Radioactive materials designation Class

This is determined by comparison with a table of values for each isotope in 49 CFR 173.436, or by comparison with values derived in accordance with the formulas in 49 CFR 173.433. Material is exempt from radioactive material designation (Class 7) if it fails either of the two criteria. 

General placarding requirements are described in 49 CFR 172.504. Placards are required at each end and on each side of a transport vehicle, bulk package, or freight container for hazardous materials in accordance with Table 1 of this section. Radioactive materials require Class 7 placards if package dose rates merit a Yellow-111 label, and for exclusive use LSA and SCO shipments. Note that placards for a highway route controlled quantity are of a different design than standard Class 7 placards. 

According to this classification an inflammable liquid or solid chemical is given a number designating its class, and a red color that indicates its physical or chemical hazard such as flammability. For toxic, corrosive, explosive radioactive material a container should be marked with different numbers and colors (Fig. 2.4). 

Travel on designated routes — or in the absence of routes, avoid tunnels, narrow roads, narrow bridges, heavily populated areas, and places where people gather. (Specific routing requirements — including the requirement for written route plans — are designated for carriers of Class 7 (radioactive) materials.)... 

The design of safety class structures, systems and components (SSCs) shall provide defense-in-depth features against the uncontrolled release of radioactive materials to the environment under normal conditions, AOEs, and DBA conditions. 

DISCUSSI ON. The reactor design should be fundamentally safe to ensure that the reactor is capable of being shutdown safely and adequately cooled following postulated accidents. In addition, the reactor facility should be designed to provide defense-in-depth needed to prevent or mitigate the consequences of accidents that could result in uncontrolled release of radioactive materials to the environment. The nuclear safety design criteria ensure that the reactor and the associated safety class SSCs perform their intended safety functions. 

DOE Order 420.1, Facility Safety, requires the detailed application of that order s requirements to be guided by safety analyses that establish the identification and functions of safety (safety class and safety significant) structures, systems, and components (SSCs) for a facility and establish the significance of safety functions performed by those SSCs. It specifies that nuclear facilities shall be designed with the objective of providing multiple layers of protection to prevent or mitigate the unintended release of radioactive materials to the environment. The safety analyses must consider facility hazards, natural phenomena hazards, and external man-induced hazards. Paragraph 4.4.1 requires safety analyses for hazardous facilities to include the ability of SSCs and personnel to perform their intended safety functions under the effects of natural phenomena. DOE O 420.1 (DOE 1995) incorporates requirements from the cancelled DOE Orders 5480.28, 5480.7A, and 6430.1A(DOE 1993). 

The Class 1 electrical equipment, identified in Table 2.5.2-1 of Reference 4.4, has electrical surge withstand capability and can withstand electromagnetic interference, radio frequency interference and electrostatic discharge conditions that would exist before, during and after a Design Basis accident without loss of safety function for the time required to perform the safety function. SSCs required to perform the plant safety functions (reactivity control, core heat removal control, exposure to radioactive material, release of radioactive material) that could be vulnerable to these effects are classified as Class 1. 

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