The iodine element in people’s food is very important and according to the available information, the central part of ??Iran is located in the belt of iodine deficiency. So it is necessary to determine the exact amount of this element. In this research, concentration of the element iodine in various kinds of salts, including sea salts and processed iodised salts have been measured. These measurements have been done by neutron activation analysis using epithermal neutrons (ENAA), along with construction of cadmium capsule in Isfahan Miniature Neutron Source Reactor (MNSR). The results of these experiments have been compared with the results of the ordinary methods of thermal neutron activation analysis and capsules containing the element boron, and the accuracy of this method has been confirmed. According to this study, due to low concentration of iodine in salt and its low absorption cross-section for thermal neutrons, and also due to presence of high concentration of interfering nuclide Na (which unlike iodine has a high absorption cross-section for thermal neutrons), the use of epithermal neutrons has increased the sensitivity of this method. By using cadmium capsules which were made for this purpose, without the user receives a significant dose and with radiation protection provisions and the results of MCNP code, the samples can be analyzed and iodine in samples can be measured with high accuracy. The flux of epithermal neutrons obtained from MCNP code in the cadmium capsule is more than the flux of epithermal neutrons in boron capsules. Since the element iodine is highly sensitive to temperature, capsule containing boron compound are not suitable, because they emit ?-particles which increase the temperature of the capsule which leads to iodine evaporation and therefore reduces the accuracy of the method. If sealing and packaging of capsules are not done carefully it causes the capsule become open inside the reactor, therefore reactors safety is extremely problematic and is not recommended. Now according to the results of this study, cadmium capsules are used in similar cases in the miniature neutron source reactor.
