Teaching note Just in case you have never tried this before. This is split into 5 spaced learning presentations. The idea is that each one is presented and the students focus on remembering the key words that are highlighted red. After each run through a completely unrelated task (the more quirky the better) is given to allow for processing time and then a run through trying to remember the key points is completed. Blue slides separate the tasks.

P2 Spaced Learning All you need to do is remember the red highlighted words!

P2 Spaced Learning All you need to do is remember the red highlighted words!

P2 Topic 6 Advantages & disadvantages of using radioactive materials

Radioactivity Dangers When handling radioactive sources: 1.Make sure appropriate shielding is used whilst handling 2.Reduce time of exposure to a minimum 3.Maintain a safe distance wherever possible Remember that ionising radiation can damage the cell and/or its DNA causing the cell to die or mutate.

Background Radiation A substance is said to be radioactive when it releases radiation (alpha, beta or gamma). Only 14 % of radiation comes from man made activities, the rest is naturally occurring. From Earth bound or outer space radioactive sources. Together they for the background count of radiation. The background count is subtracted from any experimental measure of radioactivity to make it fair. The number of decays per second or activity of the source is measured in the becquerel (Bq)

Detecting radiation A Geiger-Muller or GM tube is used to detect radiation. This uses the fact that all radiation types are ionising to work. It measures the count rate or activity of the radiation in the unit of becquerel (Bq)

Half-Life When a material emits radiation it is said to decay. The time that half the material takes to decay is known as a half life. This will be when the count rate or activity is reduced by half. This measurement is used because its impossible to know when each atom will decay but an average of a few million is constant for each type of radioactive isotope. Half of 80 is 40 Half of 40 is 20 Half-life is 2 days

Radiation equations Just like chemical equations when radioactive particles are released you need to know what happens to the atoms left behind for alpha (helium nucleus) and beta types of radiation. U ranium ThTh orium α 4 2 lpha C 14 6 arbon N 14 7 itrogen β 0 1 eta Alpha Beta Beta radiation occurs when a neutron breaks up into a proton and beta particle

Ideas about radioactivity have changed over time. Henri Becquerel investigated Uranium producing light in 1896, he also discovered it caused burns when he left it in his pocket. Marie Curie and her husband burned their hands handling radioactive materials, and ultimately died form leukaemia from the radiation, whilst investigating radioactivity. We understand the risks far better now but are also able to benefit from some of the uses of radioactive isotopes.

Uses of radiation – Alpha, smoke alarm. Because the alpha source is ionising a current flows in the smoke detector. When smoke enters the detector alpha particles cannot pass through and no current is generated, this causes the alarm to sound.

Uses of radiation – Beta, thickness detector Because the beta radiation can pass through thin materials it can be detected on the other side. However if the thickness increases fewer particles can pass through. This is detected and the rollers are adjusted to produce the right thickness

Uses of radiation – Gamma (sometimes Beta, medical images Because gamma ionises the least if a weak source is used the radiation can exit the body, whilst causing little damage, and be detected. By using short half-life sources of radioactivity damage to the patient is limited further. Radioactive gas in lungs Radioactive tracer injected

Irradiation is used to reduce the pathogens in foods. Depending on the dose, some or all of the microorganisms, bacteria, and viruses present are destroyed, slowed down, or rendered incapable of reproduction. This can be used to sterilise food or medical equipment. or Irradiation is used to as delay the ripening of fruits and the sprouting of vegetables by slowing down the speed of enzymes in foods. "Radura international" by R.M. Ulman - Ulmann, R.M Uses of radiation – Gamma, killing microbes

Uses of radiation – Gamma, killing cancer cells Because strong gamma sources have high energies they can easily kill cancerous cells (note they will also kill any surrounding healthy cells). But as they are EM waves they can be focussed onto small areas to treat cancer. Gamma knife

Radioactive waste Fission products produce high level waste (HLW) that remains radioactive for 50 years where upon it becomes intermediate level waste (ILW) for many thousands of years before becoming low level waste (LLW) for tens of thousands of years. Different levels of waste are produced throughout the fission process and hospitals produce LLW in cancer treatments. All of this waste can be harmful so it needs to be stored somewhere until it becomes safe to be disposed of.

Radioactive waste In the past it has been sealed in glass, concrete and barrels and dumped at sea, then some of the barrels corroded. This is a difficult problem to solve and no LLW has been disposed of in the UK only stored. Other Options; Send it into space – What if it falls back to Earth? Store it underground – What if it leaks or there is an earthquake?

Nuclear Fission to produce electricity Advantages No CO 2 or SO 2 produced, does not contribute to climate change. High energy density, 10,000 times the energy per gram of fossil fuel. Practically renewable as thousands of years of radioactive isotopes. Disadvantages Nuclear waste must be stored safely for 10’s of thousands of years. If accidents happen the consequences are big. It is expensive because of the decommissioning costs. Terrorist activity is a risk and security cost.

Task for you ! If one grain of rice was placed on the first square of a chess board and it was then doubled on the second square (2) and doubled on the third square (4) how many grains of rice are on the 16 th square? As I was going to St. Ives, I met a man with seven wives, Each wife had seven sacks, Each sack had seven cats, Each cat had seven kits: Kits, cats, sacks, and wives, How many were there going to St. Ives?

Radioactivity Dangers When handling radioactive sources: 1.Make sure appropriate shielding is used whilst handling 2.Reduce time of exposure to a minimum 3.Maintain a safe distance wherever possible Remember that ionising radiation can damage the cell and/or its DNA causing the cell to die or mutate

Background Radiation A substance is said to be radioactive when it releases radiation (alpha, beta or gamma). Only 14 % of radiation comes from man made activities, the rest is naturally occurring. From Earth bound or outer space radioactive sources. Together they for the background count of radiation. The background count is subtracted from any experimental measure of radioactivity to make it fair. The number of decays per second or activity of the source is measured in the becquerel (Bq)

Detecting radiation A Geiger-Muller or GM tube is used to detect radiation. This uses the fact that all radiation types are ionising to work. It measures the count rate or activity of the radiation in the unit of becquerel (Bq) 1 2 3

Half-Life When a material emits radiation it is said to decay. The time that half the material takes to decay is known as a half life. This measurement is used because its impossible to know when each atom will decay but an average of a few million is constant for each type of radioactive isotope. Half of 80 is 40 Half of 40 is 20 Half-life is 2 days

Half-Life When a material emits radiation it is said to decay. The time that half the material takes to decay is known as a half life. This will be when the count rate or activity is reduced by half. This measurement is used because its impossible to know when each atom will decay but an average of a few million is constant for each type of radioactive isotope. Half of 80 is 40 Half of 40 is 20 Half-life is 2 days

Radiation equations Just like chemical equations when radioactive particles are released you need to know what happens to the atoms left behind for alpha (helium nucleus) and beta types of radiation. U ranium ThTh orium α 4 2 lpha C 14 6 arbon N 14 7 itrogen β 0 1 eta Alpha Beta Beta radiation occurs when a neutron breaks up into a proton and beta particle

Ideas about radioactivity have changed over time. Henri Becquerel investigated Uranium producing light in 1896, he also discovered it caused burns when he left it in his pocket. Marie Curie and her husband burned their hands handling radioactive materials, and ultimately died form leukaemia from the radiation, whilst investigating radioactivity. We understand the risks far better now but are also able to benefit from some of the uses of radioactive isotopes

Uses of radiation – Alpha, smoke alarm. Because the alpha source is ionising a current flows in the smoke detector. When smoke enters the detector alpha particles cannot pass through and no current is generated, this causes the alarm to sound

Uses of radiation – Beta, thickness detector Because the beta radiation can pass through thin materials it can be detected on the other side. However if the thickness increases fewer particles can pass through. This is detected and the rollers are adjusted to produce the right thickness

Uses of radiation – Gamma (sometimes Beta, medical images Because gamma ionises the least if a weak source is used the radiation can exit the body, whilst causing little damage, and be detected. By using short half-life sources of radioactivity damage to the patient is limited further. Radioactive gas in lungs Radioactive tracer injected 1 2 3

Irradiation is used to reduce the pathogens in foods. Depending on the dose, some or all of the microorganisms, bacteria, and viruses present are destroyed, slowed down, or rendered incapable of reproduction. This can be used to sterilise food or medical equipment. or Irradiation is used to as delay the ripening of fruits and the sprouting of vegetables by slowing down the speed of enzymes in foods. "Radura international" by R.M. Ulman - Ulmann, R.M Uses of radiation – Gamma, killing microbes

Uses of radiation – Gamma, killing cancer cells Because strong gamma sources have high energies they can easily kill cancerous cells (note they will also kill any surrounding healthy cells). But as they are EM waves they can be focussed onto small areas to treat cancer. Gamma knife

Radioactive waste Fission products produce high level waste (HLW) that remains radioactive for 50 years where upon it becomes intermediate level waste (ILW) for many thousands of years before becoming low level waste (LLW) for tens of thousands of years. Different levels of waste are produced throughout the fission process and hospitals produce LLW in cancer treatments. All of this waste can be harmful so it needs to be stored somewhere until it becomes safe to be disposed of

Radioactive waste In the past it has been sealed in glass, concrete and barrels and dumped at sea, then some of the barrels corroded. This is a difficult problem to solve and no LLW has been disposed of in the UK only stored. Other Options; Send it into space – What if it falls back to Earth? Store it underground – What if it leaks or there is an earthquake?