Pu at Johnston Atoll

[Andrew McEwan <Andrew@nrl.moh.govt.nz>]

I posted this a while ago and received an error message.  If this is
appearing twice I apologise.

On 26 June David Rynders wrote:

"I am designing a verification survey plan for contaminated coral at
Johnston Atoll.  We plan to scan the surface to look for the particles.
  The
question is how, if possible, to conduct sampling for the tiny particles
that
is statistical defensible.  Has anyone done any work like this?
     Our idea to determine the maximum number of allowable particles in the
coral is to back-calculate from an allowable lung dose.  This will give a
starting point for the survey design.

Thanks in advance

CPT David Rynders"

David

The purpose of the survey is not entirely clear to me.  If lung doses from
resuspension are the critical measure, the most direct way to assess these
would be by air monitoring.  LLNL (Bill Robison and others) have done
resuspension measurements at Bikini Atoll and found very low values in the
E-10 to E-11 range for coral soils.

A resuspension factor of E-10 implies a surface areal contamination of
around 2xE07 Bq/ sq m to keep within a committed effective dose limit of 1
mSv/y for full time occupancy.

Another exposure route for consideration is contamination of a wound,
particularly if the activity is mostly in active particles.  I have further
information on this if you wish to follow it up.

Andrew McEwan

_________________________
Andrew C McEwan PhD
National Radiation Laboratory
PO Box 25-099
Christchurch, New Zealand

Ph 64 3 366 5059
Fax 64 3 366 1156
acmcewan@nrl.moh.govt.nz
________________________