Which of the following is listed as a vault entry requirement?

• A. Gantry on stand by
• B. Heat scan cables
• C. Continuous atmospheric testing
• D. Initial atmospheric testing

Answer: (D)

Entering a vault is a confined-space task, so you must establish the environment before anyone steps inside. The first step is an initial atmospheric test to measure oxygen levels and detect any toxic or flammable gases. This test provides a baseline and determines whether conditions are safe to enter or whether ventilation and additional precautions are needed. Without that initial check, you could be exposed to life-threatening conditions as soon as you enter. While ongoing atmospheric monitoring is important and performed during the job to ensure conditions remain safe, the requirement that must be completed before entry is the initial atmospheric testing. The other options relate to equipment status or monitoring during work, not the prerequisite entry condition.