A source that emits 05 mR/hr and nothing at 3 feet would require what type of label?

The label required for a source that emits 0.5 mR/hr at a distance of 1 meter and nothing at 3 feet falls under the White I category. This is due to the fact that White I labels are designated for packages that contain materials with very low radiation levels and pose minimal risk to people.

According to the classification system for radioactive materials, White I is assigned to those that emit radiation at a very low level (not exceeding 0.5 mR/hr at 1 meter). The fact that the source does not emit any radiation at 3 feet indicates that the potential exposure is negligible and within safe parameters, validating the White I label which signifies that the radiation levels at the specified distances are very low and generally not hazardous to the public or transport personnel.

This classification is in stark contrast with categories such as Yellow II and Yellow III, which apply to materials that emit higher radiation levels, necessitating more stringent precautions. A Green I label, while not an official designation in the classifications, would also indicate very low levels, but it is not a recognized category in this context. Therefore, the appropriate and correct label for this scenario is indeed White I.