About Radiant

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.

About The Role
Radiant is seeking a Senior Manager, National Security Programs to implement the controls and protection necessary for safeguarding our sensitive information and technology. You will be responsible for program security and compliance to regulation, ranging from factory site security planning to information protection programs. A successful candidate will be one who thinks creatively and implements lightweight and logical solutions to requirements.

As the Senior Manager, National Security Programs you will build out the framework for storing and accessing sensitive information, as well as the process for authorizing access and ensuring compliance. This role requires demonstrating technical leadership, ensuring engineering rigor, and fostering a collaborative environment between the Systems Security Engineering team and internal stakeholders.

Responsibilities & Duties:

• Own the full RMF Authorization & Assessment (A&A) lifecycle for Radiant’s systems.

• Ensure compliance with NRC, DOE, NIST 800-53/800-82, and other industry frameworks.

• Educate external stakeholders on modern and efficient means for protecting material and information.

• Serve as our liaison with regulators, auditors, and government stakeholders.

• Tailor NIST 800-53 controls to determine applicability to the network environment and oversee the implementation of Continuous Monitoring for respective programs.

• Create the technical documentation needed for system security accreditation.

• Maintain classified material accountability records to include inventory lists, receipt and transmittal records and final disposition documentation.

• Oversee development and execution of security test and assessment plans.

• Responsible for identification, triage, and implementation of new regulatory and contractual requirements, controls, and development of technical measures to safeguard systems.

• Conduct risk assessments, vulnerability assessments, and audits to ensure compliance with internal policies and external regulatory frameworks.

• Develop and deliver security awareness training and ensure adherence to security best practices.

Required Qualifications & Skills:

• Bachelor’s degree in information security, Engineering, or related field.

• 7+ years of experience managing cybersecurity or assurance programs in regulated environments (nuclear, energy, aerospace, defense, or critical infrastructure sectors).

• Direct experience implementing and managing systems per NIST RMF, JSIG, and other industry standards (e.g. NIST 800-53, NIST 800-82, DOE O 205.1B, NRC RG 5.71).

Desired Qualifications & Skills:

• Direct experience with nuclear cyber regulations, like NRC 10 CFR 73.54 or NEI 08-09.

• Familiarity with ICS/OT cybersecurity in energy or defense environments.

• Prior work with COMSEC, insider threat programs, or physical-cyber integration.

• Professional certifications like CISSP, CISM, CISA, or CRISC.

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.

Benefits and Perks

• 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: recruiting@radiantnuclear.com.

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.