With the horrific events that have occurred in Japan this past week one can only wonder what future nuclear power has in the United States. Other countries such as China and Germany have already announced a planned decrease in the use of nuclear power. In the United States these events have caused us to focus on our own nuclear policies while sparking a heated debate. Questions such as: "Is nuclear power too dangerous?" and "Should Japan's emergency prevent the future construction of U.S. reactors?" are leading many to re-examine the nuclear issue to a degree not seen since the early 80's (think No Nukes concerts and Jane Fonda starring in The China Syndrome movie).
Essentially our issue comes down to "Are we safer using nuclear power with a more careful approach or are we safer relying on foreign oil and all that encumbers it."
Currently, the United States produces 28% of its daily power needs from nuclear power. Some countries in Europe such as France produce closer to 75% of their daily usage.
The real question is - if we pullback on our use of nuclear power; what resource will replace it?
Please read our "nuclear power primer" below and post your questions, comments and thoughts here.
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. The most common use of nuclear reactors is for the generation of electrical power and for the power in some ships. Heat from nuclear fission is used to raise steam, which runs through turbines, which in turn powers either ship's propulsion or electrical generators.
Fission - When a large fissile atomic nucleus such as uranium-235 or plutonium-239 absorbs a neutron, it may undergo nuclear fission. The heavy nucleus splits into two or more lighter nuclei, releasing kinetic energy, gamma radiation and free neutrons; collectively known as fission products. A portion of these neutrons may later be absorbed by other fissile atoms and trigger further fission events, which release more neutrons, and so on. This is known as a nuclear chain reaction.
The reaction can be controlled by using neutron poisons, which absorb excess neutrons, and neutron moderators which reduces the velocity of fast neutrons, thereby turning them into thermal neutrons, which are more likely to be absorbed by other nuclei. Increasing or decreasing the rate of fission has a corresponding effect on the energy output of the reactor. Commonly used moderators include regular (light) water (75% of the world's reactors) solid graphite (20% of reactors) and heavy water (5% of reactors). Beryllium has also been used in some experimental types, and hydrocarbons have been suggested as another possibility.
The energy of fission products is converted to energy when nuclei collide with nearby atoms.
Some of the gamma rays produced during fission are absorbed by the reactor, their energy being converted to heat. Heat produced by the radioactive decay of fission products and materials that have been activated by neutron absorption. This decay heat source will remain for some time even after the reactor is shut down.
A nuclear reactor coolant — usually water but sometimes a gas or a liquid metal or molten salt — is circulated past the reactor core to absorb the heat that it generates. The heat is carried away from the reactor and is then used to generate steam. Most reactor systems employ a cooling system that is physically separated from the water that will be boiled to produce pressurized steam for the turbines, like the pressurized water reactor. But in some reactors the water for the steam turbines is boiled directly by the reactor core, for example the boiling water reactor.
The power output of the reactor is controlled by controlling how many neutrons are able to create more fissions. Control rods that are made of a nuclear poison are used to absorb neutrons. Absorbing more neutrons in a control rod means that there are fewer neutrons available to cause fission, so pushing the control rod deeper into the reactor will reduce its power output, and extracting the control rod will increase it.
In some reactors, the coolant also acts as a neutron moderator. A moderator increases the power of the reactor by causing the fast neutrons that are released from fission to lose energy and become thermal neutrons. Thermal neutrons are more likely than fast neutrons to cause fission, so more neutron moderation means more power output from the reactors. If the coolant is a moderator, then temperature changes can affect the density of the coolant/moderator and therefore change power output. A higher temperature coolant would be less dense, and therefore a less effective moderator.
In other reactors the coolant acts as a poison by absorbing neutrons in the same way that the control rods do. In these reactors power output can be increased by heating the coolant, which makes it a less dense poison. Nuclear reactors generally have automatic and manual systems to insert large amounts of poison (often boron in the form of boric acid) into the reactor to shut the fission reaction down if unsafe conditions are detected or anticipated.
BIG Unveils A Green-Roofed Ice rink that is outright cool.
Taking cues from the natural landscape of a bowl-shaped site, BIG carves out a nice spot for an underground ice rink. Naturally lit from the south, the rink enjoys bright daylighting on the interior and the adjacent amphitheater park becomes a protected area to enjoy the out of doors. The green-roofed Ice Hockey Rink in Umeå in northern Sweden is all about combining recreational programs maintaining the existing natural qualities of the site.
The existing site is a naturally recessed bowl and BIG takes the concept and extends it further by sinking the ice rink into the bowl and covering it with a green roof. Facing the south, a huge east-west window naturally lights the interior of the rink and lets people on the outside see the ice hockey action inside and vice versa. A corner of the rink is peeled up to a small peak to act as a landmark and entrance facing the street. The green roof also becomes an extension of the adjacent Umedalen Sculpture Park.
Open to the public, the ice rink and surrounding park become a year round recreational facility, and in the summer the recessed bowl becomes an amphitheater for concerts and plays, and the windows of the rink open up to create a stage. Ramps allow wheelchair and stroller access down to the bottom of the bowl and inside the rink. The 4,600 sq meter ice rink includes a variety of different user spaces including a cafe, outdoor seating, a bonfire area and winter sliding zone...read on
Who is the hottest young architect to watch? What are the best big and small architecture firms? Who are the best promoters of design, be it websites, twitter or Tumblrs? Design isn't just about buildings; it's part of everything we do, everywhere we go.
Weigh in before 11:59pm EDT on Friday, April 1 and decide on your favorites for TreeHugger's annual Best of Green Awards in the Design and Architecture category.
7 Intoxicating Green Booze Design Stories for St. Patrick’s Day - Happy St. Paddy's Day everyone! Today's holiday is definitely an homage to Ireland, but there's no denying that it also pays tribute to something a little more universal - booze. And while you may be thinking "What the heck does alcohol have to do with green design?" there are actually a keg's worth of hooch-related eco innovations out there that you might not know about yet. From a man that recycles his own pee into whisky to a machine that turns beer brewery waste into power, read on to see the best boozy green stories we have on tap...read on
Q and A on the Nuclear Crisis in Japan - New York Times reporters answered questions from readers about the continuing nuclear crisis in Japan. Readers asked about media coverage of the crisis, health risks from radiation exposure, problems with the reactors and nuclear waste, the workers at the plant, comparisons to Chernobyl and the danger of building nuclear power plants in earthquake-prone regions...read on
EPA Announces U.S. Cities with the Most Energy Star Certified Buildings / Third annual list shows dramatic growth, savings of energy efficient buildings - The U.S. Environmental Protection Agency (EPA) is releasing a list of U.S. metropolitan areas with the greatest number of energy-efficient buildings that earned EPA’s Energy Star certification in 2010. The list of 25 cities is headed by Los Angeles; Washington, D.C.; San Francisco; Chicago; New York; Atlanta; Houston; Sacramento; Detroit; and Dallas-Fort Worth. The growth in Energy Star certified buildings across the country has prevented greenhouse gas emissions equal to the emissions from the energy use of nearly 1.3 million homes a year, protecting people’s health, while saving more than $1.9 billion...read on
Direct FuelCell Power Plant Operational by End of 2011 - FuelCell Energy’s 300 kilowatt DFC300 has been sold and is ready for its installation in Central London’s Regent Street at a re-developmental project titled Quadrant 3. The Crown Estate is developing an area spread over 250,000 sq.ft. for residential, office as well as retail use. While it will incorporate sustainable energy such as fuel cell power and use modern day technology, the project will retain the location’s historical character...read on
Local Law 84 - The Deadline is coming!
All buildings in New York City over 50,000 square feet are required to submit an annual energy benchmark. We're here to help make it as easy as possible for you to meet this requirement, while putting a valuable financial evaluation tool in your hands.
Building owners and operators are growing more concerned with the upcoming deadline to have their properties properly benchmarked. Professionals in the industry are reporting a sharp increase in the RFQ's for building benchmarking. What surprises most industry professionals is how easily and quickly these buildings can be benchmarked - assuming of course you hire the correct professionals.
Benchmarking is easy-to-do, inexpensive, and accessible. In addition to supporting the requirement, we can provide intuitive monthly reports on your energy usage and spotlight opportunities for energy savings. The first benchmark report is due to the city on May 1, 2011, but there are benefits to starting as soon as possible so that you can take control of your energy usage sooner.
Own buildings in New York City? Let us help you comply with NYC's new mandatory benchmarking requirement (Local Law 84).
Click here to find out more information about benchmarking and complying with the LAW!
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