Friday, August 10, 2007

Reliable old nuclear power!

An unexpected build up of algae on a lake-water intake system used for cooling has forced Ontario Power Generation to temporarily shut down one of its Pickering nuclear reactors until the fast-growing green muck is cleaned up.

Experts say bad-smelling blooms of Cladophora algae are linked to warmer water temperatures and are likely to get worse as a result of global warming and high phosphorous levels caused by lawn fertilizers, agricultural runoff and detergents entering the lake.
Any nuclear reactors built in Canada are, more than likely, going to be built along the great lakes (whose water levels are dropping and becoming warmer with climate change) or possibly along the Athabasca (which is similarly threatened.)

People don't think of the number of inputs nuclear power takes -- daily use of fossil fuels to mine uranium being just one, but also vast amounts of cold water for cooling. If the available water is too little, or too warm, the reactor has to shut down.

Solar and wind do not face similar constraints.


JimBobby said...

Whooee! Yer on the money a hunnert percent's worth, JohnnyBoy. Here in Nanticoke, they're talkin' about a new nuke plant. Lake Erie is the shallowest and warmest of the Great Lakes. Levels are dropping and by the time a plant could come online, levels and temperature could be inadequate -- especially in the warmest months when we need the most energy.

This issue with warm water i sonly compounded by using it to cool reactors and thereby heating the water directly. It is allowed to cool before being put back in the lake but it cannot be cooled to teh temp it was when drawn. The reason for that is that cooling water is taken from the coldest part of the lakes. The Nanticoke plant would require an intake pipe 30 km out into the middle of the lake to attaempt to draw cold enough water to cool the reactors.

Last year, a Michigan reactor had to be shut down because there was not enough cold water in Lake Michigan. Same thing in France in 2003 and 2006. Reactors had to be shut down and France had to import power because they didn't have cool enough river water.


scottie said...

I may be mistaken , but do they not use HEAVY water for cooling, NOT from the lake.

Adam said...

They use heavy water for some things, more directly with the radioactive parts of a reactor, but cool water is still used to provide adequate cooling in general. The heavy water has to be kept cool, for instance.

I'm worried someone will get the idea to build them on the coasts, and just run pipes down to the bottom of the ocean for cool water. Why worried? Well, if sea levels do rise, land will be difficult to maintain. Also, I live on a coast, and don't want a nuclear power plant nearby. Now wind and solar power, that sounds better. OR those cool floating windwill above water/turbine underwater combos they can put in strong tides/rivers.

scottie said...

I know the CANDU's use nohing but heavy water. I remember when the Bruce Reactor was built near Lake Huron, they had to get heavy water from Nova Scotia, at the time , Circa 1960. I lived about 12 miles away, but never afraid.

Jim said...

The latest CANDU design (ACR-1000) uses light water as it's main coolant. They talk this up in the literature as a two-thirds reduction in the amount of heavy water previously required by earlier designs.

Heavy water is used as a "moderator" - I'm not sure what that means.

John said...

Heavy water is used as a moderator, which means it controls the flow of neutrons in the reactor. It is not a coolant -- deuterium is expensive, and you don't send it up a turbine and out into the sky.

You still need steam to turn the turbine, so you get cheap cool water from a nearby lake or river (France has some ocean-front plants) and recycle the deuterium as much as possible.

john said...

Er, sorry. Deuterium is a coolant, but it doesn't get vented. It passes through a heat exchanger and heats the normal water.