Presentation on theme: "Radiation Safety Capt. David Ayre CAP, SWR-TX-176"— Presentation transcript:
1Radiation Safety Capt. David Ayre CAP, SWR-TX-176
2RADIATIONThe definition of radiation is the emission (sending out) of waves and/or particles thru space.In the dictionary radiation is defined as “sending out in rays” such as light or heat.“All types of radiation can cause damage to tissue such as burns. Everybody is familiar with sunburn or a burn associated with fire. A burn is simply energy deposited in an area. Some types of radiation cause more damage to issue for the relative amount of energy deposited.This is because some types of radiation have the ability to interact with atoms causing the atoms to give up electrons creating ions. It is these active ions which can cause cell damage.Ionizing radiation is more harmful than non- ionizing.Ionizing radiation will penetrate the skin and affect the body. non-ionizing radiation only affects the surface.
3IONIZING OR NON - IONIZING TYPES OF RADIATION TYPES OF RADIATION heatlightradio wavesx-raysnuclearRadiation can be classified into two different categories ionizing and non-ionizing.Ionizing radiation has the ability to knock off ELECTRONS and these charged particles are called IONS.
4Nuclear RadiationFor the purpose of this course we will use the term radiation to refer only to NUCLEAR RADIATION.Nuclear Radiation causes harm by entering the body and depositing some or all of it’s energy.Since nuclear radiation is ionizing radiation electrons are knocked off creating ions that react with the body tissue.Energy that has the ability to ionize causes more damage that the same amount of non-ionizing energy such as light.One source of radiation is the nuclei of an unstable atom. These radioactive atoms become more stable when the nuclei ejects or emits subatomic particles and/or high-energy photons (gamma rays).
5This Is the Way the Atom Probably Looks Atomic StructureElectronProtonNucleusNeutron
6Atomic Number Atomic number (Z number) is the number of PROTONS in the nucleus of an atom.The atomic number is defined as the number of protons in an atom.The atomic number determines what element the atom is. For example, the atomic number of oxygen is 8 all atoms with eight protons are oxygen.
7Atomic Mass Atomic Mass (A number), is the number of PROTONS plus the number of NEUTRONS in the nucleus of an atom.The atomic mass is defined as the number of neutrons plus the number of protons in an atom.In the case of Oxygen the atomic mass is usually 16. The typical oxygen atom contain eight protons and eight neutrons.
8Mass and Charges of Basic Atomic Particles Proton1 amu+ 1Neutron0 or neutralElectron1/2000 amu- 1Protons have a mass of 1 atomic mass unit or AMU, they have a charge of plus one and are found in the nucleus of the atom.Neutrons are neutral particles with a mass of 1 AMU and act to hold the nucleus together.Electrons have a mass of 1/2000 AMU and a charge of minus 1.
9Atoms with the same atomic number, but different atomic mass. ISOTOPEAtoms with the same atomic number,but different atomic mass.Carbon-14(6P + 8N)Atomic Mass = 14Carbon-12(6P + 6N)Atomic Mass = 12Carbon-13(6P + 7N)Atomic Mass = 136 Protons6 Neutrons7 Neutrons8 NeutronsAtoms with the same atomic number but different atomic mass are called isotopes. Isotopes of an atom react chemically the same however their mass is different.
10IODINE ISOTOPE EXAMPLE Atomic MassAtomic NumberNumber of NeutronsI 1231235370I 12512572I 13113178Iodine 123 is sable form of Iodine.Iodine 125 is radioactive and is use in the medical profession.Iodine 131 is also radioactive and is the most common type of radioactive tracer material used in the oil field.
11Discovery of Radiation Henri Becquerel 1896Ernest RutherfordThe type of ionizing radiation which was first discovered was the X-ray. In 1895 Roentgen discovered something that would pass through glass and cause a zinc sulfide screen to become florescent. He didn’t know what to call these “things” so he called these “rays” X-rays for the Unknown.Then in 1896 Becquerel discovered that some type of radiation from certain materials could fog photographic film. Studies revealed that this was Uranium.Also discovered thorium.The Curies found that certain materials would give off radiation in a amount proportional to the amount of material present.They also discovered a pitch blend ore that gave off more radiation than uranium or thorium.After more research they discovered a new element Radium.Wilhelm Roentgen 1895Marie Curie-To describe the behavior of uranium and thorium she invented the word “radioactivity” --based on the Latin word for ray.
12RUTHERFORD’S EXPERIMENT Photographic PlateUsing radium in a lead shield with a round opening Rutherford Noticed that a round circle would appear on a zinc sulfide screen. Placing a strong magnet near the source three round circles would appear on the screen.Thus proving that there are at least three types of radiation coming from the source one positive, one negative and one neutral.He named these Alpha, Beta, and Gamma Radiation.
13Several Inches of Lead or Steel TYPES OF RADIATIONTypes of RadiationMassChargeStopped ByAlpha4+ 2Thin Sheet of PaperGamma RayNo MassNo ChargeSeveral Inches of Lead or SteelX RayBeta1/2000- 1Thin AluminumNeutron1High Hydrogen ContentAn atom that undergoes spontaneous decay is called Unstable or radioactive.Alpha Decay (an unstable isotope can under go several types of change or what is called decay. Basically there are three types of radiation given off by the decay of an atom. They are Alpha, Beta and Gamma.)Alpha particles consists of two protons and 2 neutrons, has a charge of plus 2 and a mass of 4 AMU. These are relatively large can travel a few inches in air and can be stopped by a thin sheet of paper. When a alpha particle is given off the atoms the atoms atomic number decreases by 2 and atomic mass decreases by 4. For example when Radium 226 gives off an alpha particle it becomes Radon 222.Many times a atom will be in an excited state and possess to much energy. The atom will sometimes give off this energy in the form of Gamma Rays. Gamma Rays are massless packets of pure energy with no charge. Can be stopped with thick lead or steel.Beta particles are particles with the mass and charge of an electron that are emitted from the nucleus of an atom. This can be thought of as a neutron becoming a proton. When a beta particle is given off the atomic number increases by one and the atomic mass stays the same. Beta particles can travel several feet in air and can be stopped by a thin sheet of Aluminum. When Lead 214 gives off a beta particle it becomes Bismuth Some radioactive isotopes go through one decay to reach a stable state while others go through a chain of decays to reach a stable state. On the cover of your workbook is and drawing of Radium 226 decay.NEUTRON REACTION - Often times a alpha particle can react with other atoms to produce neutrons. Neutrons can be stopped by materials that have high hydrogen content. For example in our Neutron Logging Sources Americium 241 gives off an Alpha particle and it reacts with the Beryllium Atoms to produce neutrons.
15INDUSTRIAL USES OF RADIOACTIVE MATERIALS Power PlantsMedicalFarmingRanchingTextileAutoSoda CanMedicalOil Well LoggingMilitaryNuclear power plantsHAVE CLASS NAME A INDUSTRY THAT DOESN’T USE RADIATION!
16CASES OF HIGH OCCUPATIONAL EXPOSURE TO RADIATION Early ScientistsWatch Dial PaintersNuclear Weapons ResearchMilitary PersonnelEmergency/Medical PersonnelSeveral examples are:Early scientists received large doses of radiation while performing experiments resulting in several cancer deaths.The watch dial painters in the 1920’s would moisten there brushes with there tongue and consequently ingested large amounts of Radium resulting in a few hundred deaths from bone cancer.Another case is during the later 1930’s there were deaths due to accidents with particle accelerators.Also during the development of nuclear weapons during the 1940’s there were several deaths due to high exposure to radiation.Also in the early 1950 large shoe stores had fluoroscopes in them.Kids playing with them caused bone cancer to feet and ankles.Fluoroscopes are a X - Ray machine.Now all x - ray machines are licensed just like all radioactive materials.
17COMMON PREFIXES Giga (G) = 1 billion Mega (M) = 1 million kilo (k) = 1 thousandmilli (m) = 1 thousandthmicro (u) = 1 millionthIn the SI System of Measure different prefixes are used to denote multiplies of units or parts of units.Mega = 1 millionKilo = 1 thousandmilli = 1 thousandthmicro = 1 millionthFor example a kilogram is 1 thousand grams, while a milligram is one thousandth of a gram.
18radioactive source and UNITS OF MEASUREMENTCurieA UNIT used to measurethe activity of aradioactive source andequals37,000,000,000disintegration's persecond.The SI UNIT is the_____Becquerel____which is one nucleartransformation orone disintegrationper second.Definition of Curie We measure the activity of a source (or source strength) in Curies, millicuries, or microcuries.One Curie is equal to 37 billion disintegration's per second. (This is the activity of one gram of Ra 226).
19Roentgen A measure of the ionization effect Gamma and X radiation UNITS OF MEASUREMENTRoentgenA measure of theionization effectGammaandX radiationhave in AIR.A measure of the ionizing effect of radiation in air.The amount of radiation that creates E 09 ion pairs in air.
20Roentgen Equivalent Man UNITS OF MEASUREMENTREMA measure of thebiological effectradiation has on man.stands forRoentgen Equivalent ManA measure of the biological effect of the absorbed radiation dose.Millirems are commonly used.
21Material after one Half-Life Material after two Half-Lives The time required for the amount of radioactive material to decrease by one half.Original MaterialMaterial after one Half-LifeMaterial after two Half-Lives
22HALF-LIVES OF VARIOUS ISOTOPES Half-LifeAm 241454 YearsCs 13730 YearsRa 2261602 YearsI 1318 DaysCo 605.2 YearsThe time required for 1/2 of the radioactive atoms to reach a stable state is called HALF-LIVE.When a particular radioactive isotope will decay cannot be predicted.However every radioactive isotope decays at a different rate.Problem: On one June you have 10 millicuries of I - 131, assuming no use of material, how much I would you have on June 17? (I half-life is 8 days)
23Detecting Radiation and the PHOTOGRAPHIC PROCESS FILM BADGESRadiation will expose film just as light will.The greater the dose of radiation the darker the film will become.Film badges are used in the medical profession a lot because usually only trying to measure only one type of radiation. ( X-RAY ).As you know Becquerel discovered that radiation can expose film just as visible light can.This photographic process is used in industrial radiography and medical X - rays, and in some personnel monitoring.For personnel monitoring the badges must be changed monthly since the film can fade with age.Some film badges have various filters to try to determine energy level of the radiation.Film is also sensitive to developing errors.
24THERMOLUMINESCENT DOSIMETER TLD’s use threechips that whenexposed to radiationstore the energy.When the chip isheated it gives offlight proportional tothe radiationabsorbed.LANDAUERJohn DoeNJAN 01, Z1COMMON TLD’S MEASURES BOTH GAMMA AND NEUTRON.THE NEUTRON MONITORING PORTION OF THE BADGE CONSISTS OF TWO PIECES OF PLASTIC.THE FIRST ONE IS SIMPLY A PIECE OF POLYETHYLENE TO SLOW THE NEUTRONS.THE OTHER IS A SPECIALLY TREATED PLASTIC THAT, WHEN EXPOSED TO NEUTRONS LEAVE TRACKS ETCHED INTO THE PLASTIC.TO PROCESS THE BADGE THE CHIP IS READ UNDER A MICROSCOPE AND THE TRACKS ARE COUNTED.TT
25OPTICALLY STIMULATED LUMINESCENCE (OSL) DOSIMETER OSL’s use two thin Al2O3 strips which when exposed to radiation record Photons (X & d Rays) in the 5 keV / 40 MeV range & Beta Particles in the 150 keV / 10 MeV range.During analysis, the Al2O3 is stimulated with selected frequencies of laser light, which cause it to become luminescent in proportion to the amount of radiation exposure received.A third component, for the measurement of Neutrons, is also enclosed. This is a Neutrak 144 Allyl Diglycol carbonate solid state track detector. In this case measurement is made by chemical etching followed by track counting. Energies measured are between 100 keV / 30 MeV.JOHNDOETRAININGluxelLANDAUER®OSL MEASURES BOTH GAMMA AND NEUTRON.THE NEUTRON MONITORING PORTION OF THE BADGE CONSISTS OF TWO PIECES OF PLASTIC.THE FIRST ONE IS SIMPLY A PIECE OF POLYETHYLENE TO SLOW THE NEUTRONS.THE OTHER IS A SPECIALLY TREATED PLASTIC THAT, WHEN EXPOSED TO NEUTRONS LEAVE TRACKS ETCHED INTO THE PLASTIC.TO PROCESS THE BADGE THE CHIP IS READ UNDER A MICROSCOPE AND THE TRACKS ARE COUNTED.FRONT
26OPTICALLY STIMULATED LUMINESCENCE (OSL) DOSIMETER Dose Measurement RangePhoton 1 mREM to 1000 REMBeta Particle 10 mREM to 1000 REMNeutron 20 mREM to 25 REMAccuracyDeep Dose = ±15% at the 95% confidence interval for photons above 20 keVShallow Dose = ±15% at the 95% confidence interval for photons above 20 keV and beta particles above 200 keVTWhole Body (chest)A2TLD’S USED BY HALLIBURTON MEASURES BOTH GAMMA AND NEUTRON.THE NEUTRON MONITORING PORTION OF THE BADGE CONSISTS OF TWO PIECES OF PLASTIC.THE FIRST ONE IS SIMPLY A PIECE OF POLYETHYLENE TO SLOW THE NEUTRONS.THE OTHER IS A SPECIALLY TREATED PLASTIC THAT, WHEN EXPOSED TO NEUTRONS LEAVE TRACKS ETCHED INTO THE PLASTIC.TO PROCESS THE BADGE THE CHIP IS READ UNDER A MICROSCOPE AND THE TRACKS ARE COUNTED.BACK
27OPTICALLY STIMULATED LUMINESCENCE (OSL) DOSIMETER JohnDoeTRAININGluxelLANDAUER®The OSL is the principle deviceused to measure radiationexposure personnel.The OSL will only measure whatyour body will receive and does not“protect” from radiation.A OSL will simply measure whatyou have been exposed to and willallow us to determine if you havereceived to much radiation.
28Radiation Quality is an indication of the type of radiation received RADIATION MONITORINGRadiation Quality is an indicationof the type of radiation receivedRadiation Quality Type of Radiation ReceivedP Gamma OnlyCPN Combination Gamma and NeutronNF Fast NeutronM Minimal (Less than 1.0 mR)If you lose your badge during the quarter you should immediately notify your supervisor so a replacement badge can be issued.Exposure records must be retained for a period of thirty years after termination of employment.Employees who leave the company may and should request there radiation exposure from the HSE department.This request must be in writing and come from the emplyee not his new employer.Whenever an employee transfers a new TLD service card should be completed and listing his new location and forwarded to the HSE Department. Then the employees TLD service will be transferred to his new location.Up until Jan. 1, 1994 if a TLD was not returned the company used to add a maxium exposure of one quarter to your report. (1250mR).Since then now a extensive investigation into your radiation exposure during the applicable quarter is done and a best guess exposure is added to your exposure records. Will look at TLD’s of the people working with you during the time the TLD was lost.Show old Landauer Report.You should intial the report after veiwing it.
29MAXIMUM PERMISSIBLE EXPOSURES 5 REM per YearLifetime Dose – ( Age - 18 ) * 5 REMRecommended exposure while pregnant500 mREMAverage exposure for WirelineLogging & Perforating PersonnelmREM per QuarterThe maximum permissible exposure permitted while pregnat is no different than any other employee according to the regulations. However the National Council on Radiation Protection Recommends that a pregnant employee receive a maximum occupational dose of radiation less than 500 millirems for the entire term of pregnancy.The average exposures for L & P employees is low. The group with the highest exposure are open hole crews.Their average is in the millirem/quarter range.If your actual reading is greater than about 300 mR you may need to look at your procedures and see if there is anything that you can to reduce your exposure.The average Halliburton exposure is lower than the industry average for well loggers.
30Detecting Radiation and the ENCLOSED GAS VOLUME PROCESS Electrical Current Measuring DeviceAnode +Cathode -+-Voltage SourceInert GasIncident Ionizing RadiationTypes of equipment that use an enclosed gas are GM probes (Geiger counter), ionization chambers, and proportional counters.The survey meters Halliburton uses are both Enclosed Gas Volume process of detecting radiation.Geiger-Mueller CountersAn enclosed tube has an anode and a cathode and usually an inert gas inside the tube. The radiation enters the tube ionizing the gas thus creating a current flow. The amount of radiation is proportional to the current flow.
31Detecting Radiation and the SCINTILLATION CRYSTAL PROCESS Optical CouplingGreaseScintillating CrystalPreampHighVoltageDynodesPhoto-CathodeGlassVacuum Tubee- ElectronsP PhotonsGamma RayPhoto-MultiplierTubeWhen radiation strikes a special crystal, light is emitted and the light is converted to electrical energy.Approx. five times more sensitive than the GM probe.Type of detection used in most Gamma Ray Tools.Also used are liquid scintillation “cocktails” for detecting low level beta particles and leak testing.
32Detecting Radiation and the Direct-Read Pocket Dosimeter Milliroentgens50100150200EYEPIECEDLENSCB+-DIRECT - READING POCKET DOSIMETERA. Charging RodB. Metal Support for FibersC. Movable Fine Metal CoatedQuartz FiberD. Transparent ScaleAnother deceive used to measure exposure to radiation is the direct reading pocket dosimeter.The pocket dosimeters that most L & P PSL districts have usually only measure Gamma and X-rays.However also available are neutron and thermal neutron dosimeters.Not really needed, because all of the tracers material Halliburton uses are Gamma emitters, so therefore have no need for neutron dosimeters.Gives a direct reading of exposure by discharging a filament.Dosimeter can be charged in the shop using a charger.It recommended , but not required that a direct reading dosimeter be worn on tracer jobs or when unusual activities will cause you to receive potential high exposure. Such as performing leak tests.
33VICTOREEN MODEL 493The most commonly used survey maters are Ludlum model 2 or Victoreen 493.Both measure radiation from 0 up to 50 mr/hr.All must be calibrated in intervals not to exceed six months.The the current calibration sticker must be attached to the meter.The calibration is done by local personnel in the district if have own calibration source. Most now use outside vendors to perform the calibrations.Remember to follow these steps when using a survey meter.In addition to the multiple range witch positions a battery check position should be checked every time the meter is used.Check for current calibration sticker.Starting well back of the source switch to the most sensitive scale. The exposure rate would be the meter reading times the range setting.Slowly approach the item being surveyed while monitoring the meter.If the meter reaches full scale switch to the next higher scale.You may use the reset button ( if available ) to re - zero the meter to eliminate the time delay in taking a reading.Make and record the required reading and record the meter serial number used for surveying.
34Ludlum Model 2The exposure rate would be the meter reading times the range settingAlways go to battery check position to insure the batteries are good.HV Switch You can use the reset button to re-zero the meter to eliminate the time delay in taking a reading.Audio Switch Off and On This meter has a audio which can be used to give a warning to people in the area.It is a good practice to use a meter with audio while calibrating tools to give a warning to people in the area.Switch F and S Is available to slow the response to eliminate some of the statistical response.
35What exposure rate is this meter reading? X 1 _______mREM/hourX 10 _______mREM/hourX 100_______mREM/hourX ______mREM/hourX ______mREM/hourX ______mREM/hourThe exposure rate would be the meter reading times the range settingThe Victoreen 493 reads.25 mR/h2.5 mR/h25.0 mR/hThe Ludlum model 2 reads
36OCCUPATIONAL DOSE RATES _____ mREM/hour100 mREM/year(General Public)500 mREM/year(If Attended Awareness Training)5 REM/yearThe second chapter is mainly concerned with heath effects of radiation exposure.First lets look at the occupational dose rate, or the amount of radiation we can receive working with radiation.This also will give us something to compare background exposure we receive from living on the planet earth.
37BACKGROUND RADIATION DOSE SourceRadiation ReceivedRadon Gas200 mREM/yearDaughter Products28 mREM/yearFood & Water40 mREM/yearCosmic RaysMedical Radiation53 mREM/yearT.V. Consumer Products7 mREM/yearTOTAL 356 mREM/yearAll people are continuously exposed to ionizing radiation from natural background sources.Gamma and X-rays from outer space.Radioactive isotopes are present in the soil and sometimes find their way in the food chain.Also, radon from the decay of radium, exposes us to background radiation.From background sources the average individual receives the following amounts of radiation.This total represents an average exposure for all people.The medical is the total medical exposure divided by the total number of people in the US.The cosmic exposure will increase depending on altitude and latitude.For example you would receive more radiation for cosmic rays in Denver than you would in Miami.This figure is a higher than previously thought due to the addition of the Radon Hazard.
38RADIATION DOSES FROM OTHER SOURCES SOURCE EXPOSUREOne Hour of Jet Flight at 37,000 Feet mREM/hourChest X-Ray or Dental Exam mREM/hourDose to Unborn Child Due to Background mREM/hourPelvic Exam mREM/hourLower GI Series mREM/hourAreas of High Background Up to 5000 mREM/yearFrom other sources you would receive the following potential exposures:The areas of high background are several areas in the world where there are high concentrations of naturally occurring radioactive materials in the soil certain areas in Brazil and India are such areas.
39Biological Effects Due to Exposure Can Be Divided Into Two Groups EARLY EFFECTS LATE EFFECTS(ACUTE) (DELAYED)Blood Count Changes Genetic DamageVomiting Increased Cancer RiskNausea Shortened Life SpanDeathUnfortunately there is not much known about the effects of long term exposure to low levels of radiation.Most of the studies use survivors of the atomic weapons blasts in Japan and then extrapolate the data back to the low level exposure.Biological effects due to exposure can be divided into two groups, early or acute and late or delayed.Early EffectsEarly effects are effects that can be observed within several weeks of the initial exposure. They include changes in blood counts, vomiting, nausea, and possibly even death. These effects usually observed in case of high exposure in a relatively short period of time. Usually at levels greater than 30 REMS in less than one week.Late EffectsLate or delayed effects are not observed often times for years after the exposure. This includes an increase in the rate of cancers, shortened life span, and genetic defects. The difficulty come in determining whether these are radiation effects or effects due to other sources. Example, if a person develops leukemia it is impossible to determine if this was caused by radiation exposure or a different cause. Another problem is that industrial exposure to radiation is a relatively new health risk and there hasn’t been enough of time lapse to allow all the data to be collected.
40Some Acute Effects of High Exposure Over a Short Period Are DOSE (1 week) EFFECT (30 days)REM Detectable changes in blood countsREM Nausea and vomiting within 24 hoursREM Death may occur350 REM % will Die within 30 daysREM Death will probably occurover 600 REM % will die within 30 daysGive example that up to 30 REMs medical science can not measure a effect on the human body.Give example of 50% rule. Which one dies depends on the physiological make up of both people at the time of exposure. If one person had a cold he would be the one who dies.The average exposure for fireman fighting the nuclear power plant that blew up in Russia was 1650 REMS to whole body. Where all ready dead and didn’t know it.
41Estimated Loss of Life Expectancy From Health Risks HEALTH ESTIMATES OF DAYS OFRISK LIFE EXPECTANCYLOST, AVERAGESmoking (6.5 years)Cigarettes/DayOVERWEIGHT (1.2 years)(by 20 %)The effect of low level exposure to radiation can be compared to other everyday risks we all take and accept, these risks can include driving a car, smoking, drinking and accidents at the home.When comparing these risks the average number of days shortened from your life span is often used.Here is a chart comparing various conditions.Occupational exposure to radiation shortens the average life span by 40 days.This is less than consuming alcohol, car accidents.Some conditions can actually increase your life expectancy such as air bags or the use of a smoke detector.
42RISK CHART CONTINUED AUTO ACCIDENTS 200 DAYS ALCOHOL CONSUMPTION Auto Accidents 200 day reduction in life expectancy.This is the biggest risk all of us face each day.Alcohol Consumption130 days reduction in life span.
43RISK CHART CONTINUED HOME ACCIDENTS 95 DAYS DROWNINGS’ 41 DAYS
44RADIATION (Calculated) RISK CHART CONTINUEDSAFEST JOBS(SUCH AS ………………..)30 DAYSNATURALBACKGROUNDRADIATION (Calculated)8 DAYSEven the safest jobs like teaching has a risk with it! The risk of teaching is a 30 day reduction in life span.By living on the planet earth you have the risk of 8 day reduction in life span from natural background radiation.
45RISK CHART CONTINUED 1 REM Occupational Radiation Dose Calculated (Industry Average Is 0.34 REM/year)1 DAY1 REM/year for 30 Years, Calculated30 DAYS5 REM/year for 30 years, Calculated150 DAYSThese estimates indicate that the health risk from occupational radiation exposure are not greater than risk associated with many other events or activities we encounter in normal day-to-day activities.SHOW OTHER RISK CHART ABOUT WORKING IN A HIGH-RISK OCCUPATIONS IF WANT TO.
46Everyday Items Containing Radioactive Materials Scale Found on Oil Field PipeBrazil NutsSmoke DetectorsLantern MantlesSome CeramicsSalt SubstitutesCertain everyday items contain radioactive materials.Smoke DetectorsLantern Mantles (Use Survey Meter in class and put a lantern mantle on probe to with audio on so class can he the different from background and lantern mantle.)Some CeramicsSalt SubstitutesBrazil NutsSome scale found on oil field pipe.
47AS LOW AS REASONABLY ACHIEVABLE ALARA PRINCIPLEALARAstands forAS LOW AS REASONABLY ACHIEVABLEAlara stands for as low as reasonable achievable.Halliburton subscribes to this ALARA principle.It means that employers are committed to maintain radiation exposure for its employees as low as achievable even if they are currently well below the maximum permissible exposures.Part of the ALARA principle states that we should receive no exposure if we gain no benefit from that exposure.
48REDUCING YOUR EXPOSURE The three most important safety rules to remember while working with radiation areTimeDistanceShieldingWhile most Halliburton exposures are well below limits set by the NRC or the state you still need to keep exposure as low as possible since there is still relatively little known about the long term effects of low level exposure to radiation.There are three different concepts you should utilize to reduce your exposure to radiation.This is probably the three most important concepts in Radiation Safety.The three concepts are Time, Distance, and Shielding.
49The Effect of Time on Radiation Exposure EXPOSURE = DOSE RATE X TIMEFor Example: 495 mREM per hour1 HOUR = 495 mREM2 HOURS = 990 mREM3 HOURS = 1485 mREM
50The Effect of Distance on Radiation Exposure The Equation for CalculatingRadiation Exposure as aFunction of Distance:I 1 x ( D1 ) 2 = I 2 x ( D 2 ) 2ORI 2 = I 1 x ( D 1 ) 2( D 2 ) 2I1 x (D1)2 = I2 x (D2)2ExampleI1 = Intensity at point one equals 100 mR per hourD1 = Distance at point one equals one footI2 = Intensity at point two ( The Unknow)D2 = New distance of three feet OR100 mR x (1)2 = I2 x (3) I I1 x ( D1)2100 mR x 1 = I2 x (D2)2100 mR = 9 I x (1) mR I (3)211.11 mR = II mR per hour
51Using some material as a shield to reduce the radiation exposure. SHIELDINGGAMMA RAYSDEFINITIONOFSHIELDINGUsing some material as a shield to reduce the radiation exposure.The third concept that is stressed in radiation protection is shielding. Simply stated shielding is using some material as a shield to reduce the radiation exposure. The effectiveness of a depends on several things. They are the type of radiation and the energy level. (GAMMA, NEUTRONS, ETC.), the type of shielding material being used and the thickness of the material. Depending on the type of radiation different materials are used for shielding.To effectively shield gamma an X rays dense materials are used commonly lead or steel are used. The shielding material used in L & P operations for density source transport shields contain lead.To effectively shield neutrons materials which have high hydrogen contents are often used. Materials such as plastic, paraffin or water are used. The shield used for L & P Operations neutron sources are filled with a WATER EXTENDED POLYMER.SHIELD
52SHIELDING MATERIALS ALPHA PAPER SKIN SEVERAL INCHES OF AIR GAMMA LEAD STEEL GOLDBETA TIN THIN DEPLETEDALUMINUM URANIUMNEUTRONS WATER WAX PARAFFINShielding alpha particles can be accomplished by using a sheet of paper or just several inches of air. While shielding alpha particles is rather a simple task alpha particles still can cause damage. Alpha particles because of their relatively large size have a very strong potential to ionize. Radiation causes damage by ionizing atoms in the body. While alpha particles usually don’t penetrate the skin they represent little hazard from external exposure. However sources of alpha radiation can cause a large amount of damage if they are taken in to the body. This can happen if we breathe dust which contain alpha emitting nuclides. This is a hazard associated with the uranium mining industry.Beta particles are shielded by thin aluminum or tin. Typically beta particle will not penetrate deeply in to a human. However exposures to large sources of Beta emitting nuclides result in burns to the skin, referred to as beta burns. Source transport shields are constructed form the appropriate shielding material for the source which the shield was designed to hold. As a result one must always use the correct source/ shield combination.NEVER USE A DENSITY SHIELD WITH A NEUTRON SOURCE AND VICE - VERSA.