Staff Application Security Engineer

The Nuclear Company is the fastest growing AI tech-enabled startup in the nuclear and energy space, pioneering a fleet-scale approach to building the next generation of nuclear reactors. Through our design-once, build-many model, we're accelerating the deployment of safe, reliable, and affordable nuclear energy. We operate with an AI-first mindset. Every employee is expected to leverage AI, technology, and the Nuclear Operating System (NOS) as integral components of their role to improve the quality, speed, and impact of their work. We expect every team member to continuously identify opportunities to automate workflows, enhance decision-making, improve processes, and contribute to the ongoing evolution of NOS as a strategic operating capability that enables The Nuclear Company to scale with excellence. We hire people who are driven by purpose, thrive in ambiguity, and are energized by building what has never been built before.  Our team combines intellectual curiosity with high agency, embraces candid feedback and continuous learning, and holds themselves and others to exceptional standards. Our values— Transparency, Responsibility, Unity, Scrappiness, and Tenacity —guide how we hire, collaborate, and make decisions every day. They are not words on a wall; they are the standard by which we operate. TRUST is the foundation of our safety culture, fostering intellectual honesty, accountability, and open communication, while our values challenge every team member to execute with urgency, humility, resilience, and an unwavering commitment to our mission. About the role The Nuclear Company is searching for an  Application Security Engineer  to help secure the software, data systems, and developer workflows that power our Nuclear Operating System, internal platforms, and mission-critical applications. This is a high-ownership role for a builder who is equally comfortable reviewing application architecture, threat modeling an API, improving GitHub security controls, and partnering directly with engineers to ship secure software quickly.   You will work across product engineering, platform engineering, data science, infrastructure, and operations to embed security into the way we design, build, test, and deploy software. You will help define secure development standards, review high-impact product designs, harden CI/CD workflows, and guide teams through vulnerability remediation in a practical, risk-based way.   This role reports to the Senior Manager for Application and Product Security. Responsibilities Application & Product Security   Perform security reviews and threat models for NOS modules, internal tools, APIs, data workflows, AI-enabled features, and cloud-connected applications.    Partner with engineering teams to identify and remediate risks across authentication, authorization, tenant isolation, input validation, secrets handling, encryption, logging, and data access.    Review application designs and code changes for security issues before they become production risk.   Define reusable security patterns for web applications, APIs, mobile workflows, internal platforms, and data-heavy systems.   Help establish secure-by-default approaches for applications that support regulated, high-consequence infrastructure.    Secure SDLC & Developer Enablement   Build and improve DevSecOps practices across the GitHub-based software development lifecycle, including code scanning, dependency review, secret scanning, branch protections, CI/CD hardening, and secure developer workflows.   Partner with engineering teams to create paved roads: secure templates, checklists, automation, documentation, and lightweight review processes that help teams move faster with confidence.   Triage and prioritize application security findings from SAST, SCA, secrets scanning, penetration tests, code reviews, and internal assessments.    Develop pragmatic vulnerability management workflows, remediation guidance, and engineering-facing metrics.    Support secure coding education through design reviews, office hours, documentation, and hands-on partnership with developers.   Platform, Cloud & Data Security   Collaborate with cloud and platform engineers to secure AWS workloads, infrastructure-as-code, service integrations, data pipelines, and deployment workflows.    Review integrations involving Palantir Foundry, partner APIs, internal data platforms, and AI-assisted engineering workflows.   Help secure sensitive data flows across application, platform, and operational environments.    Partner with infrastructure and developer teams to ensure application events, audit logs, and security signals are captured in ways that support investigation and response.    Navigate the security expectations of a regulated nuclear energy environment, including relevant cybersecurity frameworks and critical infrastructure considerations.   Cross-Functional Partnership   Serve as a trusted security partner to software engineers, product managers, data engineers, infrastructure teams, and business stakeholders.    Communicate risk clearly and practically, balancing security, delivery speed, product usability, and operational impact.   Contribute to the application and product security roadmap as the company scales from early-stage systems to fleet-scale operations.   Help build a culture of ownership, velocity, and technical rigor across engineering and cybersecurity.   Experience 4+ years of experience in application security, product security, software security, or software engineering with a strong security focus.    Hands-on experience reviewing, building, or securing modern software systems, including web applications, APIs, distributed systems, or cloud-native services.   Strong understanding of common application security risks, including authentication, authorization, access control, injection, insecure deserialization, SSRF, secret