Science 10: Nuclear Radiation

Particulate (nuclear) radiation

"coming" from the nucleus wave particle

Strong Force

A force that acts only on subatomic particles that are extremely close (must be right next to the subatomic particle) together that overcomes proton repulsion

Electrostatic forces

A force that results from moving charged particles Proton-proton repulsion Proton-electron attraction

Ionizing Alpha cont

Alpha particles are the same as the nuclei of helium. This means that they have a (relatively) large mass. The atomic number of helium is 2 so an alpha particle carries a double positive charge. Alpha particles don't travel very fast - because they have such a large mass. This means that they tend to collide with plenty of other atoms. Therefore, they cause a lot of ionization by pulling electrons off the atoms. All these collisions mean that they lose energy quickly, so they have a short range in air and they are easily stopped by anything solid - even a piece of paper will stop alpha radiation.

Radiotherapy

Although ionizing radiation can cause cancer, high doses can be directed at cancerous cells to kill them. This is called radiotherapy. About 40 per cent of people with cancer undergo radiotherapy as part of their treatment. It is administered in two main ways: from outside the body using X-rays or the radiation from radioactive cobalt from inside the body by putting radioactive materials into the tumor, or close to it Some normal cells are also damaged by the radiation, but they can repair themselves better than the cancer cells are able to. Radiotherapy is often used together with chemotherapy - using chemicals which also kill cancerous cells.

Sievert

Amount of radiation absorbed by biological tissue

Becquerel

Amount of radiation released

Halflife

Amount of time it takes for half the atoms to become more stable Rate of decay is determined by halflife

Fast beta cont

Beta radiation is a stream of fast moving electrons. These particles have very little mass (about 7000 times lighter than an alpha particle) and travel close to the speed of light (300,000 km/s). They tend to pass through the air and solid matter without many collisions with other atoms. So beta radiation is only weakly ionizing. However, it means that it has a long range in air and will pass through paper, and thin sheets of aluminum and steel. However, it is stopped by lead or thick pieces of other metals.

Boron Neutron Capture

CA boron containing drug is injected into the body of the patient, it is attracted to the cancer cells in the head and the neck a neutron alone, and a boron alone is not at all hazardous to a cell, however, when a boron and a neutron goes together and forms boron-11, it is very dangerous which kills the cancer cells because alpha particles are released and that kills the cancer cells. Side effects: Stomatitis Fatigue Oral pain Boron neutron capture therapy (BNCT) is a treatment that has been proposed to combat glioblastomas of the brain and malignant melanomas, two tumors that are resistant to traditional cancer therapies.

Electron

Charge: Negative Location:Electron cloud Mass: 9.109x10^-28 Mass: 0amu

Neutron

Charge: Neutral Location: Nucleus Mass: 1.675x10^-24 Mass:1amu

Proton

Charge:Postive Location: Nucleus Mass: 1.673x10^-24 Mass: 1amu

Intermediate level nuclear waste disposal

Components from nuclear reactors, radioactive sources used in medicine or research

Low level nuclear waste disposal

Contaminated equipment, materials and protective clothing Put in drums and surrounded by concrete, and put into clay lined landfill sites

Radioactive tracers

Doctors may use radioactive chemicals called tracers for medical imaging. Certain chemicals concentrate in different damaged or diseased parts of the body, and the radiation concentrates with it. Radiation detectors placed outside the body detect the radiation emitted and, with the aid of computers, build up an image of the inside of the body. When a radioactive chemical is used in this way it is not normally harmful, because: it has a short half-life and so decays before it can do much damage it is not poisonous

Nuclear power fission chain reaction

Nuclear energy Heat- water h2o steam Kinetic Energy Generator Electrical energy

Atomic Mass

Number of protons and the number of neutrons (electrons are small enough in weight to neglect)

Atomic Number

Number of protons can be used to identify atoms

Cosmic radiation

The earth, and all living things on it, are constantly bombarded by radiation from space, similar to a steady drizzle of rain. Charged particles from the sun and stars interact with the earth's atmosphere and magnetic field to produce a shower of radiation, typically beta and gamma radiation. The dose from cosmic radiation varies in different parts of the world due to differences in elevation and to the effects of the earth's magnetic field.

Fission

The process of splitting a nucleus is called nuclear fission and is used in nuclear power reactors. Fission is another word for splitting Ex. uranium235 fission nuclear power plant in order to generate electricity

High level nuclear waste disposal

Used nuclear fuel and chemicals from reprocessing fuels Stored underwater in large pools for 20 years, then placed in storage casks in purpose-built underground stores where air can circulate to remove the heat produced. High level waste decays into intermediate level waste over many thousands of years.

Fusion

coming together The bombarding particles are alpha particle, a neutron, a gamma photon, or an iron, or a proton. For bombardment of particles, the particles must possess enough amount of energy. The reaction can be completed between a heavy nucleus and a light particle. Fusion reaction takes place between the sun and stars, the source of the sun's energy is nuclear fusion

Uranium ore

naturally occurring uranium sources

Ionizing radiation

to make an ion, adding or taking away electrons Higher energy electromagnetic waves, heavy particles (beta and alpha) High enough energy to pull electron from orbit

Positron

Electrons with a positive charge

Radiation

Emission of energy in the form of a wave or particle

Electromagnetic radiation (wave)

Energy is determined by wavelength Gamma radiation is part of this

What can target alpha therapy treat?

For instance: treatments for Leukemia,melanoma, leukemia, colorectal, breast and prostate cancers

Penetrating Gamma cont

Gamma radiation is at the high frequency end of the electromagnetic spectrum. It has a very short wavelength (much less than the radius of an atom) and will pass through atoms with very little chance of being deflected or absorbed. It has an extremely long range in air and will get through thin samples of most materials without any noticeable decrease in intensity. However, its intensity is reduced by lead or very thick pieces of other metals. The thicker the sample, the greater the reduction in intensity.

Detectors used to measure radioactive decay

Geiger Muller tube/counter. Different models are available for detecting alpha,gamma an beta radiation Ionization chambers Proportional counters Spark chamber

Isotope

Losing and gaining neutrons, same number of protons, but different number of neutrons

Nonionizing radiation

Lower energy electromagnetic waves Not enough energy to pull an electron from orbit, but can excite the electron (can temporarily, push the electron to high energy levels)

Beta

Medium penetrating power, can be blocked by wood contains 1 electron -1 charge Electrons and positrons having small mass and variable energy electrons form when a neutron transforms into a proton/electron High speed electron ejected from nucleus

Gamma

Packet of energy Has no mass Very high penetrating power because it has no mass Can only be blocked by lead Just energy, not particles Larger atoms have more energy if traveling at the same time

Internal radiation

Potassium40 Carbon14 Lead210 In addition to the cosmic and terrestrial sources, all people also have radioactive potassium-40, carbon-14, lead-210, and other isotopes inside their bodies from birth. The variation in dose from one person to another is not as great as the variation in dose from cosmic and terrestrial sources. The average annual dose to a person from internal radioactive material is about 40 millirems/year.

Gamma Knife

Procedure: Gamma Knife is a technique used to usually treat brain tumor. A Gamma ray emitting machine carries out the Gamma Knife technique. The machine concentrates the gamma rays from many different angles to the one point where the tumor is located. About 200 focused beams of gamma radiation is sent to a small target in the brain (tumor location). Since they come from many different angles the other tissues are spared. The helmet directs the beams to its location. Emitters such as cobalt are used to make gamma rays. Gamma knife is a safer alternative to surgery as it is non-invasive and has high penetration levels making it easy as it goes through the skull. This means that the skull would not need to be cut open to treat the tumor.

Carbon Dating

The amount of carbon-14 in the atmosphere has not changed in thousands of years. Even though it decays into nitrogen, new carbon-14 is always being formed when cosmic rays hit atoms high in the atmosphere. Plants absorb carbon dioxide from the atmosphere and animals eat plants. This means all living things have radioactive carbon-14 in them. When an organism, eg a tree, dies it stops taking in carbon dioxide. The amount of carbon-14 in the wood decreases with time as it decays into nitrogen with a half-life of about 5700 years. By comparing how much carbon-14 there is in the dead organism with the amount in a living one, the age of the dead organism can be estimated.

Terrestrial radiation

Radioactive material is also found throughout nature. It is in the soil, water, and vegetation. Low levels of uranium, thorium, and their decay products are found everywhere. Some of these materials are ingested with food and water, while others, such as radon, are inhaled. The dose from terrestrial sources also varies in different parts of the world. Locations with higher concentrations of uranium and thorium in their soil have higher dose levels.

Alpha

Relatively low penetrating power Contains 2 protons, 2 neutrons +2 charge particles travel short distances, have large masses only a hazard when inhaled

Biological Effects of ionizing radiation

Several things can happen when ionizing radiation hits a living cell: the cell is not damaged as the radiation passes through it the cell is damaged, but is able to repair itself the cell is killed The cell's DNA is damaged but remains able to reproduce itself, in its modified form. This cell could become malignant and turn into a cancer. If the cell is a sex cell, the radiation may cause a mutation in a gene. What actually happens to a cell will depend on depending on the absorbed dose of radiation, the type of radiation and the cell type.

How can chemists know if nuclei are unstable?

The ration of neutrons- neutron is the primary factor when determining atom stability Stable atoms are most likely not naturally occurring.

Dangers of ionizing radiation

When radiation collides with molecules in living cells it can damage them. This can cause a mutation. If the DNA in the nucleus of a cell is damaged, the cell may become cancerous. In this case the cell divides rapidly and causes serious health problems.

Radon

a radioactive gas

If the radioactive source is outside the body:

alpha radiation is not as dangerous because it is unlikely to reach living cells inside the body beta and gamma radiation are the most dangerous sources because they can penetrate the skin and damage the cells inside

If the radioactive source is inside the body, perhaps after being swallowed or breathed in:

alpha radiation is the most dangerous because it is easily absorbed by cells beta and gamma radiation are not as dangerous because they are less likely to be absorbed by a cell and will usually just pass right through it

Ion

atoms with a positive/negative charge

anion

gain electrons

cation

lose electrons

Background radiation

radiation coming from the environment. environmental sources can be both natural and man made.

Targeted Alpha therapy

targeted cancer therapies are drugs designed to interfere with specific molecules necessary for tumor growth and progression. Mainly aimed at microscopic residual disease offers the potential to inhibit the growth of micrometastases by selectively killing isolated and pre-angiogenic clusters of cancer cells. It is the process of emitting alpha particle radioisotopes to tumor carrier molecules selectively targeting cancer cells even though they are spread throughout the body The drug that carries the alpha emitters docks with the surface of the cancer cells,antigen, and shoots the alpha particle directly to their genes and destroy the cell. This process is known as the radioimmunotherapy, as it uses radioactive isotopes, the interactions between the antigen and the alpha resources. Antibody is attracted only to a specific antigen, the one on the cancer, and the metastatic cancers spread throughout the body. Lead -212 could the the alpha emitter that could be used for the treatment as it is short range and highly ionizing, emits more than one which suitable for the cell that is being targeted