What form must be posted in any laboratory where radioactive materials are used?

The correct form that must be posted in any laboratory where radioactive materials are used is NRC Form 3. This form provides important information regarding the rights of workers to be informed about their exposure to radiation, safety measures, and the procedures to be followed in the event of an incident involving radioactive materials.

NRC Form 3 specifically outlines the basic components of radiation safety and employees' rights, thereby ensuring that all personnel working in environments with radioactive materials are aware of safety guidelines and their entitlements. Displaying this form is a regulatory requirement, aiding in compliance with safety regulations outlined by the Nuclear Regulatory Commission (NRC).

In contrast, the other NRC forms serve different purposes. For example, NRC Form 1 is primarily related to license applications or renewals. NRC Form 2 is typically used for specific correspondence or requests from licensees. NRC Form 4 deals with personal monitoring and exposure records and does not pertain to the posting requirements for laboratory environments. Therefore, NRC Form 3 uniquely fulfills the mandate for posting in laboratories utilizing radioactive materials.