A wipe test, also called a smear or swipe test, samples a surface with an absorbent material wiped over a defined area, usually about 100 to 300 square centimeters. The wipe is then counted in a radiation detector to estimate removable (non-fixed) contamination. A pickup or removal efficiency is assumed because a wipe only collects a fraction of the removable activity present.

Radioactive Package Receipt and Wipe Testing: Survey Procedures, Removable Contamination Limits, and Recordkeeping

Q: When must an incoming radioactive package be monitored?

Under NRC 10 CFR 20.1906, licensees who expect to receive packages containing quantities above defined thresholds must monitor the external surfaces for radiation and test for removable contamination. Monitoring must occur as soon as practicable after receipt, but no later than three hours after the package is received during working hours, or within three hours from the beginning of the next working day if it arrives after hours.

Q: What are the removable contamination limits for radioactive packages?

The U.S. Department of Transportation limits in 49 CFR 173.443 set non-fixed (removable) external contamination limits of 4 becquerels per square centimeter (about 10^-4 microcuries per square centimeter) for beta, gamma, and low-toxicity alpha emitters, and 0.4 becquerels per square centimeter for all other alpha emitters, averaged over not more than 300 square centimeters.

Q: What do you do if a package exceeds the contamination or dose-rate limits?

If removable contamination exceeds the limits, or if the surface dose rate exceeds 200 millirem per hour or the dose rate at one meter exceeds 10 millirem per hour, the licensee must immediately notify the final delivery carrier and the NRC (or Agreement State). The package should be isolated and handled under contamination-control procedures while the cause is investigated.

Q: What do the Yellow-II and Yellow-III labels mean?

These are DOT transport labels indicating the package's external radiation level. White-I has very low surface radiation. Yellow-II and Yellow-III indicate progressively higher radiation levels and carry a transport index reflecting the dose rate at one meter. The label category determines handling, storage, and segregation requirements during transport.

Q: How long must package receipt records be kept?

Survey and wipe-test records should be retained per the licensee's procedures and the applicable NRC or Agreement State requirements. Receipt monitoring records, including date, package description, measured radiation levels, removable contamination results, instrument and efficiency used, and the surveyor's identity, are commonly retained for at least three years and reviewed during inspection.

Q: Who is responsible for package receipt monitoring?

The radiation safety officer establishes the package-receipt procedure, trains authorized recipients, and ensures instruments are calibrated and efficiencies are known. Trained staff perform the monitoring under the RSO's program, and the medical physicist or health physicist often supports instrument calibration, efficiency determination, and procedure review.

Radioactive package receipt monitoring is the regulatory and radiation-safety process of checking every incoming package of byproduct material for external radiation levels and removable surface contamination before it enters the facility's workflow. NRC 10 CFR 20.1906 sets the timing and triggers, while DOT regulations set the contamination and dose-rate limits a package must satisfy. A wipe test is the quantitative tool that converts a counter reading into removable activity per unit area for comparison against those limits. ^{1, 3}

For a nuclear medicine department, radiopharmacy, or research lab, packages of Tc-99m generators, F-18 unit doses, I-131 capsules, or Lu-177 therapy doses arrive routinely, sometimes daily. Each one is a potential source of external exposure and, if a vial leaked or a shipper mishandled it, of removable contamination. Package receipt monitoring is the first line of defense: it catches damaged or contaminated shipments at the loading dock before they reach hot labs, patients, or unmonitored staff. Done well, it is a fast, documented routine; done poorly or skipped, it is one of the most commonly cited radiation-safety deficiencies. ^{1, 7}

This guide explains the receipt-monitoring procedure, the wipe-test physics and math, the DOT and NRC action levels, the transport-label system, and the records that make the program defensible. DRPS supports package-receipt procedures as part of its radiation safety officer and radioactive material license support services across Florida, Maryland, Virginia, Washington DC, California, and Nevada.

Introduction

The purpose of receipt monitoring is to detect two distinct hazards: external radiation that exceeds expectations, and removable contamination that could spread. These are different problems. A correctly packaged, intact shipment can produce a measurable but entirely normal surface dose rate; that is expected and labeled. The thing the survey is really hunting for is the abnormal package — one that was crushed, leaked, or mislabeled — where either the radiation level or the removable contamination signals a breach of containment. ^{1, 3}

The regulatory architecture reflects this. The U.S. Department of Transportation governs the package while it is in transit, setting limits on external radiation level and non-fixed contamination and requiring labels that communicate the hazard. The NRC (or an Agreement State) governs the licensee who receives it, requiring monitoring on a defined schedule and immediate notification if limits are exceeded. The two systems hand off at the loading dock, and the receiving licensee's procedure is where they meet. ^{1, 3, 5}

Because the consequences of a missed contaminated package can include spread of contamination through the department and avoidable staff exposure, receipt monitoring is treated as a core element of the radiation protection program. It is also inexpensive and fast — a survey meter reading and a wipe count take minutes — which is why regulators expect it to be done consistently and documented every time. This article gives the procedure, the math, and the limits.

Topic Explanation

What package receipt monitoring covers

Receipt monitoring has two measurements: an external radiation survey and a removable-contamination wipe test. The external survey uses a calibrated survey meter to measure the dose rate at the package surface and at one meter; the wipe test samples the external surface for non-fixed contamination and counts it in a detector. Both are compared against limits and recorded. ^{1, 3}

Key terms used throughout this guide:

Removable (non-fixed) contamination — radioactive material that can be transferred from a surface by wiping; the hazard for spread and intake.
Fixed contamination — material bound to the surface that a wipe does not pick up; relevant to dose but not to spread.
Wipe (smear/swipe) test — sampling a defined area with an absorbent medium and counting it to estimate removable activity.
Pickup (removal) efficiency — the fraction of removable activity a wipe actually collects, conventionally assumed to be about 0.1 (10%).
Counter efficiency — counts registered per nuclear disintegration for the instrument, geometry, and radionuclide.
Transport index (TI) — a number on the package label reflecting the dose rate (in mrem/h) at one meter.

Which packages must be monitored and when

Under 10 CFR 20.1906, a licensee that expects to receive packages containing quantities of radioactive material above the regulatory thresholds (for example, packages labeled with DOT radioactive-material labels, or containing more than a Type A quantity) must establish procedures for safe opening and must monitor external surfaces and test for removable contamination. The monitoring must be performed as soon as practicable, but not later than three hours after receipt if the package is received during working hours, or within three hours from the beginning of the next working day if received after hours. ¹

The wipe test must be evaluated and any contamination above limits reported promptly. Packages known to contain only certain exempt or very low-activity quantities may not require the full survey, but the licensee's procedures should define exactly which incoming packages trigger which steps. For how this fits into the broader compliance picture, see common radiation safety violations and how to avoid them.

Key Technical Principles

From counts to removable activity

A wipe test gives a count rate; the physics is in converting that count rate to removable activity per unit area. The wipe samples a known area (commonly 100 cm² for benchtops and small surfaces, or up to 300 cm² for package and contamination-control surveys), is counted in a calibrated instrument, and the net count rate is converted using the counter efficiency and the assumed pickup fraction. ^{1, 8}

The removable activity collected on the wipe, expressed in disintegrations per minute (dpm), is:

A_{removable} = \frac{C _{net}}{E \times f}

where $C_{net}$ is the net count rate (gross minus background, in cpm), $E$ is the counter efficiency (counts per disintegration), and $f$ is the pickup (removal) efficiency. Normalizing to area gives the surface activity:

a_{surface} = \frac{A _{removable}}{A _{wiped}}

in dpm/cm² (or dpm/100 cm²). To compare against limits expressed in SI units, recall:

1 Bq = 60 dpm

Worked wipe-test example

Suppose a technologist wipes a 300 cm² area of a generator package surface, counts the wipe in a well counter, and obtains a gross count rate of 850 cpm against a background of 50 cpm. The counter efficiency for the radionuclide and geometry is $E = 0.40$ (40%), and the conventional pickup fraction is $f = 0.10$ .

Net count rate:

C_{net} = 850 - 50 = 800 cpm

Removable activity on the wiped area:

A_{removable} = \frac{800}{0.40 \times 0.10} = 20, 000 dpm

Surface activity averaged over the wiped area:

a_{surface} = \frac{20 , 000 dpm}{300 cm ^{2}} = 66.7 dpm/cm^{2} = \frac{66.7}{60} = 1.1 Bq/cm^{2}

Comparing to the DOT limits below: $1.1 Bq/cm^{2}$ is below the 4 Bq/cm² limit for beta/gamma emitters (acceptable), but it would exceed the 0.4 Bq/cm² limit if the contaminant were an alpha emitter. The same count rate yields a different compliance result depending on the radionuclide — which is why the emitter type must be known. ³

Removable contamination and radiation-level limits

The DOT non-fixed (removable) external contamination limits in 49 CFR 173.443, averaged over not more than 300 cm², are: ³

Contaminant type	Removable contamination limit	Approximate dpm/cm²
Beta and gamma emitters and low-toxicity alpha emitters	4 Bq/cm² (≈ 10⁻⁴ µCi/cm²)	≈ 240 dpm/cm²
All other alpha emitters	0.4 Bq/cm² (≈ 10⁻⁵ µCi/cm²)	≈ 24 dpm/cm²

External radiation-level limits for transport (49 CFR 173.441) and the receipt-notification triggers in 10 CFR 20.1906 combine to define the package label categories and the action thresholds: ^{1, 2}

DOT label	Max surface dose rate	Transport index (dose rate at 1 m)
White-I	≤ 0.005 mSv/h (0.5 mrem/h)	Essentially 0
Yellow-II	≤ 0.5 mSv/h (50 mrem/h)	≤ 1.0 (≤ 1 mrem/h at 1 m)
Yellow-III	≤ 2 mSv/h (200 mrem/h)	> 1.0 up to 10 (exclusive-use higher)

At receipt, 10 CFR 20.1906 requires immediate notification of the final delivery carrier and the NRC if removable contamination exceeds the 49 CFR 173.443 limits, or if the surface dose rate exceeds 2 mSv/h (200 mrem/h) or the dose rate at one meter exceeds 0.1 mSv/h (10 mrem/h). ^{1, 2, 3} For instrument selection behind these surveys, see choosing the right radiation survey meter.

Clinical Impact

Package receipt monitoring protects staff, prevents contamination spread, and keeps the department's dose records clean. A leaking I-131 capsule shipment or a cracked Tc-99m generator vial caught at the dock is contained at a single, controlled location; the same shipment opened and distributed before monitoring can contaminate hot-lab surfaces, dose-draw areas, and the hands and clothing of multiple staff, turning a minor packaging failure into a department-wide decontamination event. The few minutes spent monitoring are a high-leverage investment in worker protection and ALARA. ^{1, 7}

The program also has direct operational consequences. A package that fails the survey must be isolated, the carrier and regulator notified, and the cause investigated — a workflow that the department must be prepared to execute without improvisation. Facilities that practice this, including spill-response and contamination-control drills, handle real events calmly; those that have never rehearsed it tend to spread contamination during the response itself. The link between receipt monitoring and the broader contamination-control program is tight, and the same survey instruments, wipe-counting setup, and trained personnel serve both; see nuclear medicine decontamination best practices.

Receipt monitoring further supports the facility's overall exposure-control program. By confirming that incoming radiation levels match labels and that surfaces are clean, it validates assumptions used elsewhere in the radiation safety program, including occupational dose estimates. For how those exposures are tracked, see occupational exposure monitoring.

Practical Optimization Tips

A defensible package-receipt program is built on calibrated instruments, known efficiencies, trained staff, and consistent documentation.

Establish a clear receipt procedure

Define which incoming packages trigger full monitoring versus reduced steps, based on activity and DOT labeling.
Specify the three-hour timing windows for working-hours and after-hours receipt explicitly in the SOP.
Designate and train the staff authorized to receive and open packages, including gloves, lab coats, and dosimetry.

Know your instrument and efficiency

Use a calibrated survey meter appropriate to the emissions for the external radiation survey, and a calibrated counter (well counter or contamination monitor) for wipes.
Determine the counter efficiency for each radionuclide and geometry you receive; do not assume a single number across isotopes.
Apply a defensible pickup fraction (commonly 0.1) and document the assumption; it is conservative because the actual removal can vary.

Perform the wipe correctly

Wipe a defined area (commonly 100–300 cm²) with moderate, consistent pressure across the package's external surfaces, focusing on seams and the area near the contents.
Count promptly, subtract background, and record gross, background, and net counts — not just the final result.
Convert to dpm/cm² (or Bq/cm²) and compare to the correct limit for the emitter type.

Respond and document

If limits are exceeded, isolate the package, notify the carrier and NRC/Agreement State immediately, and initiate contamination control.
Record every receipt: date, shipper, radionuclide and activity, label category, surface and 1-m dose rates, removable-contamination result, instrument and efficiency, and surveyor identity.
Trend results periodically to catch recurring shipper problems.

Common pitfalls to avoid

Skipping or delaying monitoring. The three-hour window is a hard requirement, not a guideline. ¹
Using the wrong limit for the emitter. Alpha emitters have a tenfold tighter removable limit. ³
Assuming 100% counter efficiency. Forgetting efficiency and pickup fraction underestimates removable activity by an order of magnitude or more.
Recording only "pass." Inspectors expect the underlying counts, areas, instrument, and efficiency.
Failing to calibrate or check instruments. An out-of-calibration counter invalidates every wipe result.

Regulatory Considerations

Package receipt sits at the junction of NRC/Agreement State materials regulation and DOT transport regulation, and a defensible program documents both. ^{1, 2, 3, 4, 5, 6}

Key frameworks:

10 CFR 20.1906 — Procedures for receiving and opening packages. Requires monitoring of external surfaces and removable contamination on the defined schedule, safe-opening procedures, and notification when limits are exceeded. ¹
49 CFR 173.443 — Contamination control. Sets the non-fixed (removable) external contamination limits (4 and 0.4 Bq/cm²). ³
49 CFR 173.441 — Radiation level limitations and 49 CFR 172 labeling — define surface dose-rate limits and the White-I / Yellow-II / Yellow-III label system with transport index. ²
10 CFR Part 71 — Packaging and transportation of radioactive material. Governs package design, Type A/Type B quantities, and the licensee's transport responsibilities. ⁴
IAEA SSR-6 — Regulations for the Safe Transport of Radioactive Material. The international basis that the U.S. transport rules align with. ⁵
NUREG-1556, Volume 9 — medical-use licensing guidance, including expectations for receipt, surveys, and contamination control. ⁶

Because package contents are byproduct material, the receiving licensee is regulated by the NRC or an Agreement State. Of the states DRPS serves, Florida, Maryland, Virginia, California, and Nevada are Agreement States that administer their own equivalent receipt and contamination-control rules, while Washington, DC is regulated directly by the NRC. The DOT transport requirements apply nationwide regardless of agreement-state status. Facilities should confirm which authority issues their license and which exact thresholds, notification contacts, and recordkeeping periods apply. For the licensing context, see our NRC license guide and the radiation safety officer role. ^{1, 4, 6}

International or air shipments add the IATA Dangerous Goods Regulations on top of DOT requirements; facilities receiving such shipments should ensure their procedures account for those additional controls. ⁵

Frequently Asked Questions (FAQs)

When must an incoming radioactive package be monitored?

Under NRC 10 CFR 20.1906, licensees expecting packages above defined thresholds must monitor external surfaces for radiation and test for removable contamination as soon as practicable, but no later than three hours after receipt during working hours, or within three hours from the start of the next working day if received after hours.

What is a wipe test?

A wipe test (smear or swipe test) samples a surface with an absorbent material wiped over a defined area, usually about 100 to 300 cm². The wipe is counted in a radiation detector to estimate removable (non-fixed) contamination. A pickup efficiency is assumed because a wipe collects only a fraction of the removable activity present.

What are the removable contamination limits for radioactive packages?

DOT limits in 49 CFR 173.443 set removable external contamination limits of 4 Bq/cm² (about 10⁻⁴ µCi/cm²) for beta, gamma, and low-toxicity alpha emitters, and 0.4 Bq/cm² for all other alpha emitters, averaged over not more than 300 cm².

What do you do if a package exceeds the contamination or dose-rate limits?

If removable contamination exceeds the limits, or the surface dose rate exceeds 200 mrem/h or the dose rate at one meter exceeds 10 mrem/h, the licensee must immediately notify the final delivery carrier and the NRC (or Agreement State). Isolate the package and handle it under contamination-control procedures while investigating.

What do the Yellow-II and Yellow-III labels mean?

These DOT transport labels indicate the package's external radiation level. White-I has very low surface radiation; Yellow-II and Yellow-III indicate progressively higher levels and carry a transport index reflecting the dose rate at one meter. The category determines handling, storage, and segregation during transport.

How long must package receipt records be kept?

Survey and wipe-test records are retained per the licensee's procedures and applicable NRC or Agreement State requirements — commonly at least three years. Records should include date, package description, measured radiation levels, removable-contamination results, instrument and efficiency, and the surveyor's identity.

Who is responsible for package receipt monitoring?

The radiation safety officer establishes the procedure, trains authorized recipients, and ensures instruments are calibrated and efficiencies known. Trained staff perform monitoring under the RSO's program, and the medical or health physicist often supports instrument calibration, efficiency determination, and procedure review.

Key Takeaways

Monitor every triggering package on time. 10 CFR 20.1906 requires external radiation and removable-contamination checks within three hours of receipt or the next working day. ¹
Wipe tests need real math. Removable activity = net cpm ÷ (counter efficiency × pickup fraction); assuming 100% efficiency badly underestimates contamination.
Know the emitter. The removable limit is 4 Bq/cm² for beta/gamma but only 0.4 Bq/cm² for most alpha emitters. ³
Know the dose-rate triggers. Surface > 200 mrem/h or 1-m > 10 mrem/h, or contamination over limits, requires immediate carrier and NRC notification. ¹
Calibrate and document. Out-of-calibration instruments and "pass-only" records are common inspection findings.
Receipt monitoring is contamination control's front door. Catching a breached package at the dock prevents department-wide spread.

Conclusion

Radioactive package receipt monitoring is a small, fast routine with outsized importance. A calibrated survey meter, a wipe and a counter, a few minutes, and a complete record stand between a leaking shipment and a contaminated department. The regulatory limits are explicit, the wipe-test math is straightforward once efficiency and pickup fraction are accounted for, and the timing requirements are firm.

Facilities that treat receipt monitoring as a disciplined, documented step — with trained staff, known instrument efficiencies, correct emitter-specific limits, and complete records — protect their workers, satisfy NRC and DOT requirements, and contain the occasional damaged package before it becomes a problem. Those that treat it as a formality invite both contamination events and inspection findings. The procedure is simple; doing it consistently and documenting it well is what makes it defensible.

How DRPS Can Help

Diagnostic Radiation Physics Services helps medical and research facilities build defensible package-receipt and contamination-control programs. This includes writing receipt-monitoring procedures aligned with 10 CFR 20.1906 and DOT limits, determining radionuclide- and geometry-specific counter efficiencies, advising on survey and wipe-counting instrumentation, training authorized recipients, and supporting radioactive material license and radiation safety officer program needs.

DRPS provides medical physics consulting across our service locations, including Florida, Maryland, Virginia, Washington DC, California, and Nevada.

A strong receipt-monitoring program is not just about passing inspection. It is about making sure the first time anyone notices a damaged package is at the loading dock — not after it has spread through the department.

Related Resources

References

U.S. Nuclear Regulatory Commission. 10 CFR 20.1906: Procedures for receiving and opening packages. ecfr.gov
U.S. Department of Transportation. 49 CFR 173.441: Radiation level limitations and exclusive use provisions. ecfr.gov
U.S. Department of Transportation. 49 CFR 173.443: Contamination control. ecfr.gov
U.S. Nuclear Regulatory Commission. 10 CFR Part 71: Packaging and Transportation of Radioactive Material. nrc.gov
International Atomic Energy Agency. Regulations for the Safe Transport of Radioactive Material. IAEA Safety Standards Series No. SSR-6 (Rev. 1). Vienna: IAEA; 2018. iaea.org
U.S. Nuclear Regulatory Commission. NUREG-1556, Volume 9, Revision 3: Consolidated Guidance About Materials Licenses — Program-Specific Guidance About Medical Use Licenses. nrc.gov
U.S. Nuclear Regulatory Commission. 10 CFR Part 20: Standards for Protection Against Radiation. ecfr.gov
American National Standards Institute / Health Physics Society. ANSI/HPS N13.12: Surface and Volume Radioactivity Standards for Clearance. hps.org
U.S. Department of Transportation. 49 CFR Part 172: Hazardous Materials Table, Special Provisions, Hazardous Materials Communications (labeling and marking). ecfr.gov
U.S. Nuclear Regulatory Commission. 10 CFR 71.87: Routine determinations. ecfr.gov
International Air Transport Association. Dangerous Goods Regulations (DGR). Montreal: IATA. iata.org
American National Standards Institute. ANSI N323A: Radiation Protection Instrumentation Test and Calibration, Portable Survey Instruments. ansi.org