EnviroLink Forum

The Chernobyl and Three Mile Island disasters in Russia and the US respectively are often argued as one-offs, but what is never highlighted are the smaller nuclear accidents that occur alarmingly on a regular basis at the world’s numerous power plants. Nuclear power plants and nuclear waste would be potential targets for terrorist attacks and if such attacks were to transpire.............

The irony of the matter is that uranium (the base element) is a depleting source of energy and may be used up in the next four to five decades.............
http://keelynet.wordpress.com/2008/06/07/don%E2%80%99t-overlook-downside-of-using-nuclear-power/



Nuclear generating plants are not benign. They use vast quantities of water, an increasingly scarce resource. For example, a plant in Georgia consumes 33 million gallons a day, returning 24 million gallons of heated water to the river, where it forms a thermal plume that alters the river ecology.

Future electric generation also should not rely on big baseload plants. It should combine locally produced bioenergy with solar, geothermal and wind power. The "intermittent and unpredictable" generation of electricity by solar and wind power, as Mr. Moore described it, can be mitigated by producing hydrogen locally and storing it in fuel cells to be used as needed.
http://www.washingtonpost.com/wp-dyn/content/article/2006/04/20/AR2006042001849.html

Useful info, Al. Two thumbs up!

nuclear power has by far too many downsides - I wish that mankind would stop using it

These were good threads, so I had to bump.

Would it be possible or advisable to cool nuclear plants with seawater?

It depends on the type of reactor. When the neutrons are going fast, they do not break uranium into two to release the energy. These neutrons need to be slowed down to make the reactor work. Carbon found in materials like slate rock were originally used to slow neutrons down but if the reactor starts working too much, the reactor gets too hot and a "melt-down" could occur. What ever is slowing the neutrons needs to be removed if things get too hot. "Heavy water" is a lot like regular water except the extra neutrons in the nucleus of either the hydrogen or the oxygen in the heavy water will slow down neutrons. If things get too hot, they can simply quit adding water and put air in instead, the steam leaves and the neutrons stay fast and no more nuclear divisions are happening and the melt-down is avoided. Because of this, reactors using heavy water are preferred (safer). The cooling towers are used to make the turbines more efficient because you want all the steam to turn back into water on the cool side of the turbine. This is usually accomplished with lake or sea water being poured over the pipes that contain the heavy water (heavy water is expensive and if the hydrogen is the heavy part, it is also toxic). Salt water that evaporates leaves salt which is a problem if it builds up so fresh water is preferred. On the other hand, if some other way is used to slow the neutrons down, then filtered salt water will work fine in a turbine and will also work fine pumping the turbine output into the ocean to eliminate the need for a cooling tower.

The best way to avoid a cooling tower (and all the water it needs) is to use "co-generation" where there is a use for the heat that is removed by cooling towers. This is done in Europe in some cities where the hot water is sold to heat houses and their hot water needs. Another thing that works is the use of heat pumps and if the heat pump is efficient, the energy used in the heat pump to cool is less then the energy gained in higher efficiency of the turbines by having the exit water/steam cooled.

Bump.

Cooling the Steam used in the turbine with salt water isn't a problem. Ships have been doing that for years.
But you would still have the same problems as with fresh water. Heated water changing the ocean near the plant.
A ship is (usually) moving and as such doesn't create the same sort of problems.

The reactors I have seen (naval) do not use the stuff in contact with the control rods to move the turbine. And any powerplants or propulsion machinery certainly do not use salt water in the turbine itself.

This is a fictional representation from the novel, Green Power, portraying the real accident that occurred at Rancho Seco Nuclear Power Plant exactly ten years after the Three Mile Island incident.
Prologue
March 28, 1989
Flashing red lights on the control panels and the annoying intermittent deafening blast of the buzzing alarms startled the technicians in Rancho Seco’s control room. Trained eyes zeroed in on the numerous gauges and banks of indicator lights. A supervisor burst out of his glassed-in office and yelled, “OK people! What do we have?”
Confusion broke loose as numerous responses overwhelmed the bewildered supervisor. He raised both arms up with palms out and shouted, “One at a time! Sam, you go first.”
A short, slim balding man in glasses yelled back, “John, we’ve got a big problem! If these readings are correct, the main feed water pump for the reactor coolant system has shut down.” Before he could continue, the room vibrated forcibly knocking coffee cups to the floor. More red lights on the many indicator panels started flashing.
“I’ve got an overload on turbine one! We’ve got automatic turbine shutdown taking place,” a technician reported.
The significance of this event triggered John’s analytical mind as he asked one of the female technicians standing in front of a wall of gauges, “Cindy, what’s the primary system pressure looking like?”
“ It’s rising, but the indicator light for the pilot-operated relief valve is green.” She replied. “It should be correcting itself, but I am still getting a reading for rising pressure.”
He turned to yet another technician and asked, “How’s the core temperature holding?”
“It’s approaching critical,” he answered.
Another voice interrupted. “I’ve got high radioactive reading for vented gases!”
John had enough information to know that a meltdown was imminent, but he was puzzled by why the automatic SCRAM (Safety Control Rod Axe Man) had not initiated the shutting down of the nuclear reactor. Therefore, he gave the order, “That’s it, let’s shut her down!”
With that order, technicians immediately went into an automatic mode themselves. This wasn’t the first time they had gone through this scenario. Each knew their role as they toggled switches into position. A manual SCRAM had to be initiated so that the control rods could be lowered into position starting the shut-down of the nuclear fission process.
Rancho Seco was once again off-line.

From all I've read over the past 15 years on them, new reactor designs are way safer than the ones running now, and the Nevada waste site is perfectly OK for very long storage of nuclear waste. It seems a segment of the environmental community is dead set against nuclear power and using the Nevada waste storage site. They have blocked usage of the site and the building of the newest design safe reactors.
This is really anti-environmental when using such plants and shutting down coal fired plants would be part of the solution for CO2 mitigation. Using cow dung for methane fired heaters and generators is fine as long as it is small scale and the end product is compost to replenish the soil growing the grasses and grains the cows eat. How about the energy needed to go out and scrape up all the cow pies in the fields? Usually, the cow pies break down and become part of the soil. The cow pies in the straw of the barn floors could be used without wasting energy out in the fields, with the end product being compost, and methane captured for energy, with a special sealed building for it.

BUmp.