{"id":2589495,"url":"https://alion.io/job/radiant-nuclear-senior-reactor-engineer","title":"Senior Reactor Engineer","company":{"id":690814,"name":"Radiant Nuclear","domain":"radiantnuclear.com","url":"https://alion.io/company/radiantnuclear","size_band":"201-500","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":{"grade":"A","score":92,"open_postings":26,"ghost_share":0,"stale_share":0.115,"repost_share":0,"time_to_fill_p50_days":89,"computed_at":"2026-10-15T05:46:00Z"}},"role":"Industrial Engineering","role_family":"Industrial Engineering","seniority":"senior","employment_type":"full_time","work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["El Segundo, United States"],"countries":["US"],"hiring_countries":[],"hiring_countries_total":0,"salary":{"min":150025,"max":211838,"currency":"USD","period":"year","gross":null,"usd_annual":211838},"salary_estimate":null,"experience_years_min":5,"visa_sponsorship":false,"relocation_package":false,"has_equity":true,"technologies":[{"name":"MATLAB","optional":true},{"name":"Python","optional":true}],"status":"live","first_seen_at":"2026-10-15T02:38:11Z","employer_posted_date":"2026-10-15","last_verified_at":"2026-10-15T13:11:14Z","board_verified":true,"closed_at":null,"days_open":0,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":0},"description":"About Radiant\nRadiant 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, fail-safe microreactor that can be transported anywhere power is needed and run for up to 5 years without refueling. 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 leverages modern software engineering to rapidly deliver safe, factory-built microreactors that use existing, well-qualified materials. Founded in 2020, Radiant is on track to test its first reactor at the Idaho National Laboratory this summer, with initial customer deliveries beginning in 2028.\nAbout the Role\nRadiant is seeking a Senior Reactor Engineer to lead the testing and verification of critical components, mechanisms, and subsystems within the Kaleidos microreactor. You will work closely with nuclear, mechanical, thermal, controls, and test engineering teams to ensure reactor hardware meets its functional, performance, and safety requirements.\nThis role combines hands-on test engineering with direct involvement in reactor design and development. You will own testing activities from requirements definition and test planning through execution, data analysis, and technical review. Your work will focus on core-related hardware, reactivity control mechanisms, instrumentation, and other reactor subsystems, using test results to inform design decisions and improve hardware performance.\nThe ideal candidate brings strong engineering fundamentals, practical testing experience, and sound technical judgment. You should be comfortable developing and reviewing test procedures, evaluating hardware performance, collaborating with reactor operations, and driving complex engineering problems through resolution.\nResponsibilities & Duties\nLead testing and verification of reactor components, mechanisms, and subsystems, including core assemblies, reactivity control mechanisms, instrumentation, and associated hardware.\n\nOwn test activities from requirements definition and planning through execution, data analysis, and documentation.\n\nDevelop test plans, procedures, instrumentation requirements, and acceptance criteria to verify hardware performance against design and safety requirements.\n\nCollaborate with nuclear, mechanical, thermal, and controls engineers to develop test strategies, evaluate designs, and resolve technical challenges.\n\nPerform engineering analyses and compare experimental results against analytical predictions and design assumptions.\n\nReview and technically approve test procedures, verification reports, and engineering documentation within assigned authority.\n\nSupport reactor operations, commissioning, and integrated testing through procedure reviews, readiness assessments, and technical evaluations.\n\nInvestigate hardware failures and test anomalies, identify root causes, and work with design teams to implement corrective actions.\n\nTranslate test findings into design improvements while maintaining rigorous requirements traceability, documentation, and configuration control.\n\nRequired Qualifications & Skills\nBachelor's degree in nuclear engineering, mechanical engineering, or a related technical discipline from an accredited institution.\n\n5+ years of relevant experience in reactor engineering, hardware testing, design verification, or complex hardware development.\n\nDemonstrated experience developing and executing component or subsystem tests, including planning, instrumentation, data analysis, and performance evaluation.\n\nStrong engineering fundamentals in mechanical systems, heat transfer, materials, instrumentation, and component performance.\n\nUnderstanding of reactor operating principles, safety functions, and component-level performance requirements.\n\nExperience developing technical procedures, establishing acceptance criteria, and evaluating results against engineering requirements.\n\nExperience troubleshooting hardware failures, conducting root cause investigations, and implementing design improvements.\n\nAbility to interpret engineering drawings, specifications, and technical requirements while independently owning multidisciplinary engineering projects.\n\nPreferred Qualifications & Skills\nMaster's degree or Ph.D. in nuclear engineering, mechanical engineering, or a related technical discipline.\n\nExperience with reactor components, core assemblies, reactivity control mechanisms, instrumentation, or safety-critical hardware.\n\nExperience with high-temperature gas-cooled reactors, microreactors, advanced reactors, or first-of-a-kind nuclear systems.\n\nFamiliarity with reactor physics, thermal-hydraulics, nuclear safety, and reactor operations.\n\nExperience supporting reactor testing, commissioning, startup, or operational readiness.\n\nExperience with test instrumentation, data acquisition systems, and testing under demanding thermal, mechanical, or environmental conditions.\n\nProficiency with Python, MATLAB, or similar engineering tools for test automation and analysis.\n\nFamiliarity with DOE authorization processes, NRC licensing, nuclear industry standards, or nuclear quality assurance requirements.\n\nAdditional Requirements\nMust be mission driven and willing to support extended hours when needed.\n\nMust work 100% onsite at Radiant's El Segundo headquarters.\n\nBenefits and Perks\nStock: Substantial incentive stock plan for all full-time employees.\n\nMedical: 100% up to base silver level plan for employee + 50% dependents, offers up to Platinum plans.\n\nOne Medical: Sponsored memberships for employees and their dependents.\n\nVision: 100% top tier plan coverage + 50% for dependents.\n\nDental: 100% top tier plan coverage, orthodontia extra, 50% for dependents.\n\nVoluntary life, accident, hospital, critical illness, commuter and FSA/HSA are offered as employee contributed benefits.\n\n8-weeks of paid parental leave for all parents. Additional paid pregnancy leave for CA employees.\n\nDaily catered lunch. Free snacks and drinks.\n\nFlexible PTO policy. Remote workday allocation.\n\nCompany and team-bonding events, happy hours and in-person camaraderie.\n\nBeautiful El Segundo headquarters close to the Pacific Ocean.\n\nTotal Compensation and Benefits\nRadiant compensates people for impact and invests in those who continue to raise the bar. Radiant’s 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.\nThe 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: .\nWe 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.\nThis 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.","description_format":"text","description_chars":7601,"description_truncated":false,"requirements":{"experience_years_min":5,"management_years_min":null,"team_size_min":null,"manages_managers":false,"education":{"level":"bachelor","optional":false},"security_clearance":false,"languages":[]},"benefits":["Equity","Parental leave"],"hiring_locations":[],"hiring_excludes":[],"relocation_offered":false,"industries":["Nuclear Energy"],"lifecycle":[{"event":"open","at":"2026-10-15T05:21:17Z"}],"visa":[],"liveness":{"score":86,"band":"hot","label":"Hiring now","p_open":1,"p_active":0.86,"p_room":1,"age_days":0,"expected_fill_days":89,"reasons":["conf:0","win:early"],"computed_at":"2026-10-15T05:46:00Z"},"pay":{"stated_usd_annual":211838,"is_top_pay":true},"html_url":"https://alion.io/job/radiant-nuclear-senior-reactor-engineer","json_url":"https://alion.io/job/radiant-nuclear-senior-reactor-engineer.json","meta":{"generated_at":"2026-10-15T14:46:03Z","cache_seconds":300,"methodology":"https://alion.io/methodology","terms":"https://alion.io/terms","contact":"https://alion.io/contact","api":"https://alion.io/developers","about":"Alion is a live layer of people, companies and AI agents: who they are, whether they are real and active right now, what they do and how to work with them, readable by people and by agents and paid per call.","catalog":"https://alion.io/catalog.json","usage":{"tier":"crawler_verified","counted_by":"address","units_charged":1,"used_today":22462,"day_limit":null,"remaining_today":null,"minute_limit":300,"resets_at":"2026-10-16T00:00:00Z"}},"offers":[{"id":"company.slices","title":"One company in depth, by slice","status":"live","price":{"credits":0.02,"usd":0.002,"plus_per_slice":{"credits":0.05,"usd":0.005}},"unit":"per company, plus each slice with data","note":"the employer in depth","call":{"mcp_tool":"get_company","arguments":{"id":690814},"rest":"https://alion.io/mcp/rest/get_company?id=690814"},"human":"https://alion.io/catalog?offer=company.slices&for=job%2Fradiant-nuclear-senior-reactor-engineer"},{"id":"market.stats","title":"A market slice: pay, demand and time to fill","status":"live","price":{"credits":1,"usd":0.1},"unit":"per slice","note":"pay, demand and time to fill for this role and place","call":{"mcp_tool":"market_stats"},"human":"https://alion.io/catalog?offer=market.stats&for=job%2Fradiant-nuclear-senior-reactor-engineer"},{"id":"job.search","title":"Open jobs by role, technology, place, pay and visa","status":"live","price":{"credits":0.02,"usd":0.002},"unit":"per posting in a list","note":"similar open postings","call":{"mcp_tool":"search_jobs"},"human":"https://alion.io/catalog?offer=job.search&for=job%2Fradiant-nuclear-senior-reactor-engineer"},{"id":"company.verify","title":"Is this company real and active right now","status":"pilot","price":null,"unit":"per company","request":{"url":"https://alion.io/catalog/request","method":"POST","body":"{\"offer\": \"company.verify\", \"for\": \"job/radiant-nuclear-senior-reactor-engineer\", \"note\": \"what you need it for\"}"},"human":"https://alion.io/catalog?offer=company.verify&for=job%2Fradiant-nuclear-senior-reactor-engineer"}]}