Cedo - (Section 2) NDT Introduction

Question 0

In Industrial Radiography, how is radiation produced?

Answer 0

By x-ray machines and radioactive materials contained in capsules.

Question 1

What is Industrial Radiography?

Answer 1

The process of using radiation to see inside manufactured products to determine if flaws, discontinuities, imperfections or deformities exist in the product.

Question 2

What changes the amount of radiation reaching the film and causes darker areas of exposer?

Answer 2

Holes, cracks, impurities and various other flaws.

Question 3

Who discovered X-Rays? In what year?

Answer 3

Wilhelm Roentgen, in 1895.

Question 4

Who discovered Gamma rays?

Answer 4

Pierre & Marie Curie.

Question 5

Radiation can be found in what two forms?

Answer 5

High speed particles or electromagnetic waves.

Question 6

X-rays and Gamma rays are forms of what?

Answer 6

Electromagnetic energy.

Question 7

What’s the main difference between different forms of electromagnetic energy?

Answer 7

Frequency and wavelength.

Question 8

What weight and charge do the various parts of an atom posses?

Answer 8

Electron (negative -1) light, Neutron (no charge) heavy, Proton (positive +1) heavy.

Question 9

What weight does a electron have in comparison to a neutron or proton?

Answer 9

1/1840

Question 10

The weight of an atom can be regarded as?

Answer 10

The weight of the nucleus?

Question 11

An electrically neutral Aton will have?

Answer 11

The same number of electrons and protons.

Question 12

Valence electrons orbit the nucleus in shells starting with what letter and end in with what letter?

Answer 12

K-Q

Question 13

What law states that the binding energy of electrons is greater the closer they are to the nucleus?

Answer 13

Coulomb’s Law.

Question 14

Electrons orbiting in the outer shells of the nucleus have a higher energy content that?

Answer 14

Electrons orbiting in shells closer to the nucleus.

Question 15

Atomic number is represented by which letter?

Answer 15

(Z)

Question 16

Mass Number (Atomic Weight) is represented by which letter?

Answer 16

(A)

Question 17

What does Atomic Number refer to?

Answer 17

The total number of protons in the nucleus of an atom.

Question 18

Mass Number (Atomic Weight) refers to what?

Answer 18

The total number of protons and neutrons in the nucleus.

Question 19

How do you determine the number of neutrons in an element?

Answer 19

Subtract the Atomic Number (Z) from the Mass Number ( A).

Question 20

What is an Isotope?

Answer 20

Atoms of the same element but with different Mass Numbers (A).

Question 21

How many known isotopes are stable and how many are unstable (Radioactive)?

Answer 21

Around 3000 stable, 500 radioactive.

Question 22

Why are some isotopes unstable?

Answer 22

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.

Question 23

What do X-ray’s result from?

Answer 23

A transfer of energy between a high speed interaction of electrons and a dense target material.

Question 24

Nuclear generators artificially produce radioisotopes in three major categories, what are they?

Answer 24

Neutron activation, fission product separation and charged particle production.

Question 25

What is an Ion?

Answer 25

An atom or molecule which has a resultant electric charge due to loss or gain of valence electrons.

Question 26

When almost completely ionized, gases from?

Answer 26

A fourth state of matter known as Plasma.

Question 27

Ion pairs consist of what?

Answer 27

A positive ion and a negative ion having charges of the same magnitude.

Question 28

How are ion pairs formed?

Answer 28

From a neutral atom or molecule by the action of radiation or any other supply of energy.

Question 29

The ionization that occurs in human blood cells and tissue poses a what?

Answer 29

Serious health risk.

Question 30

Ionization is the process of?

Answer 30

Adding or removing electrons from atoms or molecules.

Question 31

What sets X-rays and Gamma rays apart from other types of electromagnetic radiation?

Answer 31

They are ionizing radiation.

Question 32

Why do Alpha particles cause more ionization than X-rays, Gamma rays or Beta particles?

Answer 32

Because of their relatively heavy mass.

Question 33

Name the effects and properties produced by X-rays and Gamma rays.

Answer 33

• 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

Question 34

Which type of radiation is the biggest hazard to humans?

Answer 34

Gamma radiation, because it can travel large distances, is highly penetrating and ionizing.

Question 35

What are the most common radioisotopes used in radiography?

What radioisotopes are also used but for specialized applications?

Answer 35

• Cobalt 60 (Co60), Iridium 192 (Ir192) and Selenium 75 (Se75)
• Cesium 137 (Cs137) and Ytterbium (Yb169)