Senior Mechanical Engineer, Structures

The job

LIVE Employer public job feed (private-sector employer) Source: the employer's public careers feed · Data: listed 2026-10-28

Job description

About Radiant

Radiant is an El Segundo, CA-based company building the world's only mass-produced, transportable nuclear microreactors. The U.S. grid is under growing strain, with power demand accelerating, driving higher utility costs, rising carbon emissions, and interconnection backlogs. Radiant has a solution, transportable, on-site power. Our first reactor, Kaleidos, is 1 megawatt: small enough to be factory-built, transported by land, sea, or air, and deployed wherever power is needed. 1 MW can power 1000 homes for five years. Ship it back and we refuel for a 20 year operating life. We made energy a product that can be used for critical infrastructure like military bases, data centers, hospitals, and remote sites, as well as the commercial main street businesses that keep America running. Founded in 2020, Radiant is under contract to deliver power to the U.S. Army, Navy and Air Force and has signed pre-order agreements with Equinix, with deployments beginning in 2028.

About the Role

Radiant is seeking a highly motivated Senior Mechanical Engineer to design and develop critical structures within Kaleidos. You will solve unique challenges creating efficient and reliable structures that facilitate fission while surviving extreme temperature environments and meeting volumetric constraints. You will be responsible for the following: trade studies, material selection, detailed structural analysis, assembly, integration, and testing. You will have an instrumental impact of fueling the first new commercial reactor design in over 50 years by 2026.  

Responsibilities & Duties: 

• Ownership of critical structures such as mass-efficient transportable shielding systems, container system, and high temperature graphite and metallic systems.

• Conduct trade studies and develop designs to meet program requirements. 

• Perform detailed thermomechanical analysis (static strength, durability/fatigue) and dynamic analysis (vibration, shock) to determine structural integrity (margins of safety) using both hand calculations and finite element tools.

• Develop and execute manufacturing/assembly instructions and test plans.

  • Create and manage a Bill-Of-Materials (BOM).

  • Find and develop suppliers for components.

• Own subassembly design, manufacturing, and test schedules.

• Own risk analysis (FMEA) for subsystems.

• Collect requirements, provide expertise and feedback to engineers in other functional areas via clear, constructive communication.

Required Qualifications & Skills:

• Bachelor’s degree from an accredited institution in Mechanical, Aeronautical, Civil or Structural Engineering.

• 6+ years of experience designing structures.

• 4+ years of experience performing stress analysis using both hand calculations and finite element tools (Abaqus, Ansys, FEMAP, or similar).

Desired Qualifications & Skills:

• Experience with design of multi-component assemblies in CAD (NX or similar).

• Experience designing hardware that was manufactured, deployed, and iteratively improved.

• Experience resolving thermal expansion issues in designs.

• Experience working with interdisciplinary teams.

• Solid understanding and application of GD&T.

• Proficiency with both “hand calc” analytical methods and higher fidelity finite element-based analysis methods.

• Ability to derive free-body diagrams for systems with which one was not previously familiar.

• Self-motivated with strong organizational, written, and oral communication skills.

• Experience with using text-based software development tools.

Additional Requirements:

• Must be willing to work extended hours and weekends as necessary to accomplish our mission.

• Must work 100% onsite at El Segundo HQ.

Benefits and Perks

• Stock: Substantial incentive stock plan for all full-time employees.

• Medical: 100% up to base silver level plan for employee + 50% dependents, offers up to Platinum plans.

• One Medical: Sponsored memberships for employees and their dependents.

• Vision: 100% top tier plan coverage + 50% for dependents.

• Dental: 100% top tier plan coverage, orthodontia extra, 50% for dependents.

• Voluntary life, accident, hospital, critical illness, commuter and FSA/HSA are offered as employee contributed benefits.

• 8-weeks of paid parental leave for all parents. Additional paid pregnancy leave for CA employees.

• Nuclear Engineering Certificate Program: 100% covered educational program with Penn State University, for eligible employees, to rapidly upscale into nuclear.

• Daily catered lunch. Free snacks and drinks.

• Flexible PTO policy. Remote workday allocation.

• Company and team-bonding events, happy hours and in-person camaraderie.

• Beautiful El Segundo headquarters close to the Pacific Ocean.

Total Compensation and Benefits
Radiant compensates people for impact and invests in those who continue to raise the bar. Radiant’s full-time new hire compensation package includes base salary, substantial equity grants, and comprehensive health benefits. Total compensation and level are determined through a rigorous evaluation of interview performance, experience, education, and qualifications, and are designed to support continued growth as scope, responsibility, and impact expand at Radiant.

The best of today’s advanced reactor builders don’t wait for job postings. They join the winning team. If that’s you, contact us directly for immediate opportunities: recruiting@radiantnuclear.com.

We are an equal opportunity employer and all qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity or expression, pregnancy, age, national origin, disability status, genetic information, protected veteran status, or any other characteristic protected by law.

This position involves access to technology that is subject to U.S. export controls. Any job offer made will be contingent upon the applicant’s capacity to serve in compliance with U.S. export controls.

Explore around this job

Field: Engineering, Construction and Energy Sub-niche: Manufacturing and hardware engineering All jobs at Radiant Industries Inc. Jobs in California Jobs in El Segundo, CA California state guide Pay for this occupation (BLS) All 254 open jobs for this occupation

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About the role

This is a — role in the Engineering, Construction and Energy field (Manufacturing and hardware engineering) at Radiant Industries Inc..

The closest occupation in the official wage statistics is Mechanical engineers (a match by name, so treat it as an estimate). Nationally its median pay is $104,110 a year (BLS OEWS, May 2025), employment is projected to change by +11.2% between 2025 and 2035, and the typical entry route is: Bachelor's degree.

Pay by state and metro area for this occupation →

How to prepare and behave

This is editorial guidance, not information from the employer.

• Read the whole description and match your examples to its requirements; use the same words the posting uses where they are true for you.
• Research the employer before the interview: what it does, who its customers are and recent news; prepare two or three questions about the work.
• Arrive early (or log in early for a video call), dress one step above the daily dress code, and test your camera and audio beforehand.
• Answer with short stories: the situation, what you did and the result. Give numbers when you have them and never invent them.
• Be honest about gaps; say what you did to learn and how fast you can close them.
• Ask about the team, the first 90 days, how success is measured and the schedule; do not open with salary and time off.
• When pay comes up, know the market range for the occupation and your lowest acceptable offer before you answer; ask for the full package in writing.
• Send a short thank-you message within a day, mentioning one thing you discussed.

Know your rights as a candidate and an employee:

• U.S. Equal Employment Opportunity Commission: prohibited employment practices
• U.S. Department of Labor: Wage and Hour Division
• CareerOneStop (U.S. Department of Labor): job search help, interview tips and resumes
• USA.gov: avoiding job scams

The city

El Segundo, CA is not one of the cities with its own page in our guides, so here is the state: California.

The state economy in brief

California is in the West region (Pacific division) and has 39,287,376 residents (the 1st largest of the 50 states and DC by population), with a median age of 37.9. Its economy produced about $4,438,822 million in the latest four quarters (BEA), 1st among states and DC, equal to $112,983 per resident.

Jobs and the labour market

The unemployment rate was 5.1% in 2026M09, which is 49th lowest of 51 (1st is the lowest). Employers had job openings equal to 3.6% of employment, 37th highest of 51, a measure of how hard it is to hire. The median wage across all occupations is $58,240 a year ($28.00 an hour), 14% above the national median ($58,240 against $50,980).

What people do and what it pays

The occupations with the most jobs in California are Home Health and Personal Care Aides (970,150 jobs, median $34,320); Fast Food and Counter Workers (449,840 jobs, median $42,280); Retail Salespersons (376,460 jobs, median $38,440); Laborers and Freight, Stock, and Material Movers, Hand (355,500 jobs, median $44,710); Registered Nurses (338,940 jobs, median $140,270). Among occupations with at least 2,000 jobs, the best paid are Airline Pilots, Copilots, and Flight Engineers (median $353,900); Psychiatrists (median $353,500); General Internal Medicine Physicians (median $313,890). Compared with the nation, the state is most specialised in farming, fishing, and forestry (4.1 times the national share of workers) and healthcare support (1.5 times the national share of workers).

Cost of living, taxes and workplace rules

Prices are above the national average in California: the regional price parity is 110.7 against 100 for the whole country (51st lowest of 51). Median gross rent is $2,036 a month and the median household income $99,122, so a year of rent equals 24.6% of income; the median home value is $734,700. The state minimum wage is $16.90 (the higher of state and federal rates applies to most workers). State income tax on wages: Graduated, top rate 13.30%. It is not a right-to-work state, so union contracts can require fees from covered workers. It runs a state paid family and medical leave programme.

People and commuting

27.0% of residents were born abroad and 37.1% of adults hold a bachelor's degree or higher. Among workers, 65.7% drive alone, 2.9% use public transit and 17.2% work from home; 19.4% commute 45 minutes or more.

State guide: California →

Where to live

CITY Official statistics Source: U.S. Census Bureau, American Community Survey 2020–2024 5-year (via Census Reporter) · Data: ACS 2020–2024

Places within 50 miles (straight line) of El Segundo, CA that have a guide, with what living there costs. The last-but-one column divides a year of rent by the median pay of the closest occupation ($104,110 a year), an estimate, not this employer's pay.

Career paths

Occupations close to Mechanical engineers in the official classification, with pay, outlook and whether there are open jobs for them on this site right now.

Distances

CITY Calculation (straight line) Source: U.S. Census Bureau Gazetteer (coordinates) · Data: 2024

How far El Segundo, CA is from the 20 largest US cities, in straight-line miles (not driving distance). Click a column to sort.

Nearby cities with open jobs (within 120 miles)

The employer

Radiant Industries Inc. is the employer in this listing. See all its open jobs here →

We do not hold headcount or revenue for this employer. Check its careers site and, if it is listed on a stock exchange, its public filings (SEC EDGAR search).

What it is like to work at a company (culture, schedules, benefits) is not in the source data, so we do not describe it. Read the description and ask the questions under "How to prepare".

Other open jobs at Radiant Industries Inc.

Similar jobs

Same sub-niche: Manufacturing and hardware engineering

More jobs in El Segundo, CA

All Manufacturing and hardware engineering jobs → · All Engineering, Construction and Energy sub-niches →

FAQ

What is the Senior Mechanical Engineer, Structures job at Radiant Industries Inc.?

A private-sector role in engineering, construction and energy (manufacturing and hardware engineering) listed 12 days ago. The full description is on this page and on the employer's page.

Where is this job?

El Segundo, CA.

How do I apply?

Use the "View this job and apply on the employer's page" button. AtiveSite does not receive applications.

How much does it pay?

The listing does not publish pay. For the closest occupation (Mechanical engineers) the national median is $104,110 a year (BLS OEWS, May 2025).

What is the cost of living there?

See the state or country guide for rent, income and taxes.

How old is this listing?

It was posted on 2026-10-28 (12 days ago). Jobs older than 90 days are not shown.

Are there similar jobs?

Yes: browse manufacturing and hardware engineering jobs in California.

Sources and terms

• Job data: Radiant Industries Inc. careers page public feed (listing dated 2026-10-28). The job disappears from this site when it disappears from the source.
• Wages and projections: BLS OEWS (May 2025) and Employment Projections 2025–35.
• City and county figures: Census Bureau ACS 2020–2024, BEA, BLS QCEW and LAUS, NASA POWER climatology; distances from Census Gazetteer coordinates.

AtiveSite is not affiliated with or endorsed by the employer or any government agency, and does not process applications. Verify every detail with the employer before acting.

Sources

• BLS OEWS (wages and employment by occupation, May 2025)
• BLS Employment Projections 2025–35
• BLS Local Area Unemployment Statistics
• BLS JOLTS
• BLS State and Metro Area Employment
• Census Bureau American Community Survey (via Census Reporter)
• BEA GDP by state and Regional Price Parities
• IRS 2026 tax adjustments
• U.S. Department of Labor, minimum wage by state
• Tax Foundation state income tax rates 2026
• USAJOBS
• USCIS
• U.S. Department of State, visas
• NASA POWER climatology
• GeoNames / Census Gazetteer (coordinates)