Re: high-level and low-level

[772EAR@delphi.com]

In 10CFR60,  the NRC defines high-level waste as irradiated reactor fuel
and liquid or converted solid wastes extracted from the reprocessing of
reactor fuel.  In 10CFR62,  low-level radioactive waste is defined as
not high-level waste, spent nuclear fuel or byproduct material and 
that which the NRC classifies as low-level radioactive waste.

One of the common misconceptions among the general public is that
"low-level" means low activity.  This is not true.  For example,  one
type of Class A low-level waste (the lowest of the low-levels) is 
less than 700 curies per cubic meter of Co-60 (roughly 580 curies per
55 gal drum).  However, above 0.8 curies per cubic meter of C-14 is
roughly 660 millicuries in a 55 gal drum and is classified as Class C
waste which would require inadvertent intrusion protection and 
rigourous stability requirements.  Not only do many Broad Scope Type
A licensees have much more than 660 millicuries of C-14 in their labs
but if I had to make a choice,  I would select to stand next to the 
C-14 Class C barrel rather than the Co-60 Class A barrel.

The NRC classifies waste as for one reason only,  to set criteria for
the construction of new LLRW disposal sites.  To use the definition
beyond the scope of that objective is not reasonable.

By the way,  I seem to recall that the reason you can have so much
Co-60 in a drum and still call it Class A LLRW is the 5 year half
life versus the 100 year lifetime of a Class A dump site.  Even
though the initial activity is high when the drum is disposed of,
if will have easily gone through 11 halflives by the end of the
dumps projected lifetime.  Again,  the above example is a recollection
based on some work I did some years back.  I would contact the NRC for
the appropriate basis material used in promulgating the Part 60 regs.

Vince Chase
772ear@delphi.com
Radiation Safety Officer
Boehringer Ingelheim Pharmaceuticals
The opinions expressed here are those of the author and do not represent
the opionions, policies or practices of Boehringer Ingelheim Pharmacuticals.