Senior People Business Partner

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 mission-obsessed and hands-on Senior People Business Partner to support an industry-leading People Operations function. This operator will help shape Radiant’s critical asset: our team.

The ideal candidate thrives in high-growth, high-ambiguity environments and brings expertise across human resources and program operations to scale technical teams. You should be energized by tough challenges and committed to building the people practices and programs to develop a high-performing and highly engaged team. This is a rare opportunity to shape the future of nuclear energy and the team that will make it happen.

Responsibilities & Duties:

Strategic HR Business Partnership

• Act as a trusted advisor and embedded partner to engineering leaders across all levels, helping them build, develop, and retain high-performing teams.

• Translate business objectives into people strategies in partnership with Talent Acquisition, including workforce planning, organizational design, and headcount forecasting and succession planning aligned to company milestones.

• Coach and develop managers and senior leaders on performance management, team dynamics, and leadership effectiveness. Equip them with frameworks and tools that make them better operators.

• Lead and facilitate talent reviews and calibration sessions. Ensure the right people are in the right roles at the right time.

• Build and maintain dashboards tracking key people metrics and present actionable insights to leadership on a regular cadence.

• Drive accountability for goals. Partner with leadership to set measurable team and individual performance expectations, and ensure consistent, rigorous performance review cycles are executed on time and with quality.

• Identify organizational risks and workforce gaps before they become problems. Proactively surface trends and recommend interventions.

Employee Relations & Culture

• Serve as the primary point of contact for employee relations matters in your business unit(s). Conduct thorough, impartial investigations and drive timely, well-documented resolution.

• Build and protect a culture of high standards. Radiant's culture is not accidental; it is built deliberately and defended actively.

• Maintain strict confidentiality across all employee matters without exception.

Change Management & Communications

• Partner with leadership to develop internal communications that are clear, direct, and consistent with Radiant's voice and values. At a company moving this fast, how we communicate change is as important as the change itself.

• Lead the people-side of organizational change. Develop and execute structured change management plans with clear owners, timelines, and success metrics.

• Anticipate how organizational decisions will land across different teams and functions. Identify potential points of friction early and build strategies to address them.

• Serve as a steady, credible voice during periods of ambiguity. Model the calm, high-trust communication culture Radiant expects from its leaders.

Compliance & Operations

• Support operational readiness as Radiant scales: onboarding infrastructure, HRIS integrity, policy development, and cross-functional coordination with Finance and Operations.

• Ensure Radiant remains compliant with federal, state, and local employment law.

• Continuously improve systems, processes, and procedures, with an eye toward scalability, auditability, and a frictionless employee experience.

Required Qualifications & Skills:

• Bachelor's degree in Business Administration, Human Resources, Psychology, Economics, or a related field.

• 8+ years of progressive HR business partner experience in fast-paced or startup environments. Prior experience supporting engineering, manufacturing, or production teams strongly preferred.

• Deep expertise in California labor law and compliance.

• Proven track record of partnering with technical leaders to drive measurable people outcomes.

• Strong analytical skills. Comfortable building reports, interpreting workforce data, and translating metrics into leadership recommendations.

• Excellent interpersonal, verbal, and written communication skills.

Desired Qualifications & Skills:

• Multi-state labor compliance expertise across exempt and non-exempt workforces.

• Experience in hard tech, aerospace, defense, energy, or similar industries where precision and accountability are non-negotiable.

• Mission-obsessed. Able to articulate why this work matters and inspire others to perform at their best.

• Highly autonomous with strong judgment; knows when to escalate and when to execute.

• Demonstrated ability to build trust quickly at all levels of an organization.

• Track record of delivering consistent, high-quality outcomes under tight timelines with a focus on growth over comfort.

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.

• 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 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 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: [email protected].
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.