On the afternoon of October 25, 1993, a drum in the heater jacket
was allowed to cool before all of the sodium had been extracted. Due to a
mathematical error by the operator, approximately 100 lb. of sodium,
almost one quarter of the drum’s capacity, was left in the drum when the
heaters were turned off. The resolidified mass of sodium could not be
reheated and drawn into the processing system, because it had been
contaminated by contact with outside air.
The company’s standard operating procedures contained detailed
specific instructions on how to bum-off the sodium residue from a drum,
anticipating that less than 10 pounds of residue would have to be burned
off. There was no reference to guide employees on disposal of a large heel
of sodium.
Similar situations were reported to have happened occasionally in
the past and caused major problems for the employees responsible for
disposal of the drums. On one occasion, several months earlier, they had
used a chipping hammer to chip the sodium out of the barrel and bum it
off in small quantities. The chipping-out process was labor intensive and
time consuming and, when the sodium was chipped out, the chips came in
contact with the sweaty skin of the worker. This caused painful bums as
the sodium reacted with his perspiration. They had decided to do
something different if it happened again. The alternatives are to dispose of
the drum as hazardous waste or to return it to the original supplier for
recycling.
On the night of October 25, the night shift supervisor advised the
worker who handled the drums that they had another drum with a large
quantity of residual sodium and they were going to try burning it off,
following the normal disposal procedure. They anticipated that it would
take longer, possibly all night to bum this quantity of sodium.
The room had been used earlier in the evening to wash a reactor
head and the floor grates were reported to be damp when the drip pan was
placed on top of them. The pan, which is leaned against the wall of the
room when it is not in use, is also believed to have been wet when it was
laid on top of the floor grates and there may have been water under the
grates.
The drum was removed from the process area and transported to
the disposal room where the top was removed. When it was attempted to
place the drum in the cradle, the mass of solid sodium at the bottom would
not allow it to sit in the normal near-horizontal position; a metal agitator
shaft was used as a strut to keep it from tilting back to the upright position.
The braced drum was placed in the normal position for burning, on top of
the drip pan with the open end toward the door.
Shortly after the sodium was ignited with the MAPP gas lance, the
worker looked through a viewing port and noted that the fire was creating
much more smoke than usual. He also noted within a few minutes that the
solid sodium was liquefying and creating a liquid pool that was quickly
filling the deep end of the drum. He became concerned and summoned
the supervisor who had directed him to bum the drum in this manner.
Moments later, as the supervisor and two employees were discussing
possible courses of action, they noted that the liquid level was almost up to
the lip of the drum at the open end and the heavy smoke was filling the
burnroom. A few seconds later an explosion occurred inside the burnroom
that shook the area and knocked them off their feet. Although the blast
doors held closed, some flecks of burning sodium were expelled through
the openings in the door and struck the two of the plant personnel, causing
minor bums. White smoke filled the immediate area and began to spread
to other parts of the building. All three employees evacuated the area,
assisted by other plant personnel. The injured personnel were treated for
minor bums by other employees.
Next » Fire Department Response
Save to del.icio.us
