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RE: Drill Scenario
Actually, the senario isn't really that that farfetched. I can
remember a situation where an overhead crane operator
was homing the crane at the end of the day. They had
used the overhead crane in the spent fuel pool due to some
problems with the refueling crane. When lifting the hook, a
dangling cable snagged a poison rod and starting lifting it
towards the surface. Had an RP tech not been nearby at
the control point and heard the frisker alarm and stop the
movement of the crane, it most likely would have broken
surface.
Bob
-----Original Message-----
From: Gerry W. Kindred [SMTP:gwkindred@centerior.com]
Sent: Monday, January 12, 1998 2:16 PM
To: Multiple recipients of list
Subject: RE: Drill Scenario
Drillmanship...That is the word coined for performing
compensatory actions for events during a drill. Yes, you
can expect unrealistic scenarios. However, the associated
radiological consequences should be in the ranges in the
design bases and documeted in the Final Safety Analysis
Report (FSAR), section 12 should list the values. As far
as the realness, consider the design basis for a commercial
nuclear power plant? Is R.G. 1.3 realistic? I don't think so.
Commercial nuclear power plants are required to be designed
for a "core-on-the-floor" instantaneuous release (as others have
stated real events usually occur over a period of time). But,
back to the original scenario. An irradiated fuel bundle raised
above the pool surface. Is it realistic? No - reason being,
interlocks and other inherent safety features are typically
designed into the bridge that would prevent that from
occurring. However, if someone wanted to commit suicide,
they could probably get away with it, with some effort involved.
As far as the lethal dose rate 10 miles from the plant -- the
answer is no way!!! The dose rate on the lateral surface of an
irradiated fuel bundle that has decayed for >30 days is in the
neighborhood of 5E5 to 1E6 R/hr contact. Assuming the active
area of the bundle is 12' long, it would be treated as a line
source. At ten times the largest dimension (i.e. 120' ) it would
be treated as a point source. The following are approximate
free air dose rates and time to achieve a lethal dose.
Assumptions: Dose-rate at 1/4" 1E6 R/hr, lethal dose (without
medical attention) 450 rem.
1/4 inch = 1E6 R/hr
8 inches = 33,750 R/hr 48 sec
~5 feet 4200 R/hr 6.4 minutes
~ 21 feet 1000 R/hr 27 minutes
These are rough numbers; but something to think about. It's
obvious that anyone that wanted to get out of the area probably
could without receiving a lethal dose.
gwkindred@FirstEnergyCorp.com