Broad Based Technology Education

Introduction to nuclear power in New Brunswick:

Text Introduction:

Uranium, a natural mineral found abundantly in the earth’s crust (and especially in Saskatchewan), contains a small percentage of material useful for radioactivity applications. Uranium is dug up, purified, and sometimes enriched (to remove the parts that aren’t radioactively useful) and then loaded into fuel bundles for use in a nuclear reactor vessel. Radioactivity is initiated in the fuel bundles, which begin to emit radioactive particles and heat into neighboring fuel bundles and the surrounding cooling water. The heat is transferred into the cooling water. See Figure 1.

Figure 1. Schematic of a nuclear power plant. http://b-inet.com/intellect/technology/nuclear-reactor/

After contact with the fuel bundles, the heated water transfers its heat to a separate water cycle used to generate steam. The high energy steam is allowed to drop in pressure as it passes through a steam turbine. As it passes, its heat energy is transferred into motion by causing the turbine to spin. The spinning turbine causes a shaft to spin in an electric generator (which is the same electric generator technology seen in a wind turbine or almost any other electricity generation technology!) which generates electricity.

Nuclear power plants, because of their complexity and expense, are designed to be large. A typical new nuclear power plant is around 800 MW.  They depend on local geography only in that they require water for cooling the reactor (which can be sourced from a river or the ocean).

• Upfront Costs – Nuclear power plants are typically the most expensive electricity generation technology because of their complex engineering, thorough safety requirements, and technical know-how required to build and operate them. New nuclear power plants are around $5,000,000 per MW.
• Fuel Costs – Nuclear power plants enjoy low fuel costs compared to many generation technologies. Uranium is fairly abundant and costs around $0.20 per GJ (giga joule) of energy released.
• Flexibility on the grid – Because so many different components have to be heated up, and because the nuclear reactions have to be carefully controlled, nuclear reactors can take days to get to operating temperature from a state of total shut down. Similarly, their output can’t be changed very quickly, changing on the order of tens of MW/hour.
• Capacity Factor: In functioning electric grids, nuclear power plants have capacity factors in excess of 90%.
• Environmental Impact – There are little CO₂ emissions associated with nuclear power (because there is no carbon in the fuel), with 40 grams of CO₂ per kWh being common. Nuclear power plants using water to cool the reactor, thus, there can be disruptions to local ecosystems from warm waters; there is no radioactivity associated with the cooling water. The main environmental impact of nuclear power plants is the nuclear waste generated. Once a fuel bundle has been put through its useful life, it continues to emit harmful radiation for tens of thousands of years (although the intensity of this emission drops dramatically with time). It is most dangerous when immediately removed from the reactor. There are currently no “clean up” methods available to deal with the waste so it is stored in protective canisters on-site. A typical reactor generates around 27 tonnes of used fuel per year.