UN3332: Shipping Sealed Sources in Type A Packages (Special Form)

Why UN3332 Matters

The special form classification exists for one reason: a sealed source that will not break apart or disperse in an accident is inherently safer than loose material at the same activity level. Because the dispersal risk is lower, the regulations allow a higher activity limit — A1 instead of A2. For some isotopes, this difference is enormous.

Consider Am-241: the A2 value (normal form) is 0.001 TBq (27 mCi). The A1 value (special form) is 10 TBq (270 Ci). That is a 10,000-fold difference. An Am-241 source at 100 mCi would require Type B packaging if shipped as normal form (exceeds A2), but fits easily in a Type A package as special form (well below A1). The special form certificate is literally the difference between a straightforward shipment and a massively more expensive Type B operation.

I cannot overstate how important this distinction is. I have seen facilities spend thousands of dollars on Type B packaging for a source that had a valid special form certificate sitting in a filing cabinet. And I have seen the opposite — shippers using UN3332 on the shipping paper when they did not have the certificate, which is a misclassification.

Who Ships Under UN3332

UN3332 is the classification for:

• Industrial radiography companies — Ir-192 and Co-60 sealed sources for NDT work
• Nuclear gauge users — Cs-137 and Am-241/Be sealed sources in portable gauges (when shipped outside the gauge)
• Medical facilities — brachytherapy seeds and sealed therapy sources
• Well-logging companies — Am-241/Be and Cs-137 sources used in oil and gas exploration
• Source manufacturers and distributors — new sealed sources being shipped to end users
• Waste brokers — sealed sources being returned for disposal with valid certificates

What Does “Special Form” Actually Mean?

Special form is not just a description — it is a regulatory certification. Under 49 CFR 173.469, radioactive material qualifies as special form if it is either:

1. An indispersible solid — the material itself is a solid that will not break, shatter, or generate particles under accident conditions, OR
2. A sealed capsule — the material is contained in a sealed capsule that will not release its contents under accident conditions

In either case, the material must pass four tests defined in 49 CFR 173.469:

The manufacturer performs these tests (or equivalent calculations) and issues a special form certificate. This certificate is your documentation that the source qualifies. Without it, you cannot claim special form status.

A1 Activity Limits and Why They Matter

The A1 value is always greater than or equal to the A2 value. For some isotopes the difference is minimal; for others it is dramatic. Here are the most relevant examples:

Look at those ratios. For Co-60 and Sr-90, special form makes zero difference — A1 equals A2 because even dispersed, these isotopes are not significantly more hazardous. But for Am-241, the difference is 10,000×. That is because Am-241 is an alpha emitter — extremely dangerous if inhaled but not dangerous at all if sealed inside a capsule. The A1 value reflects the sealed risk; the A2 value reflects the dispersal risk.

What Qualifies for UN3332?

A shipment classifies as UN3332 when all of the following are true:

1. Activity exceeds excepted package limits — the material does not qualify for excepted packages (UN2908–UN2911)
2. Activity does not exceed A1 — the total activity per package is at or below the A1 value for the radionuclide
3. Material is certified special form — you have a valid special form certificate per 49 CFR 173.476
4. Material is non-fissile or fissile-excepted — it either does not contain fissile isotopes, or qualifies for an exemption under 49 CFR 173.453

If the activity exceeds A1, you need Type B packaging (UN2916 or UN2917). If you do not have the special form certificate, classify as UN2915 (normal form). If the material is fissile and not exempted, use UN3333.

The Special Form Certificate

The special form certificate is the single most important document for UN3332 classification. Without it, you cannot use this UN number. Here is what you need to know:

What It Contains

• Identification of the source type (model number, manufacturer)
• Description of the radioactive material and its form
• Statement that the source meets the requirements of 49 CFR 173.469
• Reference to the test reports or calculations
• Applicable radionuclide(s) and maximum activity
• Certificate number and issuing authority

Where to Get It

The source manufacturer provides the certificate when you purchase the source. If you did not receive one, or cannot locate it, contact the manufacturer. For sources manufactured in the United States, the NRC maintains a registry of approved special form designs. For international sources, the competent authority of the country of origin issues the certificate.

My experience is that the special form certificate is the most commonly misplaced document in a radiation safety office. I always recommend keeping a copy with the source's license documentation and another copy in the shipping files. When you need to return a source for disposal 10 or 15 years later, you will be glad you kept it. Without that certificate, a source that could ship as UN3332 in a Type A package may have to go as UN2915 — and if the activity exceeds A2, that means Type B packaging and significantly higher shipping costs.

UN3332 Shipping Requirements

UN3332 has the same general shipping requirements as UN2915 — it is still a Type A shipment. The key differences are in the proper shipping name and the documentation:

Marking

• “TYPE A” specification marking on the package
• UN number: UN3332
• Proper shipping name: Radioactive material, Type A package, special form
• Shipper and consignee names and addresses
• Gross weight if over 50 kg

Shipping Papers

The shipping paper entry is: “UN3332, Radioactive material, Type A package, special form, 7” followed by the radionuclide, physical form, activity, label category, and TI.

Additional Documentation

In addition to the standard shipping paper, you should have:

• The special form certificate (keep on file; not required to accompany shipment but must be available for inspection)
• 24-hour emergency response telephone number on the shipping paper

Everything else — radioactive labels, Transport Index calculation, Type A packaging requirements, contamination limits — is the same as UN2915. The Type A Packages guide covers these in detail.

Common UN3332 Shipping Scenarios

Industrial Radiography Sources

Ir-192 is one of the most frequently shipped isotopes under UN3332. Industrial radiography companies use Ir-192 sealed sources to inspect welds on pipelines, pressure vessels, and structural steel. A typical Ir-192 radiography source is 1–4 TBq (27–108 Ci). With an A1 of 1 TBq, a source at 1 TBq or less ships as UN3332 in Type A. Above 1 TBq, it crosses into Type B territory (UN2916 or UN2917). Most radiography operations involve sources that straddle this line, which is why having the special form certificate is essential — without it, you would be comparing against the A2 of 0.6 TBq instead.

Portable Gauge Sources

Cs-137 and Am-241/Be sources in portable density and moisture gauges are often shipped separately from the gauge for recalibration, source exchanges, or disposal. These sources almost always have special form certificates. A typical Cs-137 gauge source is 0.3 GBq (8 mCi) — well within the A1 of 2 TBq. The Am-241/Be sources are also comfortably within the A1 of 10 TBq. These are straightforward UN3332 shipments as long as you have the certificate.

Source Disposal and Return

When returning sealed sources for disposal, the question I hear most often is: “Do I still have the special form certificate?” If yes, ship as UN3332. If no, you have two options: contact the manufacturer to get a replacement copy, or classify as normal form (UN2915) using the A2 limit. For most gauge sources, A2 is still high enough that the source fits in Type A either way. But for Am-241, losing the certificate could mean the difference between Type A and Type B — and that is a significant cost difference.

How RadShip.com Helps

RadShip.com handles the special form vs. normal form classification automatically:

• RAMcalc — select your material form (special form or normal form), enter the radionuclide and activity, and it applies the correct limit (A1 for special form, A2 for normal form) and assigns the correct UN number
• A1 vs A2 comparison — see both limits side by side so you know exactly what you gain (or don't gain) from the special form classification for your specific isotope
• LabelCalc — calculate the correct label category once your classification is determined

The classification logic takes the guesswork out of special form vs. normal form. Enter your source details and let the calculator determine the right UN number. Try it free for 7 days.

Common Questions

What is the proper shipping name for UN3332?

“Radioactive material, Type A package, special form.” On shipping papers: “UN3332, Radioactive material, Type A package, special form, 7” followed by the radionuclide, activity, label category, and TI.

What if my special form certificate has expired?

Check the certificate terms. Some special form certificates have expiration dates; others are tied to the source design and remain valid as long as the source has not been modified. If the certificate has genuinely expired, contact the manufacturer about a renewal or updated certificate. In the meantime, classify as normal form (UN2915) using the A2 limit.

Can I ship UN3332 by air?

Yes. Special form material can be shipped by air under the IATA Dangerous Goods Regulations. In fact, IATA has some provisions that are more favorable for special form material, particularly around passenger aircraft activity limits. The special form certificate must be available to the carrier if requested.

Does special form affect the packaging requirements?

The packaging must still meet Type A requirements per 49 CFR 173.412. However, because special form material will not disperse, some practical requirements are simpler — for example, you do not need absorbent material for a solid sealed source the way you would for a liquid shipment under UN2915.

Summary: Your UN3332 Checklist

Before shipping under UN3332, verify:

• ☐ You have a valid special form certificate for the source model
• ☐ Activity exceeds excepted package limits but does not exceed A1
• ☐ Material is non-fissile or qualifies for a fissile exemption under 49 CFR 173.453
• ☐ Package meets Type A design requirements (49 CFR 173.412)
• ☐ Package marked with “TYPE A,” UN3332, proper shipping name, shipper/consignee
• ☐ Correct radioactive label applied (I-White, II-Yellow, or III-Yellow) on two opposite sides
• ☐ Shipping paper completed with “UN3332, Radioactive material, Type A package, special form, 7”
• ☐ 24-hour emergency response telephone number on shipping paper
• ☐ Transport Index calculated and recorded
• ☐ External dose rate within regulatory limits
• ☐ Non-fixed external contamination within Table 9 limits
• ☐ Special form certificate on file and available for inspection

Regulatory References

Classification and Limits:

• 49 CFR 173.435 — Table of A1 and A2 values
• 49 CFR 173.431 — Activity limits for Type A packages

Special Form:

• 49 CFR 173.469 — Tests for special form radioactive material
• 49 CFR 173.476 — Approval of special form radioactive materials

Packaging:

• 49 CFR 173.412 — Type A package design requirements
• 49 CFR 173.410 — General design requirements

Marking, Labeling, and Documentation:

• 49 CFR 172.101 — Hazardous materials table (UN numbers and PSNs)
• 49 CFR 172.403 — Radioactive material label requirements