Hydroelectric Power Stations and Doomsday What Ifs

[caveat]

In the event that a vast majority of the human population is wiped out, how long would you expect a country living mostly on hydroelectricity to lose all power?
I guess my question is really how automated is a hydroelectric power station? Are the people there mainly for maintenance or are there more "buttons to push" than one would expect?

[Bluevision]

Oh god, this reminds me of a book I was forced to read that I found quite dreadful. The main premise was that the main characters had to open the flood gates for the hoover dam in a post-plague apocalypse world, or else the overflow water would erode the dam and eventually destroy it.

I'm quite sure that it's all automated, and the supply of water is endless (well, depends on how humans were wiped out, but assuming climate patterns aren't changed majorly.) A quick Google search finds that hydroelectric power stations are built for their core components to last for 70 years, though efficiency might be lost with damaged parts. I do recall though that new power plants (this was in Brazil, so I can't be sure,) are built to closer to 110-130 years. The dam structure itself can pretty surely last for much longer, but the components would run out.
However, I know that they require pretty constant maintenance. Whether that's to maintain maximum efficiency and safety or to prevent catastrophic failure, I don't know.

If the plant is automated (which I assume they are,) it would shut off some turbines completely if demand was reduced considerably (i.e. 99.99% of the world dies.) In that case, some turbines would be almost untouched as others die. If the dam was still somewhere around "structurally sound," it might take some manual overriding, but the old turbines could probably be closed and the "new" ones open.

I know it's a what if question, but I'm curious as to how this came about

[joema]

In the event that a vast majority of the human population is wiped out, how long would you expect a country living mostly on hydroelectricity to lose all power?
I guess my question is really how automated is a hydroelectric power station? Are the people there mainly for maintenance or are there more "buttons to push" than one would expect?

This was addressed by the National Geographic TV series Aftermath: Population Zero: http://channel.nationalgeographic.co...tion-zero-3225

I don't remember the exact details but in general the electrical distribution grid requires a significant amount of manual control. It has nothing to do with the power sources such as hydroelectric. Within about 24 hours the grid would collapse and there would be no power, even if hydroelectric turbines were still turning locally at each site.

It's also likely each nuclear plant would eventually melt down and become something like Chernobyl. Science fiction typically depicts the "last man on earth" wondering through a decaying, moss-covered civilization as he looks for food, runs from vampires, etc. In reality he'd be at great risk of lethal environmental contamination from all the industrial plants which quickly failed without human oversight. Think of a combination of Chernobyl plus the Union Carbide Bhopal disaster multiplied by a thousand times: http://en.wikipedia.org/wiki/Bhopal_disaster.

[Nowhere Man]

The Straight Dope addressed this question. Not only hydro, but also electric plants of all types. It would take about a week for most of the continent/world (depending on the spread of the zombie plague) to go dark.

Fred

[Maha Vailo]

This was addressed by the National Geographic TV series Aftermath: Population Zero: http://channel.nationalgeographic.co...tion-zero-3225

I don't remember the exact details but in general the electrical distribution grid requires a significant amount of manual control. It has nothing to do with the power sources such as hydroelectric. Within about 24 hours the grid would collapse and there would be no power, even if hydroelectric turbines were still turning locally at each site.

It's also likely each nuclear plant would eventually melt down and become something like Chernobyl. Science fiction typically depicts the "last man on earth" wondering through a decaying, moss-covered civilization as he looks for food, runs from vampires, etc. In reality he'd be at great risk of lethal environmental contamination from all the industrial plants which quickly failed without human oversight. Think of a combination of Chernobyl plus the Union Carbide Bhopal disaster multiplied by a thousand times: http://en.wikipedia.org/wiki/Bhopal_disaster.

Would a region that lost, say, 80% of its people have the same problems with power plant shutdowns/meltdowns and chemical plant explosions as a world without people would? I'd like to know this so I can determine just how crapsack my new RPG campaign really would be.

- Maha Vailo

[cjl]

It's also likely each nuclear plant would eventually melt down and become something like Chernobyl. Science fiction typically depicts the "last man on earth" wondering through a decaying, moss-covered civilization as he looks for food, runs from vampires, etc. In reality he'd be at great risk of lethal environmental contamination from all the industrial plants which quickly failed without human oversight. Think of a combination of Chernobyl plus the Union Carbide Bhopal disaster multiplied by a thousand times: http://en.wikipedia.org/wiki/Bhopal_disaster.

The design and containment structure of modern reactors should prevent that level of distaster from happening. The reactors might (eventually) destroy the cores, but it should remain entirely self contained, rather than a complete contamination like Chernobyl was.

[geonuc]

The design and containment structure of modern reactors should prevent that level of distaster from happening. The reactors might (eventually) destroy the cores, but it should remain entirely self contained, rather than a complete contamination like Chernobyl was.

Yes, essentially correct. Perhaps not entirely contained - there would be some venting to atmosphere, I would imagine.

[mugaliens]

If 50% of humans simply vanished, with no damage to buildings or the transportation infrastructure, they'd get by on a skeleton crew until augmentees could be found to fill in the gaps. Many of those would simply come out of retirement. The rest would come from either parasitic or service jobs which would fold overnight. A burger king on every block becomes pointless when it requires electricity and natural gas that won't get there if people don't throw their backs behind keeping the infrastructure alive.

If it were closer to 90%, then you'd have a critical loss of intellectual wealth, but you'd also have less infrastructure to support, as well. That would definately be a national crisis, and well worth it to aggregate the population so as to minimize infrastructure requirements. Abandon suburbia and move to the cities. Simply cutting off electricity and gas to the suburbs would be incentive enough for most to move.

[joema]

The design and containment structure of modern reactors should prevent that level of distaster from happening. The reactors might (eventually) destroy the cores, but it should remain entirely self contained, rather than a complete contamination like Chernobyl was.

For the currently-operating pressurized water power reactors, the containment is NOT designed to prevent this in the total and continuing absence of power and human oversight. In theory you could design a passively safe reactor which could sustain this, but currently operating reactors are NOT of this design.

Current reactors would autonomously shut down (scram) but they can't be turned off like light. Even in the scrammed state, the core would continue to generate large amounts of waste heat, which can ONLY be removed by active cooling (pumps, valves, etc). Those cooling systems are dependent on power, normally supplied from OTHER power plants via the utility grid. If that isn't available, on-site diesel generators provide power until the fuel runs out -- about one week. After that the reactor core would be uncooled. It wouldn't explode like Chernobyl, as that didn't even have a containment vessel. But containments are not designed to permanently endure an uncooled reactor with no external power and no human intervention.

But -- whatever happens to the core itself is almost immaterial. There's a spent fuel storage pool adjacent to each reactor. These hold the fuel rods, after being removed from the core. The rods are both radioactively and physically hot. They require water immersion and continuous cooling. The storage pools aren't passive tanks, but require active waterflow.

In the absence of humans, the diesel fuel powering the cooling pumps on the spent fuel tanks would be exhausted in about a week. When the pumps stop, the decay heat boils the water away, the zircaloy-clad fuel rods would melt and catch fire, then the entire spent fuel building. It would be exactly like a containment breach, as the rods in the pool are the same as those in the core. Radioactive smoke from the burning waste products would rise into the atmosphere. In the U.S. that would happen at about 100 different plants.

Re hydro power without human oversight, this exact question was put to the manager of Hoover Dam. He said if everybody suddenly vanished, the dam would probably continue generating power for months, theoretically even years. By contrast fossil-fueled plants would shut down within hours or days from lack of fuel: http://www.youtube.com/watch?v=rICDy...eature=related

However the Hoover Dam manager said after about a year, aquatic mollusks would likely build up in cooling pipes for the hydro generators. This in turn would trip high temperature limits, causing an automatic generator shutdown. We often forget how dependent on maintenance our industrial systems are.

But as we've seen from widespread power outages, the utility grid requires constant human management and oversight. Within a day to a week, the entire grid would probably collapse. Whether a few isolated hydro generators were turning or not, the power wouldn't get to you.

Instead of worrying about zombies, our intrepid "last man on earth" should have a map of each nuclear plant location and a weather chart of prevailing wind patterns, and stay far away from those.

[geonuc]

But containments are not designed to permanently endure an uncooled reactor with no external power and no human intervention.

Maybe not, but the containments are fairly robust and are probably sufficient to contain the core given a seven day run on the EDG's. The TMI-2 containment did pretty well.

[caveat]

Sorry I had forgotten to even check on that thread. Some very interesting answers as always.

I know it's a what if question, but I'm curious as to how this came about

Well like all my questions on this board so far, this is for a fiction I am writing. It's a good old zombie apocalypse, and the story follows a small group that finds shelter in a shack that was built exactly for a situation like that. It runs on solar panels and generators, but I was wondering whether or not that was necessary, thought maybe the hydroelectric plants would run themselves. However some very good points were brought about powergrid and and such. Thanks guys.

[jj_0001]

If it were closer to 90%, then you'd have a critical loss of intellectual wealth, but you'd also have less infrastructure to support, as well. That would definately be a national crisis, and well worth it to aggregate the population so as to minimize infrastructure requirements. Abandon suburbia and move to the cities. Simply cutting off electricity and gas to the suburbs would be incentive enough for most to move.

Just pointing out that this might not be the wise move, depending on WHY 90% of the people are gone. There might, in such cases, be some wisdom in very wide geographic diversity, yes?
http://en.wikipedia.org/wiki/Diversity_scheme

Also, somebody would still have to grow food.