Radioactive potassium

A store-bought container of potassium chloride, aka Salt Substitute, contains enough of the naturally occurring potassium-40 isotope ( 0.0117% abundance per the CRC, page 4-24) to produce 5.5x the amount of background radiation when placed on a geiger counter, with the container intact. The rate would have been higher if I had taken the salt out of the container, as the metal base shields some percentage of the 1.31MeV(max) beta electrons.



Paul Frame at Oak Ridge has a great site about radioactive consumer products at http://www.orau.org/ptp/collection/consumer%20products/consumer.htm
and see the potassium info page at http://www.orau.org/ptp/collection/consumer%20products/potassiumgeneralinfo.htm