Senior Security Software Engineer

About Valar Atomics

At Valar Atomics, we're redefining what's possible in energy. Our mission is to make clean, high-temperature nuclear power scalable—unlocking abundant energy for industry, hydrogen, and next-generation manufacturing. We are a team of builders, engineers, and operators who believe nuclear energy should be fast to deploy, factory-made, and built for the real world. Our first pilot plant in Orangeville, Utah will demonstrate how advanced nuclear systems and fuel fabrication can power the future. Joining Valar Atomics means becoming part of a company where autonomy, ownership, and impact exist at every level.

The Team

As part of the Business organization, IT & Enterprise Software delivers the technology infrastructure, enterprise applications, and digital tools that power Valar's operations. The team ensures secure, reliable, and scalable technology solutions that support every function across the company.

The Role

We're looking for a Software Security Engineer to embed security into our software development lifecycle — from initial design through shipped code. This role is split across two key moments: early-stage design and planning reviews, where you'll help engineering teams make secure architectural decisions before code is written, and post-development code review, where you'll dig into implemented code to find and fix vulnerabilities before release.

You'll work closely with engineering teams across our C#, Python, and React stack, along with our Postgres data layer, acting as a security partner rather than a late-stage gatekeeper. We strongly value candidates with backgrounds in large-scale technology organizations or the defense sector, where security rigor and compliance discipline are non-negotiable.

Key Responsibilities

Design & Planning Reviews

Participate in design and architecture discussions early, before implementation begins

Perform lightweight threat modeling on new features and services — identifying trust boundaries, data flows, and likely attack surfaces

Flag risky design patterns (auth schemes, data handling, third-party integrations, database access patterns) and recommend secure alternatives

Provide security requirements and acceptance criteria that get built into planning/ticketing, not bolted on afterward

Code Review (Post-Development)

C#, Python, React: Perform manual and tool-assisted secure code review across all three

Postgres: Review queries and schema design for injection risks, access control issues, data exposure, and unsafe query patterns

React: Review front-end code for common web vulnerabilities (XSS, insecure state/data handling, unsafe use of dangerouslySetInnerHTML, client-side auth assumptions)

C#: Review backend code for issues like insecure deserialization, improper input validation, authorization flaws, and unsafe use of reflection/dynamic code

Provide clear, actionable remediation guidance directly to engineers — not just a list of flagged lines

Compliance & Ongoing

CMMC 2.0: Support alignment with Cybersecurity Maturity Model Certification (CMMC) 2.0 practices where applicable to contracts and data handling requirements

Maintain and refine secure coding guidelines specific to our stack (C#/.NET, Python, React, Postgres)

Track recurring vulnerability patterns across reviews and feed them back into design guidance and developer training

Partner with engineering leads to balance security rigor against delivery timelines

Basic Qualifications

Professional experience in application security, software security engineering, or a related security-focused engineering role

Strong proficiency reading and reasoning about C# and Python code

Working knowledge of React and common front-end/web security issues

Experience reviewing Postgres (or other relational database) queries and schemas for security issues

Demonstrated experience doing security reviews at both the design/planning stage and the code-review stage — this is a dual-mode role, not just one or the other

Familiarity with OWASP Top 10, secure design principles, and basic threat modeling (e.g., STRIDE)

Strong written and verbal communication — you'll need to explain security tradeoffs to engineers and, sometimes, non-technical stakeholders

Preferred Skills and Experience

Experience at a large-scale technology company ("big tech") or within the defense industrial base

Familiarity with CMMC 2.0 requirements and how they translate into engineering and software practices

Experience working under DFARS, NIST 800-171, or similar federal/defense compliance frameworks

Software/application security certifications: CSSLP (Certified Secure Software Lifecycle Professional), GWAPT (GIAC Web Application Penetration Tester), or GSSP (GIAC Secure Software Programmer)

General security certifications: CISSP, OSCP, or Security+

Nice to Have

Experience with SAST/DAST tooling and integrating security checks into CI/CD

Experience with SBOM / software supply chain security

Familiarity with cloud environments (AWS/Azure/)

What Success Looks Like

Security issues get caught in design discussions, before they're ever coded

Code review findings are specific, actionable, and rarely repeat the same root cause twice

Engineering teams bring you into planning conversations proactively, rather than security being an afterthought

The C#/Python/React/Postgres stack has clear, documented secure coding practices that teams actually follow

The organization maintains a clear path toward, or sustains, CMMC 2.0 compliance where required

What We Offer

Competitive base salary

Equity ownership in a rapidly growing advanced energy company

Comprehensive medical benefits

Unlimited PTO

Free daily lunch and dinner provided onsite

Generous PPE stipend

High-impact startup environment with significant ownership and autonomy

Opportunities for rapid career growth and internal advancement

Direct collaboration with experienced operators, engineers, and industry leaders

The opportunity to help build and scale transformative energy technology from the ground up

Equal Employment Opportunity Statement

Valar Atomics is an equal opportunity employer. We consider all qualified applicants without regard to race, color, religion, sex, gender identity, sexual orientation, national origin, age, disability, veteran status, or any other protected status under applicable law.

We are committed to providing a workplace free of discrimination and harassment and will provide reasonable accommodation as required by law.

Applicants must be legally authorized to work in the United States as a U.S. citizen or lawful permanent resident (green card holder).

Salary$175,000—$200,000 USD