Senior Mechanical Engineer - Active Clearance Required

Mid-Senior Level | Full-time Engineering | Livermore, CA | 09/02/2026Reference #: REF8803KJob Code: SES.3 Science & Engineering MTS 3 / SES.4 Science & Engineering MTS 4Organization: EngineeringPosition Type: Career IndefiniteSecurity 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: A job-related pre-placement medical examination may be required Company DescriptionJoin 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 DescriptionWe have an opening for a Senior Mechanical Engineer to participate in new and ongoing projects within our Initiation Systems Group (ISG). The Initiation System Group provides nuclear weapon engineering design expertise; integration within systems engineering; experimental device design; shock & vibration and thermal testing; fabrication and assembly; and assessment of nuclear stockpile components for evaluation and maintenance of the enduring and future nuclear weapon stockpile with most of your focus on the ISG products. You will interface with colleagues at other National Laboratories and Production Agencies, National Nuclear Security Administration (NNSA), and Department of Defense (DoD) and their contractors. These positions are in the Defense Technologies Engineering Division (DTED), within the Engineering Directorate. DTED provides support to Strategic Deterrence Programs.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.This position will be filled at either level based on knowledge and related experience as assessed by the hiring team. Additional job responsibilities (outlined below) will be assigned if hired at the higher level.You willProvide technical expertise in mechanical and electromechanical design.Conduct research in structural, thermal, hydraulic, or dynamics modeling of mechanical systems.Produce advanced conceptual and detail designs in support of on-going projects.Prepare supporting health and safety documentation that is aligned with the Integrated Safety Management (ISM) requirement and participate in design and Management Prestart Reviews.Coordinate project interfaces and deployment interfacing with other organizations internal and external to the Laboratory.Lead and/or provide guidance and technical direction to multidisciplinary project teams in a growing, dynamic environment.Perform other duties as assigned.Additional job responsibilities, at the SES.4 level Set broad project vision and strategy and influence technical direction for self and others.Provide expert capability in highly complex mechanical design and analysis.QualificationsThis 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 Mechanical Engineering or a related field, or the equivalent combination of education and related experience.Advanced knowledge of mechanical design.Significant experience in prototype development and testing, as well as hardware design and analysis.Ability to devise solutions for unique and complex problems.Ability and flexibility to reprioritize and change programmatic direction depending on emergent requests.Significant experience in managing, overseeing, and delivering multiple projects on budget and schedule.Ability to lead, manage, and mentor junior team members.Advanced communication skills with proven ability to present concepts and ideas in a clear and coherent manner, both verbal and written for presentation and interaction with other technical staff members. Additional qualifications at the SES.4 level Expertise in highly complex mechanical design and analysis and significant experience in project planning and highly complex technical leadership.Significant experience developing and implementing creative solutions to a diverse range of highly complex problems and leading corrective actions where necessary.Expert communication, facilitation, and collaboration skills necessary to present, explain, and advise senior management and/or external sponsors and proven record of team building and conflict resolution.Qualifications We DesireMaster's degree or PhD in Mechanical Engineering or a related field.Advanced knowledge of systems engineering principles and practices and their application.Production experience specifically in aerospace, gas & oil, or medical industries. Certified in Six Sigma Green BeltPay Range$175,530 - $267,060 Annually$175,530 - $222,564 Annually for SES.3 Level $210,630 - $267,060 Annually for SES.4 LevelThis is the lowest to highest salary in good faith we would pay for this role at the time of this posting. Pay will not be below any applicable local minimum wage. 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-HybridPosition InformationThis 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 Package401(k)Relocation AssistanceEducation Reimbursement ProgramFlexible schedules (*depending on project needs)Our values - visit Security ClearanceThis 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 TestExternal 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 DevicesPer 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.Pre-Placement Medical ExamA job related pre-placement medical examination may be required.How to identify fake job advertisementsPlease be aware of recruitment scams where people or entities are misusing the name of Lawrence Livermore National Laboratory (LLNL) to post fake job advertisements. LLNL never extends an offer without a personal interview and will never charge a fee for joining our company. All current job openings are displayed on the Career Page under “Find Your Job” of our website. If you have encountered a job posting or have been approached with a job offer that you suspect may be fraudulent, we strongly recommend you do not respond.To learn more about recruitment scams: Equal Employment OpportunityWe are an equal opportunity employer that is committed to providing all with a work environment free of discrimination and harassment. All qualified applicants will receive consideration for employment without regard to race, color, religion, marital status, national origin, ancestry, sex, sexual orientation, gender identity, disability, medical condition, pregnancy, protected veteran status, age, citizenship, or any other characteristic protected by applicable laws.Reasonable AccommodationOur 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. 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