Radiation Physics Flashcards
radiation comes in the form of?
high speed particulate or energy travelling in electromagnetic waves
The main difference between forms of electromagnetic energy is their?
frequency and wavelength
The primary parts of an atom are?
Proton (p): • located in the nucleus of an atom • heavy • positively charged (+1) Neutron (n): • located in the nucleus of an atom • heavy • no electric charge Electron (e): • located in orbit (shells) around the nucleus • light • negative charge (-1)
Electron shells are lettered?
K to Q
The change of binding energy based on the the distance the orbiting electrons are to the nucleus is ?
Coulomb’s Law
total number of protons in a nucleus is known as?
Atomic Number (Z)
total number of neutrons and protons in a nucleus is known as?
Atomic Weight/Mass number (A)
To determine the number of neutrons in a nucleus you ?
Take the Atomic Weight/Mass Number (A) and subtract it by the Atomic Number (Z). N= A-Z
Isotopes are?
Atoms of the same element and chemical characteristics but with different mass numbers
Why are some isotopes unstable?
They have too many or too few neutrons
Isotopes do what to stabilize the number of Protons and Neutrons?
Emit Alpha or Beta particles
capture orbital electrons
emit gamma radiation
What does X radiation come from
X-rays result from the transfer of energy between the high speed interaction of electrons and a dense target material
What does gamma radiation come from?
emitted from the unstable atom and cannot be controlled.
What are the 3 ways artificial isotopes are made?
Neutron activation
Fission product separation
Charged particle production
What is an Ion?
any atom or molecule which has a resultant electric
charge due to loss or gain of valence electrons (electrons that orbit near the outer shell of the atom)
What is the 4th state of matter
Plasma- When Gases are almost completely ionized
What is an ion pair?
Formed from a neutral atom or molecule by the action of radiation, or any other agency that supplies energy. Consist of a positive and negative ion charged to the same magnitude
What is ionization?
process of adding electrons to, or removing electrons from, atoms or molecules.
Ionizing action of Xrays produce what effects?
Biological effects
Chemical effects
Cause certain materials to fluoresce
Ionizes gases and conducts electricity
Some important properties of X-radiation and Gamma radiation are?
Travels in straight lines Not affected by electrical or magnetic fields Can't be focused Will affect photo emulsions Damage or kill living cells Can't be detected by human senses
What is Radioactivity?
The emission of radiation from an unstable atom
What is an Alpha Particle?
Large and slow particle can't penetrate a dead layer of skin harmful if ingested or inhaled stopped by thin sheet of paper Most ionizing, least penetrating
What is a Beta Particle?
comes from decay of either proton or neutron
Light with high velocity
will travel several 100’s of centimetres
can absorbed by a few millimetres of aluminum, a layer of clothing or 1 cm of skin
What is Neutron Radiation
particle radiation with the same mass as a proton but no electrical charge
most efficient shielding is water or other hydrogenous material, NOT LEAD
Used for Neutron Radiography
What is Gamma Radiation?
Electromagnetic Radiation with very high energy
Can travel up 100 meters in air or more
highly penetrating and ionizing
What are the 3 common Industrial Isotopes?
Iridium-192
Cobalt-60
Selenium-75
How does cobalt-59 and iridium-191 become radioactive?
They are put in a reactor and bombarded with fissioned neutrons until one is captured creating cobalt-60 and Iridium-192
What is Radioactivity measured in?
CGS: Curie Ci 3.7x10^10 disintegrations per second
SI: Becquerel Bq 1Bq= 1 disintegrations per second
What is specific activity?
measure of concentration of radioactive material
CGS: Curie(Ci) per gram SI:Becquerels(Bq) per gram
Small the source—> the sharper the image
small the source—> less self absorption within the isotope
What is characteristic activity?
Amount of Radioactivity measured at 1 metre
CGS: Sieverts per hour @ 1 metre
SI: Roentgen per hour @ 1 metre
What are the 3 main Isotopes used and what are their Characteristic Intensities
Selenium-75 CGS: 200mR/hr@1m SI: 0.05mSv/hr@1m
Iridium-192 CGS: 550mR/hr@1m SI: 0.15mSv/hr@1m
Cobalt-60 CGS: 1350mR/hr@1m SI: 0.36mSv/hr@1m
What is the equation for Intensity?
Intensity = Source Activity x Characteristic Intensity
What does RAD stand for and what are the Units?
Radiation Absorbed Dose
CGS: RAD SI: Gray(Gy)
1Gray = 100 RADS
What is Quality Factor?
Effects on tissue based on the type of radiation(QF)
formally relative biological effectiveness (RBE)
XRays, Gamma Rays, electrons, Beta particles: 1
Neutrons less energy than 10KeV : 3
Neutrons more energy than 10KeV: 10
Protons : 5
Alpha Particles : 20
Fission fragments, Recoil Nuclei : 20
What is Dose Equivalent?
CGS: Roentgen Equivalant Man (REM)
SI: Sievert
Dose Equivalent = Radiation x the quality factor
CGS: REM = RAD x QF
SI: Sievert = Gray x QF
What is Half-Life?
Time taken by a specific Isotope for the activity to decay by one half level
What are the 3 main Isotopes and their half-life?
Iridium-192 is 74 days
Cobalt-60 is 5.3 years
Selenium-74 is 120 days
What is the equation for Half life?
A2= A2/ 2^n A2= new activity A1= original activity n= number of half-lives
What are the 5 types of radiation monitoring devices
Survey Meter Direct Reading Dosimeter (DRD) Thermoluminescent Dosimeter (TLD) Optically Stimulated Luminescence Dosimeter (OSL) Alarming Dosimeter
What is radiation intensity/dose rate
energy which is absorbed by any matter placed in a radiation beam
CGS: Roentgen per hour
SI: Sieverts per hour
Definition of exposure
quantity of radiation incident upon an object. It is the
quantity of electric charge produced per unit mass of air
CGS: Roengtens
metric/other: coulomb/kilogram
Survey Meter
must be capable of measuring
20microsieverts/hr to 100 millisieverts/hr
must have battery check function must be calibrated in last 12 months most important field instrument measures charge from ion pairs created in a gas by radiation measures Gamma radiation
Direct Reading Dosimeter (DRD)
Looks and carried like a pen Must be calibrated every 12 months Works on Ion chamber principals recharge and record at the start and end of each shift worn on the trunk of the body
Advantages of DRD
Tough and low maintenance
small and clips to clothing
weatherproof
easily read by user anytime
Disadvantages of DRD
Limited range usually below 5mSv
No permanent record
can give false readings
Thermoluminescent Dosimeters (TLD)
monitors both skin and body
contains aluminum planchet aluminum foil and 2 lithium fluoride crystals
phased out 2009
Optically Stimulated Luminescence Dosimeter (OSL)
Replaced TLDs
A thin strip of aluminium oxide (Al2O3) is sandwiched within a multi-element filter pack
Clips between waist and neck
X & Gamma-ray = 10 microSv to 10 Sv
(1 mrem to 1000 rem)
Beta Particle = 100 microSv to 10 Sv
(10 mrem to 1000 rem)
Advantages of OSL
Can measure the background dose and possible high doses in case of an emergency
Tough with low maintenance
Accumulates very high doses and can therefore be used for a reasonable period of time.
Provides a permanent record
Range is limitless
Disadvantages of OSL
Must be sent away with a consequent delay in receiving dose information
Objectives of the dosimetry service
estimates doses received by worker and keeps records on a national basis
To report to subscribing organizations the
individual doses received
To draw to the attention of the
managers and government agencies, the dose records of those radiation workers
whose absorbed dose has exceeded the regulatory limits.
What are the steps of the dosimetry service cycle
- Wear the dosimeter
- Return the dosimeter at the end of the wearing period to Health Canada or National or International Org
- Dosimeter is analyzed and processed. Then a exposure report is sent to you containing previous two weeks dose, quarterly for the year dose and lifetime dose
- Dose info is sent to the National Dose Registry
- Worker notifies of changes to account (if Req’d)
- Dosimeter is prepared and to shipped to you
Personal Alarming Dosimeter
Must be worn when using gamma radiation must alarm at 5mSv/hour or total dose of 2mSv/hour must be calibrated with 12 months worn on trunk cant be used instead of survey meter
4 types of biological effects from radiation
Acute
Chronic
Somatic
Genetic
What are Acute Effects
Prompt effects from large doses of radiation
occurs within hours, days or weeks of radiation
(ie radiation burns or sickness)
What are Chronic Effects
long term effects that take years or generations to appear (ie cancer, cataracts, genetic defects in children or grand children)
What are somatic effects
delayed radiation injury to work but not reproductive cells
what are genetic effects
radiation exposure that results in some chromosome damage
long term genetic effects can be caused by extremely low radiation doses and occur independently of the actual intensity
10 sieverts dose will cause
death to all people
5 sieverts dose will cause
50% of people will die with 30 days
2 to 4 sieverts dose will cause
certain disability and injury, possible death
1 to 2 sieverts dose will cause
injury, possible disability
0.5 to 1 sieverts dose will cause
blood and cell changes , some injury , no disability
0.25 to 0.5 sieverts dose will cause
possible temporary blood changes
0 to 0.25 sieverts dose will cause
nothing
What is the latent period
time after the initial radiation exposure until the effects of the radiation become visible
what is the recovery period
Following exposure to radiation, recovery can and does take place to a certain extent.
This is particularly true with acute effects
what are radio-responsive tissues
Blood forming organs – bone marrow, spleen, etc
Sex organs – gonads
Other tissues – liver, lens of eye
what are radio-resistant tissues
Connective tissue – tendons, ligaments Muscle Fat Bone Nerves, brain
What are factors that influence the extent of biological damage
Total amount of radiation absorbed Type of radiation Rate of absorption Area exposed Individual variability Relative sensitivity of cells and tissue
What are the most used materials for shielding
Uranium Lead Tungsten Steel Concrete
What’s Half Value Layer (HVL)
The thickness of a material which reduces the radiation to 1/2 its density
What’s Tenth Value Layer (TVL)
The thickness of a material which reduces the radiation to 1/10 it’s intensity
What’s the radiation barrier dose limit?
0.1 mSv/hr
What’s the storage limit dose limit?
0.025 mSv/hr
What’s the dose limit on the surface of device?
2 mSv/hr before use or upon installation of new source
what reading on a new DRD would cause a stop to work and need for investigation?
2mSv/hr
How often should a leak test be done?
once a year or upon a new source installation
200bq = withdraw device from use
minimum length for long handle tongs
1.5 metres
emergency tunnel shielding attenuation factor
100
source tag must be made of ________ and inscribed with ________?
made of steel or brass inscribed with : name quantity in becquerels date of Bq measurement form of substance in device
Safety Inventory check list
Survey meter battery level Audible alarms battery levels calibration stickers for survey meter, audible alarms and DRD 1.5 meter tongs bolt cutters emergency tunnel go-no-go gauge tester decay chart source ID tag
which effect represents the complete absorption of the energy from the gamma ray and drives the electron free of its orbit?
Photoelectric Effect
which effect represents the electron being ejected and the scattered energy remaining from the ray speed
off making additional collisions with other electrons?
Compton Effect
What document controls the transportation of nuclear substances?
Packing and transport of nuclear substances regulations
What is the maximum permissible dose (MPD) for a Nuclear Energy Worker (NEW) for a 1 and 5 year period?
1 year 50mSv
5 Year 100mSv
What is the MPD for a pregnant NEW ?
4mSv for the balance of the pregnancy
What is the MPD for someone who isn’t a NEW ?
1mSv a year
Whats the maximum dose allowed in a quarter year for a NEW as long as the annual limit is not exceeded?
30mSv
In an emergency source retrieval what is the MPD to the body and skin?
Body: 500 mSv
Skin: 5000 mSv
What type of packaging is used for most exposure devices?
Type B
who is responsible for the proper packaging and that the source capsule is locked in the safe position and key removed?
The shipper
When transporting radioactive material what must be placarded to the vehicle
diamond shaped radioactive signs.
must be removed when not transporting
All type B packing being transported requires approval from whom?
Canadian Nuclear Safety Commision (CNSC)
What is issued by the CNSC that approves transport of the type b device?
a certificate that describes the device and states the allowable contents
What are four steps to follow when in an emergency situation
- Stop and Think
- Verify source location
- Establish barriers
- Advise the Radiation Safety Officer (RSO)
On source retraction and there is no sudden increase , where is the source?
likely in the collimator
On source retraction and there is a sudden increase but no drop off , where is the source
most likely in the guide tube
on a source retraction the levels increase and then decrease but not at guide tube end of the exposure device, wear is the source
in the device , just not in the fully shielded position
whats the sequence for connecting a exposure device together?
- drive cable to camera
- collimator to source guide tube
- source guide tube to camera
what are the basic steps to doing and exposure shot
- survey meter verification
- survey exposure device
- examine all equipment(follow company sign out procedures)
- affix film numbers and penetrometers
- move and secure collimeter into place
- establish and confirm source to film distance
- locate and secure film into place
- connect the drive cable and source guide tube(go-no-go gauge)
- layout drive and source cables
- locate and employ additional shielding where possible
- employ barriers and guards
- unlock exposure device once area is secured
- rapidly crank source to exposure position
- time the exposure
- rapidly retract source into exposure device
- lock and secure exposure device (ensure is in fully shielded position)
- store the equipment
