Graphite also burns in the presence of water. Thus extraordinary measures would be needed to prevent air and water from entering the core. Genera Atomic says Lyman is wrong because nuclear grade graphite does not burn. 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. After removing the heat source, the graphite cooled to room temperature.
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. Is this true? The New Scientist investigation pointed out that the graphite in the Windscape 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 blow ovr the red hot graphite which would not catch fire. Needless to say Ed Lyman did not attend one of those demonstrations. 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.
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. Kroeger remarked, 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 signi- ficant air ingress and combustible gas discharge from a single break; butonly 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. 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 kg of graphite.
Thus, air Ingress consequences under natural circulation conditions appear to be less severe than those under the above forced cooldown scenarios. Kroeger found that, Separate code applications for air Ingress with auxiliary loop cooling [34,43,44] generally indicate that fuel temperatures are only raised slightly due to local burning, at most reaching C for a core with C design temperature. Thus, fuel failure from excessive temperature is not to be ex- pected.
It should be noted that the higher values are obtained for extremely large assumed air ingress rates, which may not be realistic. Learn more. What temperature is required to burn pencil lead graphite? Ask Question. Asked 5 years, 9 months ago. Active 1 year, 10 months ago.
Viewed 33k times. Improve this question. StayOnTarget 4 4 bronze badges. I was easily able to ignite graphite by using point 5 - point 9 lead, using a simple concoction of alligator clips Copper holding up the lead, and connecting it to a mere 18 volts of energy!
Show 1 more comment. Active Oldest Votes. Improve this answer. Eh, not really. Graphite can melt but it takes a temperature of 3, degrees Celsius or degrees Fahrenheit to do so. If you were observing the process waiting for liquid carbon to emerge, you would be very disappointed. Because the boiling temperature of carbon is very close to the melting temperature in both graphite and diamond there are other forms of carbon where this is not true and thus graphite boils at a temperature of 3, degrees Celsius or degrees Fahrenheit.
While the temperatures in the meltdown of the reactor at Chernobyl would have been extremely high, there was one element missing and without it, the graphite could not burn. You may have heard at school that graphite was poisonous, but in reality, this is not true. The reason that many students hear that pencil lead is toxic is because their teachers have mistaken graphite for actual lead.
If you were to eat lead , even in small quantities, you would be poisoned. This means that in most cases, graphite is very much non-toxic unless consumed in very unusual ways. This is a dangerous form of pneumoconiosis which sees the dust build up in your lungs and bronchial tubes and can impede breathing. When you burn graphite, you get two products: carbon monoxide and carbon dioxide. It is not poisonous per se, but if you have a fire and carbon dioxide displaces the air from the room, you cannot breathe carbon dioxide and you will suffocate.
This is, in fact, why smoke inhalation kills more people in fires than the fire does. If you breathe too much carbon dioxide, the cure is to start breathing air again. So, when carbon monoxide bonds to a red blood cell, it effectively prevents that cell from ever carrying oxygen around your body again. This is why they install carbon monoxide detectors in homes, it can save your life.
You need micrograms of graphite in every milliliter of blood to die from graphite poisoning. Is Lead Flammable?
Will it Burn? Is Aluminum Flammable?
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