Radiation Safety Training and Procedures for XRF Device Users Tom Kellogg Associate Radiation Safety Officer University of Vermont Radiation Safety Office

Cobalt-57 Ionizing Radiation Source Fun Facts Co-57 emits gamma ray photons which are high frequency, short wavelength waves of energy. Co-57 emits 122 keV (85%) and 136 keV (11.1%) gamma rays. (medical x-rays can be about 30 – 100 keV) Gamma ray photons have no electrical charge, travel at the speed of light and in a straight line, unless scattered. Able to remove electron from atoms. This process is called ionization.

Cobalt-57 Ionizing Radiation Source Fun Facts Co-57 has a radioactive half-life of 271 days. 10 mCi Co-57 source only contains 1.2 μg of Co-57! 10 mCi Co-57 source emits 370,000,000 gamma rays every second. Annual Limits of Intake (ALI) for Co-57, oral ingestion, is 4 mCi or 8 mCi – depending on chemical compound. Co-57 is made by bombarding Nickel with high energy protons from a linear accelerator or cyclotron.

Loss or Theft Notify the Radiation Safety Office, UVM Police, and RMD Instruments immediately in the case of theft. Notify the Radiation Safety Office immediately in the event the device is lost. The RSO must notify the Vermont Health Dept., Radiological Health Office and possible the Nuclear Regulatory Commission (NRC) in writing within 30- days of loss or theft. (for Co-57; 1 – 99 mCi require written notification within 30 days.)

How to Avoid Loss or Theft Always keep device locked in storage when not in use. When in field, lock the device in a vehicle (preferably the trunk). Do not leave the device unattended when at temporary job sites. Do not loan the device to someone else.

What to do if the Device is Severely Damaged Keep people away Use time, distance, shielding principles Open the analyzers case and position it to receive the broken analyzer or source housing. Use tools, tweezers, tongs, to place analyzer or source housing inside case. Close case and transfer to trunk of car. Use same DOT shipping/transportation procedures. Call the RSO and bring the damaged device to us for further analysis and instruction to return to manufacturer.

Shipping/Transportation Follow DOT 49 CFR , “Excepted packages for radioactive instruments and articles, UN 2911”. Shipping paper must contain the statement “Excepted packages for radioactive instruments and articles”. Device should be secure/tied down to prevent movement while in transport. Shipping paper should be near the driver, either in the divers-side door or within arms reach. Outside of case should contain the word, “Radioactive” and “UN 2911”

Responsibilities of the RSO Maintain the safe use of radioactive materials or x-ray generating devices according to UVM’s radiation safety program, Nuclear Regulatory Commission and the Vermont Dept. of Health, Radiological Safety Office. Inspect radiation use and users for compliance with UVM’s radiation license conditions. Perform and maintain the required 6-month leak test results. Monitor and maintain records concerning individual radiation exposure. Training and reviewing proper operation and emergency procedures.

Responsibilities of Asbestos & Lead Management Program Notify the RSO of any personnel changes. Operate device according to manufacturer guidelines. Keep device secure and safe when in storage and at temporary job sites. Keep a log of XRF device use. Limit accessibility and use to authorized persons only. Wear personal radiation dosimeter when using device. Assure proper packaging and labeling of device for transportation to temporary job sites or when returning to manufacturer for repair or disposal. Notify the RSO for any unusual events (theft, loss) or in an actual or suspected emergency

Typical Radiation Exposures ExampleDose USA Natural Background rem/yr Smoker add to BKG rem/yr Kerala, India BKG 3 rem/yr Chest x-ray (entrance skin exposure) rem Dental x-ray (entrance skin exposure) rem Round trip flight NYC to LA rem Radiation Burns (acute-threshold) 300 rem Lethal Dose to 50% in 60 days 450 rem Dose to hand holding XRF for 1 hour rem

Occupational Radiation Dose Limits Region of the body Occupational Dose Limits Whole Body (deep dose) 5 rem/year Lens of the Eye 15 rem/year Extremities (hands/feet) 50 rem/year Skin (shallow dose) 50 rem/year Public Dose 0.1 rem/year UVM XRF User Estimated dose.002 rem/year.001 rem/year.05 rem/year.002 rem/year.0001 rem/year

Radiation Exposure from Tungsten Encapsulated 10 mCi Co-57 Source Dose to hand of operator holding XRF device rem/hr (166,667 hours to reach annual extremity dose of 50 rem) Dose of bare Tungsten encapsulated Co-57 source less than rem/hr at 1 meter Dose of bare Tungsten encapsulated Co-57 source is about 10 rem/hr at 1 cm Increase distance from 1 cm to 10 cm reduces your dose by a factor of 100! Use remote handling device (i.e. tweezers, tongs) if bare source ever needed to be grabbed.

Reducing Radiation Dose Time, Distance, Shielding Signs and labels Good work practices (dry run, obey SOPs) Personnel monitors (whole body & finger) Area monitors (GM counters)

Important Safety Considerations Device contains a radiation source sealed in tungsten. It is leak tested every 6 months. Only to be used by authorized and trained individuals. Device must be stored under lock and key. Personal monitoring devices must be worn by user. At a temporary job site; Keep locked when not in use Keep instrument with user at all times Operation manual & emergency procedures kept in the device Do not leave locked case at any job site Must follow Federal (DOT) transportation rules

Conclusion This device is designed in such a way that the operator is exposed to a very small amount of radiation but it still contains a significant source of radiation. In an emergency situation use time, distance, shielding Always make certain that the device is under constant surveillance or under lock-and-key. Contact the RSO for any unusual events that occur with this device. Contact the RSO for any questions, concern or for any suspected or actual emergencies.