Claim: The Norwegian Civil Defence's Radiation Measurement patrols (RAD) is the biggest unit in the organization and consists of four thousand personnel trained in measuring sonar activities which measures background sounds at set locations and times; this is a technique that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.
Evidence: This is the smallest unit in the organization and consists of four personnel trained in measuring radioactivity.