Radiant
Mechanical Engineer - 2026 New Grad (Fluid Systems, Mechanisms, or Structures)
Radiant, El Segundo, California, United States, 90245
Mechanical Engineer - 2026 New Grad (Fluid Systems, Mechanisms, or Structures)
Radiant is an El Segundo, CA-based startup building the world’s first mass-produced, portable nuclear microreactors. The company’s first reactor, Kaleidos, is a 1-megawatt failsafe microreactor that can be transported anywhere power is needed and run for up to five years without the need to refuel. Portable nuclear power with rapid deploy capability can replace similar-sized diesel generators, and provide critical asset support for hospitals, data centers, remote sites, and military bases. Radiant’s unique, practical approach to nuclear development utilizes modern software engineering to rapidly achieve safe, factory-built microreactors that leverage existing, well-qualified materials. Founded in 2020, Radiant is on track to test its first reactor next year at the Idaho National Laboratory, with initial customer deliveries beginning in 2028. Mechanical Engineer (Fluid Systems, Mechanisms, or Structures) Radiant is seeking a highly motivated
New Graduate
Mechanical Engineer
to join the KDU Engineering team. You will contribute directly to the design, assembly, and testing of the Kaleidos Development Unit (KDU) – the United States’ first new fueled reactor design in over 50 years. Depending on your background and interests (fluid systems, mechanisms, or structures), you will take ownership of projects that advance KDU’s readiness for fueled operations, working alongside a cross-disciplinary team of engineers. Responsibilities and Duties
Contribute to the design, analysis, and testing of KDU subsystems (fluid systems, mechanisms, or structural components). Take ownership of deliverables from concept through build and validation, with guidance from senior engineers. Collaborate across disciplines to integrate designs and resolve technical challenges. Support system-level testing, troubleshooting, and design iteration to accelerate KDU development. Communicate results through design reviews, technical reports, and presentations to peers and leadership. Required Skills and Qualifications
BS in Mechanical Engineering, Aerospace Engineering, or a related discipline (completed or expected Spring 2026). Strong foundation in engineering first principles, including thermodynamics, fluid mechanics, statics, dynamics, and strength of materials. Hands-on experience in design and build through projects, research, labs, or internships. Proficiency with engineering tools (e.g., CAD, analysis software, lab instrumentation). Desired Skills and Qualifications
MS in Mechanical Engineering, Aerospace Engineering, or related discipline (completed or in progress). Prior internship, co-op, or project-based experience related to fluid systems, mechanisms, or structures. Ability to independently solve complex engineering tasks and seek out resources proactively. Comfortable working in a fast-paced, startup environment with a collaborative, mission-driven mindset. Excitement for Radiant’s mission to rapidly deploy nuclear microreactors to remote locations requiring abundant, clean energy. Knowledge of reactor physics is helpful but not required. Additional Requirements
This role is based onsite at Radiant’s HQ in El Segundo, CA. Extended hours or occasional weekend work may be required to support project milestones. Total Compensation and Benefits Radiant's new hire compensation package includes base salary, substantial equity grants, and comprehensive benefits. Total compensation and level are determined through a holistic evaluation of your interview performance, experience, education, and qualifications. Benefits and Perks for Eligible Employees: 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. 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. 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. 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. Unfortunately, we are unable to provide visa sponsorship at this time. 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. Apply for this job
* indicates a required field First Name * Last Name * Email * Phone * Resume/CV * Enter manually Accepted file types: pdf, doc, docx, txt, rtf Enter manually Accepted file types: pdf, doc, docx, txt, rtf Education School * Select... Degree * Select... Select... End date month * Select... End date year * LinkedIn Profile Website Select... Are you legally authorized to work in the United States? * Select... Will you now or in the future require sponsorship for employment visa status? * Select... Voluntary Self-Identification
For government reporting purposes, we ask candidates to respond to the below self-identification survey.Completion of the form is entirely voluntary. Whatever your decision, it will not be considered in the hiringprocess or thereafter. Any information that you do provide will be recorded and maintained in aconfidential file. As set forth in Radiant ’s Equal Employment Opportunity policy,we do not discriminate on the basis of any protected group status under any applicable law. If you believe you belong to any of the categories of protected veterans listed below, please indicate by making the appropriate selection.As a government contractor subject to the Vietnam Era Veterans Readjustment Assistance Act (VEVRAA), we request this information in order to measurethe effectiveness of the outreach and positive recruitment efforts we undertake pursuant to VEVRAA. Classification of protected categoriesis as follows: A "disabled veteran" is one of the following: a veteran of the U.S. military, ground, naval or air service who is entitled to compensation (or who but for the receipt of military retired pay would be entitled to compensation) under laws administered by the Secretary of Veterans Affairs; or a person who was discharged or released from active duty because of a service-connected disability. A "recently separated veteran" means any veteran during the three-year period beginning on the date of such veteran's discharge or release from active duty in the U.S. military, ground, naval, or air service. An "active duty wartime or campaign badge veteran" means a veteran who served on active duty in the U.S. military, ground, naval or air service during a war, or in a campaign or expedition for which a campaign badge has been authorized under the laws administered by the Department of Defense. An "Armed forces service medal veteran" means a veteran who, while serving on active duty in the U.S. military, ground, naval or air service, participated in a United States military operation for which an Armed Forces service medal was awarded pursuant to Executive Order 12985. Select... Voluntary Self-Identification of Disability
Form CC-305 Page 1 of 1 OMB Control Number 1250-0005 Expires 04/30/2026 Voluntary Self-Identification of Disability
Form CC-305 Page 1 of 1 OMB Control Number 1250-0005 Expires 04/30/2026 Why are you being asked to complete this form? We are a federal contractor or subcontractor. The law requires us to provide equal employment opportunity to qualified people with disabilities. We have a goal of having at least 7% of our workers as people with disabilities. The law says we must measure our progress towards this goal. To do this, we must ask applicants and employees if they have a disability or have ever had one. People can become disabled, so we need to ask this question at least every five years. Completing this form is voluntary, and we hope that you will choose to do so. Your answer is confidential. No one who makes hiring decisions will see it. Your decision to complete the form and your answer will not harm you in any way. If you want to learn more about the law or this form, visit the U.S. Department of Labor’s Office of Federal Contract Compliance Programs (OFCCP) website at www.dol.gov/ofccp . How do you know if you have a disability? A disability is a condition that substantially limits one or more of your “major life activities.” If you have or have ever had such a condition, you are a person with a disability.
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Radiant is an El Segundo, CA-based startup building the world’s first mass-produced, portable nuclear microreactors. The company’s first reactor, Kaleidos, is a 1-megawatt failsafe microreactor that can be transported anywhere power is needed and run for up to five years without the need to refuel. Portable nuclear power with rapid deploy capability can replace similar-sized diesel generators, and provide critical asset support for hospitals, data centers, remote sites, and military bases. Radiant’s unique, practical approach to nuclear development utilizes modern software engineering to rapidly achieve safe, factory-built microreactors that leverage existing, well-qualified materials. Founded in 2020, Radiant is on track to test its first reactor next year at the Idaho National Laboratory, with initial customer deliveries beginning in 2028. Mechanical Engineer (Fluid Systems, Mechanisms, or Structures) Radiant is seeking a highly motivated
New Graduate
Mechanical Engineer
to join the KDU Engineering team. You will contribute directly to the design, assembly, and testing of the Kaleidos Development Unit (KDU) – the United States’ first new fueled reactor design in over 50 years. Depending on your background and interests (fluid systems, mechanisms, or structures), you will take ownership of projects that advance KDU’s readiness for fueled operations, working alongside a cross-disciplinary team of engineers. Responsibilities and Duties
Contribute to the design, analysis, and testing of KDU subsystems (fluid systems, mechanisms, or structural components). Take ownership of deliverables from concept through build and validation, with guidance from senior engineers. Collaborate across disciplines to integrate designs and resolve technical challenges. Support system-level testing, troubleshooting, and design iteration to accelerate KDU development. Communicate results through design reviews, technical reports, and presentations to peers and leadership. Required Skills and Qualifications
BS in Mechanical Engineering, Aerospace Engineering, or a related discipline (completed or expected Spring 2026). Strong foundation in engineering first principles, including thermodynamics, fluid mechanics, statics, dynamics, and strength of materials. Hands-on experience in design and build through projects, research, labs, or internships. Proficiency with engineering tools (e.g., CAD, analysis software, lab instrumentation). Desired Skills and Qualifications
MS in Mechanical Engineering, Aerospace Engineering, or related discipline (completed or in progress). Prior internship, co-op, or project-based experience related to fluid systems, mechanisms, or structures. Ability to independently solve complex engineering tasks and seek out resources proactively. Comfortable working in a fast-paced, startup environment with a collaborative, mission-driven mindset. Excitement for Radiant’s mission to rapidly deploy nuclear microreactors to remote locations requiring abundant, clean energy. Knowledge of reactor physics is helpful but not required. Additional Requirements
This role is based onsite at Radiant’s HQ in El Segundo, CA. Extended hours or occasional weekend work may be required to support project milestones. Total Compensation and Benefits Radiant's new hire compensation package includes base salary, substantial equity grants, and comprehensive benefits. Total compensation and level are determined through a holistic evaluation of your interview performance, experience, education, and qualifications. Benefits and Perks for Eligible Employees: 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. 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. 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. 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. Unfortunately, we are unable to provide visa sponsorship at this time. 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. Apply for this job
* indicates a required field First Name * Last Name * Email * Phone * Resume/CV * Enter manually Accepted file types: pdf, doc, docx, txt, rtf Enter manually Accepted file types: pdf, doc, docx, txt, rtf Education School * Select... Degree * Select... Select... End date month * Select... End date year * LinkedIn Profile Website Select... Are you legally authorized to work in the United States? * Select... Will you now or in the future require sponsorship for employment visa status? * Select... Voluntary Self-Identification
For government reporting purposes, we ask candidates to respond to the below self-identification survey.Completion of the form is entirely voluntary. Whatever your decision, it will not be considered in the hiringprocess or thereafter. Any information that you do provide will be recorded and maintained in aconfidential file. As set forth in Radiant ’s Equal Employment Opportunity policy,we do not discriminate on the basis of any protected group status under any applicable law. If you believe you belong to any of the categories of protected veterans listed below, please indicate by making the appropriate selection.As a government contractor subject to the Vietnam Era Veterans Readjustment Assistance Act (VEVRAA), we request this information in order to measurethe effectiveness of the outreach and positive recruitment efforts we undertake pursuant to VEVRAA. Classification of protected categoriesis as follows: A "disabled veteran" is one of the following: a veteran of the U.S. military, ground, naval or air service who is entitled to compensation (or who but for the receipt of military retired pay would be entitled to compensation) under laws administered by the Secretary of Veterans Affairs; or a person who was discharged or released from active duty because of a service-connected disability. A "recently separated veteran" means any veteran during the three-year period beginning on the date of such veteran's discharge or release from active duty in the U.S. military, ground, naval, or air service. An "active duty wartime or campaign badge veteran" means a veteran who served on active duty in the U.S. military, ground, naval or air service during a war, or in a campaign or expedition for which a campaign badge has been authorized under the laws administered by the Department of Defense. An "Armed forces service medal veteran" means a veteran who, while serving on active duty in the U.S. military, ground, naval or air service, participated in a United States military operation for which an Armed Forces service medal was awarded pursuant to Executive Order 12985. Select... Voluntary Self-Identification of Disability
Form CC-305 Page 1 of 1 OMB Control Number 1250-0005 Expires 04/30/2026 Voluntary Self-Identification of Disability
Form CC-305 Page 1 of 1 OMB Control Number 1250-0005 Expires 04/30/2026 Why are you being asked to complete this form? We are a federal contractor or subcontractor. The law requires us to provide equal employment opportunity to qualified people with disabilities. We have a goal of having at least 7% of our workers as people with disabilities. The law says we must measure our progress towards this goal. To do this, we must ask applicants and employees if they have a disability or have ever had one. People can become disabled, so we need to ask this question at least every five years. Completing this form is voluntary, and we hope that you will choose to do so. Your answer is confidential. No one who makes hiring decisions will see it. Your decision to complete the form and your answer will not harm you in any way. If you want to learn more about the law or this form, visit the U.S. Department of Labor’s Office of Federal Contract Compliance Programs (OFCCP) website at www.dol.gov/ofccp . How do you know if you have a disability? A disability is a condition that substantially limits one or more of your “major life activities.” If you have or have ever had such a condition, you are a person with a disability.
Disabilities include, but are not limited to: Alcohol or other substance use disorder (not currently using drugs illegally) Autoimmune disorder, for example, lupus, fibromyalgia, rheumatoid arthritis, HIV/AIDS Blind or low vision Cancer (past or present) Cardiovascular or heart disease Celiac disease Cerebral palsy Deaf or serious difficulty hearing Diabetes Disfigurement, for example, disfigurement caused by burns, wounds, accidents, or congenital disorders Epilepsy or other seizure disorder Gastrointestinal disorders, for example, Crohn's Disease, irritable bowel syndrome Intellectual or developmental disability Mental health conditions, for example, depression, bipolar disorder, anxiety disorder, schizophrenia, PTSD Missing limbs or partially missing limbs Mobility impairment, benefiting from the use of a wheelchair, scooter, walker, leg brace(s) and/or other supports Nervous system condition, for example, migraine headaches, Parkinson’s disease, multiple sclerosis (MS) Neurodivergence, for example, attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder, dyslexia, dyspraxia, other learning disabilities Partial or complete paralysis (any cause) Pulmonary or respiratory conditions, for example, tuberculosis, asthma, emphysema Short stature (dwarfism) Traumatic brain injury Disability Status Select... PUBLIC BURDEN STATEMENT: According to the Paperwork Reduction Act of 1995 no persons are required to respond to a collection of information unless such collection displays a valid OMB control number. This survey should take about 5 minutes to complete.
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