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Comment Re:Thorium is NOT the holygrail (Score 1) 334

"Thorium is not any "safer" than Uranium. I have to say that proliferation risk is not a risk anymore - it's a political word. Any nation that can build a nuclear weapon can do so anyway via thorium. It is not that much more difficult to build a Pu-239 bomb than to build a U-233 bomb (from thorium). Also, a thorium reactor needs U-235 to prime it, so that point about proliferation is moot."

This is flat out wrong. The only nation ever to try to make a U233 bomb core was the US and it was a fizzle. It was a hugely expensive effort to refine that amount of U233 and with the inevitable U232 contamination issue, no nation ever would use a Th232-U233 cycle to make a bomb core. Look up that Thallium-208 gamma ray, it's nasty and messes with bomb core electronics. Plus it's shines like a movie premier beacon to anyone with detectors looking for fission weapons.

The U238-Pu239 path is known to work, the U235 enrichment path is very simple and known to work, and both paths have known science behind the data for their bomb core designs. None of which is true about the Th232-U233 path. It is much much more difficult to try and use a Th232-U233 path. So difficult that no nation has ever succeeded. Not saying it cannot be done, it's just that it's not worth the effort when two relatively mature paths to a bomb core are available and KNOWN to work.

Comment Re:No uranium (Score 1) 334

Ok granting the New Scientist is not peer reviewed (except by readers) I love how you ignored the second reference to the DoE Information Bridge and a real live "peer reviewed" paper that proved you are a fool back in 1985. Which was probably before you were even born judging by the immaturity of your statements here.

I have 30+ years experience in military and civilian nuclear power? What do you have?

You are a pathetic joke.

Comment Re:No uranium (Score 1) 334

You are an FUD-idiot.

It is often incorrectly assumed that the combustion behavior of graphite is similar to that of charcoal and coal.
Numerous tests and calculations have shown that it is virtually impossible to burn high-purity, nuclear-grade graphites. Graphite has been heated to white-hot temperatures (~1650C) without incurring ignition or self-sustained combustion. After removing the heat source, the graphite cooled to room temperature. Unlike nuclear-grade graphite, charcoal and coal burn at rapid rates because:
* They contain high levels of impurities that catalyze the reaction.
* They are very porous, which provides a large internal surface area, resulting in more homogeneous oxidation.
* They generate volatile gases (e.g. methane), which react exothermically to increase temperatures.
* They form a porous ash, which allows oxygen to pass through, but reduces heat losses by conduction and radiation.
* They have lower thermal conductivity and specific heat than graphite.
In fact, because graphite is so resistant to oxidation, it has been identified as a fire extinguishing material for highly reactive metals.

The oxidation resistance and heat capacity of graphite serves to mitigate, not exacerbate, the radiological consequences of a hypothetical severe accident that allowed air into the reactor vessel. Similar conclusions were reached after detailed assessments of the Chernobyl event; graphite played little or no role in the progression or consequences of the accident. The red glow observed during the Chernobyl accident was the expected color of luminescence for graphite at 700C and not a large-scale graphite fire, as some have incorrectly assumed. The New Scientist published a discussion of the General Atomic claim in its November 4. 1989 edition. The New Scientist investigation pointed out that the graphite in the Windscale fire was inpure, while the relatively pure graphite at Chernobyl contributed little to the that fire's heat. General Atomics in the past offered a demonstration to skeptics who wanted further convincing of their "Graphite does not burn," claim. A block of graphite would be brought out and heated to a red hot temperature. Then oxygen would be blown over the red hot graphite which would not catch fire. The New Scientist did not entirely support the General Atomics Graphite does not burn claim, but the analysis came down on the side of a graphite does burn reluctantly, and is not very dangerous conclusion, pointing to Peter Kroeger's research for support.

Peter Kroeger of Brookhaven National Laboratory (http://www.osti.gov/bridge/product.biblio.jsp?query_id=0&page=0&osti_id=6131128&Row=1)used a compluter simulation to check on General Atomic's claim. He found that if openings developed at two opposite ends of a graphite reactor containment structure, air could flow through the core, and graphite structures would burn some, but not very much, and certainly not enough to release radioactive materials embedded in the graphite.
Air ingress into the primary loop requires prior depressurizatlon with significant subsequent air inflow. Scenarios that have been considered are, for Instance, a primary vessel leak such that during decay heat removal via a main loop or an auxiliary loop, significant amounts of gas can be exchanged between the primary loop and the RB, while the operating loop forces the re- sulting gas mixture through the core [34]. (It may be hard to conceive significant air ingress and combustible gas discharge from a single break; but only with such a large break or with several separate breaks and with simultaneous forced flow conditions can significant amounts of air be forced through the core.) Order of magnitude computations indicate that natural circulation can only result In about .1 to .3 kg/s of gas circulation through the core of a typical modular pebble bed reactor. The initial RB air Inventory of about 80 kg mol (even if none were lost during the Initial blowdown) can only cause the burning of about 400 kg of graphite. Thus, air Ingress consequences under natural circulation conditions appear to be less severe than those under the above forced cooldown scenarios. Four hundred kilograms? That is less than a thousand pounds, hardly a roaring confligration.

Space

How To Destroy a Black Hole 364

KentuckyFC writes "The critical concept that makes a black hole black is the event horizon: a theoretical boundary in space through which light and other objects can pass in one direction but not the other. Since light cannot escape the event horizon, it must be black. The event horizon is a nuisance to astrophysicists because it hides the interesting new physics that must go on inside a black hole. What they would like is a way to get rid of the event horizon so that they can see what goes on behind it. It turns out that just such a thing may be possible, say physicists. According to the mathematics of general relativity, the event horizon should disappear if a black hole were fed enough charge and angular momentum relative to its mass. However the calculations are so fiendish (PDF) that nobody knows whether the black hole would shed this extra angular momentum and charge before it could settle into a stable 'naked' state. However, the possibility that the event horizon could be destroyed raises the question of what astrophysicists would see behind this veil. According to some, black holes are regions of spacetime with infinite curvature called singularities. Many believe that 'naked' singularities cannot exist in nature. And yet there are enough question marks to suggest that this mystery is far from settled."

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