Implementing NEI 08-09 and RG 5.71 for Advanced Reactors: Practical Zero Trust Controls to Meet Nuclear Cyber Baselines

This article (Part Two) provides a practical operating model for implementing the U.S. nuclear cybersecurity baseline (10 CFR 73.54, Regulatory Guide 5.71 Rev.1, and NEI 08-09) in advanced reactor projects supporting hyperscaler AI and cloud data centers. It outlines six core implementation disciplines: (1) Define and stabilize Critical Digital Asset (CDA) boundaries early in design to avoid costly rework; (2) apply defense-in-depth segmentation with zones and mediated conduits, eliminating temporary backdoors; (3) enforce privileged access and vendor operations via just-in-time, least-privilege, auditable sessions with rapid revocation; (4) integrate change control into fast delivery processes, including configuration drift detection and emergency change protocols; (5) maintain continuous, audit-ready evidence through centralized logging, correlation, and inspection-grade reporting; (6) secure the supply chain with verified updates, controlled delivery pipelines, and contractually enforced vendor obligations. The piece recommends identity-based Zero Trust architectures and platforms (citing Xage Fabric Platform) to operationalize policy enforcement, access brokering, tamper-resistant audit trails, and segmentation without slowing schedules. Leaders are advised to test readiness by confirming stable CDA scope, mediated segmentation, time-bound vendor access, governed change, continuous evidence, and verified supply inputs. The guidance aims to help reactor programs embed cybersecurity as an architectural discipline from day one, enabling scale for rapid deployments while satisfying NRC high-assurance requirements.