 2 years of relevant experience -OR-
 * MS/MA -OR-
 * PhD, * Foundational knowledge of reactor physics, PWR core design, fuel behavior, and nuclear fuel cycles.
 * Familiarity with burnup, depletion, neutron transport, and isotope-production modeling.
 * Interest in applying reactor physics methods to TPBAR design, performance, and operational analyses.
 * Experience with one or more reactor physics or radiation transport codes, such as CASMO/SIMULATE, PARAGON, ANC, MCNP, or SCALE.
 * Programming or scripting experience in Python, Fortran, C/C++, or a similar language.
 * Familiarity with Linux-based HPC environments and Git or other version-control tools.
 * Strong analytical, technical writing, and problem-solving skills.
 * Ability to learn new software and methods, work collaboratively, and communicate technical results clearly.

Hazardous Working Conditions/Environment

Not Applicable

Additional Information

This position requires the ability to obtain and maintain a federal security clearance.

A security clearance background investigation includes review of your employment, education, financial, and criminal history, as well as interviews with you and your personal references, neighbors, and co-workers to determine trustworthiness, reliability, and loyalty to the United States. The investigation also examines your foreign connections, drug and alcohol use, foreign influence, and overall conduct., * U.S. Citizenship

 * Background Investigation: Applicants selected will be subject to a Federal background investigation and must meet eligibility requirements for access to classified matter in accordance with 10 CFR 710, Appendix B.
 * Drug Testing: All Security Clearance positions are Testing Designated Positions, which means that the applicant selected for hire is subject to pre-employment drug testing, and post-employment random drug testing. In addition, applicants must be able to demonstrate non-use of illegal drugs, including marijuana, for the 12 consecutive months preceding completion of the requisite Questionnaire for National Security Positions (QNSP).

Note: Applicants will be considered ineligible for security clearance processing by the U.S. Department of Energy if non-use of illegal drugs, including marijuana, for 12 months cannot be demonstrated.

## Description

The Nuclear Engineering Group at Pacific Northwest National Laboratory (PNNL) is seeking an early-career nuclear engineer to support reactor physics analyses, modeling, and simulations for commercial pressurized water reactors (PWRs).

This position supports PNNL's Tritium Technology Program, which provides technical leadership for the U.S. national security infrastructure. The program serves as the design authority for Tritium-Producing Burnable Absorber Rods (TPBARs), specialized rods installed in commercial PWRs to produce tritium. The successful candidate will apply nuclear engineering principles to support TPBAR performance analysis, reactor modeling, and related technical activities.

Responsibilities

 * Model PWR core physics and TPBAR performance using neutron transport, diffusion, depletion, and fuel-cycle methods.
 * Analyze TPBAR effects on reactivity, power distribution, neutron flux, and tritium production.
 * Develop, run, and evaluate simulations using established reactor physics codes.
 * Automate analyses and process results with Python or similar scripting tools.
 * Perform data checks, sensitivity studies, and basic uncertainty assessments to support technically defensible results.
 * Document methods and findings in technical reports and presentations.
 * Collaborate with experienced engineers and contribute to projects involving both near-term analyses and longer-term model development.
 * Expected to work with non-sensitive, sensitive, and classified information as appropriate for individual projects and should demonstrate an ability to navigate sensitive business situations and contribute to positive outcomes. The person in this position must recognize and accept that they will be working in technical areas associated with the National Security of the United States

This position offers a hybrid work arrangement. The selected individual should expect regular on-site work to support project activities involving sensitive information and collaboration with team members.


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