REFERENCE SOURCES: Training Manual, Chapter 4; TS-R-1, Section II; and TS-G-1.1 DISCUSSION: The graded approach in the Regulations provides, in part, for greater control over shipment and in turn allows more flexibility in packaging and contents when such control is used. The greater control is provided through the specification of Exclusive Use.
PROBLEM: A vehicle is dedicated by its owner/operator to the shipment of radioactive material packages. No other commodities are carried in that vehicle. The owner/operator of that vehicle (i.e., the carrier) picks up packages from various suppliers (i.e., consignors) and delivers them to various users (i.e., consignees).
a. Are there any conditions under which the shipments in this vehicle can be made under exclusive use?
b. If the vehicle were to be used under exclusive use, what advantages would there be?
ANSWER:
EXERCISE 4.5. Packages
REFERENCE SOURCES: Training Manual, Chapter 4; TS-R-1; TS-G-1.1
DISCUSSION: Safety during transport is achieved by using packaging adequate for the radioactive contents.
PROBLEM:
a. What is the difference between a package and the packaging?
b. What are the types of packages?
ANSWER:
5. BASIC SAFETY CONCEPTS: MATERIALS AND PACKAGES 5.1. Basic safety concepts
As discussed in the first chapter, the core philosophy of the transport of radioactive material is that it should be performed safely. Safety can be achieved in a number of different ways. Some would argue that not transporting radioactive material at all is the only way to be assured of safety. However, this disregards the very significant benefits of using radioactive material and the ultimate need for properly treating and disposing of the existing material when it is no longer needed.
To properly understand the basic concepts for safely transporting packages containing radioactive material it is essential to always keep in mind a clear picture of the package components. These are shown in Figure 5.1
• • Package - The packaging with its Package - radioactive contents as presented for transport
• • Packaging - The assembly of components Packaging - necessary to enclose the radioactive contents completely
+ =
PACKAGING PACKAGE RADIOACTIVE
CONTENTS
FIG. 5.1. Radioactive contents, packaging and package 5.1.1. Inherent safety
While such aspects as administrative and procedural controls such as marking, labelling, notifications, and communications have their place, it is clearly best to have as much reliance on inherent safety as possible. This minimizes the human factor and the tendency to make mistakes. An example of inherent safety would be shipping the material in such a way that even if all the controls failed, and an individual ingested the material it would not have a detrimental effect. The difficulty is that radioactive material has a very large variety of properties and a very large range of specific activities. To incur a small dose the quantity of ingested material could range from a few milligrams to many kilograms. Because of this phenomenon, the accurate characterization of radioactive material type is a basic safety aspect of the IAEA TS-R-1 Transport Regulations, as will be seen later.
5.1.2. Passive safety
Once one can no longer rely on the inherent safety of the radioactive material itself, then the next best step is to use passive safety. An example of passive safety is packaging. If the quantity of radioactive material is such that it is not inherently safe, then it could be made part of a package that can withstand all the assaults to which it is likely to be exposed. It then does not matter how the radioactive material is treated during the transport process. The difficulty with this is that such a packaging may be extremely expensive compared to the value of the radioactive material content. It is also unreasonable to have a very tough packaging for material that might only be marginally hazardous.
This leads to the concept of a graded approach to packaging requirements. In other words, the package integrity is a function of the hazard associated with the radioactive material. The more hazardous the material, the tougher the packaging. Packaging ‘toughness’
is measured in its ability to withstand various conditions of transport. There are three basic conditions used in the IAEA Regulations with some variations within each condition (see para 106 of TS-R-1):
- Routine conditions of transport (incident free);
- Normal conditions of transport (minor mishaps); and - Accident conditions of transport.
Routine conditions of transport are those that are totally incident free, apart from the conventional stresses and strains resulting from the conveyance operation. Normal conditions of transport include the typical small incidents that a package might endure during shipment.
These include such things as being rained upon, being dropped, and having other packages stacked on top.
The graded approach to packaging in the Regulations is illustrated pictorially in Figure 5.2. The packaging at the top of the figure is typical of that used for small limited quantities of radioactive material posing a minimal hazard. This package is designed to withstand only the routine conditions of transport. If the packaging fails, the consequences are insignificant because of the levels of radioactivity involved. The packaging in the centre of the figure is typical of that used for moderate quantities of radioactive material posing a small hazard. This package is designed to withstand both the routine, and the normal conditions of transport. If this packaging fails in an accident, there may a release of radiation, but they are unlikely to cause any measurable biological effects. The packaging at the bottom of the figure is typical of that used for more significant quantities of radioactive material, which would pose a large hazard if released. This package is designed to withstand not only the routine and normal conditions of transport, but also accident conditions of transport.
FIG. 5.2. Pictorial representation of the graded approach to packaging
5.1.3. Active safety
Once all that is reasonably possible has been done with respect to inherent safety and passive safety, then the next level of safety is that associated with active controls. This generally requires the implementation of procedures of some sort. Included in this category would be labelling; marking and placarding; loading, stowage, storage, and segregation provisions; Quality and Compliance Assurance controls, and shipping documentation.
5.1.4. Summary of objectives of Transport Regulations
In summary, the objective of the Regulations is to protect persons, property and the environment from the effects of radiation during the transport of radioactive material (paragraph 104 of TS-R-1). In the words of the Regulations, this protection is achieved by requiring:
- Containment of the radioactive contents, - Control of external radiation levels, - Prevention of criticality, and
- Prevention of damage caused by heat.
In terms of this chapter, this can be thought of as applying the principles of inherent safety, passive safety, and active safety controls. The IAEA Regulations incorporate these principles by:
- Limiting the nature and activity of the radioactive material which may be transported in a package of a given design (see Section IV of TS-R-1);
- Specifying design criteria for each type of package (see Section VI of TS-R-1);
- Providing information on hazards by labels, marking, placards, and shipping papers (see Section V of TS-R-1);
- Applying simple rules of handling and stowage of the packages during transport and in-transit storage (see paragraphs 562 – 569 of TS-R-1).
5.2. Radioactive material
Following these basic safety concepts, it is important first to accurately characterize the radioactive material that is planned for shipment. The various possibilities were introduced in the previous chapter on terminology. The factors that need to be known in order to characterize the radioactive material include:
- the form (special form or not);
- the applicable A1/A2 value;
- the A2/g value; and
- the nature of the material itself (e.g. instrument or article, surface contamination, combustibility, fissile properties, irradiated fuel, UF6, and other dangerous properties).
The derivation of A1/A2 values and their application to material types are the subjects of Chapter 6.
Knowledge of the factors listed, along with the quantity of radioactive material that needs to be shipped, will largely characterize the material and determine the packaging needed. This process is discussed in the next few chapters.
Continuing with the basic safety theme, material that is exempt from the Regulations (see Section 4.3) clearly falls under the inherently safe criterion. The same can be said for material that can be shipped in excepted packagings. In addition, the nature of LSA-I is such that it would be very difficult to ingest or inhale sufficient quantities to cause a radiological problem. More hazardous material types however, need to progressively rely on the packaging for some aspects of safety.
5.3. Packages
The correlation between the three conditions of transport discussed earlier in 5.1.2. and the eight basic packaging types is an important aspect of the safety built into the Regulations.
Table 5.1 just gives the broad overview.
TABLE 5.1. CONDITIONS OF TRANSPORT ASSOCIATED WITH DIFFERENT PACKAGES
Conditions of transport Type of package
Routine Excepted; Industrial Type IP-1, -2 and -3; Type A; Type B(U) and Type B(M); Type C
Normal Industrial Type IP-2 and 3; Type A; Type B(U), and B(M); Type C
Accident Type B(U) and Type B(M); Type C
Since packages are very much the key to the Regulations, information on them is found in several sections of TS-R-1. The contents limits and material restrictions for the different types of packages are defined in Section IV. The requirements for packagings and packages, including the tests needed as well as the pass criteria, are presented in a hierarchical fashion in Section VI of the Regulations. These build from the "General requirements for all packagings and packages” (TS-R-1 paragraphs 606-616) to "Requirements for packages containing fissile material" (TS-R-1 paragraphs 671-682). The specific procedures for all of the tests referred to in Section VI for the various types of package designs are specified in a similar fashion in Section VII of the Regulations.
Because of this method of presentation in the Regulations, it is sometimes difficult to gain a general overview of the requirements applicable for all of the packages. For this reason, information on packages is presented differently in this training manual. Following the general philosophical introduction given here, the package types, their limits, and typical contents are covered in Chapter 7. The requirements, design considerations, and examples of packages are given in the Chapter 8. In Chapter 8, the Figures 8.1 and 8.2 and the Tables 8.1, 8.2, 8.3 and 8.4, have been developed as a summary of much of these data. The figures and tables provide at a glance both the requirements needed for a particular package type as well as the package types for which a particular requirement is applicable. Because there is always more detail in the Regulations than can be provided in the table, the relevant paragraphs are given for reference. Tables 8.2, 8.3 and 8.4. provide a general and a detailed listing of the requirements for all package types from excepted packages to Type C packages. They also include a summary of the test procedures that apply. These three tables can be used to assist in understanding the hierarchical nature of requirements imposed on package designs following the basic philosophical principles discussed in this chapter. Finally, detailed information about the package tests, and how to perform them, is provided in Chapter 8.
It should be noted that the additional considerations for packages containing fissile material are covered separately in Chapter 11.
5.4. Optimization
Optimal practice in radioactive material transport involves seeking the best combination of material type and packaging, as well as considering other factors such as exclusive use and conveyance. Sometimes the radioactive material to be shipped can be characterized to meet more than one of the definitions of material given in the Regulations. In addition, there is often more than one packaging type that may be used. This is especially true if the radioactive material can be split into smaller lots.
Since the Regulations have been designed with the safety principles discussed above, the minimum allowable packaging and transport methods should be used. For example, there is nothing in the regulatory requirements to prevent shipping some radioactive material with an activity totalling 0.5 A2 in a Type B(U) packaging. However, this is clearly excessive and expensive. The material could almost certainly be shipped more economically in a Type A packaging. Moreover, depending on a number of other factors, it might even be transportable in an industrial package as one of the LSA or SCO categories.
There are many advantages to be gained from optimally characterizing the radioactive material to be shipped and selecting the best packaging and transport options. This is the art of radioactive material transport. However, it can only be practised effectively when one has a complete knowledge of the Regulations.