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Radiation Safety Training Basic Radiation Physics Washington State University Radiation Safety Office.

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Presentation on theme: "Radiation Safety Training Basic Radiation Physics Washington State University Radiation Safety Office."— Presentation transcript:

1 Radiation Safety Training Basic Radiation Physics Washington State University Radiation Safety Office

2 Radiation Fundamentals Objectives: Identify the three basic particles of an atom Define radioactive material, radioactivity, radioactive half-life Define ionization and ionizing radiation Distinguish between ionizing radiation and non-ionizing radiation Identify the four basic types of ionizing radiation Physical characteristics Range Shielding Biological hazards

3 What is an Atom

4 Atomic Structure The basic unit of matter is the atom. The three basic particles of the atom are: protons, neutrons, and electrons. The central portion of the atom is the nucleus. The nucleus consists of protons and neutrons. Electrons orbit the nucleus.

5 Notations A Z X A = Atomic Mass (number of protons or electrons plus number of neutrons) Z= Atomic Number (number of Protons) or (number of Electrons in an electrically neutral atom) Number of Neutrons = A - Z

6 Notations Tritium is designated as : T or H-3 or H Uranium (238) is designated as: U-238 or U 3 1

7 What are Isotopes ? They are not just a sports team on the Simpsons.

8 The Isotopes Atoms which have the same number of protons but different numbers of neutrons are called isotopes. Isotopes of Carbon.

9 The Isotopes. ISOTOPES of hydrogen Protium HDeuterium D Tritium T No neutrons 1 neutron 2 neutrons H D T n n n The different isotopes of an atom are chemically identical. The above isotopes of hydrogen all act chemically the same.

10 What is Radioactivity ? If there are too many or too few neutrons for a given number of protons, the nucleus will not be stable. The unstable atom will try to become stable by giving off excess energy. This energy is in the form of particles or rays (radiation). These unstable atoms are known as radioactive atoms, or radioactive materials.

11 How do unstable Isotopes become stable?

12 By Radioactive decay Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide.

13 How long does Radioactive decay take? Half life it’s more than just a game.

14 Radioactive half-life The radioactive half-life for a given radioisotope is the time for half the radioactive nuclei in any sample to undergo radioactive decay. After one half-life, there will be one half the activity of the original sample. After two half-lives, there will be one fourth the activity of the original sample, after three half-lives one eighth the activity of the original sample, and so forth.

15 Radioactive Decay is an Exponential Process The activity at time (t) is related to the initial activity at time (0)

16 To determine the activity present after time (t) You need to know 1. The initial activity of the isotope involved. (Activity at time “0” or A o ) 2. The half life of the radioactive isotope. (T 1/2 ) 3. The time after the initial activity was determined. (  T after the determination at time “0”)

17 Example You have 10 mCi of P-32 on January 1, How much activity will you have on January 29, 2008? Given:The half life of P-32 is 14.3 days.

18 Solution Known:1. A o = 10 mCi 2. T1/2 = 14.3 days 3. Time after initial activity (t) = 28 days Using A (t) = A o e - t = 10 e –(0.693/14.3)(28) = 2.57 mCi Example: Decay of 32 P in time

19 Radioactivity may be defined as: Spontaneous nuclear transformation

20 Non-ionizing vs. Ionizing radiation Non-ionizing radiation refers to any type of electromagnetic radiation that does not carry enough energy per quantum to ionize atoms or molecules — that is, to completely remove an electron from an atom or molecule. Examples of non-ionizing radiation: microwaves, ultraviolet light, lasers, radio waves, infrared light, and radar.

21 Ionizing radiation consists of subatomic particles or electromagnetic waves that are energetic enough to detach electrons from atoms or molecules, ionizing them. Examples of ionizing radiation: alpha particles, beta particles, neutrons, gamma rays, and x-rays.

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23 Ionization Ionization is the process of removing electrons from neutral atoms. It is important to note that exposure to ionizing radiation, without exposure to radioactive material, will not result in contamination of the worker.

24 Two general categories of ionizing radiation: PARTICLES alpha neutron beta PHOTONS X-ray gamma ray

25 Radiation Fundamentals The Four Basic Types of Ionizing Radiation alpha particles, beta particles, gamma or X rays, neutrons.

26 Alpha Particles Physical Characteristics: Large mass, highly charged, helium nuclei (2 protons, 2 neutrons) Range: 1-2 inches in air Shielding: Dead layer of skin, paper. Biological Hazards: Internal, it can deposit large amounts of energy in a small amount of body tissue.

27 Alpha Particles

28 Beta Particles Physical Characteristics: Small mass, electron size, Range: Short distance (one inch to 20 feet). Shielding: Plastic Biological Hazard: Internal hazard. Externally, may be hazardous to skin and eyes.

29 Beta Particles

30 Gamma Rays/X-Rays Physical Characteristics: No mass. No charge. Electromagnetic wave or photon. Range: Very far. It will easily go several hundred feet. Very high penetrating power. Shielding: Concrete. Water. Lead. Biological Hazard: Whole body exposure. The hazard may be external and/or internal. This depends on whether the source is inside or outside the body.

31 Gamma Rays/X-Rays Gamma and X-rays are photons (massless electromagnetic energy) stopped by dense shielding naturally present in soil and in cosmic radiation medical, radioactive materials

32 Neutrons Physical Characteristics: Fairly large. No charge. Has mass. Range: Range in air is very far. Easily can go several hundred feet. High penetrating power due to lack of charge (difficult to stop). Shielding: Water. Concrete. Plastic (high hydrogen content). Biological Hazard: External whole body exposure.

33 SUMMARY of External and Internal Hazards ExternalInternal AlphaMinimumSevere BetaHigher than AlphaLess severe than Alpha X-ray and Gamma SevereLess severe than Alpha, Beta NeutronSevereNot considered

34 Review. T he three basic particles of an atom are, protons, neutrons, and electrons. Radiation is energy in the form of particles or rays given off by unstable atoms. The half-life for a given radioisotope is the time for half the radioactive nuclei in any sample to undergo radioactive decay.

35 Review cont. Ionizing radiation consists of radiation energetic enough to detach electrons from atoms or molecules, ionizing them. Non-ionizing radiation refers to any type of electromagnetic radiation that does not carry enough energy to completely remove an electron from an atom or molecule.

36 Review cont. The four basic types of ionizing radiation are: alpha particles, beta particles, gamma or X rays, neutrons. Alpha particles, Large mass, highly charged, Range: 1-2 inches in air, Shielding: Dead layer of skin, paper. Biological Hazards: Internal Beta particles, Small mass, Range: one inch to 20 feet. Shielding: Plastic. Biological Hazard: Internal hazard. Externally, may be hazardous to skin and eyes.

37 Review cont. The four basic types of ionizing radiation cont: Gamma or X rays, No mass. No charge. Range: It will easily go several hundred feet. Very high penetrating power. Shielding: Concrete. Water. Lead. Biological Hazard: External whole body exposure. Neutrons, Fairly large. No charge. Has mass. Range: Easily can go several hundred feet. High penetrating power due to lack of charge. Shielding: Water. Concrete. Plastic (high hydrogen content). Biological Hazard: External whole body exposure.

38 Test Time! Follow this link to the test. https://myresearch.wsu.edu https://myresearch.wsu.edu Use your WSU user name and password to sign in. Click on the training tab. Then click on the available training tab Find the basic radiation physics course, in the OR section, click on it and take the test.


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