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Radiation Area Posting Guide

Determine correct area posting and access controls based on measured dose rate per 10 CFR 20

Free source-aware radiation posting threshold screen for RSOs, radiation workers, and compliance staff who need a quick review prompt from a measured external photon dose-rate row. The tool keeps the 30 cm context for Radiation Area and High Radiation Area threshold values visible, keeps the Very High Radiation Area 1 m absorbed-dose source context visible, and points to 10 CFR 20 source sections for sign wording, access-control, monitoring, survey, and posting-exception review. It does not determine legal posting, no-posting status, sign placement, access controls, dosimetry, public dose, Agreement State applicability, license conditions, or entry authorization.

Pro Tip: Treat the 5 mrem/hr and 100 mrem/hr rows as RSO review triggers, not as automatic sign instructions. A current calibrated survey, the exact source or beam condition, accessible locations, license conditions, Agreement State rules, and facility procedure can change what must be documented or controlled. The derived 30 cm Very High Radiation Area row is only a point-source screen because the regulatory definition uses 500 rad/hr at 1 meter.

Screen inverse-square dose-rate prompts before RSO boundary review

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Review shielding HVL prompts before qualified health physics review

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Estimate source-to-dose prompts before survey confirmation

Activity to Dose Rate Calculator →

Review stay-time arithmetic only after RSO procedure checks

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Radiation Area Posting Guide
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How It Works

  1. Enter a Survey Dose-Rate Prompt

    Enter the measured dose-rate row and unit. The app assumes the reading is an external photon screening prompt and does not verify calibration, geometry, source condition, or survey method.

  2. Review the Threshold Prompt

    Review whether the local row is below the radiation-area prompt, at the radiation-area prompt, at the high-radiation-area prompt, or at the derived point-source very-high-radiation-area prompt. The active row is a review trigger, not a posting decision.

  3. Resolve Source and Procedure Gaps

    Use the listed source pointers to verify sign wording, sign symbol context, access-control requirements, monitoring context, posting exceptions, current license conditions, Agreement State rules, and RSO procedures before field use.

Assumptions

  • Dose-rate rows are local external photon screening prompts and are not calibrated survey records.
  • Radiation Area and High Radiation Area source definitions use 30 cm context; Very High Radiation Area source context uses 1 m and absorbed dose.
  • Posting, access-control, monitoring, exception, and labeling decisions require current source records, accessibility review, procedures, and RSO approval.
  • Neutron, beta, airborne, contamination, pulsed, mixed-field, internal-dose, and radioactive-material quantity contexts require separate review.

Limitations

  • Does not decide legal posting, no-posting, exceptions, sign placement, individual monitoring, or access-control adequacy.
  • Does not cover state-specific rules, license conditions, 10 CFR 34 radiography procedures, or Agreement State differences.
  • Does not solve airborne radioactivity, contamination, radioactive-material quantity posting, storage, waste, transport, or container labeling.
  • Does not replace calibrated surveys, ALARA review, work permits, emergency procedures, or qualified health physics review.

References

  • 10 CFR 20 Subpart G - Control of Exposure from External Sources in Restricted Areas
  • 10 CFR 20.1003 - Definitions (radiation area, high radiation area, very high radiation area)
  • 10 CFR 20.1501-1502 - Surveys, monitoring, and individual monitoring context
  • 10 CFR 20.1601-1602 - Control of Access to High and Very High Radiation Areas
  • 10 CFR 20.1901-1903 - Caution signs, posting requirements, and posting exceptions

Frequently Asked Questions

The source definitions use dose-rate thresholds at 30 cm from the source or a penetrated surface. The app uses those values as local review prompts. Whether a location is legally posted or controlled depends on current survey records, accessibility, license conditions, exceptions, and RSO review.
No. It shows source wording prompts from 10 CFR 20.1902 and the sign-symbol source pointer from 10 CFR 20.1901. Final sign wording, sign size, placement, durability, exceptions, and related labels must be verified against the current regulation, license, procedure, and site condition.
No. A low local dose-rate row does not demonstrate annual public dose, radioactive-material quantity posting, container labeling, survey-record adequacy, or exception status. It is only a prompt for RSO review.
Use it as an escalation prompt for 10 CFR 20.1601, individual monitoring context, access-control procedure, authorization, and qualified review. The app does not select locks, alarms, surveillance, dosimeters, or entry controls.
Use calibrated surveys and the current license/procedure record. Sealed-source exceptions and storage conditions are fact-specific; this app cannot decide whether a source housing, vault, room, or work boundary qualifies for an exception or needs another posting or label.
Only as a checklist-style source pointer. Enforcement, violation severity, corrective action, and legal exposure depend on current facts, agency program, license conditions, inspection record, and qualified regulatory review.
Disclaimer: This tool provides preliminary 10 CFR 20 posting-threshold prompts. It does not replace the full text of the regulations, the facility radiation protection program, calibrated survey records, license conditions, Agreement State rules, or RSO/qualified health physics review.

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Complete posting requirements for Radiation Areas, High Radiation Areas, and Very High Radiation Areas. Includes sign specifications, access controls, and exceptions per 10 CFR 20.1902-1903.

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