straight dope on some nuclear facts?

Factual Questions
1

So I’ve been discussing tipping points and climate change with a very intelligent friend of mine who lists some facts that I would like to throw to the masses.

• nuclear reactors take 40 years to build, so they can’t be a solution to climate change.
That seems absurd to me, I guess thats the time to get a new design approved. Whats the realistic time to build an approved proven passive safety design like CANDU?
If we had to phase out all coal power within 10 years could we build enough nuclear power stations world wide in that time using already existing tested designs that incorporate passive safety and cooling?

• Still no solution to Nuclear waste.
If we used CANDU which can reprocess light water reactor waste, whats the actual total volume of nuclear waste we’d be producing every year if we replaced coal with nuclear globally? Vitrification seems like a safe solution to me, any better options recently?

• All nuclear power is too dangerous.
Except as far as I know there has never been an accident with any CANDU reactor or a similar modern design that incorporates proper passive cooling and containment. Did I miss any?

Is there another design better than CANDU that has a proven track record (at least 10 years operation) that would be a better candidate if we globally wanted to replace all coal with nuclear?

BTW, the above is all factual questions about designs, construction periods, and accidents. I don’t want this to be a great debate, lets keep it in general questions.

2

Even with approval, I’m pretty skeptical of 40 years. Most of the units operating in the US were built before 1979, which is less then fourty years from the first operating plant.

There is one reactor in Tennessee being finished now thats taken forty years, but thats because the project was started and stopped due to economic factors, not because there’s any intrinsic reason it takes forty years to build a reactor. I suspect thats the source of the “forty years” figure though.

3

Let me add one more question. Has there ever been a significant accident with any nuclear reactor built within the last 20 years? Eg Commissioned after 1990 ?

4

I don’t think so. But then, I suspect the fraction of reactors that are younger then 21 years is pretty small (only one in the US), so I’m not sure you can really conclude anything from that.

5

This one’s easy: You put it in a big hole in the ground. That’s a lot easier than trying to find a solution for coal waste, which is far greater in quantity, and mostly gaseous.

6

So true.

When the NRC and EPA talk about problems at Yucca Mountain, they’re at the stage when they’re talking about things like “what happens if in one million years people don’t speak any known human language any more? How will we warn them about this giant hole of nastiness?” If we applied the same critical scrutiny to coal, it would be more like “what do we do about the fact that every single year this product kills thousands of people?”

7

We’re talking world wide. Ok I’ll relax it slightly, lets make it since 1980 that’s 30 years.
That then includes all of China’s reactors, most of India’s and many many others. See here:
http://en.wikipedia.org/wiki/List_of_nuclear_reactorsbook.com/NeochaEDGE?sk=wall

As far as I can tell there has not been one significant or even notable accident world-wide on any reactor built since 1980. Am I missing anything?

8

Only the obligatory observation on the awesome username/post combo. :cool:

9

Even the most strident anti-nuclear souirces admit that it takes just 7 to 12 years to build a nuclear power plant. However that is in the US, with US style regulations. China is projecting 2-4 years construction time for its next wave of nuclear plants. That is time from turning the first sod to the first consumer available power.

So yeah, nuclear power is the ideal solution to climate change.

Yes, easily.

As others have said, there’s a really simple solution: dig a big hole in outback Australia, throw the garbage in, cover the hole over. Problem solved.

This is one of those questions where the answer varies. However either way it is still orders of magnitude less than the amount of coal waste

There are two basic grades of nuclear waste. The vast majority of what we produce is low grade waste. It’s stuff like the overalls worn by the workers. These things become mildly radioactive with time, and because of regulations we dispose of them with great care. The waste is actually much less radioactive than your granite bench top, but because Americans have this unreasonable fear of the word “radiation” we ship the stuff in sealed drums, in bomb-proof trucks, with armed guards and bury the shit in a hole in the ground at great expense. It’s ridiculous that someone takes off their clothes, and the clothes are then stored in lead lined drums and treated like poison, but there you have it.

I don’t have exact figures, but if you count that low level waste, any plant will produce afew hundred tonnes of waste every year. In contrast a typical coal mine/plant system will produce abut 90 million tonnes of waste every year.

Except that nuclear power is demonstrably less dangerous.

Something like 250 people have died as a result of radiation exposure from the nuclear electricity industry in the entire history of the world. In contrast about 1, 000 people die every year as a result of radiation exposure from the coal electricity industry.

And that is just the radiation from the coal industry. By the time you factor in respiratory diseases, water contamination with hydrocarbon, deaths from coal mining and handling etc the death toll from coal mines is tens of thousands a year. Compared to at most a dozen individuals from nuclear power.

If you want to add in the effects of climate change, then coal can probably be tarred with hundreds of thousands of deaths a year, and climbing.

So it’s a bit silly claiming that coal is too dangerous.

Never mind CANDU. Chernobyl killed 64 people.

The worst nuclear “catastrophe” in the history of the world, and 64 people have died in the 25 years since.

In contrast about a thousand people died in coal mines in the past 12 months.

10

Nuclear power also has a better safety record than renewable power. The Banqiao Dam collapse in China during 1975 killed more than 170,000 people, vastly more than every nuclear power accident put together.

Per amount of power generated, nuclear even beats out wind and roof-top solar power. Since people occasionally fall off of wind towers while fixing them, or roofs while installing or cleaning the panels. Ground level solar edges out nuclear power, safety-wise.

11

I’m mostly in favor of nuclear power, especially when you do a numbers comparison as you did between the overall effects of coal vs. nuclear. And we’re gonna have to get energy from somewhere if we’re gonna continue a modern lifestyle.

But the above quote, IMO doesn’t address what makes people uneasy about nuclear power. Death is not the worst thing that can happen to you. People don’t like the idea of evacuating their city or their children being born with missing limbs or dying of leukemia. There was more to chernobyl than just ‘64 people dead’.

12

Far more people have been evacuated in far more countries over far more years and for far more time because of coal electricity disasters than because of nuclear electricity disasters.

Here are some typical examples, as youcan see, these events occur regularly even in the US, and always have. They are much worse in foreign coal electricity production schemes that are comparable to Chernobyl.

As already noted, coal power plants release far more radioactive material then nuclear powers plants. Not slightly more, but orders of magnitude more.

So coal electricity has already resulted in far more children being born with missing limbs or dying of leukemia than nuclear power ever could if we continue to use it for the next thousand years.

Indeed. And in terms of deaths, evacuation and congenital defects, coal is still orders of magnitude more hazardous than nuclear.

By any metric you care to name, coal is more dangerous than nuclear.

13

thanks for all the great information.

Can anyone specifically address the issue of whats the best specific current generation design with a proven 10 year track record built since 1980? Would that be CANDU or something else? Globally I mean.

14

The current designs can be build in 3 to 4 years. The real constraint isn’t construction time, but components. The reactor vessel is forged as a single piece and there are only a few plants that make those, so ramping up the infrastructure is the main problem. That is one of the reasons for the push to small modular reactors that can be build in a factory and delivered to the power plant site and don’t require huge forgings.

Replacing all the existing coal plants in 10 years isn’t practical or necessary. The important thing is to stop building new coal plants, I would be thrilled if we got rid of our coal plants in 50 years.

One interesting suggestion is to convert existing coal plants to nuclear by replacing the coal burning part with a nuclear reactor. I personally suspect that it will take too much engineering to adapt the reactor to the needs of each site, but it might work someplace where the coal plants are fairly standardized.

http://www.coal2nuclear.com/

The whole nuclear waste problem was created when our spent fuel recycling facilities were shut down. Here is a Google tech talk by Kirk Sorenson titled “Is Nuclear Waste Really Waste?”:

http://www.youtube.com/watch?v=rv-mFSoZOkE

Most of the rest of the rest of the spent fuel is actually valuable rare earths or fairly harmless. The hardest to deal with is the cesium-137. Sorenson suggests the CS-137 be used in Radioisotope thermoelectric generators (RTG). Since 1 gram of CS-137 contains 33kWh of energy and has a half life 30 years if can be used for a long term power source. In any case it is harmless in 300 years (10 half lifes).

15

I’m a fan of nuclear, but this isn’t really possible. You’d never be able to get the materials and qualified workers to build that many plants at once. You also would never be able to get enough regulatory approval.

Finally, it would push electric rates way to high. Your electric rates are basically broken down into 4 main components - fuel, operations and maintenance, administraive and general expenses, and return on capital. In most jurisidctions in the US all of these except for return on capital are ‘pass-thru’ expenses (the costs are passed on to the customers, but not profit is made by the utility).

The profit comes from return on capital. The utility will get a regulated rate of return on its assets, which is made up of mostly the generation plants and transmission & distribution network (along with some other things inventory, AFUDC, etc…).

A state commission will usually allow a return on equity of around 10 to 12 precent, grossed up for taxes. That means that in any given year, the utility will add about 10% of the net plant book number into the total demand revenue requirement.

BUT that net plant number is after depreciation. Most of the country’s coal fleet is heavily depreciated. The strategy in general is to space out new construction of generation assets so that ratepayers never experience too much of an increase at once on the asset side (the fuel side is tougher to control since commodities can be volatile and weather can fluctuate).

If you were to replace a bunch of coal plants that have depreciated to around a hundred million dollars with new nuclear that cost around 10 billion each. Well, not pretty. You get a huge savings in fuel costs - around 30 to 40 dollars per MWhr, but putting that much into rate base at once would just be way, way too expensive. You need to phase things out and build new nuclear over time letting one plant depreciate a little before bring on the next one.

eta: also, the utilities just don’t have the capital to actually build them - another little detail :slight_smile:

16

The “bury it in a great big hole in the ground” approach to nuclear waste ignores several considerations. First of all, a considerable volume of radioactive wastes comes not from spent fuel (in a once through cycle) but the processing operations to manufacture fuel, and this is not readily vitrified or otherwise stabilized. Second, the fuel we put through the reactor once has to sit in cooling pools for a number of years before it can be processed and shipped for disposal, so it isn’t as if spent fuel instantly disappears as soon as you pull it from service. Then there is the issue of monitoring; it is obviously easier to monitor leakage or heat build up and remediate issues in aboveground storage than when “disposed” several thousand feet underground. While underground may be away from people, it is also nearer to the water table and undetected geological faults. And finally, there is a lot of energy remaining in that “spent” fuel; in fact, the once through cycle produces only a fraction of the energy that can be obtained from [sup]235[/sup]U in a complete burnup cycle; we may at some point decide we need that waste as fuel. Vitrifying and burying underground makes it harder to recover and process.

I would agree that remediating waste from fossil fuel, and particularly coal burning (which also releases radioactive material into the environment) is overall more difficult than nuclear waste, but let us not minimize the issues with dealing with the wastes of the entire nuclear fuel cycle. There are inherent dangers in the use of nuclear fission (aptly described by the Los Alamos scientists as “twisting the dragons tail”) and we need to be aware of the costs and risks associated with them.

As for the safety of reactors, it is true that the CANDU is passively safe. This doesn’t make it immune from damage or hazard but does contribute significantly to its reliability. One the other hand, it produces tritium, which, should the reactor experience a core breach, will release highly ionizing radiation into the water supply. (Fortunately the quantities are relatively low and tritium can be removed and used for other industrial purposes.) CANDU also requires collecting or producing deuterium (heavy water) which adds to cost, and is far from the most efficient cycle. You also need to bear in mind that while the frequency of reactor accidents is (relatively) low, the criticality of such accidents can be extreme in terms of both cost and persistence in the environment, making them “black swan” events that “won’t happen” (per expert predictions) until they do. We tend to underestimate catastrophic events that we don’t fully understand or having experienced yet, and the design and operation of nuclear fission reactors is still not at a point that it can be considered a mature, statistically reliable technology.

I personally think that the high temperature inert gas (helium-cooled) reactor is a better way to go for the once through cycle, and the development of enclosed molten salt reactors with a complete burn-up cycle would be better. Nuclear fission should be considered a stepping stone to other methods of energy production such as more efficient PV solar or nuclear fusion.

Stranger

17

One problem with nuclear power is that every install seems to be a custom design, even with something like Candu. It’s not like they have a shelf design, and say “build me footings X by Y and plunk this design on it”.

In the early days, every Candu was a government project. Many were subsidized make-work projects, especially outside Ontario. I knew an old-timer who had friends working on the New Brunswick Candu. Obviously, the purpose of a project like that was to pour billions into the local economy, rather than build a power plant quickly and efficiently. Many of the workers were local, and trained to do work for that specific project - how skilled were some of these welders, considering the were trained so they could build the plant? Plus, he mentioned that since many knew the moment the plant was finished, the gravy train was over unless they moved west; they would do things like weld their tools into the piping, knowing that the safety Xrays would find these tools and they would be called back to cut them out and re-weld the pipes. IIRC that plant went way over budget.

If the industry wanted cheap, reliable nuclear power they would move away from massive power plants to arrays of small cores that could be mass-produced.

s for nuclear storage - even in “solid” rock, there are cracks and fissures that seep water, if you did not add to the situation by using explosives to make the tunnels for storage. Over tens of thousands of years, that seepage will recirculate to the surface. Nulcear waste therefore needs to be stored in a very dry area like desert - and preferably in a mountain that’s above water table.

Recall that part of the problem with the Japanese reactors was that they stored their waste in pools/tanks on the top floors of their buildings; they did not have the problems with waves washing it away, but they did have problems with cracked tanks draining all the cooling liquid. Plus, like much of the nuclear world, they do not have permanent dumps; most used fuel keeps piling up in “temporary” storage near the reactor, hoping that one day (after the current politicians have retired) someone else will make a decision where to permanently store it. So the problem with nuclear waste storage is we really don’t have any sites yet, and not everyone has a hug dry deset in the southwest like the USA.

The next problem is that once you operate a reactor, you’ve created contaminated material. If your reactor spring a leak, it’s not a matter of sending in a welder. SOme work may need to be done by remote control. If the reactor is a write-off as the Ukranian and Japanese ones are, It’s not like you can just cut it into truckable pieces and move them to a dump site. Even if a reactor just comes to normal end of life, how do you “decommission” it? 6-storey lump of concrete in the landscape? Does constant nuclear bombardment eventaully weaken the crystal structure and strength of metals? Can we expect reactors to be end-of-life long before similar coal and gas powerplants?

18

Sorry I’m aware that this is close to great debate territory but you are assuming “business as usual” thinking. My question was if there was unilateral political will to phase out coal in 10 years (assume scientific consensus that if we don’t then we’re facing a species extinction event), could we technically do it?

So forget regulation, it’s all done by pre-approved designs, CANDU or something better, and assume we throw manhattan project level resources at it. Could we do it?

19

I don’t think so - the supply chain just isn’t there. The industry isn’t built out to support so many builds at once.

20

Ok, so why the hell is this the case? Why can’t we have one standard design with the exact same safety features pre-approved and then duplicate it 1000 times? It doesn’t need to be perfect, it just needs to be “good enough”… eg multiple levels of both passive and active cooling and multiple containment levels.

As far as I know we reached this level of design sometime around 1980, but am I right to think that the issue is that the nuclear industry is still trying to get new designs approved (which takes decades) rather than rolling out mass copies of proven designs that have had no accidents?