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California State University, Long Beach
College of Natural Sciences and Mathematics

How to Do Radiation Contamination Surveys

There are two kinds of contamination surveys:

  1. Experiment Surveys: required after ever experiment
  2. Monthly Surveys: give to RSO before the 20th of every month.

Please read the following. The way you survey differs according to what isotope you are looking for!

 

3H

  1. Wipe at least 5 areas with a piece of filter paper, add a "clean wipe" control vial, and count in the LSC. Don't forget freezer handles, doorknobs, sinktops, counters, equipment etc. Treat plastic LSC vials with anti-static wipes before counting to reduce false, high readings; If contamination is detected (>200dmp/100cm2 above background), it's time to clean! Re-swipe and count in machine until clean.
  2. Write your name and the wiped areas on the LSC printout, and put it into the lab radiation notebook today; if this was a monthly survey, give the printout to the Rad Safety office today.

 

14C, 35S and 109Cd Users

  1. Use the hand-held meter to find any hot spots. Use the meter with the CYLINDRICAL probe for 109Cd; use the meter with the FLAT or "pancake" probe for the other isotopes. Remember, these meters cannot detect 3H.
  2. Wipe at least 5 areas with a piece of filter paper, add a "clean wipe" control vial, and count in the appropriate machine (Gamma counter for 109Cd, LSC for all others). Include wipes on any hot spots you found in STEP 1. Don't forget freezer handles, doorknobs, sinktops, counters, equipment etc. Wipe plastic LSC vials with anti-static sheets before counting to reduce false, high readings; If contamination is detected (>200dmp/100cm2 above background), it's time to clean! Re-swipe and count in machine until clean.
  3. Write your name and the wiped areas on the LSC printout, and put it into the lab radiation notebook today; if this was a monthly survey, give the printout to the Rad Safety office today.

 

32P, 125I, 65Zn, 60Co, and 54Mn Users

Just use the hand-held survey meter!

  1. Use the hand-held meter to find any hot spots. Make sure you use the correct meter! Use the meter with the flat or "pancake" probe, unless you are looking for 125I, in which case you need the meter with the cylindrical probe. For high background areas, wipe with filter paper then survey the paper with the meter. Clean any areas that have more counts than background, then re-survey.
  2. Immediately write your name, areas surveyed, and the results on the "contamination survey" log sheet found in the Rad Notebook or posted in the lab. Give monthly surveys to the Rad Office today.