Director, Nuclear Engineering

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, 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.

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, 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.

Radiant is seeking a highly motivated Director, Nuclear Engineering to organize nuclear design and analysis strategy spanning the design, operation, and iteration of our microreactor fleet.

• Lead and grow a team of nuclear engineers spanning core physics, shielding performance, dose and consequence analysis, and nuclear instrumentation domains
• Manage team execution to efficiently deliver against the strategy, remove roadblocks, and adapt to shifting priorities
• Identify, manage, and effectively communicate technical, schedule, and regulatory risks
• Develop and standardize analysis roadmaps to enable fast iteration across multiple reactor programs
• Foster an attitude of ownership and mentorship within the team
• Define the approach to nuclear engineering design margins and methodical peer reviews
• Interact with universities, national labs, and other outside entities as necessary to accomplish key objectives

• Hold a degree in nuclear engineering, physics, or engineering physics from an accredited institution
• Minimum 10 years of experience managing a team in reactor design and analysis
• Fluency in engineering first principles across nuclear, thermal, electrical, and mechanical domains
• Excellence in communicating nuclear engineering concepts to a multidisciplinary audience
• Familiarity with DOE authorization and/or NRC requirements and processes, and demonstrated experience with the development of nuclear facility safety bases
• Must be willing to relocate to Radiant’s El Segundo office
• Experience with Monte Carlo neutron transport codes, including OpenMC, Serpent, or MCNP

• Hands‑on experience designing products, hardware, or tests

• Must be willing to work extended hours and weekends as necessary to accomplish our mission
• Must work 100% onsite at El Segundo HQ

• 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.
• Daily…