Cedo - (Section 2) NDT Introduction Flashcards
In Industrial Radiography, how is radiation produced?
By x-ray machines and radioactive materials contained in capsules.
What is Industrial Radiography?
The process of using radiation to see inside manufactured products to determine if flaws, discontinuities, imperfections or deformities exist in the product.
What changes the amount of radiation reaching the film and causes darker areas of exposer?
Holes, cracks, impurities and various other flaws.
Who discovered X-Rays? In what year?
Wilhelm Roentgen, in 1895.
Who discovered Gamma rays?
Pierre & Marie Curie.
Radiation can be found in what two forms?
High speed particles or electromagnetic waves.
X-rays and Gamma rays are forms of what?
Electromagnetic energy.
What’s the main difference between different forms of electromagnetic energy?
Frequency and wavelength.
What weight and charge do the various parts of an atom posses?
Electron (negative -1) light, Neutron (no charge) heavy, Proton (positive +1) heavy.
What weight does a electron have in comparison to a neutron or proton?
1/1840
The weight of an atom can be regarded as?
The weight of the nucleus?
An electrically neutral Aton will have?
The same number of electrons and protons.
Valence electrons orbit the nucleus in shells starting with what letter and end in with what letter?
K-Q
What law states that the binding energy of electrons is greater the closer they are to the nucleus?
Coulomb’s Law.
Electrons orbiting in the outer shells of the nucleus have a higher energy content that?
Electrons orbiting in shells closer to the nucleus.
Atomic number is represented by which letter?
(Z)
Mass Number (Atomic Weight) is represented by which letter?
(A)
What does Atomic Number refer to?
The total number of protons in the nucleus of an atom.
Mass Number (Atomic Weight) refers to what?
The total number of protons and neutrons in the nucleus.
How do you determine the number of neutrons in an element?
Subtract the Atomic Number (Z) from the Mass Number ( A).
What is an Isotope?
Atoms of the same element but with different Mass Numbers (A).
How many known isotopes are stable and how many are unstable (Radioactive)?
Around 3000 stable, 500 radioactive.
Why are some isotopes unstable?
Because some isotopes have too few or too many neutrons in the nucleus, as they attempt to reach a stable ratio of neutrons to protons they emit either Alpha particles, Beta particles, Gamma radiation or capture orbital electrons.
What do X-ray’s result from?
A transfer of energy between a high speed interaction of electrons and a dense target material.
Nuclear generators artificially produce radioisotopes in three major categories, what are they?
Neutron activation, fission product separation and charged particle production.
What is an Ion?
An atom or molecule which has a resultant electric charge due to loss or gain of valence electrons.
When almost completely ionized, gases from?
A fourth state of matter known as Plasma.
Ion pairs consist of what?
A positive ion and a negative ion having charges of the same magnitude.
How are ion pairs formed?
From a neutral atom or molecule by the action of radiation or any other supply of energy.
The ionization that occurs in human blood cells and tissue poses a what?
Serious health risk.
Ionization is the process of?
Adding or removing electrons from atoms or molecules.
What sets X-rays and Gamma rays apart from other types of electromagnetic radiation?
They are ionizing radiation.
Why do Alpha particles cause more ionization than X-rays, Gamma rays or Beta particles?
Because of their relatively heavy mass.
Name the effects and properties produced by X-rays and Gamma rays.
- Cause certain materials to fluoresce
- Produce chemical effects
- Cause deterioration or destruction of living cells
- Causes gases to ionize and become electrical conductors (principle of ionization detectors)
- Travel in straight lines (rectilinear propagation)
- Not affected by electrical of magnetic fields
- Cannot be focused
- Affect photographic emulsions
- Can not be detected by human senses
Which type of radiation is the biggest hazard to humans?
Gamma radiation, because it can travel large distances, is highly penetrating and ionizing.
What are the most common radioisotopes used in radiography?
What radioisotopes are also used but for specialized applications?
- Cobalt 60 (Co60), Iridium 192 (Ir192) and Selenium 75 (Se75)
- Cesium 137 (Cs137) and Ytterbium (Yb169)
