36. Nuclear energy, which generates about 17 percent of world electricity supplies (roughly 6 percent of total energy consumption), is produced by enhancing the radioactive decay of naturally fissile materials to release energy. What is fissile? elements whose atoms can be split by thermal (slow) neutrons, releasing energy About 0.7 percent of natural uranium consists of the isotope uranium-235, which is fissile and is the most widely-used fuel in standard nuclear reactors. The remainder is the more stable uranium-238.

This is a "button" of bomb-grade uranium (about 90 percent U- 235), and it's worth considerably more than $60 a pound.

A nuclear reactor or nuclear power plant consists of nuclear reactor fuel, control rods, moderators, pressure vessels, coolant and containment.

37. To exploit this energy source, companies mine uranium ore and, by a process called uranium enrichment, increase the concentration of U-235 to about 4 percent. What is enriched uranium formed into? fuel rods or pellets fuel rods or pellets These are placed inside a nuclear reactor and bombarded by neutrons. This process causes U-235 atoms to split into two or more smaller atoms, called daughter products, and releases large amounts of energy. This process also releases excess neutrons, which split other U-235 atoms, causing a nuclear fission chain reaction.

Nuclear Fission Reaction Explained Video

Alpha particles are stopped by a sheet of paper and cannot pass through unbroken skin. Beta particles are stopped by an aluminium sheet. Gamma rays are stopped by thick lead.

The energy of the three radiations is absorbed by the material through which the radiation passes. The amount of energy which is absorbed depends on the type of radiation and the type of the absorbing material

Example:

An alpha particle, , is a helium nuclei. It has a mass number of 4 and an atomic number of 2. A beta particle, , is an electron. It has no mass, 0, and a charge of -1. Gamma, , is high energy radiation.

38. How do operators control the rate of fission? Operators control the rate of fission by using control rods and moderators that absorb excess neutrons and by adjusting the reactor temperature, which affects the reaction rate. Energy generated in the reactor heats water, steam, or some other fluid, which is pumped from the reactor and used to produce steam that drives electric turbines.

Nuclear operator, looks over the panels in the control room at the Crystal River Nuclear Plant, in Crystal River, Fla.

39. Nuclear power is a well-established method of electric power generation. Uranium is abundant, and a number of countries are making substantial investments in new nuclear power reactors. The United States has more than 100 licensed commercial nuclear power reactors, but no new reactor has been ordered since 1978, although interest has revived in recent years.

40. What are (2) major obstacles to the expansion of nuclear power worldwide? concerns about safety and high capital costs compared to other energy sources. What (2) accidents convinced many people that nuclear power was unsafe? Three Mile Island plant in Harrisburg, Pennsylvania, in 1979 and the Chernobyl reactor in Ukraine in 1986 What is a highly contentious issue in virtually every nuclear nation? Spent nuclear fuels remain highly radioactive for thousands of years, and finding appropriate sites to store radioactive waste is an issue.

It all was set off by an emergency water release valve that opened and failed to close and wasn’t identified or corrected by operators. The nuclear fuel overheated and ruptured metal tubes that lead to the partial meltdown. Three Mile Island, March 28, 1979, Pennsylvania

Chernobyl Nuclear Disaster April 26, Ukraine A 1200 ton cover of a reactor suddenly blast into the air. An ultra powerful stream of radioactive vapor released uranium and graphite into the air. By mid-2005, fewer than 60 deaths could be linked directly to Chernobyl.

41. In addition to environmental impacts, nuclear power also raises security concerns because of what? it produces two types of fissile material that can be used in nuclear weapons Low-enriched uranium is not usable for weapons but the same facilities can often enrich uranium to 90 percent U-235 or higher, and this highly enriched uranium is the easiest material from which to make a nuclear weapon.

North Korea nuclear weapons.

42. When nuclear fuel is irradiated in a reactor, a portion is converted to plutonium,, which is also fissile and, given somewhat greater skill on the part of weapon-makers than is needed for a uranium bomb, can also serve in the weapon role. Plutonium fuel cycles pose increased proliferation risks because plutonium can be stolen or diverted while it is being handled in bulk quantities during fuel processing.