A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management

Thesis (M.Eng.) - Asian Institute of Technology, 2014

This study aimed at finding safety level for the human through measurement of Cs-137 in soil samples in order to set baseline data for the Nakhon Nayok Province in Thailand. Study here was conducted in order to help whether there was any possible health threat imposed by Cs- 137 exposure in the residential area of the Province. Furthermore, the main rationale behind the selection of this particular district was that in coming future Thailand has plan to establish Thai institute for nuclear technology. For the sampling, 21 soil samples were collected by grid sampling method in various location of Nakhon Nayok Province{u2019}s Districts which were Ongkharak, Ban Na, Pak Plee, Mueang Nakhon Nayok. In order to measure soil sample by gamma spectroscopy A-type HPGe detector was used. The results of the study showed that activity of the Cs-137 from samples ranged from 1.23 ± 0.05to 0.11 ± 0.01Bq.Kg-1 with an average value of 0.73±0.03Bq.Kg-1. For average value of outdoor, indoor as well as annual effective doses from the samples, the results found out were 7.0x 10 -8, 5.7 x 10 -5 and 5.7 x 10 -5 mSv.y-1 respectively. The results of the study portrayed that the values found out were very minute as compared with the annual dose rate as recommended by ICRP (1.0 mSv.y-1) and also the annual external gamma radiation dose (0.48 mSv.y-1) exposed on per person from naturally occurring sources of radiation.