Thursday, August 18, 2011

DA Ryan and the Miraculous MSR Graphite Fire

And the angel of the LORD appeared unto him in a flame of fire out of the midst of a bush: and he looked, and, behold, the bush burned with fire, and the bush was not consumed. - Exodus 3:2
When I began my investigation of the graphite fire risks this spring, I had formed no fixed opinion about the supposed danger. I had, of course, run across numerous references to graphite fire risks, including a statement from the redoubtable Ed Lyman of the ever vigilant anti-nuclear Union of Concerned Scientists. Lyman tells us,
A second unresolved safety issue concerns the reactor’s graphite coolant and fuel pebbles. When exposed to air, graphite burns at a temperature of 400°C, and the reaction can become self-sustaining at 550°C—well below the typical operating temperature of the PBMR. Graphite also burns in the presence of water. Thus extraordinary measures would be needed to prevent air and water from entering the core. Yet according to one expert, “air ingress cannot be eliminated by design.”
Yet a statement from General Atomics, a business which has designed and built graphite core reactors claims,
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 (~1650°C) 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.
Thus the issue of graphite fires is open to question, and should be most properly settled by scientific investigation. The New Scientist published a discussion of the General Atomic claim in its November 4. 1989 edition. The New Scientist came to a graphite does burn reluctantly, and is not very dangerous view, pointing to research by Peter Kroeger's of Brookhaven National Laboratory for support. I concluded my initial investigation of the graphite fire danger by noting
Needless to say, Ed Lyman forgot to mention any of Peter Kroeger's research, the General Atomic's argument, or other arguments that makes his simple "Graphite burns" statement less than a serious inditement of pebble bed reactor safety.

Even less so, does the "graphite burns" statement a serious safety objection to the use of graphite in the core of Molten Salt Reactors. It should be noted that the presence of liquid fluoride salts would be a serious inhibitor of any graphite fire, and in the event of salt drainage from a MSR core, a graphite fire would not be a safety issue, because both fission products and nuclear fuel would drain out of the core along with the coolant salt. Thus even if we reject the General Atomic's contention that Nuclear Graphite does not burn, the graphite burns objection does not appear to raise a serious concern about Molten Salt Reactor safety.
My conclusions were based on facts - Peter Kroeger's graphite research, and the application of logic to those facts. Anyone wishing to disagree with my conclusions should either argue that I misrepresented Kroeger's research, or Kroeger's research was seriously flawed, or that I committed logical errors in reaching my conclusions. So far no one has used any of these rational approaches to dispute my claims.

My discovery of Kroeger's research was not the end of the line as fare as my investigation of the graphite fire risk. I had two supposed reactor graphite fire risks to explain. The Windscape fire, and the Chernobyl fire.

DA Ryan asserts
CB (Charles Barton) seem unable to absorb any information that contradicts their position.
What information? Ryan presents no facts, no analysis of logic which contradicts my views. Ryan's evidence is not based on research. In facts Ryan ignores all nuclear graphite fire risk research.

When I pointed out to Ryan a recent statement on the Windscale fire by the UK Nuclear Safety Advisory Committee that,
Inspections have shown that there was NOT a graphite fire: damage to graphite, caused by severely overheated fuel assemblies, was localised.
Ryan remarked,
the paper you point to with regard to Winscape is the minutes of a committiee meeting not an official statement or scientific anaylsis that has been subject to peer review. One could be unkind and describe it as “gossip”.
Yet the UK Nuclear Safety Advisory Committee reports the results of acrtual observations. None of the statements about the Windscape fire which Ryan refers to is based on evidence drawn from actual observation inside the core of the Windscape reactor. I went to the trouble of documenting several accounts of the Windscaple accident in0rder to show that the evidence in support of the UK Nuclear Safety Advisory Committee report has long been known, and that evidence includes photographs taken from inside the windscape reactor, and a link to a presentation by M.T. Cross, at the Brookhaven National Laboratory Graphite Research Reactor Workshop, May 9-10 2007. The presentation included numerous slides of photographs taken in the interior of the Windscape reactor that shows fuel capsules that were damaged or destroyed by fire, while the graphite structures that contain them are still intact. I wonder if Mr. Ryan would also categorize those photographs as "gossip."

If Mr. Ryan still can maintain his "Windscape was a graphite fire" position with a straight face, he must explain the miracle of the Windscape graphite, the graphite burned but was not consumed, just like Moses burning bush.

Mr. Ryan accuses me of ignoring the precaitionary principle, but he has managed to stumble very badly in his attempt to establish that there is a MSR core graphite fire risk. Ryan has posted a long response to my critique of his treatment of MSR technology, and to Bill Hannehan's critique. The first of Ryan's comments has to do with graphite fire. Ryan states:

Another critique of my critique of the LFTR can be found here:
As with the previous ones they either deliberately missread my critique in an effort to build up stray man arguments or reading just isn’t one of Mr Bill Hannahan, or “Rank Amateur” (his words Charles Barton’s stronger points. I’ll leave it to the reader to decide which.

Firstly, they misrepresent my views on graphite, which I point out is a “perceived fire risk” I was never suggesting it will catch fire if you put a match to it. I make this point repeatedly in the comments above, I even added a little section to chapter 6 to describe the two sides of the fire risk argument and clarify my position. But the fact opaque minds of BH and CB seem unable to absorb any information that contradicts their position. They also seem to have no idea about the concept of scientific uncertainty or the precautionary principle or the most basic concepts of how passive safety is guaranteed. These would require “some” action be taken on this issue. Indeed they compound there mistake by then misunderstanding why graphite is used in Class D fire extinguishers (for liquid metals!). Oh, and BH suggests you can use jet fuel to put out fires later on (yes really!). I’ll let the reader assess the practicalities of that!

Ryan starts off with a straw man argument, that is the suggestion that we were attributing to him the view that graphite

will catch fire if you put a match to it.

I never attributed that with to Ryan, and he, of course, can produce no quotes that say otherwise.

I do view Ryan's claims about about the fire risks posed by graphite cores in MSRs are at best exaggerations. Research on Graphite safety conducted in the United States after the Chernobyl nuclear accident, found that graphite was a safe material for nuclear cores, and that it posed little or no fire danger. I argued this because my own review of literature on graphite fire danger demonstrated that graphite posed no fire risks for Molten Salt Reactors. Mr. Ryan has not presented research evidence contradicting my conclusions.

Ryan attempts to discredit me by claiming that the word "perceived" in the phrase "perceived fire risk" some how invalidates our arguments against his position. In fact the word perceived has more than one meaning. It can be understood to mean, "detected by instinct or inference rather than by recognized perceptual cues," or it can mean, "detected by means of the senses." These two meanings are somewhat contradictory which makes the word "perceived"an excellent weasel word. Before we look further at what Mr. Ruan means when he uses the word "perceived," we ought first to look at what Ryan actually says about graphite and graphite fire risks. In his original essay, Ryan writes,

Another issue is that graphite core. As I detailed previously with regard to the HTGR (part 6.4.3) it’s a potential fire hazard. Thus we would need to put the MSR within a containment dome of sorts. Again, as with the HTGR, this dome need not be built to the same exacting standards of a LWR dome as we are merely trying to contain a graphite fire, not an out of control reactor.

The word perceived certainly does not decrease Mr. Ryan's certainty about the necessity of taking steps to control graphite fire risk. In addition to structural recommendations,

We would need an effective on plant fire control team and some form of fire detection and suppression system, within the containment dome and all the necessary gear that this entails. Again, I refer you the relevant section of the HTGR analysis, but needless to say such an arrangement would involve certain costs.
So Mr Ryan seems to mean by perceived fire risk, a plausible risk of graphite fire. But is there plausible risk of graphite fire in MSRs? Graphite fire research seems to show that there is none Ryan ignored that research when he made the graphite fire claims.

I argued that the evidence on graphite fire risks suggests that there are no circumstances in which the laws of nature would allow us to believe that a graphite core of a Molten Salt Reactor could catch on fire. If an idea contradicts the laws of nature, it is a misperception, a mistake, or a miracle. Mr. Ryan should have explained how the graphite core of a molten salt reactor could catch on fire despite the fact that a graphite fire in A MSR core would seemingly violate the laws of nature. Apparently Mr. Ryan's precautionary principle includes protecting the public from miracles.

Mr. Ryan fails to not the difference between assertion as rhetorical strategies, and actually demonstrating his case. Ryan acknowledges,

I could go thro this line by line but there’s no point, all they succeed in doing is demonstrating their own ignorance of the facts and inability to absorb any information that contradicts the LFTR gospel.

Ryan however, fails time after time to demonstrate that Bill and I are as ignorant as he says we are. He tells us that Bill is mistaken in asserting at low vapor pressure of MSRs is an advantage because,

The pressurization issue is a bit of red herring, the major materials stumbling block is the issue of the combination of corrosive attack under temperature, with a bit of radiation thrown in for good measure.

In this argument Ryan simply ignores ORNL finding from the MSRE. ORNL-TM-4171 (Postirradiation Examination of Materials from the Molten Salt Reactor Experiment ) reported that

The MoltenSalt Reactor Experiment operated very successfully. The fuel loop was above 500°C for 30,807 hr and contained fuel salt for 21,040 hr. A surveillance program was active during operation to follow the property changes of the graphite moderator and the INOR-8 structural material. After operation was discontinued in December 1969, several components were removed for examination. These included a graphite moderator element from the core, a control rod thimble, freeze valve 105, the sample cage and mist shield from the fuel salt pump bowl, a copper sampler capsule, tubes and a portion of the shell of the primary heat exchanger, and tubes and two thermocouple wells from the air-cooled radiator.
The overall findings were that
Examination of these materials showed excellent mutual chemical compatibility between the salts, graphite, and INOR-8. The INOR-8 exposed to fuel salt formed shallow intergranular cracks believed to be due to the ingress of the fission product tellurium. The INOR-8 was also embrittled by exposure to thermal neutrons, and this was attributed to the formation of helium by the (10)B(n,a)(7)Li transmutation.
The ORNL report found that
The primary corrosion mechanism in the fuel salt system was selective removal of chromium by 2UF4 + Cr(in alloy) Z+ 2UF3 + CrF& salt), and the concentration of chomium in salt samples was the primary indicator of corrosion. . . . The total increase in chromium in the 4700-kg charge of fuel salt is equivalent to leaching all of the chromium from the 852 ft2 of INOR-8 exposed to fuel salt to a depth of about 0.4 mil.

Since the coolant salt did not contain uranium, the corrosion rate was extremely low. During operation, the chromium content of the coolant salt remained at 32 ppm, within the accuracy of the analysis.
ORNL scientists went on to identify two solutions to the intergranular cracking problem, and proposed to solve the minor chromium corrosion problem by removing chromium from metal alloys. Mr. Ryan failed to examine the results of the ORNL experiment that was designed to determine the effects of
the combination of corrosive attack under temperature, with a bit of radiation thrown in for good measure.
Those findings were that there were some developmental problems, but none that were show stoppers.

One way to avoid mistakes due to ignorance in scientific matters is to pay careful attention to what scientists say in research related documents, and to quote them exactly and in context. This would be the approach that both Bill and I take, but Mr. Ryan does not seem to regard it as necessary to examine the actual research before he makes sweeping and all encompassing judgements on all sorts of matters. Thus his pronouncements on MSR related problems are invariably made without reference to ORNL research work product, which would be the primary source of information on MSR research.

Most of Mr. Ryan's response is an personal attack on Bill and I have left it to Bill has answer those criticisms.


donb said...

What I see when I read Mr. Ryan's assertions is someone who doesn't trust science because he 'knows' something different intuitively.

This reminds me of a 'Mr. Wizard' program I watched when I was in grade school half a century ago (this was the first series where Don Herbert focused on a single subject for the whole half-hour). One experiment was with a pendulum made from a bowling ball suspended from a rope. It was pulled away from its resting position and restrained by a string. The young assistant sat in a chair with his nose just touching the bowling ball, and was told to remain in his position. Mr. Wizard then cut the string, setting the ball into motion. It swung away and then back toward to young assistant, who jerked his head away at the last moment to avoid the heavy ball flying at his face. Then Mr. Wizard tried it. He did not move a muscle, and came away completely unscathed. The young assistant 'knew' that his face would be smashed if he did not take action to avoid the ball. Mr. Wizard knew the true science, and knew that he did not need to move a bit to avoid injury.

Sometimes reality and our perception (that word again!) of reality (or intuition) are two different things. It is the true scientist who decides to let reality rule even in the face of contrary intuition.

Andrew Jaremko said...

Thanks for continuing your rational discussion in the face of what, to me, is really puzzling responses from Mr. Ryan. I went to his blog to find out what his background and/or credentials might be, but didn't find anything like an 'about me'.

In one way it's good that you and Bill Hannahan are taking Mr. Ryan seriously and making reasoned responses to his posts. But I wonder - why is he worth the effort? Does anyone take him seriously? Is he a major force in the (hopefully constructive) criticism of nuclear energy?

On a side note - I went to Wikipedia to learn more about graphite. Its density of 2.0-2.3 gm/cm3 versus coal's density of slightly less than 1 gm/cm3 tells the tale about their comparative structure.

gallopingcamel said...

Just a quibble, but there was no "Windscape". The events took place at Windscale.


Blog Archive

Some neat videos

Nuclear Advocacy Webring
Ring Owner: Nuclear is Our Future Site: Nuclear is Our Future
Free Site Ring from Bravenet Free Site Ring from Bravenet Free Site Ring from Bravenet Free Site Ring from Bravenet Free Site Ring from Bravenet
Get Your Free Web Ring
Dr. Joe Bonometti speaking on thorium/LFTR technology at Georgia Tech David LeBlanc on LFTR/MSR technology Robert Hargraves on AIM High