RE: WOW!!!! Personal Contamination

[Glen.Vickers@ucm.com]

I think the 50k is probably related to more of a dosimetric interest rather
than a contamination control measure for a site.  Dosimetric interests and
contamination control interests exist in different orders of maginitude and
so the criteria for implementing these programs should be different.
Contamination control programs should review all contaminations, but
dosimetry personnel should not attempt to calculate dose for all
contaminations.

The most likely contributor to be found at a power plant would probably be
Co-60.  The dose contribution from 50 kdpm of Co-60 for an hour on the skin
would be:

Point source ~90 mrem "shallow dose" or "hot particle dose", not SDE
Plane source (15.5 cm^2) ~5mrem SDE

These exposure values are quite small when compared to the 50 rem "hot
particle" dose and 75 uCi-hr limits for point sources and 50 rem SDE for
planar sources.  The risk from particle is also officially recognized to be
deterministic in nature, not stochastic, which explains why some of the
discussed exposure thresholds may seem high to those not in the skin dose
business.

50k Point	0.2% dose, 0.03% uCi-hr limit
50k Planar	0.01%
TLD		10 mrem minimum reportable.  The bulk of non-outage
exposures are reduced to 0.
Monitoring 	10% of limit, some might say 100 mrem at their facility.
ALI	Can't recall, but I would expect 95% of the plants don't exceed 1%
an ALI for a single person in a year.

All contaminations should be recorded with the description of point or
planar sources, attenuating materials, and the amount of exposure in dpm-hr.
Isotopic analysis would also be performed as applicable.  This provides data
with which to make an accurate decision to calculate exposure or not.  The
contamination report would still go into the worker's record, whether or not
a formal dose calculation was done or not.  I think there is a difference in
spending the time to collect the data to accurately characterize a
contamination event versus spending additional time to calculate 0 mrem of
dose 100 times a year.  All forms of exposure have lower thresholds, its
just that most contamination thresholds are still unusually conservative as
compared to the other forms of exposure.

Sincerely,
Glen Vickers
glen.vickers@ucm.com




	-----Original Message-----
	From:	RONALD L. SHEPHERD [SMTP:SHEPHRL@GWSMTP.NU.COM]
	Sent:	Monday, August 23, 1999 7:19 AM
	To:	Multiple recipients of list
	Subject:	WOW!!!!

	WOW!!!!
	50,000 dpm isn't considered being contaminated????
	Might as well do away with your HP dept....that ought to save some
money!!!
	But just let me know where you work so I don't accidently eat at
your cafeteria
	and set my spoon down on your MRad smearable tables, or mistakenly
use your
	phones which would be screaming with contamination after a week or
so.  Oh, by
	the way, I'm sure your six week old baby will be thrilled to know
that you are
	handling her bottles with hands reading 50 K.

	I must be missing something here.
	If your program is so lousy that you have to bump up your action
levels to 50K
	you might as well forget it and get into some other business.  

	If your workers cannot perform their jobs without getting
contaminated I just
	have to wonder how well they do their work?  Contamination is
nothing but
	radioactive dirt and everywhere I have worked my boss would get more
than a
	little upset at me if I didn't try to keep my work place reasonably
clean.  So
	how can hiring slobs save you money?  If they work on anything won't
they do
	substandard work???  Won't that equipment break down quicker than if
you had
	professional people work on it?  Doesn't it cost more to fix
something three
	times instead of once?  We have literally thousands of entries into
	contaminated areas weekly in the power industry and look at
personnel
	contaminations as indicators of a much more serious problem.

	What I am saying here is that there is no excuse for people to get
contaminated
	unless there is some very unusual event that causes it.  Bumping up
the levels
	to 50 K is just trying to hide a problem that will only get worse if
it isn't
	addressed.

	Just my soapbox
	Ron Shepherd
	shephrl@gwsmtp.nu.com
	
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