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.
Screen inverse-square dose-rate prompts before RSO boundary review
Radiation Distance Calculator →Review shielding HVL prompts before qualified health physics review
Radiation Shielding Calculator →Estimate source-to-dose prompts before survey confirmation
Activity to Dose Rate Calculator →Review stay-time arithmetic only after RSO procedure checks
Radiation Stay Time Calculator →How It Works
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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.
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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.
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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