88 protons

What change in atomic number occurs when a nucleus emits an alpha particle ? A beta particle? The atomic number is reduced by two in an alpha decay. The atomic number is increased by one in a beta decay.

What are the life stages of a high-mass star? A high-mass star lives a much shorter life than a low-mass star, fusing hydrogen into helium via the CNO cycle.

Which produces more radioactivity in the atmosphere: coal-fired power plants or nuclear power plants? Coal-fired power plants produce more atmospheric radiation than nuclear power plants. Global combustion of coal produces about 13,000 tons of radioactive substances; nuclear plants produce about 10,000 tons.

As a general clarification, ounce for ounce, coal ash released from a power plant delivers more radiation than nuclear waste shielded via water or dry cask storage.

In fact, the fly ash emitted by a power plant — a by-product from burning coal for electricity — carries into the surrounding environment 100 times more radiation than a nuclear power plant producing the same amount of energy.

The radioactivity comes from the trace amounts of uranium and thorium contained in coal. These elements have been trapped in the Earth’s crust since its formation and are usually in concentrations too low to pose any serious threat.

Terms in this set (21)

• Meltdowns, terrorists & nuclear waste. The three main dangers of nuclear power:
• Reactor, generator & cooling towers. The three main parts of a nuclear power plant:
• Neutron.
• 1; more.
• 10,000 years.
• Kill; cancer.
• Concrete & stainless steel.
• Dry site, remote location & stable rocks.

Coal ash is commonly re-used in a number of ways. For example, it is used as structural fill or fill for abandoned mines; as a top layer on unpaved roads; as an ingredient in concrete, wallboard, and in school running tracks; as an agricultural soil additive; and as “cinders” to be spread on snowy roads.

The official line on adding coal or smokeless fuel ash to the garden and particularly the vegetable plot, is don’t do it. Apparently the ash can contain trace elements of arsenic and metals such as cadmium, iron, lead, zinc, aluminium and so forth.

During coal combustion, large amounts of ash are created along with carbon dioxide and other gases. The fine particle ash that rises up with the flue gases is known as fly or flue ash while the heavier ash that does not rise is called bottom ash; collectively these are known as coal ash.

Fly ash use in concrete improves the workability of plastic concrete, and the strength and durability of hardened concrete. When fly ash is added to concrete, the amount of portland cement may be reduced.

Percentage of water absorption in both fly ash and wood ash replaced cement mortar bricks increases as the percentage of fly ash and wood as content varies from 10 to 50%. It is also absorbed that fly ash replaced cement brick has less water absorption compared to the wood ash replaced bricks.

One of the major concerns with fly ash disposal is the leaching of heavy metals to. underground water sources; arsenic, antimony, lead, cadmium and other toxic. metals may be contained within the waste, as shown by the average composition.

Fly ash particles (a major component of coal ash) can become lodged in the deepest part of your lungs, where they trigger asthma, inflammation and immunological reactions. Studies link these particulates to the four leading causes of death in the U.S.: heart disease, cancer, respiratory diseases and stroke.

1 Moisture must be avoided in a dry handling system, since many fly ashes are hygroscopic and will react with water. If moisture is inadvertently added, caking, agglomeration and build-up can occur. Fly ashes are well known for their cementitious properties and are often used in low strength concrete mixes.

Fly ash is produced by coal-fired electric and steam generating plants. Typically, coal is pulverized and blown with air into the boiler’s combustion chamber where it immediately ignites, generating heat and producing a molten mineral residue.

Fly ash is a particulate material produced from the combustion of coal in thermal power plants.

Fly ash is left behind when coal is burnt. Coal-fired power plants are the biggest sources of fly ash, which contains toxic chemicals such as arsenic, barium, cadmium, nickel and lead, among others. These are known to cause cancer, lung and heart ailments and neurological damage, and contribute to premature mortality.

Concrete is susceptible to damage from freeze/thaw cycles if it does not contain air. Fly ash reduces the amount of air entrainment, and concrete mixtures high in fly ash often require more air-entraining admixture.

Because fly ash is less expensive than cement, mixes containing it are usually a bit less expensive than their straight cement counterparts. Fly ash mixes are often called “performance mixes”, so-called because of how they perform.

Owing to its pozzolanic properties, fly ash is used as a replacement for Portland cement in concrete. In some cases, fly ash can add to the concrete’s final strength and increase its chemical resistance and durability. Fly ash can significantly improve the workability of concrete.

Experimental results indicated that the substitution of fly ash consistently decreased the drying shrinkage relative to ordinary concrete; a substitution level of 25% optimally reduced the drying shrinkage by 20.81%.

The major difference between fly ash and portland cement is the relative quantity of each of the different compounds. Portland cement is rich in lime (CaO) while fly ash is low. Fly ash is high in reactive silicates while portland cement has smaller amounts. The table illustrates the basic chemical difference.

It is found that up to 100 % replacement of Fly ash aggregate is can be utilized in the production of concrete. The mechanical properties and durability properties of cement bonded fly ash aggregate concrete is studied.

Both class C fly ash and slag have about 35 percent silica and much lower calcium oxide than portland cement. In most cases, lower calcium oxide means better durability. In some fly ash, alumina and iron oxide can be quite high, leading to lower strength and unusual setting time problems.