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    Swipes are used to ensure that spaces and areas are free of radioactive contamination.

  • One-inch diameter Whatman filter paper is the best medium to use as a swipe.

  • Take an approximate 100cm2 swipe which is about 4 x 4.

  • Dry swipes are preferable.

  • Count swipes in a LSC, Gamma counter, or with a count rate meter (depending on isotope energy).

  • Swipes are required for tritium or high background areas.

  • If you swipe too great an area, you could spread contamination so always try to follow the 4" x4" rule.

  • If counts above background are found, decontaminate with a dry or wet method or call the RSO for information.

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