Type B Packages: Requirements, Certification, and When You Need One

Why Type B Is a Different World

Every other packaging tier in Class 7 shipping — excepted, industrial, Type A — is something you can source, test-document, and ship on your own authority. Type B is the tier where that stops. The design must survive severe accident conditions, the design approval comes from the NRC rather than from your own testing file, and you personally must appear on the certificate paperwork before the package leaves your dock.

The most common mistake I see is a shipper who discovers at classification time that their quantity is over A2 and assumes the fix is simply ordering a bigger, tougher box. It is not. Crossing the A1/A2 line does not change the box — it changes the regulatory regime you are operating in, and the lead time goes from days to weeks or months. If you learn one thing from this guide, learn to see that line coming before you are standing on it.

This guide covers when Type B is required, what B(U) and B(M) actually mean, how the certification chain works, and the practical logistics of getting access to a certified package. For where Type B sits among the other tiers, start with our package types overview; for the full shipping sequence end to end, see the pillar guide on how to ship Class 7 radioactive material.

Who Needs to Know This

This applies to anyone who:

• Ships or is considering shipping quantities that approach or exceed A1/A2 — large sealed sources, irradiator sources, high-activity waste, spent fuel
• Receives Type B shipments and wants to understand what the shipper's obligations were
• Is planning source replacement or decommissioning work where the old source has to leave the building somehow
• Classifies material and needs to recognize when a consignment is drifting toward the Type B threshold

When Do You Need a Type B Package? The A1/A2 Threshold

The trigger is quantity. 49 CFR 173.416 authorizes Type B packages “for shipment of quantities exceeding A₁ or A₂, as appropriate.” That is the whole test:

• Special form material (sealed capsules and other qualified non-dispersible forms): compare package activity against the radionuclide's A1 value
• Normal form material (everything else — liquids, powders, unsealed material): compare against the radionuclide's A2 value

At or below the applicable value, a Type A package is sufficient. Above it, you are in Type B territory. The A1 and A2 values are radionuclide-specific — our guide on A1 and A2 values explains where they come from and how to use them, and RAMcalc does the comparison for you automatically.

Here's a scenario I've watched play out more than once: a facility consolidating disused sources for disposal decides to save freight by combining several sources into one drum. Individually, every source was comfortably shippable as Type A. Combined, the total activity in the package crossed the A1 line — and what was going to be a routine Type A shipment quietly became a Type B problem nobody had budgeted for. The A1/A2 comparison is per package, which cuts both ways: consolidation can push you over the line, and splitting a consignment across more packages can keep you under it. When splitting is an option, it is almost always the cheaper one.

What Makes a Package “Type B”? The 10 CFR Part 71 Performance Standard

DOT's rule is short. 49 CFR 173.413 says that, except as provided in 173.416, each Type B(U) or B(M) package must be designed and constructed to meet the applicable requirements of 10 CFR Part 71. In other words, DOT hands the entire design standard to the NRC. This is one of the cleanest examples of the NRC/DOT jurisdictional split: NRC certifies the package design; DOT governs the transportation.

The performance heart of that standard is 10 CFR 71.51. A Type B package design must show that:

• Under normal conditions of transport (the tests in 10 CFR 71.71): no loss or dispersal of radioactive contents — demonstrated to a sensitivity of 10⁻⁶ A₂ per hour — no significant increase in external surface radiation levels, and no substantial reduction in the effectiveness of the packaging.
• Under hypothetical accident conditions (the test sequence in 10 CFR 71.73): no escape of krypton-85 exceeding 10 A₂ in 1 week, no escape of other radioactive material exceeding a total amount A₂ in 1 week, and no external radiation dose rate exceeding 10 mSv/h (1 rem/h) at 1 meter from the package surface.

Two details in 71.51 are worth noticing. First, compliance with those release limits may not depend on filters or on a mechanical cooling system — the containment has to be passive. Second, packages with contents greater than 10⁵ A₂ must additionally meet 10 CFR 71.61. The theme is the same throughout: a Type B package is engineered to keep its contents contained through a severe accident, not just through normal handling.

Contrast that with a Type A package, which is designed to survive the rough-and-tumble of normal transport but is expected to potentially fail in a severe accident — which is exactly why its contents are capped at A1/A2, quantities chosen so that a release stays within tolerable consequences. Type B exists because above those quantities, the package itself has to be the safety case.

Type B(U) vs Type B(M): What the Letter Means

The letter after the B tells you how the design is approved:

• B(U) — unilateral approval. The design needs certification from one competent authority (in the United States, the NRC), and other countries accept the package on the strength of that single approval.
• B(M) — multilateral approval. The design requires approval from the competent authority of each country through or into which the package is transported. B(M) designs are typically ones that could not meet every B(U) condition and need country-by-country sign-off.

For a domestic shipper, the practical difference is small — either way you need an NRC-approved design and registration under 49 CFR 173.471. For international moves, the difference is large: a B(M) package means a competent-authority paperwork chain across every border. In my experience, nearly everything you will encounter in routine commercial service — source changers, isotope transport casks — is B(U), and if a vendor quotes you a B(M) package for an international move, your schedule just got longer. Ask early.

The distinction also shows up directly in the shipping description, which is why it is worth getting straight before the paperwork stage.

The Four Type B UN Numbers

Type B shipments use exactly four entries from the Class 7 UN number list — two for non-fissile or fissile-excepted material, and two fissile counterparts:

Notice what the naming tells you: unlike most of Class 7, where the UN number describes the material, the Type B entries describe the package. UN2916 does not say what is inside — it says the contents required a B(U) package and are riding in one. Fissile contents that do not qualify for a fissile exception move the shipment to UN3328 or UN3329.

The Certificate of Compliance: Why You Can't Just Buy a Type B Container

This is the part that surprises every first-time Type B shipper, so let me say it plainly: there is no catalog you order a Type B package from. A Type B package is not a product — it is an NRC-certified design, documented in a Certificate of Compliance (CoC) issued under 10 CFR Part 71, and every shipment in it happens under the terms of that certificate.

49 CFR 173.471 spells out what DOT requires of anyone offering an NRC-approved Type B(U), B(M), or fissile material package:

1. Registration: the offeror must be registered with the NRC as a party to the packaging approval, and must make the shipment in compliance with the terms of the approval.
2. Package marking: the outside of each package must be durably and legibly marked with the package identification marking from the NRC approval.
3. Shipping papers: every shipping paper for the shipment must bear that same package identification marking.
4. Export: before export, the offeror needs a U.S. Competent Authority Certificate for the design — or must register in writing with the U.S. Competent Authority as a user of an existing one, including a description of the quality assurance program required by 10 CFR Part 71. New certificate requests must be received at least 90 days before the requested effective date.

That quality assurance program deserves emphasis. 10 CFR Part 71 requires a QA program covering activities under the certificate, and the NRC approves it. You cannot borrow a cask from a colleague, bolt it shut, and ship — the loading, maintenance, and use of the package have to happen under an approved QA umbrella, whether that umbrella is yours or the cask owner's.

How Shippers Actually Get Access to a Type B Package

In practice, almost nobody who ships Type B occasionally owns the cask. The working model looks like this:

• Lease from the certificate holder. Cask owners — typically source manufacturers and specialty logistics firms — lease certified packagings and handle adding you as a registered user of the approval.
• Vendor round-trip. For source replacement, the source vendor often ships the new source in their cask and takes the old one back in the same packaging — frequently with their own crew doing the loading under their QA program.
• Full-service contract. For one-off jobs like decommissioning, it is common to contract the entire evolution — cask, transport, paperwork — to a firm that does this weekly.

My honest advice after 15 years: if this is your first Type B shipment, do not try to be the hero who does it all in-house. The certificate terms, the QA coverage, the loading procedures, and the return logistics are exactly the kind of thing the cask owner's team does routinely and you would be doing for the first time. Your job is to classify the material correctly, understand your obligations as the offeror, and verify — not assume — that the contents you are tendering are within the certificate's authorized contents list. I have seen a shipment stall for weeks because the isotope was fine but its chemical form was not on the certificate. Read the CoC. All of it.

Budget time accordingly. Between securing a cask window, registration, and scheduling, Type B lead time is measured in weeks at best — and if the move is international and a competent authority certificate is involved, remember that 90-day minimum for new certificate requests. Nothing about this tier moves at overnight-courier speed.

How RadShip.com Helps

RadShip.com keeps you on the right side of the A1/A2 line:

• RAMcalc compares your radionuclide, activity, and form against the applicable A1 or A2 value and tells you when a consignment requires a Type B package — classifying it to UN2916, UN2917, UN3328, or UN3329 with the math shown.
• It flags fissile contents so you know whether you are looking at the fissile entries or the fissile-excepted ones.
• It generates shipping papers from the classification, so the proper shipping name and UN number on the document match the package.

The reason this matters for Type B specifically: the threshold sneaks up on people doing mental math with familiar numbers. The calculator turns “I think we're still under A1” into a documented comparison — and when you are one package consolidation away from a cask lease, you want that answer in writing before you tape the box.

Try it free for 7 days.

Common Questions

When do I need a Type B package?

When one package holds more activity than the A1 value (special form) or A2 value (normal form) for your radionuclide. 49 CFR 173.416 authorizes Type B packages for quantities exceeding A1 or A2 — below that line, a Type A package is sufficient and far simpler.

What's the difference between Type B(U) and Type B(M)?

How many countries have to approve the design. B(U) designs carry unilateral approval — one competent authority certifies, others accept. B(M) designs need multilateral approval from every country the package transits. Most commercial casks in routine service are B(U).

Can I just buy a Type B container?

Practically, no. Type B packagings are NRC-certified designs, and 49 CFR 173.471 requires the offeror to be registered with the NRC as a party to the packaging approval and to ship within the certificate's terms. The normal path is leasing a certified cask from its owner and being added as a registered user — not purchasing hardware.

What UN numbers apply to Type B shipments?

Four: UN2916 (Type B(U), non fissile or fissile-excepted), UN2917 (Type B(M), non fissile or fissile-excepted), UN3328 (Type B(U), fissile), and UN3329 (Type B(M), fissile). Uniquely in Class 7, these entries describe the package rather than the material.

Who approves Type B package designs — DOT or NRC?

The NRC. 49 CFR 173.413 requires each Type B(U) or B(M) package to be designed and constructed to meet 10 CFR Part 71, and 173.416 authorizes NRC-approved packagings shipped pursuant to 173.471. DOT governs the transportation itself — classification, marking, papers — while the NRC owns the package certification.

Do I need a quality assurance program to ship Type B?

Yes. 10 CFR Part 71 requires a quality assurance program, and 49 CFR 173.471(d) explicitly references it in the certificate-registration process. Your use of the package — loading, maintenance, shipment prep — must happen under an approved QA program, which in a lease arrangement is often the cask owner's.

Summary: Your Type B Checklist

Before committing to a Type B shipment, confirm:

• ☐ You have run the A1/A2 comparison per package with the actual radionuclide, activity, and form — and checked whether splitting or decay could keep you in Type A
• ☐ The packaging is an NRC-approved Type B(U) or B(M) design authorized for your contents — isotope, form, and quantity all within the certificate
• ☐ You (the offeror) are registered with the NRC as a party to the packaging approval
• ☐ Your activities under the certificate are covered by an approved 10 CFR Part 71 quality assurance program
• ☐ The package identification marking from the NRC approval is durably marked on the package and appears on every shipping paper
• ☐ The shipment is classified to the correct entry: UN2916 / UN2917, or UN3328 / UN3329 if fissile
• ☐ For export: a U.S. Competent Authority Certificate is in place, or you are registered as a user of one — with the 90-day lead time for new requests factored into the schedule

Regulatory References

DOT Requirements:

• 49 CFR 173.413 – Requirements for Type B packages (design and construction per 10 CFR Part 71)
• 49 CFR 173.416 – Authorized Type B packages for quantities exceeding A1 or A2
• 49 CFR 173.471 – Requirements for NRC-approved packages: registration, package marking, shipping papers, export
• 49 CFR 172.101 – Hazardous Materials Table (UN2916, UN2917, UN3328, UN3329 entries)

NRC Requirements:

• 10 CFR Part 71 – Packaging and transportation of radioactive material (design certification and quality assurance)
• 10 CFR 71.51 – Additional requirements for Type B packages (normal and hypothetical accident condition performance)

IATA (Air Transport):

• IATA Dangerous Goods Regulations – additional requirements apply to Type B packages offered for air transport; check the current edition and your operator's variations