Safety of Radioactive Waste Management in Thailand; Dismantling and Conditioning of Disused Sealed Radioactive Source by Encapsulation

The Thailand Institute of Nuclear Technology (TINT) operates the central storage facility for non-nuclear wastes in Thailand. This paper introduced the safe management of disused sealed radioactive source (DSRS) of category 3-5 by the innovative technologies; dismantling and conditioning of DSRS by encapsulation technique. The segregation and characterization of each DSRS were firstly performed. The radiation protection and safety aspects associated with the dismantling and conditioning operations were provided. Those DSRS from industrial uses, such as ⁶⁰Co, ¹³⁷Cs, ²⁴¹Am/Be, ⁸⁵Kr gauge sources and 241Am from consumer products were dismantled and conditioned and then placed into 200L drums with shield for interim storage. The encapsulation in stainless steel capsules was to facilitate their retrieval for final disposal options, such as a borehole disposal facility. The concrete was used for physical protection and security of the sources. Adequate lead shielding at the operation area must be provided for radiation protection reasons. The maximum activity per capsule multiplied by the number of capsules shall not exceed A1 limit values as set out in the IAEA transport regulations. The outcomes of this operation were that the volume of reduction was about 5 times than before and the DSRS were packaged in the secure, safe, and retrievable manner for the future disposal options. (author)