Radioactive Cheat Sheet

G.  Gross Assay Information

Activity can be determined approximately since each unshielded mCi will yield a survey meter reading at a given distance as shown in "B" above.  Example:  A vial of Iodine-131 tracer registers 1 mR/hr at three feet; hence it must contain about 4 mCi of Iodine-131.

H.  Packaging

Tracer material is shipped in 20 ml (~2/3 oz) or sometimes 15 ml screw cap vials in a lead shield referred to as a "pig".  100 mCi of activity could easily be placed in 1 ml, but larger diluted volumes are customary, e.g., 10 mCi in 10 ml.  It is possible to pack more than one vial in a container.

I.  Package Labeling

"Radioactve I" a/k/a "White I"           0.5 mR/hr or less on external surfaces.

"Radioactive II" a/k/a "Yellow II"      Over 0.5 mR/hr but less than 50 mR/hr on external surfaces, but not to exceed 1.0 mR/hr at one meter.

"Radioactive III" a/k/a "Yellow III"    Over 50 mR/hr on external surface or over 1.0 mR/hr at one meter.

The "Transport Index" (TI) is the activity in mR/hr at one meter.

Two labels are required on each package on opposing sides.

Up to about 20 mCi of Iodine131 can be shipped as "Yellow II", with standard shielding.

J.  Vehicle Placarding

Placards are required for "Radioactive III" a/k/a "Yellow III" package transport only.

K.  Formulae

     1. Inverse Square Law:

            I1 (d1)2 = I2 (d2)2     or

            I2 = (I1 (d1)2) (d2)2

            Where:  d is distance and I is intensity.

            I at One Meter = .836 I at One Yard   and   I at One Yard = 1.196 I at One Meter.

     2.  Calculation of Gamma Radiation (20% or so accuracy):

            R = 6 CE        For One Foot
            R = .53 CE     For One Meter 

            R is Radiation Intensity at a given distance in units of R/hr if C is in Ci or mR/hr if C is in mCi.
            C is Activity in Ci or mCi.
            E is Effective Energy (MeV).

L.  Handy Conversion Junk

For Gamma Radiation (in the real world):   Roentgen = rad = rem   and   mR/hr = mrem/hr.

       1 rem = .01 Sievert (Sv)
       1 ml is roughly 20 drops
       100 BPD = 2.9167 gpm
       1 psi = 2.31 feet of fresh water head

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Last 10-20-10