Hey , My classmates and I were asked to give a presntatoin about "food irradiation" and I'm the one who 's responsible about shielding calculations. I want to show that 6 m (19.69 ft) of water is enough to shield gamma source so that the exposure dose for workers doesn't exceed the maximum permissible dose(MPD) . For solving this I need to know : 1-The average total activity of gamma source array in curie. 2- The diminsion of the of gamma source array. Hopefully someone can help me to get these parameters.