Associate Criticality Safety Engineer – Active Clearance Required

Lawrence Livermore National Laboratory; Livermore (CA); Hybrid; USD 122,000 - 155,000; Part time

Benefits offered by this job

Hybrid schedule

Flexible Term appointment

Job summary

Lawrence Livermore National Laboratory (LLNL) has an opening for an Associate Criticality Safety Engineer in the Environment, Safety, and Health Directorate. You will contribute to design, development, and testing of nuclear equipment with fissionable materials and support the DOE Nuclear Criticality Safety Program.

This role offers a hybrid schedule with some days remote. A DOE Q or Top Secret clearance is required at hire, and a Bachelor’s degree in a related field is required with strong

Qualifications

• Active DOE Q clearance or Top Secret clearance at hire.
• Bachelor’s Degree in Nuclear Engineering, Physics, or closely related field, or equivalent.
• Fundamental knowledge of nuclear facilities or regulated environments.
• Ability to apply technical and analytical skills to work.
• Familiarity with radiation transport software is desirable.

Responsibilities

• Assist with criticality safety evaluations per DOE-STD-3007 and LLNL procedures.
• Conduct walk-through inspections and support annual reviews of operations and documents.
• Perform limited-complex technical assignments under supervision.
• Gather and analyze data, prepare calculations and technical documents.
• Travel to NNSS as needed and conduct training courses.

Skills

Active DOE Q clearance

Criticality safety knowledge

Technical problem solving

Verbal and written communication

Team collaboration

Education

Bachelor’s Degree in Nuclear Engineering or Physics

Master’s Degree in Nuclear Engineering or Physics (desirable)

Tools

COG

MCNP

GEANT

SCALE

Job description

Mid-Senior Level | Part-time
Environmental, Safety & Health | Livermore, CA | 09/28/2026
Reference #: REF8917D
Job Code: SES.1 Science & Engineering MTS 1
Organization: ESH and Quality
Position Type: Flexible Term
Security Clearance: Active DOE Q clearance (or active Top Secret clearance)
Drug Test: Required for external applicant(s) selected for this position (includes testing for use of marijuana)
Medical Exam: Not applicable

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.

Job Description

We have an opening for anAssociateCriticality Safety Engineerwithin the Environment, Safety, and Health (ESH) Directorate. You will contribute to the design, development, and testing of nuclear equipment and systems for Lawrence Livermore National Laboratory (LLNL) operations with fissionable materials. You will also contribute to projects and task assigned to LLNL supporting the Department of Energy (DOE) Nuclear Criticality Safety Program (NCSP). This position is in the Nuclear Criticality Safety Division (NCSD).

This position offers a hybrid schedule, blending in-person and virtual presence. You will have the flexibility to work from home one or more days per week.

You will

• Assist with criticality safety evaluations in conformance with DOE-STD-3007 and LLNL administrative procedures and support the review of new or proposed changes to existing equipment or operating procedures.
• Perform walk-through inspections and assist with basic annual reviews of operations and work authorization/work control documents and support the review of safety procedures and documents for consistency with criticality safety evaluations and adequate implementation of criticality safety controls.
• Perform technical/scientific assignments of limited complexity using established methods and procedures under general direction, and provide technical support to engineers, scientists, and facility staff as a member of a team in scientific research and development projects and/or ongoing operations.
• Gather, organize, and assist in analyzing data and information in support of the work activities, and help prepare documents, calculations, recommendations, corrective action documentation, designs, or related technical work products.
• Contribute to solutions for routine or limited-complexity problems using standard techniques and established practices, supporting project and organizational goals.
• Travel to the Nevada National Security Sites as needed.
• Conduct Fundamentals of Criticality Safety training courses.
• Perform other duties as assigned.

Qualifications

• This position requires an active Department of Energy (DOE) Q-level clearance or active Top Secret clearance issued by another U.S. government agency at the time of hire.
• Bachelor’s Degree in Nuclear Engineering, Physics, or closely related scientific discipline (e.g., mechanical/systems engineering, nuclear physics, particle physics, radiochemistry) or equivalent combination of education and prior relevant experience.
• Fundamental knowledge of and some academic, internship, research, or work experience in a nuclear facility, nuclear reactor, chemical, high hazard, radiological operation, or similarly regulated technical environment.
• Ability to apply fundamental technical, analytical, and problem-solving skills to assigned work using established methods and procedures.
• Familiarity with personal computers and exposure to radiation transport software such as COG, MCNP, GEANT, or SCALE is desirable.
• Experience modeling the Inherently Safe Subcritical Assembly (ISSA) and performing pulsed-neutron experiments.
• Experience performing reactor kinetics calculations and developing custom radiation transport code modules for specific experiments.
• Experience modeling critical and subcritical benchmark experiments in COG, MCNP, OpenMC.
• Ability to assist with preparing technical documents and calculations following established protocols and guidance.
• Basic familiarity with DOE orders, national consensus standards, and engineering practices is desirable.
• Proficient verbal and written communication and interpersonal skills to work effectively in a collaborative team environment.
• Ability to document and explain assigned technical or operational work results to supervisors, project leads, and team members.
• Ability to reprioritize and change programmatic direction depending on emergent requests and in collaboration with a variety of multidisciplinary teams.

Qualifications We Desire

• Master’s Degree in Nuclear Engineering, Physics, or closely related scientific discipline or equivalent combination of education and prior relevant experience.
• Experience in criticality safety including preparing criticality safety evaluations and implementation of criticality safety controls.
• Knowledge of LLNL’s policies, procedures, and practices.
• Knowledge of and/or experience with DOE STD-3007 and ANSI/ANS-8 Series Consensus Standards.

Pay Range:$121,830 - $154,500 Annually

This is the lowest to highest salary range in good faith 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.

Additional Information

#LI-Hybrid

Position Information

This is a Flexible Term appointment, which is for a definite period not to exceed six years.If final candidate is a Career Indefinite employee, Career Indefinite status may be maintained (should funding allow).

Why Lawrence Livermore National Laboratory?

• Included in 2026Best Places to Work by Glassdoor!
• Flexible schedules (*depending on project needs)

This position requires an active Department of Energy (DOE) Q-level clearance or active Top Secret clearance issued by another U.S. government agency at time of hire.

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 useand/or possession ofmobile devices in Limited Areas. Depending on your job duties, you may be required to work in a Limited Area whereyou are not permitted to have a personal and/or laboratory mobile devicein your possession. This includes, but not limited to cell phones, tablets, fitness devices, wireless headphones, and other Bluetooth/wireless enabled devices.

Ifyou useamedical device, whichpairs with a mobile device,you must still follow the rules concerningthe mobile device in individual sections within Limited Areas. Sensitive Compartmented Information Facilities requireseparate 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.

Reasonable Accommodation

Our goal is to create an accessible and inclusive experience for all candidates applying and interviewing at the Laboratory. If you need a reasonable accommodation during the application or the recruiting process, please use our online form to submit a request.

CaliforniaPrivacy Notice

The California Consumer Privacy Act (CCPA) grants privacy rights to all California residents. The law also entitlesjob applicants, employees, and non-employee workers to be notified of what personal information LLNL collects and for what purpose. The Employee Privacy Notice can be accessed here .

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