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3 Training Goals Basic Radiation Safety Principles Familiarization with RegulationsPurdue’s Policies and Procedures
4 What is radioactivity? Radioactivity is an energy This energy is produced when an unstable nucleus spontaneously emits particles and/or electromagnetic radiationRadioactive material sourcesSources are characterized as either sealed or unsealed (or “open”)To qualify as a “sealed” source, the source must pass a battery of stress tests and be certified under NRC regulations
5 Definition Sealed Source Means any byproduct material that is encased in a capsule designed to prevent leakage or escape of the byproduct material (USNRC Regulations 10CFR30.4)
7 Ionizing Radiation Types AlphaMolecularly large particle (2 protons and 2 neutrons), give up their energy in a short distance (approximately 1 ½ inches in air)BetaSmaller particle (electron), distance traveled ranges from several inches to a few feet (depending on its energy)GammaNon-particulate energy wave, can travel several feet and easily penetrates material with low atomic massNeutronNeutral particle, can travel greater distances than gamma radiation and easily penetrate material with low hydrogen ion concentrations
8 Risks of Radiation Exposure An average person in the United States receives annual radiation dose of ~620 mrem, which includes exposure received from cosmic and natural radiation, medical treatment, and consumer products.Large doses of radiation have been known to increase risk of cancer, birth defects, and possibly genetic effects.Low doses seem to show no statistical differences in biological risk; however, some people believe there is risk at all levels above background exposure.At radiation levels around 1 rem, it has been estimated that the increased incidence of cancer is 0.03% - the normal incidence of cancer for the average person is 25%.Risk of developing genetic effects is half the risk of cancer.
9 4 Factors to Reduce Exposure Contamination Controlgloves, lab coats, fume hoods, absorbent paperTimedo dry run, practice procedure to minimize timeDistancea little distance between you and a source can significantly decrease your exposure from it (follows the “Inverse-Square Law”)ShieldingUse proper shielding between you and a source to decrease personal exposurebetas - wood, Plexiglas (do NOT use lead)gammas - lead, leaded glass
10 Click here for a sample calculation Inverse Square LawPoint SourcesThe intensity of radiation decreases as the inverse square of the distance.Doubling distance, exposure = ¼ of original; Tripling distance, exposure = 1/9 of original.21I1d= I2dClick here for a sample calculation
13 Ionizing Radiation Shielding Different shields are needed to minimize external exposure
14 Rules Governing Use of Radionuclides Radioactive material use must be licensed by the United States Nuclear Regulatory Commission (USNRC) or state agency. In Indiana, the USNRC is the regulating body.Radiation Safety Officer (RSO) develops and maintains a Radiation Safety Manual, which must be followed by individuals working under the NRC license, and it is enforceable by lawPurdue University’s Radiation Safety Committee (RSC) also oversees and governs the radiation safety program.
15 Regulations10CFR19Rights and responsibilities of radioactive material licensees are outlined.10CFR20Standards for protection against radiation: this discusses issues such as procedures and regulatory limitsDeclared pregnant workerSecurity of radioactive materials
16 10CFR Part 19 Instruction to workers Rightsto be informed of storage, transfer, and use of radioactive materialsto further instruction on health protection problems associated with radiation exposure and procedures to minimize exposureto receive radiation exposure historyto request an NRC inspectionto be instructed in and required to observe applicable provisions of NRC regulations and licensesto be instructed in the appropriate response to warnings
17 NRC Policy StatementRetaliation against employees or students engaged in protected activities, whether they have raised safety concerns within the University or to the NRC, will not be toleratedProblems should be addressed within the existing University hierarchy – contact the radiation safety office if you have any concerns regarding issues involving radioactive materials.
18 10CFR20 Occupational dose limits Surveys and monitoring Precautionary proceduresWaste disposalRecords of surveysEnforcementStorage and control of licensed material
19 10CFR20 Occupational Dose Limits TargetDose LimitWhole Body5 rem/yrOrgan or Tissue50 rem/yrSkin or ExtremitiesLens of Eye15 rem/yrMinor (i.e. non-adult)10% of adult limitsDeclared Pregnant Worker0.5 rem per 9-month gestation periodAll dose limits include exposure from both internal and external sources.
20 Regulatory Guide 8.13 Prenatal Exposure If a worker wishes to declare her pregnancy, she must declare it in writing to the Radiation Safety Officer.A declaration of pregnancy is entirely voluntary, and can be withdrawn at any time – no reason needs to be given.For a worker wishing to declare her pregnancy, she should contact REM for Declared Pregnant Worker Training, which covers important information, and provides her the declaration form she needs in order to declare her pregnancy. REM will also provide a fetal dosimeter at the time of declaration, assuming that it is warranted by the type of radiation that has the potential for exposure to the worker.The dose limits will be reduced from 5 rem per year to the worker, to 0.5 rem to the fetus for the 9-month gestation period (this is for both external and internal exposure)
21 Radiation Units Exposure= ability of photons to ionize air Roentgen (milliroentgen, mR)Geiger-Mueller readingsAbsorbed Dose= energy deposited in matterRad (millirad, mrad)Dose Equivalent= biological weighted absorbed dose (tissue)rem (millirem, mrem)these units are what film badge (dosimetry) results are reported
22 Acute Effects of Radiation Exposure Non-stochastic:Until a minimum exposure level is reached, there is no biological effect.Once that minimum exposure level is exceeded, the biological effect grows proportionally with the exposure.The Lethal Dose to 50% of the population (LD50) is about 600 radExamples of biological response (effects) from radiationerythema (skin reddening)blood changes (marrow depression is seen at approximately 200 rad)Gastrointestinal Syndrome (severe vomiting, diarrhea) – happens at approximately 1000 rad, and death is a likely outcome.
23 Delayed Effects of Radiation Exposure Stochastic (occur by chance, statistical basis)No threshold, but as the dose increases, the probability of the effect also increasesExamples of stochastic effects: may be seen 5 to 20 years after the exposureCancerLeukemiaCataractsLife ShorteningData extrapolated from high dose data (early radiology, Hiroshima/Nagasaki bombing, Chernobyl nuclear plant fire)
24 Risk AnalysisHigh doses - there is a correlation between dose and effectLow doses (<10 rem) - it is unclear what the risk is at this leveldifficulty performing long-term studies on effected people, while eliminating other factors (e.g. did the radiation worker get cancer from her work, or that she smoked cigarettes, or that she was genetically programmed that way)Hormesis – this is a theory that low doses of radiation may actually be beneficial
25 SurveysYou can use Geiger-Mueller Survey instrument for detection of higher-energy beta and gamma sources.REM will be conducting “leak tests” on sealed sources to evaluate whether the source containment is intactthis will be done at timely intervals.Survey work areas, floors around work areas and any doors, lab coat, hands, shoes, if it is felt that the source integrity has been compromised (e.g. dropped, smashed, had acid spilled on it)Record survey results, maintain records for 3 years
26 Security NRC Area of Emphasis Secure laboratories when unoccupied (if this is not feasible, secure the radioactive material)Challenge visitors or unauthorized individualsREM accounts for RAM through inventory recordsAssume only you are approved for the type of materials you are using. If another group wants to borrow them, you must ALWAYS check with the radiation safety office before relinquishing control of the material.
27 Emergency Procedures Call 911 Assist personnel if injured Monitor personnel if contamination is suspectedControl area - inform other personnel of the situation and advise them not to enterNotify radiation safety office, once emergency personnel are en route
28 Severe Personal Injury Medical needs come first! Postpone monitoring, call 911, notify of radioactive material useWait for medical personnel - calmly advise radioactive materials may be involvedTrained radiation worker may need to accompany patient to treatment center.Notify REM
29 Review Always use ALARA No eating, drinking, or smoking in labs Always secure materials, lock doorsNever allow unauthorized users access to radioactive materialsCall REM for any related questions ( )All Emergencies – call 911
30 REM’s Radiation Safety Group James F. Schweitzer, Ph.DRadiation Safety OfficerZachariah C. TribbettHealth PhysicistSharon K. RudolphIsotope Ordering & DistributionJerry J. GibbsWaste Handling & Meter CalibrationMike NicholsonWaste Handling & Animal Hospital SupportREM Main OfficeCivil Engineering Building, Room B173Section 1
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