RESRAD Risk/Dose Question

["Frohmberg, Eric" <Eric.Frohmberg@STATE.ME.US>]

Hi All,



Here is a question for you modelers and RESRAD experts.  You also may find

it entertaining as it is modeling "proof" that there is no such thing as

zero risk.



For various obscure reasons, I've done a RESRAD run using all default

parameters with the exception of using an initial concentration of 1 pCi/g

of Sr-90 and a Kd of 6 (for all soil zones).  When looking at the results I

get an initial dose beginning at year 41.  I also find Sr 90 in the well

water at year 41 (I'm fine with this, this all makes sense, I presume, based

on breakthrough times, etc.).  But when I use RESRAD to calculate risk, I

start to get risk from drinking well water at year 8!  Granted the risks are

"small" (as one would expect with no concentration!) but one could argue

they shouldn't be there at all!



I presume this is due to a rounding issue - RESRAD is calling concentrations

below a certain limit zero - but it is doing this AFTER calculating (and

storing) the risk numbers.  Has anyone experienced this same issue?  Can

anyone confirm that this is what is happening?



I can email anyone interested the raw data, but it is easy enough to run

yourself.  The initial concentration of Sr-90 is 1 pCi/g.  Under transport

option, change the Kd in the various zones (contaminated, unsaturated and

saturated) to 6.  Leave all the other values as defaults.  Run the model and

look at the "standard graphics" for concentration in well water, dose from

drinking water, and risk from drinking water.  You'll see the risk appears

before the strontium ends up in the drinking water.  



Thanks for your collective experience,

Eric





Eric Frohmberg, Toxicologist

Environmental Toxicology Program

Maine Bureau of Health

11 State House Station

Key Bank Plaza, 8th Floor

Augusta, ME 04355



207-287-8141 (phone)

207-287-9058 (fax)

eric.frohmberg@state.me.us



************************************************************************

You are currently subscribed to the Radsafe mailing list. To unsubscribe,

send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

radsafe" (no quote marks) in the body of the e-mail, with no subject line.