CHAPTER 1.5 – GENERAL PROVISIONS CONCERNING RADIOACTIVE MATERIAL

Radioactive materials require additional regulatory attention due to the unique hazards they present. Unlike most dangerous goods, radioactive substances can release ionizing radiation even when properly packaged and handled. Exposure to ionizing radiation can cause cellular damage, radiation sickness, and long-term health effects, including cancer. Therefore, the transport of Class 7 materials is controlled by a highly specialized set of safety measures aimed at protecting personnel, the public, and the environment.

This chapter highlights provisions that supplement the general requirements of the IMDG Code, ensuring radioactive materials are transported under conditions that minimize radiation exposure and prevent accidental release.

1.5.1 Additional Considerations

Radioactive materials pose risks not only through physical contamination but also through invisible radiation emissions. These emissions can penetrate materials, including human tissue, making exposure monitoring critical.

Key additional considerations include:

• Non-obvious danger: Radiation has no smell, taste, or visual cue; safety depends on strict procedures and instrumentation.

• Cumulative health impact: Exposure adds over time; even small, repeated doses can have long-term consequences.

• Contamination vs. irradiation:

  • Irradiation is exposure to radiation without physical contact with the source.

  • Contamination occurs when radioactive particles adhere to surfaces, equipment, or personnel.

Due to these unique characteristics, the handling and transport of radioactive materials require specialized knowledge, licensing, and technical safeguards beyond those required for other hazardous cargoes.

1.5.2 Key Requirements

The IMDG Code mandates strict controls on radiation levels, shielding integrity, and exposure monitoring to ensure safety during transport. These requirements are closely aligned with standards set by the International Atomic Energy Agency (IAEA).

a. Dose Limits

Dose limits ensure that radiation exposure remains within internationally accepted safety thresholds. Limits are defined for:

• Occupationally exposed workers, who routinely handle radioactive materials,

• General crew, who may work near such cargo,

• Members of the public, who must not be exposed to harmful radiation levels during transit or storage.

Dose limits are cumulative over defined periods. Transport operations must be planned to avoid unnecessary exposure, following the principle of ALARA (As Low As Reasonably Achievable).

b. Shielding

Shielding is the primary control that prevents harmful radiation from escaping the package.
Shielding materials include:

• Lead,

• Steel,

• Tungsten,

• Concrete (in larger applications).

Functional requirements of shielding:

• Reduce radiation to acceptable transport levels,

• Remain intact under normal and foreseeable conditions of transport,

• Prevent damage during handling and stowage.

The design integrity of shielding is verified through package testing and certification procedures prescribed by the competent authority.

c. Radiation Monitoring

Monitoring ensures that radiation levels stay below established limits during storage, loading, transport, and unloading.

Monitoring activities include:

• Surface dose rate checks on packages,

• Area surveys in stowage or storage zones,

• Personal dosimetry for workers with repeated exposure,

• Leak-testing for sealed radioactive sources.

Radiation monitoring instruments must be:

• Calibrated regularly,

• Suitable for the radiation type and intensity,

• Operated only by trained personnel.

These measurements provide documented assurance that radiation protection measures are functioning correctly.

d. Transport Index (TI) Calculation

The Transport Index (TI) is a numerical value assigned to packages of radioactive material to control radiation exposure during transport and storage.

TI is based on:

• Measured radiation dose rate at one meter from the external surface of the package,

• Expressed in millisieverts per hour (mSv/h) multiplied by a conversion factor defined in the Code.

The TI determines:

• Quantity of packages allowed in a transport unit,

• Segregation distances from people and living areas,

• Placement onboard ships or in port facilities.

Higher TI values indicate higher radiation levels and therefore stricter handling and segregation requirements.

1.5.3 Competent Authority Approval

Certain radioactive shipments require formal authorization before transport. This approval ensures that packaging design, shielding performance, and operational controls meet national and international standards.

Approval is mandatory for:

• Type B and Type C packages,

• Packages containing fissile material,

• Special arrangements for shipments deviating from standard requirements,

• Large quantities classified as high consequence radioactive materials.

The competent authority typically refers to a national regulatory body responsible for:

• Nuclear safety,

• Radiation protection,

• Transport approval and inspection,

• Issuing certificates of compliance.

No shipment requiring approval may proceed without valid certification.
Authorities retain the right to:

• Suspend,

• Revoke,

• Modify approvals if safety concerns arise.

Summary of Chapter 1.5