Is the nuclear renaissance dead yet?

[jsbiff]

As you may be aware, there was a reactor in Gabon at a place called Oklo which was decommissioned some years back. The radioactive waste was left in situ exposed to ground water. Most significantly, transport of radioactive isotopes did not render the surrounding countryside a sterile wasteland. The reaction products were rendered harmless by mere passage of time. http://en.wikipedia.org/wiki/Oklo

In the second link in my top post (the one I added as an update), the author of that paper argues that the actual risk of harm due to environmental release and radiation exposure might be overstated a bit, and the public may be a little too afraid. I'm not entirely sure I buy the argument though.

For one thing, what type of radioactive waste are we talking about here? Actual spent uranium fuel? Coolant (or other plant materials) that might have become slightly radioactive due to contact/proximity to the fuel, but is much much less dangerous than the spent fuel?

I'll have to read up on the Oklo link you provided, but my gut reaction is that, even if eventually the exposure level isn't that bad, that you would still have problems during the 'initial' lead event - because the radioactive materials will be more concentrated in smaller spaces, meaning any organism which happens to be sufficiently near to the more highly concentrated release, may still be at risk.

In any case, all of the warnings we get about radiation exposure must have some basis in science? I mean, it can't possibly be that for 30 years we've been afraid of nothing? There must be some scenarios where, e.g. release of core fuel material into the air or ground water, the dangers are very real?

[Tom Ligon]

Sure, the dangers of radiation and radioactiive materials are well-studied. But the subject is moderately complex, and all most people know about it is what they pick up from the movies (mutations causing monsters, horrible deaths, etc) and the news (the media just love the heck out of hyping up actual risks to exaggerated versions of worst-case).

So when a nuclear plant has a leaky pipe joint that spills a liter of mildly contaminated coolant we'll get news reports of "radioactive spill at the South Podunk reactor! Emergency cleanup underway, federal investigators on the way."

During Three Mile Island the precautions they were taking in the event the release of radioactive material actually became serious were jumped on by the press. They loved the worst-case possibilities, and seemed rather disappointed when the event did not result in China Syndrome.

Not that a bad reactor accident can't be really bad. Chernobyl was pretty horrific.

[ladajo]

and a completely different animal. Graphite Moderated open core with no containment as part of the design, verses TMI-2, Water Moderated, Core Vessel (design failure tested), Containment Building (built to withstand interanl and external failure mechanisms, like an explosion inside or commercial aircraft impact on the outside), multiple redundant safeties, etc. The TMI-2 core failure was operator induced, and contained within the vessel, if anything completely validating our design approaches and methodologies. It was a people failure, not a design failure. In fact the design factors worked in limiting the mayhem the people factors could induce. Primary Lesson Learned at TMI-2: "Believe your indications."

Apples and Oranges, unfortunately not so much in the eye of the uninformed public.

[Tom Ligon]

Yup. I note one of those vitrification efforts discussed above is at Windscale, England. Windscale had an accident back in the day, very similar to Chernobyl. It was also a graphite pile, and caught fire. The site was surrounded by dairy pasture, and it took a couple of months before radioactive strontium was not showing up in the milk, if I recall my details. OTOH, there were no fatalities (I don't think it even hurt the cows). Radioactive material released may have eventually caused 240 excess cases of cancer.

Chernobyl was many orders of magnitude worse.

Both accidents happened in botched maintenance operations in which selected areas of the pile were being heated. At Windscale I think they were trying to stress-relieve the graphite. I forget the excuse at Chernobyl, but it was something similar. In each case it got away from them and they set the graphite on fire.

Three Mile Island released a little gas and a drizzle of radioactive coolant, but the estimate of excess cancer deaths was 1.

[ladajo]

http://www.cddc.vt.edu/host/atomic/accident/index.html

The above site gives a good read of US accidents outside of TMI-2, 1945-1970.

[TallDave]

Chernobyl was allegedly an unauthorized systems test.

http://en.wikipedia.org/wiki/Chernobyl_disaster

Of course, you have to keep in mind they were Communists, so they were incompetent at pretty much everything.

Some interesting info in the Causes section. Apparently it was a very unstable design, unbeknownst to the operators.

http://en.wikipedia.org/wiki/Chernobyl_disaster#Causes

[KitemanSA]

If I knew what "adsorption" meant, I might be able to follow what she tells me about it.

If a material enters into another material, it is aBsorbed, if it sticks onto sites on the surface of another material it is aDsorbed. Different physics.

It is VERY difficult for a dissolved material to be absorded into surrounding rock, but it can stick to the micro features quite easily and once adsorbed it is locked on almost permanently.

Adsorbtion is how activated carbon cleans the water in a water filter. Many sedimentary rocks act quite similarly, they clean the bad stuff out of water.

[KitemanSA]

KiteMan, cool if what you say is true! I'm not a nuke engineer or physicist. I have to deal with the bottom line as do all policy decision makers.

If the nuke waste trouble is easily dealt with, why haven't we dealt with it?

Way back when, the only types of reactors (Pressurize Water Reactors mostly) were U235 fueled and the primary actinide produced was Plutonium. To make it difficult to obtain Plutonium for bombs, the US made re-processing illegal, and IIRC forced the UN to make similar policies. Most of the rest of the world follows suit except the two main Old Communist countries (USSR and China) and of course the socialist and contrarian French . . . . there are probably others too. I don't know how easy it is to make solid fuel elements with mixed actinides, so I don't know if this was a serious drawback to typical PWRs. But as a result, we got stuck with the "once thru" process mentioned elsewhere.

It didn't matter that Thorium reactors make totally different actinides, it is still illegal to re-process.

With a Thorium fueled Molten Salt Reactor, it is very easy to include the actinides into the fuel and burn them as part of the fuel. But to do so the MS fuel would have to be reprocessed. Doable, but still illegal, IIRC.

[KitemanSA]

In any case, all of the warnings we get about radiation exposure must have some basis in science? I mean, it can't possibly be that for 30 years we've been afraid of nothing? There must be some scenarios where, e.g. release of core fuel material into the air or ground water, the dangers are very real?

Actually, IMHO, their warnings are almost totally contravened by the facts.

Right after Chernobyl there were warnings of 10s or 100s of thousands of deaths due to long term diseases that would result from the release. Those values were based on the NRC and EPA approved exposure/effect curves that show a straight line from zero-zero, to the multi-REM doses experienced in Japan after the bombings.

Well, with that type of curve, milli-REM doses have an assumed bad effect, and MILLIONS of people got milli-REM doses. So, statistically, many many thousands would die.

But the curve is ludicrous. Every piece of REAL data at those levels say that dosages like that are BENEFITIAL to your health. Indeed, other than the folks that got mega-doses right away, the health effect was undoubtedly that FEWER people died as would have without Chernobyl. This type of situation is known as "hormesis" and the resulting curve is known as a "J-Curve" by many.

But pointing that out isn't politically correct, so if you try to tell folks you will be branded a "tool of the nuclear lobby" or some such smear. Because obviously, the government has no adgenda and all federal employees are pure as the driven snow . No bias there ya know!

[KitemanSA]

Not that a bad reactor accident can't be really bad. Chernobyl was pretty horrific.

But as it has turned out, other than the local area, no where NEAR as horrific as was predicted.

[KitemanSA]

Windscale, England. .. had an accident back in the day, very similar to Chernobyl. ...Radioactive material released may have eventually caused 240 excess cases of cancer..

I would be willing to wager a pretty penny that there were nowhere NEAR the 240. Indeed, except for folks who may have drunk that milk before being stopped, I would suspect that the folks around there are a tad HEALTHIER that others.

Pick any to clean, near pristine places in the US, all else being equal, the place with the HIGHER background radiation will have to LOWER incidence of cancer and similar diseases. That is what the data I've seen says.

[WizWom]

"Nuclear Rennaisance" was all the buzz from the DOE, NRC, SMART and Exelon presenters at the mini-conference today.

[hanelyp]

A couple years ago I read an article about reprocessing nuclear fuel to extract mixed actinides. Apparently makes a perfectly good reactor fuel, if you have a reactor designed for it. The bulk of power reactors operating today can't use it.

As further advantage
- the extracted fuel is useless for a fission bomb.
- the fission fragments extracted have a far shorter hazardous lifetime than the actinides recycled as fuel.
- the vast majority of potential fission fuel of whatever variety is extracted, as opposed to throwing away most of the U238 as in other recycling methods.

[KitemanSA]

A couple years ago I read an article about reprocessing nuclear fuel to extract mixed actinides. Apparently makes a perfectly good reactor fuel, if you have a reactor designed for it.

Yup, and the Molten Salt Reactor is designed for it. It has molten salt carried fuel fluorides, so the specific actinide doesn't matter much. True, some are nuclear poisons but that problem can be avoided in several ways.

The bulk of power reactors operating today can't use it.

As further advantage
- the extracted fuel is useless for a fission bomb.

As long as you DON'T separate out the Plutonium!

[IntLibber]

In general I'm all for micro-distributuon of power generation, but in the case of nukes, you do realize that a 1/5 sized plant needs all the same security measures as a full sized plant, so if you build 5 1/5 sized plants, you'll spent 5X as much on security and manage 5X the risk.

Or you put 4-5 reactors (perhaps more in some cases) at one site? Seems like the security costs of a plant with 5 small reactors wouldn't be significantly more than a plant with a single giant reactor? With the PRISM modules, 5 reactors gives you 1.5GWe total output (plus change - design output being 311MWe - which is close enough to 300 for me).

Added benefit: if one or two reactors need to be shutdown for maintenance, you may still be able to keep 2 or 3 others in operation, so you are only losing *part* of your revenue during maintenance, instead of it dropping to zero? Flip side of that is, all else being equal, more parts means more chance at least one of the parts fails (which is why a computer RAID hard-disk array with 5 drives, is more likely to have a drive failure of at least one of the drives, than a computer with only a single drive - but less likely to have a complete failure which renders the computer nonoperational).

Doesn't make much sense to me, except unless you hold GE stock in which case I'm sure it's a great idea.

Or you hold stock in a security services company.

That's what the second amendment is for. Make it legally open season on anybody caught trying to break into one of these micro generators.

As for hard disk failures, thats what flashdrives are for. Disk drives are obsolete, its all solid state now.