Radiation Safety Series 1

Radiation Safety Series Lesson 1 Introduction to Radiation Discovery of Radioactivity

History of Discovery 1895 – Wilhelm Roentgen; Discovered X-Ray 1895 – Henri Becquerel; Rays from Uranium 1898 – Marie & Pierre Curie; Work with Radium 1899 – Ernest Rutherford; Alpha, Beta & Gamma 1905 – Albert Einstein; Theory of Relativity

Wilhelm Roentgen • 8 Nov 1895 Discovered X-Rays • Received the Nobel Prize in Physics 1901 • Brilliant Scientist • Never sought Honors or profit from his work

www.accessexcellence.org/AE/AEC/CC/radioactivity.html

Henri Becquerel • Third Generation Scientist • Discovered Radioactivity • Discovered charged partials. • Received the Nobel Prize in Physics 1903 www.accessexcellence.org/AE/AEC/CC/radioactivity.html

Marie & Pierre Curie • Marie coined the term Radioactivity • Both discovered Polonium & Radium • Both shared the Nobel Prize in Physics of 1903 • 1910 Curie is basic unit of radioactivity www.accessexcellence.org/AE/AEC/CC/radioactivity.html

Ernest Rutherford • The father of nuclear physics • Particles- Alpha, Beta & Neutron • Radioactive decay equation • Concept of half life • Elements transmuted • 1908 Nobel Price www.accessexcellence.org/AE/AEC/CC/radioactivity.html

Albert Einstein • General physicist • Most well-known physicist of our time • E = mc2 • Theoretical indication that the Atomic Bomb is possible

www.bartleby.com/173/

Milestones in Radiation and Radiography 1922 – Memorial to scientists in Hamburg Germany 1922 – Industrial X-Ray; Watertown Laboratory 1929 – Gamma Radiography; Naval Research Lab. 1945 – 1st Atomic Bomb; White Sands Missile Range 1946 – Atomic Energy Commission Established Radiation Safety Training Series Part 1: Radiation, Rudarmel Enterprises, inc. Lake Oswego, Oregon

Atoms are Elements • Elements are made of – – – – – –

Electrons Protons Neutrons +, positive charge -, negative charge 0, neutral charge

Radiation Safety Training Series Part 1: Radiation, Rudarmel Enterprises, inc. Lake Oswego, Oregon

Atomic Energy Levels • Electrons are arranged in shells • Electrically balanced atoms have equal number of protons and neutrons • This atom has 18 protons

SHELLS ONLY HOLD SOME ELECTRONS • • • • •

The first 18 elements k-shell only holds two l-shell only holds eight m-shell only holds eight m-shell can actually hold up to 18 electrons as you move further along the periodic table.

Radiation Safety Training Series Part 1: Radiation, Rudarmel Enterprises, inc. Lake Oswego, Oregon

ORBITAL BASICS •

•

• •

A shell is sometimes called an orbital or energy level. Shells are areas that surround the center of an atom. The center of the atom is called the nucleus. Electrons live in something called shells.

Radiation Safety Training Series Part 1: Radiation, Rudarmel Enterprises, inc. Lake Oswego, Oregon

Mathematical Probability • Orbitals are described by probability • An orbital exists as a cloud • Each atom has a different orbital cloud structure http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch6/quantum.html

www.mii.org

Element Description • • • • • • •

Atomic number 6 Atomic mass 12.01 Electron configuration Oxidation state Symbol Melting/boiling point Density/electronegativ ity

Isotopes • Hydrogen is the common stable form • Deuterium is rare but stable form • Tritium (radioactive) is an unstable form • Atoms of the same element have different characteristics

Origin and Types of Radiation • Bremsstrahlung – braking ray -high energy electron impacting a target • Nuclear decay • Manmade radioactivity

Simple X-Ray Generator • Electrons boiled off the cathode • Electrons impact the Anode -dense material • A continuous spectrum of X-Rays are emitted in all directions

Radiation from Nuclear Decay • Collimated radiation • One spot would glow • Magnetic field would make three spots glow - Alpha - Beta - Gamma

Types of Radiation • Alpha partial is two protons and two neutrons having a positive charge and mass • Beta particle is a high energy electron with a negative charge and little mass • Gamma ray is electromagnetic energy possessing no mass and no charge • Neutron particle has no charge but it does have mass

Electromagnetic Spectra

www.lbl.gov/MicroWorlds/ALSTool/EMSpec/EMSpec2.html

Differences in Gamma and X-ray • X-Ray wavelengths ranges 10-8 to 10-13 • Gamma wavelength ranges 10-11 to 10-13 • X-Ray is electronically generated and stops when you turn off the power • Gamma is naturally occurring and continuous

Creating a Radioactive Isotope

Human Exposure to Radiation Exposure from Natural Background Cosmic Rays (sun and outer space) 14% Building materials 2% Human body 12% The earth 13% Approx. % annual exposure 50%

Human Exposure to Radiation Exposure from Manmade Sources Medical (mostly diagnostic x-ray) Fallout from atomic bombs Nuclear power Consumer products (mostly color TV’s) Approx. % annual exposure

45% 2.5% 0.15% 0.5% 50%

Human Exposure to Radiation Occupational Radiation exposures Workers at Gamma Radiography Company’s Gamma radiographer’s

3X 5X

Time, Distance and Shielding • How do we reduce our exposure to radiation? • We can calculate stay times, dose rates and distance from sources. • We can calculate shielding requirements and or effects • Our first step, Inverse Square Law

Inverse Square Law, General • Any point source which spreads its influence equally in all directions without a limit to its range will obey the inverse square law. This comes from strictly geometrical considerations. The intensity of the influence at any given radius r is the source strength divided by the area of the sphere.

Inverse Square Law, General Continued • Being strictly geometric in its origin, the inverse square law applies to diverse phenomena. Point sources of gravitational force, electric field, light, sound or radiation obey the inverse square law.

Inverse Square Law, General

http://hyperphysics.phy-astr.gsu.edu/hbase/forces/isq.html

Inverse Square Law, Radiation

http://hyperphysics.phy-astr.gsu.edu/hbase/forces/isq.html

Inverse Square Law, Radiation S/4πr2 = I S = 4πr2 I S = 4πr12 I1 S = 4πr22 I2 4πr12 I1 = S = 4πr22 I2 4πr12 I1 = 4πr22 I2 r12 I1 = r22 I2

Inverse Square Law, Radiation

r 1 I1 = r 2 I2 2

2

Example If the intensity of the Andrex is 1040 R/hr at one foot from the tube head then what is the distance to the 2mR line. I1 = 1040 R/hr r1 = 1’ I2 = 2 mR/hr

r2 = ?

r12 I1 = r22 I2 → r2 = √(r12 I1/ I2) r2 = √(r12 I1/ I2)

Example r2 = √(r12 I1/ I2) r2 = √(1040 R/hr ∙ 1’ / 0.002 R/hr) r2 = 721’ r2 = 721 feet

Works Sited Partial List: http://www.accessexcellence.org/AE/AEC/CC/radioactivity.html http://www.accessexcellence.org/AE/AEC/CC/historical_background.html Radiation Safety Training Series Part 1: Radiation, Rudarmel Enterprises, inc. Lake Oswego, Oregon http://www.chem4kids.com/files/atom_structure.html http://orbitals.com/orb/ http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch6/quantum.html www.bartleby.com/173/ www.mii.org http://hyperphysics.phy-astr.gsu.edu/hbase/forces/isq.html