[ RadSafe ] Zirconium Cladding of Fuel Rods - Reaction With Water

[JOHN.RICH at sargentlundy.com]

I'll just throw this out as a possibility - - pure speculation at this 
stage of events. 

If only the upper portions of the rods were out of the water, AND the 
reactor was using hydrogen addition, there might be enough hydrogen from a 
zirc-water reaction over a short length plus the hydrogen already in the 
water to yield enough for an explosion.  However, this could be a gap 
release, which would be less than a full fuel melt release. 

we'll have to wait for a true analysis to know the extent of the damage. 
In the meantime, it sounds like the reactor team is coping in a heroic 
manner with a way-beyond-design-basis event.

 - - jmr

John Rich
312-269-3768



From:   "Larry Addis" <ajess at clemson.edu>
To:     "'The International Radiation Protection \(Health Physics\) 
Mailing List'" <radsafe at health.phys.iit.edu>
Date:   03/12/2011 08:32 PM
Subject:        Re: [ RadSafe ] Zirconium Cladding of Fuel Rods - Reaction 
With    Water
Sent by:        radsafe-bounces at health.phys.iit.edu



I had to wonder if Zirc failure was the source of the Hydrogen. But
"serious" fuel failure would have resulted in much higher dose rate
measurements from a release of primary pressure to the environment -
wouldn't it?

Dry well is in good shape probably?

LA

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Roger Helbig
Sent: Saturday, March 12, 2011 8:34 PM
To: 'The International Radiation Protection (Health Physics) Mailing List'
Subject: [ RadSafe ] Zirconium Cladding of Fuel Rods - Reaction With Water

The NEI advised that the Hydrogen gas that is the probable cause of the
explosion at Fukushima #1 Reactor was generated when the Zirconium 
cladding
of the fuel rod was exposed - how did this exposure generate the Hydrogen
gas?

"It appears that as the level of coolant in the reactor vessel lowered, a
portion of the top of the uranium fuel rods was exposed. This may have
caused zirconium cladding of the fuel rods to react with water to create
hydrogen. This hydrogen was vented, then somehow ignited, causing the
explosion."

Web Elements says that Zirconium does not react with water under normal
conditions

Reaction of zirconium with water

"Zirconium does not react with water under normal conditions."

Roger





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