
Nuclear's next generation - pg
http://www.economist.com/sciencetechnology/tq/displayStory.cfm?story_id=15048703
======
jeremyw
One form of _very high temperature reactor_ , the pebble bed reactor, was
theorized in the 1950s and has been under development at various locations for
more than a decade -- China begins commercial construction this year.

PBRs are one of several _inherently safe_ designs wherein shutoff of
circulating coolant raises core temperature and natural processes serve to
choke criticality.

<http://en.wikipedia.org/wiki/Pebble_bed_reactor>

~~~
rainier
The pebble bed reactor has inherently safe features concerning loss of
coolant, but it is not inherently safe: There are other sever accidents not
known in conventional reactors, like graphite fire (as it happened in
Chernobyl, too) and water ingress into the core with subsequent explosions.

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thaumaturgy
Another newer technology to keep an eye on: plasma gasification
(<http://www.slate.com/id/2181083/>).

Although it produces paltry amounts of energy compared to nuclear facilities,
it's a neat solution to the problem of waste management, capable of handling
low-grade nuclear waste.

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dmfdmf
The current reactor designs are safe enough, let's build them now. Debating
the pros and cons of advanced designs is dumb and accepts the enviros false
claim that current BWR or PWR light water reactors are "unsafe". Moreover,
significant real-world safety comes from operational experience on a fleet of
the same or similar designs. It would be foolish to throw away 50 years of
knowledge and experience on light water reactors to start over on sodium,
fluoride, pebble-bed, etc.

~~~
cheriot
It's also about efficiency. Nuclear power plants regularly live beyond their
designed lifespan of 30-40 years. If a new reactor can be built with 45%
efficiency rather that the 33% of existing light water reactors get, that
alone will justify the delay.

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dubcomesaveme
u.s. nuclear reactors have always been safe: if a loss of coolant failure
occurs the reaction is designed to slow down rather than speed up soviet
cheronobyl style.

the concern is what to do with all the junk from processing\using fuel rods
and depleted uranium besides dumping it on Iraqis via munitions.

~~~
bjelkeman-again
That doesn't always seem to work though:
<http://en.wikipedia.org/wiki/Three_Mile_Island_accident>

~~~
dondraper
>In the aftermath of the accident, investigations focused on the amount of
radiation released by the accident. According to the American Nuclear Society,
using the official radiation emission figures, "The average radiation dose to
people living within ten miles of the plant was eight millirem, and no more
than 100 millirem to any single individual. Eight millirem is about equal to a
chest X-ray, and 100 millirem is about a third of the average background level
of radiation received by US residents in a year."[31][52]

Read a bit closer

~~~
teeja
IIRC the figures on TMI (not broken down into phantom per-capita exposures but
to the environment) included millions of Curies released into the environment.
Some credible researchers have found evidence that figure may be 10 to 100
times too small.

Not surprising; with all the money involved, the science gets 'adjusted'. The
industry can afford the best PR.

~~~
dondraper
I think the per-capita exposures figure was simply to give a sense of scale
not to obscure the figures. Do you have a source that backs that claim?

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DanielBMarkham
I'm a fan of liquid fluoride thorium reactors (LFTR). The prevalence of
Thorium is a big positive and the ability to process out existing nuclear
waste is a tremendous boon.

We're not that far away from commercializing LFTR. It's a shame we can't find
more research funds.

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Daniel_Newby
I like the sodium fast reactor: low pressure, moderate temperature, sodium is
dirt cheap, high burn-up of non-uranium/plutonium products ("waste"), and
plutonium need never be separated from other reaction products.

The article doesn't say, but because molten salt reactors use liquid fuel,
they release the radioactive xenon gas produced by uranium fission. (In fact
this is sold as a benefit, since xenon absorbs neutrons better used for the
chain reaction.) Xenon is a noble gas and therefore volatile, so the reactor
will need strenuous containment measures. Loss of the gas seal would result in
significant radioactivity release.

Helium-cooled reactors may be constrained by shortages of helium, which is
rather rare and difficult to extract on Earth. You'd hope that government
program managers would have worked out the logistics of this, but they tend to
not see things that would get their funding cut. (Argon is plentiful but might
not be a substitute because it reacts with neutrons a lot more than helium
does.)

~~~
sp332
> Xenon is a noble gas and therefore volatile

This must be some definition of "volatile" I'm not familiar with.

~~~
Daniel_Newby
Evaporating easily. Xenon boils at -108 deg. C. Given the chance, it would
tend to rapidly escape from liquid fuel at reactor temperatures.

~~~
elblanco
We're probably both thinking of "prone to explode" vs. "prone to evaporate".

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maksimka
I like the idea, as long as it's very far away away from my house.

~~~
cmelbye
As the other poster said, it's better than living next to a coal burning
plant. The coal burning plant would actually release more radioactive material
into the environment than a nuclear power plant would.

~~~
earthboundkid
I’ve heard this before, but is there any reason to think that the issue goes
beyond the fact that CO2 has a higher natural level of radiation than H2O?

~~~
dubcomesaveme
incomplete combustion\plenty of other stuff in the ground in it(heavy metals
etc.). The smoke is not just CO2.

Plus " sulfur dioxide (SO2) and nitrogen oxides (NOx) are the primary causes
of acid rain. In the US, About 2/3 of all SO2 and 1/4 of all NOx comes from
electric power generation that relies on burning fossil fuels like coal."
[http://www.policyalmanac.org/environment/archive/acid_rain.s...](http://www.policyalmanac.org/environment/archive/acid_rain.shtml)

and acid rain causes a number of environmental problems.

~~~
bjelkeman-again
NOx also creates low level ozon when it breaks down, which has a number of
nasty environmental and health side effects as well.

