Advice to the public on how to stay away from radioactivity

Advising the public to stay away from radioactivity

·       What they can do to stay safe

o   Sheltering

§  Stay indoors

§  Doors and windows closed

·       This provides short-term protection from breathing in radioactive material in the air

·       Also gives protection from direct radiation from radioactive material in the air and on the ground

o   Listen to the radio

§  Follow the instructions given

o   Evacuation

§  Avoids high, short-term exposure

·       Removing people from the affected area.

o   Stable iodine

§  Taking stable (non-radioactive) iodine tablets

·       Prevents this happening with radioactive iodine released in reactor accidents

 

   Food (Watch what you eat)

§  Radioactive material deposited on soil or grass

·       Will go into food through crops and animals

·       Ban milk or other foods containing too much radioactive material

o   Detection and monitoring

§  Use people with the specialist knowledge, skills and equipment to monitor these measurements

§  Move away if there is radioactive material

o   If suspect self is contaminated

§  Carefully remove your outer layer of clothing

§  Put it in a plastic bag

§  Take a warm shower

§  Place the sealed plastic bag in a room away from people

·       Be alert for any type of symptoms in the coming months

·       Do not go near to any radioactive areas

o   Get as far away as possible

Nuclear Fusion

So...what is nuclear fusion?

Simply put, nuclear fusion is when two elementary particles collide and combine to make a new particle. 

The fused particle, however, is unstable, and quickly decays into a 'hot' neutron and a helium nucleus - an "alpha" particle and energy. 

    <- On the left is a picture of Tritium Nucleus (a form of                                                    hydrogen) colliding with Deuterium Nucleus (also a                                                   form of hydrogen) to combine and form a new particle.

History of nuclear fusion

·       Discovered accidentally by French physicist Henri Becquerel in 1896

·       Found that photographic plates stored in the dark near uranium were blackened like X-ray plates

Some interesting facts about nuclear fusion

·       Usually accompanied by the release of energy (depending on the masses of the nuclei involved)

·       Iron and nickel nuclei are the most stable nuclei

·       Fusion of two nuclei lighter than iron or nickel releases energy

·       Fusion of nuclei heavier than iron or nickel absorbs energy

·       Nuclear fusion (light) releases the energy that causes stars to shine and hydrogen bombs to explode

·       Nuclear fusion (heavy) occurs in the extremely high-energy conditions

·       New natural elements are created by nuclear fusion in stars and supernovae

Another form of nuclear fusion

·       Cold fusion

o   A hypothetical form of nuclear fusion

o   Proposed nuclear fusion process of unknown mechanism offered to explain a group of disputed experimental results

o   Termed  "Low Energy Nuclear Reaction" (LENR) or “Chemically Assisted Nuclear Reaction” (CANR)

How is nuclear fusion used

·       Hydrogen bomb (thermonuclear bomb) - a brief, controlled thermonuclear fusion reaction

·       Atomic bomb provide heat to start fusion reaction = very high temperature

·       Hydrogen nuclei fuse to form helium

·       During which it release huge amounts of energy = explosion

·       Currently, only used for nuclear weapons

Nuclear Fission

What is Nuclear fission?

·       Nuclear fission is the exact opposite of nuclear fusion (refer to previous topic).

·       It is a heavy elementary particle that splits into two or more lighter particles.

·       Happens because an element that is commonly stable comes across a stray slow moving neutron

·       Type of radioactivity

Interesting facts about nuclear fission

·       During the fusion process, fission occurs in the second half of the process.

·       People believe that fission occurs with heavy elements like uranium when they split into lighter elements.

·       In every nuclear fission, 3 products are formed

o   1^st product

§  Fission products

·       Consists of the smaller nuclei produced during fission.

o   2^nd product

§  Energy

·        A tiny amount of matter in the original uranium atom is changed into energy

o   3^rd product

§  Neutrons

History of nuclear fission

·       Discovered accidentally in 1938 by two German physicists

·       They had been doing a series of experiments in which they used neutrons to bombard various elements

·       Radioactive form of copper produced when copper is bombarded

·       Other elements behave in the same way

How is nuclear fission used?

·       Generate electricity via

o   Power plants

§  Uses the heat generated by a nuclear fission process

·       To drive a steam turbine which generates usable electricity

o   Nuclear reactors

Half-life

What is half-life?

·       The amount of time it takes for half of a substance to undergo some specified process

·       Radioactive elements have different isotopes that decay at different rates

o   Varies with the type of isotopes

o   Short half-life

§  Oxygen (71 seconds)

o   Long half-life

§  Thallium(1.4 × 10 ¹⁰ years)

§  Carbon(5,730 years)

·       Calculated by dividing 0.693 by the decay constant

o   Decay constant - dividing the number of observed disintegrations per unit time by the number of radioactive nuclei in the sample

o   Usually given the symbol k or λ

·       Is a measure of how reactive it is

o   Terms of radioactive decay

o   Participation in specific reactions