Nuclear Densometer Safe Work Method Statement

Operators must hold a radiation user licence specific to portable density gauges issued by the relevant state or territory radiation authority (e.g., EPA Victoria, NSW EPA, Queensland Department of Environment and Science). The licence type varies by jurisdiction but typically requires completion of approved training course, practical competency assessment, and demonstration of radiation safety knowledge. General radiation safety training is not sufficient—operators need device-specific authorisation. Licences require periodic renewal (typically every 1-5 years depending on jurisdiction) with ongoing competency demonstration. Employers must verify licence validity before authorising gauge use and maintain records of all licensed operators.

A 3-metre exclusion zone is the minimum safe distance for unauthorised personnel while the gauge is operating with source exposed. This distance is based on radiation intensity decreasing with the inverse square of distance—doubling distance reduces exposure to one quarter. The operator may work closer (typically 1 metre minimum) while deploying controls and monitoring the test, with exposure time minimised through efficient procedures. When testing in backscatter mode on vertical surfaces or in confined spaces, the exclusion zone should increase to 5 metres. These distances apply to gamma radiation from Caesium-137; neutron radiation from Americium-241/Beryllium sources has different shielding properties. Radiation surveys using calibrated instruments verify actual safe distances for specific equipment and test configurations.

Immediately establish a 10-metre exclusion zone around the gauge and prevent all access. Do not approach or touch the gauge until radiation survey is completed. Use radiation survey meter to check for elevated radiation levels indicating shielding damage or source displacement. Survey from maximum distance possible initially, gradually approaching while monitoring readings. If radiation levels exceed background (typically above 0.5 microsieverts per hour at 1 metre), treat as shielding failure and activate emergency procedures. Notify radiation safety officer and state radiation authority within 24 hours of any impact incident regardless of survey results. The gauge must be inspected and tested by qualified personnel before returning to service. Document incident details including impact force, gauge orientation, and any visible damage. Even minor impacts can compromise shutter mechanism or source positioning over time.

Stop applying force immediately to prevent probe rod bending or shutter mechanism damage. The source remains exposed while probe is deployed, so time is critical. Use steady upward force with mechanical advantage tools such as probe extractors or leverage bars. Never use excavation equipment or vehicles to extract stuck probe—excessive force can rupture shielding. If probe cannot be retrieved within 15 minutes, implement extended exposure protocol by establishing 10-metre exclusion zone and notifying radiation safety officer. Some situations require excavation around probe location to relieve soil pressure before extraction. In extreme cases where probe cannot be retrieved, the gauge must be left in place with exclusion zone established while specialised recovery procedures are arranged through radiation authorities. Document probe depth and soil conditions that caused entrapment. Prevention includes proper site assessment and avoiding insertion into unsuitable materials.

The gauge must be secured in an approved locked transport case meeting radiation authority requirements for transport of radioactive materials. The case features foam padding preventing movement and shielding to reduce external radiation levels. Radioactive material placards (Class 7 dangerous goods) must be displayed on the transport case and vehicle during transit. The gauge must be secured in vehicle using permanent mounting points to prevent movement during sudden braking or accidents. Never leave gauge unattended in vehicle—return to approved secure storage during breaks. Storage facilities must provide locked enclosure preventing unauthorised access, with radiation warning signage and emergency contact information displayed. Some jurisdictions require storage facilities to be registered with radiation authorities. Access to storage keys is limited to licensed operators only. Inventory systems track gauge location at all times with sign-out/sign-in procedures. When not in use, gauges undergo regular leak testing (typically every 12 months) and maintenance to verify source integrity and shutter function.

Loss or theft of a nuclear density gauge must be reported to the relevant state or territory radiation authority immediately upon discovery—most jurisdictions require notification within 24 hours. This is a mandatory legal obligation under radiation safety legislation with significant penalties for non-compliance. Law enforcement (police) must also be notified as theft of radioactive material is a criminal offence. The report must include gauge serial number, source details (isotope type and activity), circumstances of loss, and actions taken to recover the gauge. Radiation authorities will coordinate public safety response and may issue warnings to emergency services and scrap metal facilities where stolen gauges sometimes appear. The operator's radiation licence may be suspended pending investigation. The responsible organisation faces regulatory prosecution and substantial fines. Media notification may occur if there is risk to public safety. Even temporary misplacement of a gauge triggers notification requirements until location is confirmed and security re-established.