Senior Neutronics Engineer

Join us and make YOUR mark on the World!

Lawrence Livermore National Laboratory (LLNL) has turned bold ideas into world-changing impact advancing science and technology to strengthen U.S. security and promote global stability.

Our mission spans four critical national security areas nuclear deterrence, threat preparedness, energy security, and multi-domain defense empowering teams to take on the toughest challenges of today and tomorrow. With a culture built on innovation and operational excellence, LLNL is a place where your expertise can make a real impact.

We have an opening for a Senior Neutronics Engineer to support projects within the National Ignition Facility & Photon Sciences (NIF&PS) / Extreme Light Matter and Fusion (LMF) directorate, home to the National Ignition Facility (NIF), the world’s most energetic laser. In this role, you will work with the Radiation and Mutli-Physics Analysis Group, as well as other LLNL organizations, to perform complex radiation transport simulations of radiation environments in the NIF as well as other facilities. You will have advanced knowledge of radiation measurement techniques and work on characterizing the radiation field during NIF shots. You will work with LLNL team members to expand understanding of radiation effect on diagnostics, electronics and other materials. This position is in the Laser Systems Engineering & Operations (LSEO) Division of the Engineering Directorate.

Depending on your assignment, this position may offer a hybrid schedule, blending in-person and virtual presence. You may have the flexibility to work from home one or more days per week.

In this role, you will

• Operate under consultative direction with substantial authority, using in-depth analysis and subject matter expertise in highly advanced concepts, to resolve a diverse range of highly complex problems, independently determine strategies, modify approaches, and pursue actions that impact organizational operations or directions and achieve long-term goals.
• Perform radiation transport simulations to identify radiological hazards and identify potential shielding solutions.
• Perform detailed activation analyses and characterize decay dose rate environment.
• Apply radiation transport methods to predict potential damage to electronics due to total ionizing dose, displacement damage and single event effects.
• Characterize neutron sources and radiation fields affecting diagnostic systems.
• Develop and optimize computational tools for coupling neutronics and activation analyses.
• Support neutronics analysis activities in collaboration with the Livermore Institute of Fusion Technology (LIFT).
• Prepare supporting safety and engineering documentation for complex analyses and safety base.
• Lead and contribute to proposals for new work, applying appropriate estimating techniques.
• Participate in professional committees, conferences, or working groups with other laboratories and/or government agencies and customers to develop business strategies and programs.
• Prepare and present briefings to internal or external customers.
• Maintain current knowledge of applicable regulatory Safety Standards and Emerging Modeling Tools.
• Perform other duties as assigned.

• Ability to obtain and maintain a U.S. DOE Q-level security clearance which requires U.S. citizenship.
• Bachelor’s degree in Nuclear Engineering or related technical field, or the equivalent combination of education and previous relevant experience.
• Extensive experience developing and applying radiation transport codes, such as MCNP, Open MC, SCALE, Shift, Attila, Denovo and ADVANTG.
• Expert level application and experience developing and applying activation codes, such as FISPACT, ALARA, CINDER and ORIGIN.
• Expert level experience applying CAD to Monte Carlo radiation transport codes using conversion tools such as GEONUED, McCAD and DAGMC.
• Highly advanced knowledge of and significant experience with current state-of-the-art neutronics tool development.
• Expert knowledge of and significant experience with radiation shielding for experimental facilities.
• Expert knowledge of and significant experience in simulating post-irradiation environment in experimental facilities.
• Expert knowledge of radiation measurement techniques.
• Expert communication, facilitation, and collaboration skills necessary to prepare, present, and explain highly complex reports and effectively deliver highly advanced technical presentations, as well as influence and advise senior management and/or external sponsors.

Qualifications We Desire

• PhD degree in Nuclear Engineering or related technical field, or the equivalent combination of education and previous relevant experience.
• Significant experience in shielding design and simulation of post-irradiation environment to meet radiological protection goals in experimental facilities.
• Experience with shielding design to allow for survivability of vulnerable electronics and other equipment in high radiation environments.
• Experience with utilizing hybrid deterministic/Monte Carlo neutronics modeling.
• Experience with developing novel approaches to predict radiation backgrounds in high radiation environments.
• Experience with neutronics and activation analyses for magnetic and inertial fusion facilities and/or fusion power plant studies.
• Experience with applying sensitivity and uncertainty methods using tools such as ASUSD and SUSD3D to quantify nuclear data and modeling uncertainties.
• Experience with performing verification and validation using operating data and shielding benchmark studies.
• Experience in leading projects and managing project schedules.
• Knowledgeable about Monte Carlo radiation transport using GPU architectures.

Pay Range

$210,630 - $267,030 Annually

This is the lowest to highest salary we in good faith believe we would pay for this role at the time of this posting. An employee’s position within the salary range will be based on several factors including, but not limited to, specific competencies, relevant education, qualifications, certifications, experience, skills, seniority, geographic location, performance, and business or organizational needs.

Position Information

This is a Career Indefinite position, open to Lab employees and external candidates.

Why Lawrence Livermore National Laboratory?

• Included in 2026 Best Places to Work by Glassdoor!
• Flexible Benefits Package
• 401(k)
• Relocation Assistance
• Education Reimbursement Program
• Flexible schedules (*depending on project needs)
• Our values - visit https://www.llnl.gov/inclusion/our-values

Security Clearance

This position requires a Department of Energy (DOE) Q-level clearance. If you are selected, we will initiate a Federal background investigation to determine if you meet eligibility requirements for access to classified information or matter. Also, all L or Q cleared employees are subject to random drug testing. Q-level clearance requires U.S. citizenship.

Pre-Employment Drug Test

External applicant(s) selected for this position must pass a post-offer, pre-employment drug test. This includes testing for use of marijuana as Federal Law applies to us as a Federal Contractor.

Wireless and Medical Devices

Per the Department of Energy (DOE), Lawrence Livermore National Laboratory must meet certain restrictions with the use and/or possession of mobile devices in Limited Areas. Depending on your job duties, you may be required to work in a Limited Area where you are not permitted to have a personal and/or laboratory mobile device in your possession. This includes, but not limited to cell phones, tablets, fitness devices, wireless headphones, and other Bluetooth/wireless enabled devices.

If you use a medical device, which pairs with a mobile device, you must still follow the rules concerning the mobile device in individual sections within Limited Areas. Sensitive Compartmented Information Facilities require separate approval. Hearing aids without wireless capabilities or wireless that has been disabled are allowed in Limited Areas, Secure Space and Transit/Buffer Space within buildings.

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