{"id":2530014,"url":"https://alion.io/job/radiant-principalstaff-security-engineer","title":"Principal/Staff Security Engineer","company":{"id":8822,"name":"Radiant","domain":"radiant.com","url":"https://alion.io/company/radiant","size_band":"201-500","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":{"grade":"A","score":92,"open_postings":16,"ghost_share":0,"stale_share":0.313,"repost_share":0,"time_to_fill_p50_days":49,"computed_at":"2026-10-15T05:46:00Z"}},"role":"Security","role_family":"Security","seniority":"lead","employment_type":"full_time","work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"explicit","locations":["Gloucester, United Kingdom"],"countries":["GB"],"hiring_countries":[],"hiring_countries_total":0,"salary":null,"salary_estimate":{"min_usd":95000,"max_usd":167000,"period":"year","method":"role_seniority_country_remote_cell","sample_n":20},"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"Kubernetes","optional":false},{"name":"ISO 27001","optional":true},{"name":"SOC 2","optional":true}],"status":"live","first_seen_at":"2026-10-14T09:56:29Z","employer_posted_date":"2026-10-14","last_verified_at":"2026-10-15T06:53:30Z","board_verified":true,"closed_at":null,"days_open":0,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":0},"description":"About Radiant\nRadiant is redefining how AI infrastructure is built. We design and operate AI-native infrastructure platforms engineered for sovereignty, performance, and scale - powering GPU-native workloads, multi-tenant control planes, and high-performance AI systems for the most demanding environments. We are building purpose-built AI infrastructure from powered land, to compute, to software.\nAs we scale our operations and deploy capital into the next generation of AI infrastructure, we are looking to expand our finance team with leaders who can combine technical strength with execution excellence and are driven to build.\nRadiant was established by Brookfield, a leading global alternative asset manager with over US$1 trillion of assets under management across real estate, infrastructure, renewable power and transition, private equity and credit. Brookfield's global relationships, investment expertise and access to long-term institutional capital provide Radiant with a differentiated platform from which to develop, finance and operate AI infrastructure assets. This combination of entrepreneurial execution and institutional sponsorship enables Radiant to pursue large-scale GPU and AI infrastructure opportunities globally.\nAbout the Role\nLocation: UK (occasional travel to data centre and test environments, confirm exact cadence) | Employment Type: Full-time, Permanent | Reports to: VP Information Security\nWe're looking for a Principal/ Staff Security Engineer to join Infosec, reporting to our VP InfoSec. This is a hands-on, individual contributor role. You will need a deep, technical understanding of Kubernetes clusters, network architecture and access controls to manage our production environment.\nAs we move toward owning and operating more of our own data centre footprint, the accuracy of our firewall policies, network access controls and technical security testing matters more than ever. This role will build our internal penetration testing capability, so testing becomes more targeted and accurate over time, working alongside our external testers rather than replacing them. You will need to work proactively across engineering teams so knowledge does not sit with one person alone.\nWhat You'll Do\nSecurity Testing & Audit:\nAudit firewall policies and network access controls across the estate.\n\nConduct internal penetration testing, working alongside our external penetration testing partners.\n\nBuild a penetration testing strategy and cadence that improves accuracy and coverage over time.\n\nIdentify and help remediate security gaps found through testing and audit.\n\nProduction Estate & Technical Depth:\nBuild and maintain a deep, working understanding of our production environment, including Kubernetes clusters, network architecture and access controls.\n\nInvestigate technical issues directly and dig into root cause, rather than relying on reported findings alone.\n\nSupport the VP Infosec on controls testing across the Production Estate.\n\nAccess & Environment Management:\nOwn and maintain SSO and systems access configuration.\n\nBuild and maintain penetration testing environments, including small Kubernetes clusters as needed.\n\nMaintain the tooling and infrastructure supporting security testing.\n\nCollaboration:\nWork proactively across engineering teams to avoid becoming a single point of knowledge or failure.\n\nDocument processes, findings and configurations so knowledge is shared, not siloed.\n\nPartner with the Head of Security Operations on shared governance, risk reporting and security testing.\n\nWhat You'll Bring\nStrong Kubernetes experience, with the technical depth to investigate and resolve issues directly.\n\nExperience auditing firewall policies and network access controls.\n\nExperience conducting or coordinating penetration testing.\n\nComfortable maintaining and operating security tooling and environments on an ongoing basis.\n\nStrong written communication skills, given the solo nature of the role.\n\nExperience operating as the sole security engineer, or within a small security team.\n\nNice to Have\nNetwork engineering experience or strong networking fundamentals.\n\nBackground in data centre environments, or related infrastructure environments.\n\nExperience with AI security specifically.\n\nExposure to compliance frameworks such as ISO 27001 or SOC 2, and an understanding of how technical controls map to audit evidence.\n\nWhy Join Radiant\nBuild Radiant's internal penetration testing capability at a moment when our security and compliance obligations are scaling fast, as a Brookfield portfolio company moving into owned data centre operations.\n\nWork directly with our VP Infosec and Head of Security Operations, protecting both our corporate and production estates.\n\nBe part of a team whose work protects the infrastructure powering sovereign and enterprise AI deployments globally.\n\nDevelop your career in a Brookfield backed company with resources, mentorship and genuine growth 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