Senior Reactor Systems Engineer — Onsite, First‑of‑a‑Kind Microreactors

Speedrun Talent Network; El Segundo, Northern (CA, KY); Hybrid; USD 180,000 - 280,000; Full time

Benefits offered by this job

Stock options

Health benefits

One Medical

Vision coverage

Dental coverage

Life and disability

Parental leave

Catered lunch

Flexible PTO

On-site headquarters

Job summary

Radiant, an El Segundo startup, seeks a Senior Reactor Systems Engineer to own the technical integration of a first-of-a-kind reactor. You will coordinate reactor physics, therm hydraulics, materials, controls, and licensing to deliver a safe, on-time product.

You will work hands-on, lead without formal authority, and write essential specifications and memos to keep the team aligned while maintaining a fast-moving, startup-friendly engineering culture at Radiant.

Qualifications

• BS in nuclear, mechanical, aerospace, systems, or related engineering discipline.
• 6+ years of full-time professional engineering experience in systems engineering, integration, or technical leadership on complex hardware.
• Demonstrated ability to work across multiple engineering disciplines.
• Track record of leading cross-functional technical efforts without direct authority.
• Strong written and verbal communication, including technical documents and presentations.
• Excellent organizational and administrative skills to keep complex work moving.

Responsibilities

• Translate between reactor physics, thermal-hydraulics, materials, controls, mechanical design, manufacturing, and regulatory teams.
• Own libraries of P&IDs, sensors, and subsystem specifications to ensure alignment from design through operations.
• Identify cross-cutting risks early and drive them to resolution.
• Work with safety analysis and licensing teams to keep design decisions and regulatory submissions consistent.
• Support development of design basis, safety classification, and technical specs for regulatory engagement.
• Define test plans and success criteria for prototypes to integrated testing.
• Maintain the technical baseline with lightweight processes in a fast-moving startup.
• Communicate clearly to engineers, leadership, regulators, and customers.

Skills

Systems engineering

Cross-disciplinary collaboration

Technical leadership

Clear written communication

Documentation

Ambiguity tolerance

Education

Bachelor's degree in engineering

Job description

Radiant, an El Segundo startup, seeks a Senior Reactor Systems Engineer to own the technical integration of a first-of-a-kind reactor. You will coordinate reactor physics, therm hydraulics, materials, controls, and licensing to deliver a safe, on-time product.

You will work hands-on, lead without formal authority, and write essential specifications and memos to keep the team aligned while maintaining a fast-moving, startup-friendly engineering culture at Radiant.