Stories tagged nuclear power

May
13
2011

Actually, no.: Possibly not, anyway,
Actually, no.: Possibly not, anyway,Courtesy Garthhh
Don’t you hate it when someone tells you something, and you can’t tell them they’re wrong (just so you feel smarter than them, of course) because you don’t currently have any facts backing up your argument that they’re dumb, and maybe not a good person?

I hate that. I mean, I don’t even want to come up with an alternative argument in those situations—I just want the other person to know that they’re wrong. Again.

Example: You’re running your mouth around the fossil-fuels-aren’t-sustainable track, when someone says, “No, you’re right. They aren’t.” That, naturally, is a good start for a response, but then they go on to say, “And that’s why we have to get on the nuclear energy train, and we have to get on it hard. Done correctly, nuclear energy can provide lots and lots of clean energy, without the carbon emissions you hate. And we will no longer have to rely on foreign sources of oil. And blah blah blah. Check. Mate.”

And you just stand there, flapping your mouth open and shut, but no words are coming out, because you’re all out of words. Maybe you don’t even have anything against nuclear power—you just need to prove that person wrong. Who does he think he is?!

If a similar situation were to happen, except with, say, horse racing as the subject, you’d be back in your home town, Sit Creek, even though you hated it there so much, and you split as soon as you finished high school. Too bad for you. I can’t tell you anything contradictory about horse racing.

But if a similar situation were to come up, and the topic was nuclear energy, well, you’d be in luck. See a professor from the University of Adelaide just published a paper laying out exactly why nuclear power is not the solution to our future energy woes. Lucky, lucky you.

It’s not nuclear energy in general that the prof has a problem with, it’s that nuclear energy can’t be scaled up to replace fossil fuels (which will indeed need to be replaced eventually.) Doing so would be too expensive, require too many resources, and involve too much danger.

Today, we’re using about 15 terawatts of power around the world each year. That’s not just for electricity, it’s also for heat and transportation fuels and all that. But, at some point, we may be using electricity for those things as well.

Of those 15 terawatts, we generate about 375 gigawatts in nuclear plants—that’s just 2.5% of our global energy consumption. (Wikipedia puts the figure at 6%, but maybe that’s delivered energy, or something. Let’s leave it be for now.)

By this scientist’s estimates, we’d need 15,000 nuclear reactors going at once to produce 15 terawatts of power (and this is assuming that our power consumption doesn’t go up. Which it for sure will.). Given a nuclear power station’s lifetime of about 50 years, to maintain 15,000 working power stations, we’d need to commission a new plant and decommission an old one every day. And, currently, it tales 6-12 years to build a plant, and 20 or so years to decommission one. This would be very difficult and expensive to coordinate.

And it would take a lot of land—all those plants in the process of being built, run, and decommissioned would need about 8 square miles of land. That land would have to be near a large body of water, but also away from large population centers. Tricky.

And, says professor, at the rate we’re currently consuming uranium (our favorite nuclear fuel), it will only last for 80 years. Scaled up to 15 terawatts production, it would last for 5 years. We could potentially start extracting uranium from seawater, a source that could last for thousands of years, but that would be an expensive and energy intensive process itself.

And what of the spent fuel? We still don’t know what to do with it, and all that additional nuclear material (both fuel and waste) would almost certainly increase the proliferation of nuclear weapons around the world.

At any rate, the list goes on, long enough to allow you to shove the argument back into the hot, reeking mouth of whoever was sassing you in the first place. They might bring up technological advances (which the researcher sort of accounts for) or how people are always saying that energy sources, be they nuclear or renewable, aren’t globally scalable, or that presuming that we would use a single sort of energy production for everybody in the world, everywhere in the world, is probably silly … but they’ll probably be feeling so nonplussed in their oafishness that you will have plenty of time to make your escape and set yourself up in another conversation with a much easier opponent, like a child, or a table.

Good luck.

Mar
14
2011

The Fukushima plant: Before the earthquake.
The Fukushima plant: Before the earthquake.Courtesy KEI
Ok, well, there isn’t really such a thing as a nuclear earthquake. “Nuclear Earthquake” just sounds impressive. And I suppose “impressive” is one way to describe what’s happening in Japan right now.

I suppose you’re all aware of the 8.9 (or possibly 9.0) rated earthquake that hit Japan last week (if you aren’t, check out this post), and that the Fukushima nuclear power station there has been severely damaged.

While the country is still trying to put itself together, officials are still trying to get the power plant under control. So what happened, what’s happening, and what’s (probably) going to happen?

Well, a nuclear plant like Fukushima basically operates by using radioactive uranium to boil water. The uranium is always decaying—the number of protons and neutrons it has isn’t stable, so neutrons fly off, causing heat. If the neutrons hit other neutrons in the uranium, they fly off too, causing even more heat. If there’s too much of this neutron-on-neutron action, the uranium will get too hot, melt everything around it, and it’s a disaster. This is what happened at Chernobyl.

To prevent the neutron reaction from getting out of control, and to make sure the uranium produces just the right amount of heat, “control rods” are inserted in with the uranium fuel. The control rods absorb some of the neutrons to keep the reaction under control. When the right amount of heat is being produced, the water around the fuel boils, turns to steam, and spins electric generators. It works out pretty well.

At Fukushima, the control rods were inserted into the uranium as soon as the earthquake started, and they did work—the uranium reaction was shut down. But the decaying uranium had already produced other elements, elements with a lot of heat of their own. So there was a lot of residual heat in the power station.

Normally, water would keep circulating around the hot core, carrying away the residual heat (and turning it into electricity). But between the earthquake and the ensuing tsunami, the power to the water pumps was shut off and the backup generators were disabled. The pumps had backup batteries, but eventually those ran out. That means there was still a lot of heat in the core, but no fresh water to carry it away. The water that was there would continue to heat up until the steam was vented or the vessel containing it simply burst.

Unfortunately, both of those things sort of happened. While purposely venting some of the steam, an explosion happened in the building surrounding one of the cores. According to this site, this is probably because some of the vented water vapor had separated into hydrogen and oxygen, which built up in the building and ignited. This whole situation (the venting and the steam) was radioactive, but not that bad as those things go—the radioactive elements decayed and became stable in a very short time.

The next problem was that with all the venting, the water level around the cores was slowly falling. Without water to take away their heat, the cores could overheat, and eventually melt down. This started to happen, and some more dangerous radioactive products of the uranium started to mix with the remaining water and steam, so officials decided to start pumping seawater into the core. Seawater can get more radioactive than clean water, but it would keep the core cool and under control. And it did.

Today, there was a second explosion at the plant, however. I’m not totally sure what caused this, but it looks like it was again from the accumulation of hydrogen in one of the buildings.

With the uranium reaction under control and the cores under water, the residual heat should eventually dissipate. But the explosions have further damaged the cooling systems, and keeping the multiple cores at the station submerged in seawater has been a challenge. The longer the cores are exposed, the harder it is to control radioactive material already produced by the cores, and the greater the chance of a meltdown occurring at the plant.

Approximately 200,000 people living in the region of the nuclear plant have been evacuated, and it’s still unclear what will happen there. Nothing good certainly, but a meltdown isn’t a sure thing at this point, and even if a meltdown were to occur (again, a meltdown happens when there’s too much heat in the core, and everything around the radioactive fuel melts), the Fukushima plant was built to much higher safety standards than Chernobyl was, and it should contain the damage much more effectively. At Chernobyl, explosions sent radioactive material into the atmosphere and over the surrounding area. At Fukushima, as I understand it, the radioactive products of a meltdown would be contained inside extremely thick, tough containers, which, so far, have not been damaged by the earthquake or the explosions.

There’s more to be said about what will happen, and how this might affect the world’s attitude toward nuclear power, and whether that’s a good thing or not … but that will have to wait for another post.

Update: A Third Explosion at Fukushima
A there's been another explosion at the Fukushima nuclear plant. Now three of the four reactors at Fukushima have experienced an explosion. The previous two explosions were probably caused by a buildup of hydrogen, but it isn't certain whether that was the cause of this explosion as well.

The vents that emergency workers had hoped to use to flood the reactor chamber with seawater were malfunctioning, meaning that the core was dry (and un-cooled) for several hours. The vents finally started working in the early morning, but the chamber wasn't filling with water the way they had hoped, perhaps because of a leak.

A meltdown is still possible, but while radiation levels in the area are considered "elevated," they are low enough that it's very unlikely that the vessels that contain the reactor cores have been breached.

3/15/11 Update: Fire at 4th reactor
Shortly after the explosion at reactor 2 (the third explosion), a fire started at reactor 4. Between the fire and the explosion, radiation levels at the site briefly spiked to about 167 times the average annual dose. Reactor 4 actually wasn't producing power when the tsunami hit, but it did contain a cooling pool for spent fuel assemblies.

Nuclear fuel that has decayed to the point where it's not useful for sustaining a nuclear reaction still produces a lot of heat, and so it's stored in a pool of water for years to deal with the heat and radiation. Reactor 4 at Fukishima has one of these pools, and—just like with the active reactors—it looks like the cooling system was malfunctioning, which allowed the water in the pool to boil away, exposing the spent fuel. The spent fuel likely heated up until it ignited, or caused a fire in the building.

Authorities are now warning people living as far as 20 miles away from the plant to stay inside to avoid any radioactive fallout. As for the emergency workers at Fukushima, CNN's expert says, "Their situation is not great. It's pretty clear that they will be getting very high doses of radiation. There's certainly the potential for lethal doses of radiation. They know it, and I think you have to call these people heroes."

Update: 2 Reactor containment vessels probably cracked
Japanese officials think that the spike of radiation around the Fukushima plant last night might have been associated with a cracked containment vessel in one of the reactors. Today, they think a second container might be cracked as well, and leaking radioactive steam.

NOAA tsunami model
NOAA tsunami modelCourtesy NOAA
Some interesting scientific angles on the recent Japanese earthquake and subsequent human disasters:

Japan Does Not Face Another Chernobyl

Japan earthquake shortened days on Earth

Fukushima Nuclear Accident – a simple and accurate explanation. This post is long, but does a great job of explaining exactly how a modern nuclear reactor works, and how engineers plan for natural disasters.

NOAA models help predict the tsunami path after earthquake

Jul
15
2010

“…Welcome back, class. Please hand in your essays on the scientific fundamentals of phosphorus-driven eutrophication in the Gulf of Mexico, and note that our exam covering chapter eight, the Biogeochemistry of Acid Mine Drainage, will take place next Tuesday. Today we will be covering fluid bed catalytic oxidation, hazardous waste landfill leachates, and NIMBY. But, first, let’s take attendance: Bueller?... Bueller?... Bueller??”

Say what? “Nimby?” Girl, puh-lease! He just made that up… didn’t he??

It wasn’t long into my undergraduate stint as an Environmental Science major that I came across the word, “nimby.” Actually, it’s not a word at all. It’s an acronym, N.I.M.B.Y., standing for “Not In My BackYard,” that captures an important public attitude that affects environmental policymaking.

NIMBY explains many people’s attitude towards environmental policies, capturing sentiments like,

“That’s such a cool and important idea! As long as it’s not actually happening in my community, that is.”

“Whatever. I don’t care so long as I don’t have to see it everyday.”

NIMBY: Yuck.  Who wants to look out their bedroom window and see a mountain of trash?  Not these guys.
NIMBY: Yuck. Who wants to look out their bedroom window and see a mountain of trash? Not these guys.Courtesy The Voice of Eye

Think About It

Do you like having your trash removed from your home? Most everyone does. But, would you like having a landfill in your backyard? Almost nobody does. This is the classic example of NIMBY. Nearly everyone likes having their trash collected from their property and transported out of sight and smell, yet someone, somewhere has to live beside a mountain of trash. As long as we’re not the ones living across the street from the landfill, most of us are satisfied with this method of garbage disposal. The same idea goes for wastewater treatment facilities as well.

Another classic example is nuclear power. Some people support nuclear power as an inexpensive and “clean” alternative to fossil fuels like oil and natural gas. However, the construction, maintenance, and decommissioning of a nuclear power plant poses risks and creates radioactive waste. Whether or not you think the risks and waste production are acceptable consequences depends largely on your proximity to the plant and/or ultimate disposal site for the nuclear waste.

A recent example of NIMBY is occurring in California this summer as covered in Green, a New York Times blog. In a valley near Santa Clara, Martifer Renewables canceled their plan to build a hybrid solar power plant. Set on 640 acres of agricultural land, the plant was supposed to produce electricity by solar power during the day and biomass burning by night. How sweet is that?? A 24-hour source of renewable energy! The California utility PG&E thought it was a great idea too and signed a 20-year power purchase agreement for 106.8 megawatts, which became part of their energy portfolio. PG&E must obtain 20% of its electricity from renewable resources by December of this year and another 13% (for 33% total) by 2020, as mandated by California state energy goals. Now that the project is canceled, PG&E will have to look elsewhere for sources of renewable electricity or risk missing their mandated targets.

Regarding the canceled project, Martifer executive, Miguel Lobo, wrote in a June 17th letter that,

“We were not able at this time to resolve some of our issues regarding project economics and biomass supply amongst other things.”

What Lobo was likely referring to are the complaints of local residents and regulators who contested several aspects of the project. Chief amongst the complaints was the around-the-clock operation made possible by burning biomass. What exactly were they so excited about? Noise, waste, and air pollution – all realities of energy production, yet things we’d rather not experience ourselves. In short, NIMBY.

Alright, so what?

Now that I’ve opened your eyes to the existence of NIMBY, you might be wondering how it influences environmental policymaking. The easiest answer is that environmental policymakers seek to find a balance between the conflicting desires for new technology like this power plant and local opposition and the NIMBY attitude. Often both sides make compromises and projects move forward on a slightly different path than previously proposed. However, as in the California case of Martifer Renewables, occasionally a project is completely scrapped. Other times, the project proceeds as originally planned. Which of the outcomes occurs depends largely on the organization and influence of the local opposition. In turn, this often raises issues of environmental or eco-justice.

Clearly our modern society cannot exist without landfills or wastewater treatment facilities as smelly and unsightly as they may be. Whether or not nuclear or other renewable energy power plants are equally necessary today is debatable, but it’s not hard to imagine a future in which they will be. If no one agreed to have these facilities in their community, life as we know it would be very different. This begs the question: how do you think policymakers should balance the needs of society at large against the NIMBY attitude of locals?

Jan
11
2010

Radioactive Peace: With all countries taking from a nuclear fuel bank, no one country will have to enrich its own uranium.
Radioactive Peace: With all countries taking from a nuclear fuel bank, no one country will have to enrich its own uranium.Courtesy kso
Talk of nuclear power has been brought back into the spotlight, especially after the discovery of Iran’s uranium enrichment plant last September. A solution to the debate about whether countries should even have the capability of enriching uranium (the process required for attaining both nuclear energy and nuclear weapons) was posed more than 50 years ago by President Eisenhower. Eisenhower suggested that various countries should allocate uranium from their stockpiles for peaceful pursuits (i.e. nuclear energy). At the time it wasn’t received very well, but a recent BBC article reported that this vision has been renewed. As of November of last year, the United Nation’s International Atomic Energy Agency (IAEA) successfully negotiated with Russia to store 120 tonnes of nuclear fuel in a plant in Angarsk (a city in the south central-ish part of Russia). In 2010, similar arrangements are said to be made with Kazakhstan. The idea is to get developing countries that are thinking about using nuclear energy in the future to join in this program, eliminating their need to enrich their own uranium.

All of this got me thinking about how nuclear energy actually works. It turns out that nuclear power plants are not that different from regular coal-burning power plants. Both plants heat water to produce pressurized steam. This steam then drives a turbine, which spins a generator to produce electricity. The only difference between the plants is how the water is heated. Coal-burning plants…well, burn coal (fossil fuels) to produce the heat, while nuclear plants rely on nuclear fission. This is where nuclear power gets really cool!

So atoms are made up of protons, neutrons, and electrons; protons are positively charged, neutrons carry no charge, and electrons are negatively charged. Atoms have an equal number of protons and electrons (making the atom, itself, electrically neutral), but the number of neutrons can vary. Atoms of the same element with a different number of neutrons are called isotopes. The isotope of uranium that is needed for nuclear fission, and therefore, nuclear energy, is Uranium-235. This isotope is unique because it can undergo induced fission, which means its nucleus can be forced to split. This happens when a free neutron runs into the nucleus of U-235. Nuclear fission
Nuclear fissionCourtesy wondigama
U-235 absorbs the neutron, becomes unstable, and breaks into two new nuclei. In the process, two or three neutrons are also thrown out. All of this happens in a matter of picoseconds (0.000000000001 seconds)! The neutrons that are released in this reaction can then go and collide with other on-looking U-235 atoms, causing a huge chain reaction (much like this). The amount of energy released when this happens is incredible- a pound of highly enriched uranium has about the same energy as a million gallons of gasoline. This energy comes from the fact that the products of the fission (the two resulting nuclei and the neutrons that fly off), together, don’t weigh as much as the original U-235 atom. This weight difference is converted directly into energy. It’s this energy that is used to heat the water that creates the steam, which turns the turbine that spins the generator, that produces power in the nuclear reactor that Jack built.

On the plus side, with nuclear power there wouldn’t be a reliance on fossil fuels. Nuclear power plants are cleaner because they don’t emit as much carbon dioxide as traditional coal-burning and natural gas plants. However, there are some downsides as well. Mining uranium is not a clean process, transporting nuclear fuel creates a risk of radioactive contamination, and then there’s the whole issue with what to do with the still-dangerous nuclear waste once the fuel has been used up.

Whether or not we should increase our nuclear power program is still debatable, but one thing I do know is that the science behind it is fascinating!

A 6.8-magnitude earthquake shut down the Kashiwazaki Kariwa nuclear power plant, the world's largest in terms of electricity output resulting in a fire and causing a reactor to spill radioactive water into the sea. Associated Press via Yahoo News

May
01
2007

Some Science Buzz writers specifically go looking for science stories to write about. Then there are lazy folks like me, who just surf the web as per usual, and when something sciencey crosses our path, we bookmark it.

Over the last several weeks, I’ve been running across a lot of stories on energy. None of them seemed big enough to merit its own story, but they are too good to completely ignore. So, here’s a potpourri:

Recycling nuclear waste

America’s energy needs keep growing. Producing energy by burning coal or oil pollutes the environment. Nuclear energy is much cleaner, but it produces radioactive waste. Now a government-funded project in Tennessee is trying to recycle the waste from nuclear power plants to produce a new type of fuel—one that could produce up to 100 times as much energy, and produce 40% less waste.

Gassification

One old technology that may be making a comeback is gasification—turning organic material, such as coal, into a gas which can be burned for energy. It’s cleaner than burning coal directly for energy—a lot of the pollutants are captured and re-used. And, you can gasify any organic material, including plants and farm waste.

The problem with ethanol

In other threads on this blog, we’ve discussed some of the downsides of ethanol-- increased demand for corn causes farm prices to shoot up. A report from Brazil outlines some of the other potential problems, from pollution created in its manufacture, to destroying large ecosystems to raise the crops that will be turned into ethanol.

Oil shale

When drillers go looking for oil, they look for large pockets of liquid trapped in the earth, surrounded by non-porous rock. This is sometimes called “easy oil”—ready to refine as soon as it comes out of the ground. But there are vast amounts of oil in porous rock, like sand or shale. Miners have to dig up vast amounts of oil-soaked rock, and then separate the usable oil from the sand. It’s a very expensive process. But, as the price of crude oil keeps climbing, we are getting to the point where shale oil makes sense. And what’s even better, some of the largest deposits in the world are found here in North America.

The article linked above describes a shale oil operation in Canada. There are also operations underway in the
United States. And there’s another project underway in Israel.