Estmating airborne contamination

[ChopperBob]

      Just discovered this website today and it's way cool.  I've reading it all day. Just wish there was something like this when I got out in '86.
      Question:  How would someone go about estimating airborne contamination from using an air operated tool exhausting within a few inches of loose surface contamination levels of 800,000 dpm/swipe? I realize there would need to be some assumptions made. But, humor me for a minute, and tell me what reasonable asumptions could be made. Also, I'm use to using "cpm" vs "dpm". Are they the same or is there a conversion I need. Alot of things have changed since I got out; or else it's just different in the civilian nuclear power community, or I have just forgotten that much. Probably the latter, LOL.
      Thanks
       Bob

[wlrun3@aol.com]

if a floor contamination level of 666 dpm/100 cm^2, in a room measuring 10 m x 10 m x 10 m, becomes uniformly suspended in the air of the room, using the Co60Y DAC value of 1E-8 uCi/mL, the DAC fraction of the air in the room would be 0.3 DAC...(666 dpm/100 cm^2)(1 uCi/2.22 E6 dpm)(100m^2/floor)(1 E4 cm^2/1 m^2)(room/1000 m^3)(1m^3/1 E6 cm^3)(1 DAC/1 E-8 uCi/cm^3) = 0.3 DAC

[alphadude]

that is an extremely difficult to realize situation, swipe eff. would have to be determined as well as the AMAD of the particulate that may be suspended, radionuclide type and air velocity. 

If you make simple assumptions, its a plug and chug model.  Assume 100% or 5%, with the information given, at best, its a poorly educated guess.

the information provided by wlrun3 is a plug and chug model example.

no reasonable assumption can be made based upon the information provided.  A SWAG may be given and any conclusion provided here would be just that.

[peteshonkwiler]

Eight hunred thousand dpm per swipe with an air operated tool generating airborne.  Interesting.  Is that swipe a hundred cm squared, or a square foot masslin sample?  Is the contamination media loose, dusty stuff or of an oil, greasy type?  is the surface that is contaminated a small area, as in a shelf or table top or is the entire floor surface affected and being worked upon?  Is the air operated tool a small hand held unit or a large piece with the exhaust located well away from the surface in question?  Then there is always the matter of time of exposure of the work activity which will affect the generation of airborne activity.  Of course the room's volume has already been addressed so there is no sense in re-addressing that issue.  However, there are other physical considerations to be considered besides the simple activity dispersion model.

[Marlin]

   Estimating airborne in the commercial industry is more complex and less predictable than the carefully controlled environment the Navy uses which (at least when I was in) controlled contamination to virtually zero intake even at the cost of external exposure.
   While at an outage at Clavert Cliffs (early 80s) I was on the refuel floor whlie the Reactor Head was being lifted to the head stand, I suddenly felt a large rush of air on my legs. After a short moment of confusion I realized that the open under side of the reactor head was traveling over a ventialtion unit that had not been not turned off. We cleared containment but the result was no air sample over .25 DAC and no indication of intake, if I had tried to predict airborne concentration it would have been much higher than the reality. During a remediation of a warehouse full of deteriating drums of thorium compound everyone expected that the failure of a drum when it was dropped from the third tier of the stacks would cause the highest airborne. The reality was that the forklift traveling around the floor generated the highest airborne levels throughout the warehouse, even with a daily cleaning regime with a powered floor cleaner. The highest local contamination was generated by size reduction of plywood with a skill saw even though there was very little product on it.
   I remember calculating potential airborne while in the Navy but it was only used as a training tool to help the trainee understand relative risk. Experience gained on a specific facility or function is the best predictor failing that run the numbers and then lower controls to fit reality as you gain experience.

[SloGlo]

i yam currently trying to find some formulas that i lost regarding work applied to contaminated surfaces that'd give an estimated airborne concentartion 'n wood appreciate any that you have.  watt i remember was a plug 'n chug with the surface contamination level multiplied by a factor which product was divided by the room volume.  tanks.

[alphadude]

those are perfect model formulas- boric acid, magnatite, etc all play into the real world formula and its dern near impossible to say if its 100k it will be x dac .. suspension factors, room volume thats all test question stuff- aint like that for real... but u know this

[SloGlo]

not looking for dac.  looking to get concentration.  it may be test instead of real world.  but i want it anyway.  i remember there were three factors that could get plugged in for light traffic, average work level activity, and heavy work or mechanical agitation.  but i can't pull the formulas.  frigging grey matter is gitting to clogged.

[ageoldtech]

Chopperbob also wanted to know about CPM to DPM, it depends on the instrumentation, if you were to use an RM-14 it has an efficiency of 10%, so if you had 80,000 counts that would = 800,000 DPM/100cm2 assuming that the smear you took was actually 100cm2

[LaFeet]

If they died from the Airborne   it was too high

[alphadude]

1.0 E-5/m - For non-heat generating aggressive work such as sweeping
1.0 E-6/m - For minimal activities such as general inspections and surveillance
1 .0 E-7/m - For stationary working conditions

is that the magic numbers u was wantin?

[SloGlo]

alphadude,  cood be.  eye seem to remember a wider range in da factors.  hafta weight 'n see iffen enny buddy else gots sum.  butt tanks fer da input.

[LaFeet]

42

[alphadude]

they is a lots mo infermation..boiled down to a thick syrup

[LaFeet]

they is a lots mo infermation..boiled down to a thick syrup

 As long as it tastes good on pancakes or waffles

[alphadude]

i think those numbers i gave you were the results of the boil down on those wide ranges... the ole navy thumb rule cards had a lot of those factors on them but i only have a few of those layin around and its all based on Co60