Homework 1 Flashcards
Why does cobalt 60 have the highest penetrating power of the common industrial radioactive isotopes?
Shorter wavelength (higher energy)
What is the maximum thickness of steel that can be practically radiographed with Iridium 192?
75mm
Modern industrial X-ray machines, typically, have a range between 50 - 450 kV. What do you think will be the maximum steel weld thickness that could be examined using such equipment?
60mm
Which of the following factors determines the “penetrating power” of a radiation source?
Thickness of the object and density of the object (not the physical size of the radiation source)
How is an “exposed film” converted into a “radiograph”?
Needs to be processed (not just developed)
What do you think is a major limitation of Radiographic Testing?
In order that defects may be detected by radiography, they must produce, effectively, a reduction in wall thickness of the specimen, typically in the order of a 2% reduction.
Inability to detect laminations in plate.
May be difficult to detect ‘lack of fusion’ or ‘cracks’ perpendicular to the axis of the radiation beam.
What do you think is a major limitation of Radiographic Testing?
In order that defects may be detected by radiography, they must produce, effectively, a reduction in wall thickness of the specimen, typically in the order of a 2% reduction.
Inability to detect laminations in plate.
May be difficult to detect ‘lack of fusion’ or ‘cracks’ perpendicular to the axis of the radiation beam.
The ‘A’ number of the ‘element symbol’ in the periodic table represents the:
Mass number AND number of neutrons and protons
The ‘Z’ number of the ‘element symbol’ in the periodic table represents the..?
Atomic number AND number of protons
Which of the following radioisotopes has the longest ‘Half-life’?
Caesium 137 30 years
Cobalt 60 5.3 years
Selenium 75 119 days
Iridium 192 74 days
What is the term used to relate the number of disintegrations per unit time in a decaying, unstable element?
Activity (not specific activity which is Ci/Gbq per gram)
How would you define the term ‘specific activity’?
The maximum activity of a given physical source size.
It is a value measured in curie per gram (Ci/g or Gbq/g)
How would you describe an ‘ion’?
Electrically charged particle which may be positive (+) or negative(-).
An ion (/ˈaɪ.ɒn, -ən/)[1] is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convention. The net charge of an ion is not zero because its total number of electrons is unequal to its total number of protons.
Electron transfer between lithium (Li) and fluorine (F). Forming an ionic bond, Li and F become Li+ and F− ions.
A cation is a positively charged ion with fewer electrons than protons[2] (e.g. K+ (potassium ion)) while an anion is a negatively charged ion with more electrons than protons.
Which of the following ‘radioactive isotopes’ are produced by neutron bombardment (thermal neutron capture) in a reactor?
Iridium 192 & Thulium 170
(Caesium 137 is produced by nuclear fission)
What is the difference between Gamma radiation and Corpuscular radiation?
Gamma radiation has no mass and travel at the speed of light.
Corpuscular radiation has mass and do not travel at the speed of light.
