Ionizing Radiation: Radiography & Nuclear Gauges

Ionizing radiation can damage cells. Construction and industry use it in industrial radiography (X-ray or gamma images of welds and pipes) and in nuclear gauges that measure soil, asphalt or fluid levels. You cannot see, smell or feel it, so rules and signs matter.

• Construction
• Inspectors
• Industrial

Where workers meet it

• Industrial radiography: inspectors use X-ray machines or sealed sources (such as iridium-192) to check welds and castings. Crews work at night or in controlled areas so others are away.
• Portable nuclear gauges: used to measure compaction of soil and asphalt, and moisture. They hold small sealed sources.
• Fixed gauges on tanks, pipes and conveyors.

Health effects

High doses can cause burns, radiation sickness and later cancer. Low doses over time raise the long-term risk. The goal is to keep exposure as low as reasonably achievable (ALARA).

Time, distance, shielding

• Time: spend as little time near the source as possible.
• Distance: exposure falls quickly as you move away. Doubling the distance cuts it to about one quarter.
• Shielding: dense material such as lead, steel or concrete blocks the rays.

Signs and boundaries

• Radiography crews rope off a controlled area with signs such as "Caution: Radiation Area" or "Danger: Radiographic Operations." Never cross the boundary.
• A gauge or source is kept in a locked, labeled container and a log. Do not move or open it.
• Stay out of marked areas even if the crew seems to be done; the source may still be out.

Rules for those who work with sources

• Licensed by the regulator (the Nuclear Regulatory Commission or the state) and specifically trained
• Wear a personal dosimeter or badge and an alarming ratemeter; read them
• Survey the area with a meter before and after use
• Store sources locked and secure; never leave one unattended
• Report any lost, stolen or damaged source immediately to the radiation safety officer

Last updated: October 8, 2026