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Radiation Safety Refresher for Radiation Producing Machine (xrd) Safety Conrad Sherman x9-3911 RSO/Health Physicist Marcus Balanky x9-5167 ARSO/ Health Physicist Vern Ares x9-5167 Assistant Health Physicist Environmental Health & Safety Radiation Safety
Annual Refresher Training is Required • Option 1 –Challenge the test • Option 2 – review this presentation, radiation safety manual, rpm fundamentals workbook (ucsc radiation) • Option 3 –request a class then • Pass the Test • Test is on e-commons • Please complete within 30 days of your last test date (if you don’t know it, then look on e-commons, in your PI’s radiation safety folder/training is a report showing training for all users within your lab group. Location of EHS/Radiation published materials http://ehs.ucsc.edu/lab_research_safety/xray_safety.php
Purpose of This Class • Annual x-ray XRD RPM users at UCSC • Fulfill regulatory requirements • Campus and UC Policy
X-ray Diffraction Safety Training Slides modified from a class offered by John Pickering SJSU Radiation safety Officer
What are x-rays? • X-rays are photons (electromagnetic radiation) which originate in the energy shells of an atom, as opposed to gamma rays, which are produced in the nucleus of an atom.
What are x-rays? • X-rays are produced when accelerated electrons interact with a target, usually a metal absorber, or with a crystalline structure. This method of x-ray production is known as bremsstrahlung. • The bremsstrahlung produced is proportional to the square of the energy of the accelerated electrons used to produce it, and is also proportional to the atomic number (Z) of the target (absorber).
Photon Energy and Total Power As the voltage increases the penetration increases As the Current increases the dose rate increases The total power P = V x I
What are x-rays? • Many different types of machines produce x-rays, either intentionally or inadvertently. Some devices that can produce x-rays are x-ray diffractometers, electron microscopes, and x-ray photoelectron spectrometers. • X-rays can also be produced by the attenuation of beta particles emitted from radionuclides.
How X-rays are Produced When fast-moving electrons slam into a metal object, x-rays are produced. The kinetic energy of the electron is transformed into electromagnetic energy. X-ray Tube
Radiation Sources • X-ray diffraction is a source of very intense radiation. • The primary beam can deliver as much as 400,000 R/minute • Collimated and filtered beams can produce about 5,000 to 50,000 R/minute • Diffracted beams can be as high as 1 R/minute
At HIGH Doses, We KNOW Radiation Causes Harm • High Dose effects seen in: • Radium dial painters • Early radiologists • Atomic bomb survivors • Populations near Chernobyl • Medical treatments • Criticality Accidents • In addition to radiation sickness, increased cancer rates were also evident from high level exposures.
Ionizing Radiation Produces damage through ionization and excitation
Bioeffects • Somatic (body) effects of whole body irradiation can be divided into "prompt" effects and "delayed" effects. • Prompt – effects that appear quickly • Delayed – effects that may take years to appear Prompt Diagnostic X-ray Exposure Delayed
Genetic Effects • Somatic • Damage to genetic material in the cell • May cause cell to become a cancer cell • Probability is very low at occupational doses • Heritable • Passed on to offspring • Observed in some animal studiesbut not human
Biological Effects of Radiation • are dependent upon: • Total energy deposited • Distribution of deposited energy Low dose, low-dose rate radiation exposure. The effects are in great dispute. It is thought that the effects of a protracted dose of radiation are not as great as with an acute dose because of biological repair mechanisms.
Prenatal Radiation Exposure • Sensitivity of the unborn • Rapidly dividing cells are radiosensitive • Potential effects • Low birth weight - (most common) • Mental retardation • Chance of childhood cancer
Bioeffects- X-rays and Skin • Most radiation overexposures from analytical x-ray equipment are to the extremities. • For x-rays of about 5-30 keV, irradiation of the fingers or hands does not result in significant damage to blood-forming tissue. • At high exposures some general somatic effects to the skin can occur. Very high exposures may necessitate skin grafting or amputation of the affected extremity. • Biological effects can be observed at 10 rem in special blood studies. Typically effects are visually observed at 50 to 100 rem.
X-Ray Burns vs. Thermal Burns • Most nerve endings are near the surface of the skin • High energy x-rays penetrate the outer layer of the skin that contains most of the nerve endings so one does not feel an X-Ray burn until the damage has been done • X-rays penetrate to the deeper, basal skin layer, damaging or killing the rapidly dividing germinal cells, that are destined to replace the outer layers
Accident Case Study • 3 days after exposure • Note erythema and swelling • 1 month after • Note blistering and erythema • 2 months after • Case Study - A radiation accident at an industrial accelerator facility • 3MV accelerator. 40 rad/s inside victim’s shoes, 1300 rad/s to hands.
ALARA As Low As Reasonably Achievable
Documenting Surveys • surveys must be documented • Record the following: • date performed • area(s) surveyed (a map helps!) • results • identity of surveyor • instrument used • action taken if problem is found
Engineering Controls • Interlocks – never bypass interlocks or other safety devices • Warning Lights – know the beam status whenever working with XRD • Shielding • Locked doors
Failsafe Equipment • Getting better • High reliability • Still see reports of failures • Always use survey meter
Precautions • If you rely on an interlock to turn off the beam for the purposes of accessing the sample area, you must confirm the beam is off using a calibrated survey meter before your put your hand in the cabinet enclosure.
Interlock as on-off switch • Never
Key Control • Who has keys • Special alignment bypass keys • Never Left Out, always locked in case/cabinet • Only PI and Lab Manager hold access to bypass keys
Access • You are required to secure access to your RPMs. • Rooms where RPMs are present must be kept locked if the machine is left unattended. • If your RPM is equipped with a key interlock then the key must be removed when the machine is not being used.
New MachineMoving Machine?Decommissioning? • Call RSO
Problems with equipment • If there are any questions or concerns about the functioning of an XRD unit, it must be taken out of service immediately and reported to the unit supervisor. [Be aware that shutter mechanisms can fail. Warning lights can fail.]
General Methods of Protection • Time • Distance • Shielding
Verify you have viewed this powerpoint • Logon to ecommons RAD SAF Exams and take 2011 RPM XRD Refresher
Test • To receive credit for this online training course, you must complete the exam and receive a score of 80% or greater. • You may take test up to 3 times • Some questions have multiple correct answers • You can review answers at end of each test • Each test is a new set of questions randomized from test bank • If you do not pass, we will go over failed questions with you
Test Completion • Online e-commons RADSAFE EXAMS • PAPER PRINT A COPY OF TEST, • Send to ehs trailer
Verify you have viewed this powerpoint • Logon to ecommons RAD SAF Exams and take 2011 rpm machine user Refresher quiz e-commons portal(https://ecommons.ucsc.edu/xsl-portal)
We’re there for you. Environmental Health & Safety x9-2553 • Conrad Sherman x9-3911 • RSO/Health Physicist • Marcus Balanky x9-5167 • ARSO/ Health Physicist • Vern Ares x9-5167 • Assistant Health Physicist • Environmental Health & Safety • Radiation Safety • (831) 459-3911 Web sitehttp://www.ehs.ucsc.edu/