49 CFR § 173.434 - Activity-mass relationships for uranium and natural thorium.

---
identifier: "/us/cfr/t49/s173.434"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "49 CFR § 173.434 - Activity-mass relationships for uranium and natural thorium."
title_number: 49
title_name: "Transportation"
section_number: "173.434"
section_name: "Activity-mass relationships for uranium and natural thorium."
chapter_name: "PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "C"
subchapter_name: "HAZARDOUS MATERIALS REGULATIONS"
part_number: "173"
part_name: "SHIPPERS—GENERAL REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 5101-5128, 44701; 49 CFR 1.81, 1.96 and 1.97."
cfr_part: "173"
---


# 173.434 Activity-mass relationships for uranium and natural thorium.

The table of activity-mass relationships for uranium and natural thorium are as follows:

|  |  |  |  |  |
| --- | --- | --- | --- | --- |
| 0.45 (depleted) | 1.9 × 10 | 5.4 × 10 | 5.0 × 10 | 2.0 × 10 |
| 0.72 (natural) | 2.6 × 10 | 3.8 × 10 | 7.1 × 10 | 1.4 × 10 |
| 1.0 | 2.8 × 10 | 3.6 × 10 | 7.6 × 10 | 1.3 × 10 |
| 1.5 | 3.7 × 10 | 2.7 × 10 | 1.0 × 10 | 1.0 × 10 |
| 5.0 | 1.0 × 10 | 1.0 × 10 | 2.7 × 10 | 3.7 × 10 |
| 10.0 | 1.8 × 10 | 5.6 × 10 | 4.8 × 10 | 2.1 × 10 |
| 20.0 | 3.7 × 10 | 2.7 × 10 | 1.0 × 10 | 1.0 × 10 |
| 35.0 | 7.4 × 10 | 1.4 × 10 | 2.0 × 10 | 5.0 × 10 |
| 50.0 | 9.3 × 10 | 1.1 × 10 | 2.5 × 10 | 4.0 × 10 |
| 90.0 | 2.1 × 10 | 4.7 × 10 | 5.8 × 10 | 1.7 × 10 |
| 93.0 | 2.6 × 10 | 3.9 × 10 | 7.0 × 10 | 1.4 × 10 |
| 95.0 | 3.4 × 10 | 3.0 × 10 | 9.1 × 10 | 1.1 × 10 |
| Natural thorium | 8.1 × 10 | 1.2 × 10 | 2.2 × 10 | 4.6 × 10 |
| The figures for uranium include representative values for the activity of uranium-234 which is concentrated during the enrichment process. The activity for thorium includes the equilibrium concentration of thorium-228. |  |  |  |  |

[Amdt. 173-244, 60 FR 50307, Sept. 28, 1995, as amended by 63 FR 52849, Oct. 1, 1998]