RE: Loose fuel fragments at Chornobyl

["Vargo, George J" <vargo@pnl.gov>]

This really isn't news although it is interesting.  At the time of the accident
the kinetic energy of  the steam and hydrogen explosions, estimated at
approximately 40 tons TNT-equivalent (Vargo 2000) caused about 4% of the 192
tons of nuclear fuel to be discharged directly to the environment.  Most of this
was in the form of small particles, however, there are several instances in
which intact fuel pellets were recovered on the site.

During our work to stabilize the ventilation stack in 1998, we encountered
numerous fuel and graphite particles on the stack walkways.  These had been in
place since the 1986 accident.  Phase I of the stabilization project involved
extensive decontamination and removal of this high activity material.  Many hot
spots were weathered in place and a total of 30,000 pounds of lead blankets were
imported from the US and used for localized shielding.

I question the accuracy of the report that the particle/chunk in question was
recovered from the Shelter roof since the roof was completely reconstructed in
the six months after the accident.  It is possible, however, that this may have
been on one of the stack walkways and knocked off some time in 1998.

Reference:  Vargo, GJ, ed.  The Chornobyl Accident - A Comprehensive Risk
Assessment.  Columbus:  Battelle Press.  2000.

George J. Vargo, Ph.D., CHP
Pacific Northwest National Laboratory
International Nuclear Safety Program
PO Box 999
902 Battelle Boulevard
Richland, WA  99352-0999
509-375-6836; -2019 (fax)
vargo@pnl.gov
http://insp.pnl.gov:2080 
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