RE: Microwave "Criticality" Thread --Actual Meltdown Anecdote

["Neil, David M" <neildm@id.doe.gov>]

I've never had that much of a problem, but I did "brand" my palms by using a
dish that had a decorative border with significant metal content (gold
leaf?).  No permanent scarring, but I had burn stripes from the heels of my
hands out to the tips of my middle fingers. :-)

Dave Neil 

> -----Original Message-----
> From:	RADPROJECT@aol.com [SMTP:RADPROJECT@aol.com]
> Sent:	Tuesday, January 25, 2000 9:15 PM
> To:	Multiple recipients of list
> Subject:	Re: Microwave "Criticality" Thread --Actual Meltdown
> Anecdote
> 
> Radsafers:
> I've followed some of the interest in the Microwave "Criticality" thread 
> which has caught the interest of numerous readers. I myself had an
> experience 
> with a microwave meltdown that demonstrates just how high a temperature
> can 
> be reached in a microwave.  Superheated water is one thing.  How about a 
> white hot mass of carbon melting borosilicate glass.
> 
> The situation as it developed is described below. In the early 1980s
> before I 
> purchased my first microwave, my wife and I stopped to check in on her 
> sister's ski house in VT for some reason on our return from a trip. While
> my 
> wife was on the phone with her sister, I decided to make microwave popcorn
> 
> from scratch. I had used a hot air popper for many years and assumed I
> could 
> throw some hot air popping corn into a microwave for a few minutes and do
> the 
> same thing.
> 
> I found some popping corn and put it into a white pyrex bowl with a clear 
> pyrex [borosilicate] glass top. I had never made microwave popcorn before
> so 
> I set some short time interval to start, but  no popcorn popped. I then 
> quickly keyed in some longer time and left the microwave while I went to
> the 
> phone perhaps 20 feet away, to discuss chat  with my brother-in-law. I
> forgot 
> about the microwave since I never heard any popcorn pop. The popcorn must 
> have been old and dried out enough that it was just not going to pop.
> 
> Apparently, I must have punched in an extra digit on the duration of
> heating, 
> because after some five or so minutes I went back to the microwave and
> found 
> it still running. I looked through the panel and saw an odd "glow" coming 
> from within the bowl and the cover could be seen to be sagging [melting]
> into 
> the bowl.
> 
> I stopped the microwave and in opening the door saw that there was a mass
> of 
> material in the bottom of the bowl which was glowing white hot. The clear 
> pyrex glass cover had begun to soften and had almost melted at its center 
> into the bottom of the bowl. The covered pyrex bowl with its white hot
> carbon 
> mass within was very carefully taken out of the micro and placed onto a 
> trivet to cool to avoid any further damage to the micro.
> 
> Afterwards, in thinking about what had happened, I understood why the
> Steath 
> bomber wings are covered with a carbon containing coating to absorb 
> microwaves and prevent or minimize radar signals from bouncing back to
> radar 
> stations trying to track it.
> 
> Maybe someone can post the melting point of borosilicate glass, and what 
> temperature is approximately achieved in a "white" hot object. This
> curious 
> and interesting happening shows that even a home  microwave oven is
> capable 
> of pumping a surprising amount of energy into an object like a carbon
> mass, 
> and in reaching very high temperatures [if one makes a few mistakes as to 
> on-time and inattention to what is going on]. 
> 
> I went on to buy a microwave and use it rather uneventfully with one minor
> 
> [ie: it didn't blow off the door, but did make quite a noise] explosion.
> This 
> was a time when an eggplant exploded and filled the micro with eggplant
> mush 
> due to my having failed to poke some steam vent holes before microwaving
> the 
> eggplant to soften the contents for some recipe I was following. 
> 
> Thankfully, there has been no morbidity or mortality associated with these
> 
> infrequent microwave "unusual events" leading to any CDC reports or
> federal 
> regulations.
> 
> Stewart Farber
> Public Health Sciences
> email: radproject@aol.com
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