RADFAX: Radionuclide Facts Program

by
Dave Wertz

Department of Environmental Health
and Occupational Safety
Uniformed Services University
of the
Health Sciences
4301 Jones Bridge Road
Bethesda, Maryland 20814-4799
(202) 295-3323


1. Background: This program provides reference data for thirty-
four radioisotopes commonly used in research, including half-life,
physical data (types of radiation, energies, etc.), occupational
limits, exempt quantities, internal emitter limits, and laboratory
limits. The information for each isotope is displayed on a single
screen, which is color-coded to provide easier readability. You
are given the option of performing decay calculations, if desired.

2. Description:

a. The program opens with a title screen, followed by a menu
listing each isotope which is included in the program. Isotopes
are listed by increasing atomic weight. Page one of the menu is
displayed; the second and third pages are accessed by pressing the
PgUp or PgDn keys. When the desired menu page is displayed, you
press any of the keypad keys to highlight the desired isotope, then
press RETURN. The reference screen for that isotope is displayed.

b. At the bottom of the screen, you are asked if decay
calculations for that isotope are desired. If you enter "Y" or "y"
at this prompt, a window appears, and the program proceeds with the
decay calculations (see below). If you press any other key at this
prompt, the program returns to the menu.

c. If you press the ESC key while the menu is displayed, the
program terminates, and you are returned to the point from which
the program was run.

3. Specific instructions for decay calculations: If the isotope
selected has a physical half-life of 100 days or less, a menu
window appears giving you two options for calculating the decay of
the isotope. Option 1 "Decay for (t) time period" is described in
subparagraph a below. Option 2 "Decay for (n) half-lives" is
described in subparagraph b. If the isotope has a physical half-
life of more than 100 days, only option 1 is available; therefore,
the menu window does not appear.

a. Decay a known quantity for a given time period

(1) You are prompted to enter the date to begin the decay
calculation. The date must be entered using the format MM-DD-YYYY.
The current date may be specified by entering the word "TODAY" or
"today" at this prompt.

(2) You are then asked for the date to end the
calculation. This date must also be entered in the format MM-DD-
YYYY. If the first date is sometime in the past, and the current
date is desired, you may enter the word "TODAY" or "today" at this
prompt. The current date may not be specified for both entries at
the same time.

(3) The program will not accept invalid dates (i.e. 02-
29-1987, or 09-32-1988), or dates not in the specified format (MM-
DD-YYYY). In addition, the first date entered must be earlier than
the second date entered. Any of these conditions will produce an
error message, and the opportunity to correct the error.

(4) You are then asked to enter the original quantity of the
isotope in millicuries (mCi).

(5) The program will display the quantity of the isotope
remaining on the second date, and the number of half-lives which
have elapsed.

(6) At this point, the prompt "ESC to exit, RETURN to repeat"
appears at the bottom of the window. If you press ESC, the window
disappears, and you may then continue to view the isotope data, or
press any key except "Y" or "y" to return to the menu. If you
press "Y" or "y", the decay window will reappear.

b. Decay an unknown quantity for a given number of half-lives.

(1) This option is available for those isotopes on the menu
which have physical half-lives of 100 days or less, the limit (by
USUHS's NRC license) for isotopes which may be held for decay
(instead of being disposed of as radioactive waste). In addition,
the long half-lives of isotopes such as Carbon-14 make the
calculation meaningless.

(2) You are first asked for the date to begin the decay. As
above, this date must be in the format MM-DD-YYYY. Invalid dates,
or dates not in this format will not be accepted. The word "TODAY"
or "today" may be entered in lieu of the current date, if desired.

(3) The program next asks for the number of half-lives you
want to decay. This may be any number greater than 0, but will
not normally exceed 10. The program limit is 15 half-lives.

(4) The program will display the approximate date on which the
material will have undergone the specified number of half-lives.
Also displayed is the percentage of the original quantity which
remains on this date.

(5) At this point, the prompt "ESC to exit, RETURN to repeat"
appears at the bottom of the window. If you press ESC, the window
disappears, and you may then continue to view the isotope data, or
press any key except "Y" or "y" to return to the menu. If you
press "Y" or "y", the decay window will reappear.


THIS PROGRAM IS PROVIDED FREE OF CHARGE FOR ANYONE WHO FINDS A USE
FOR IT. IT MAY BE FREELY COPIED AND DISTRIBUTED, PROVIDED ALL THE
FILES INCLUDED IN THE FILE RADFAX.ZIP ARE INCLUDED IN THE
DISTRIBUTION FILE. ANY COMMENTS (GOOD, BAD, OR RUDE) REGARDING
THIS PROGRAM OR SUGGESTIONS FOR ITS IMPROVEMENT WOULD BE GREATLY
APPRECIATED BY THE AUTHOR.