# Determine and assess threats after protected-zone intrusion indications > Use 10 CFR 73.50 - Physical protection of licensed activities to review this narrow operational decision without extending the source beyond its stated scope. - Canonical URL: https://update.dsesecurity.com/updates/determine-and-assess-threats-after-protected-zone-intrusion-indications/ - Publisher: Detection Systems & Engineering (DSE Security) - Author: DSE Security Editorial Team - Published: 2026-08-27T12:11:48+00:00 - Modified: 2026-08-27T13:06:59+00:00 - Last reviewed by DSE: 2026-08-26 - Resource type: Explainer - DSE priority: Advisory - Topics: Access Control, Cybersecurity, Video Surveillance - Reading time: 3 minutes ## What you need to know Use 10 CFR 73.50 - Physical protection of licensed activities to review this narrow operational decision without extending the source beyond its stated scope. ## Potentially affected Teams, systems, services, or facilities within the stated scope of 10 CFR 73.50 - Physical protection of licensed activities ## DSE recommendation Compare the observed state with the cited official source, document applicability and exceptions, and test any approved change with rollback safeguards. ## Article Frame this document as a source-led configuration and assurance check: Determine and assess threats after protected-zone intrusion indications. Only the official source and traced locations below supply facts. Confirm applicability before acting. ## Source fact: The official [10 CFR 73.50 – Physical protection of licensed activities](https://www.ecfr.gov/current/title-10/section-73.50) from U.S. Nuclear Regulatory Commission via eCFR supports the following bounded statements: - Under 10 CFR 73, after detecting abnormal presence, activity, or intrusion indications in a protected zone, the security organization must assess the threat’s extent. The research record locates this support at 10 CFR 73.50(g)(3)(ii), read with 10 CFR 73.50(g)(3) (eCFR anchor p-73.50(g)(3)(ii)). - Under 10 CFR 73, after detecting abnormal presence, activity, or intrusion indications in a protected zone, the security organization must determine whether a threat exists. The research record locates this support at 10 CFR 73.50(g)(3)(i), read with 10 CFR 73.50(g)(3) (eCFR anchor p-73.50(g)(3)(i)). These statements are the factual basis for this document. Do not extend them into a broader assurance. Review access control, video, intrusion detection, communications, supporting facilities, operators, and documented response paths only where the source and recorded environment align. ## What the source does not establish NRC regulation with specific scope, thresholds, and license conditions; qualified review is required before concluding that an activity is covered or a control is sufficient. It does not establish a deployment’s current state, authorize a production change, prove compliance, or show that identity, Windows DNS where used, time, networks, power, life-safety systems, vendors, and monitoring personnel are healthy. Documented options are review inputs, not universal mandates. ## Applicability questions - For source statement 1 at 10 CFR 73.50(g)(3)(ii), read with 10 CFR 73.50(g)(3) (eCFR anchor p-73.50(g)(3)(ii)), which observable configuration, record, or test can confirm applicability here? - For source statement 2 at 10 CFR 73.50(g)(3)(i), read with 10 CFR 73.50(g)(3) (eCFR anchor p-73.50(g)(3)(i)), which observable configuration, record, or test can confirm applicability here? - Which owner can attest to the recorded state of access control, video, intrusion detection, communications, supporting facilities, operators, and documented response paths, including exceptions? - What baseline for identity, Windows DNS where used, time, networks, power, life-safety systems, vendors, and monitoring personnel must accompany the source-specific observation? - Which success, stop, and escalation criteria are written before testing begins? ## DSE recommendation: DSE recommends using the cited source as the evidence anchor for this decision. Start with applicability, then compare the observed state with the cited source. Record the source location, examined part of access control, video, intrusion detection, communications, supporting facilities, operators, and documented response paths, observed and expected states, owner, and reason for deviation. Translate the conclusion into change control only after documenting dependencies, impact, test method, expected signals, failure signals, and restoration steps. Include identity, Windows DNS where used, time, networks, power, life-safety systems, vendors, and monitoring personnel, while excluding secrets and sensitive personal or topology data from ordinary tickets. ## Verification and evidence A reviewer should be able to retrace the decision from 10 CFR 73.50(g)(3)(ii), read with 10 CFR 73.50(g)(3) (eCFR anchor p-73.50(g)(3)(ii)); 10 CFR 73.50(g)(3)(i), read with 10 CFR 73.50(g)(3) (eCFR anchor p-73.50(g)(3)(i)) through asset and firmware inventories, configuration exports, event tests, inspections, alarm response records, and maintenance findings. Record what was collected, where, when, by whom, and which system or role it represents. Keep before-state evidence, approval, test or change result, exceptions, and after-state evidence together. Use an approved lab, window, or nonproduction path for risky tests. Set a recheck trigger for version, architecture, dependency, vendor, incident, or ownership change. A check proves only what was observed. ## Official references - [10 CFR 73.50 – Physical protection of licensed activities](https://www.ecfr.gov/current/title-10/section-73.50) — U.S. Nuclear Regulatory Commission via eCFR ## Primary reference - Name: 10 CFR 73.50 - Physical protection of licensed activities - Authority: www.ecfr.gov - URL: https://www.ecfr.gov/current/title-10/section-73.50 - Source publication date: Not stated by the source ## Citation and use Preferred citation: “Determine and assess threats after protected-zone intrusion indications,” DSE Security, https://update.dsesecurity.com/updates/determine-and-assess-threats-after-protected-zone-intrusion-indications/ Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/ Usage and citation policy: https://update.dsesecurity.com/usage/ Copyright © 2026 Detection Systems & Engineering. All rights reserved.