Many countries have radioactive sources that need to be managed and disposed of carefully and in a safe and secure manner. Increasing attention is being given to the disposal of disused sources in borehole facilities with a view to providing a safe, secure and cost effective disposal option.
AMBER has been used to carry out a generic post-closure radiological safety assessment (GSA) for the borehole disposal concept in support of the IAEA, with the purpose of identifying the concept's key safety features, under varying disposal system conditions, in order to support the concept design and licensing processes, and facilitate its site-specific implementation. The GSA has been undertaken using an approach that is consistent with best international practice. Specifically, the ISAM safety assessment approach has been used, with the aim of ensuring that the assessment is undertaken and documented in a consistent, logical and transparent manner.
The results show that with a suitable combination of inventory, near-field design and geological environment, the borehole disposal concept is capable of providing a safe solution for the disposal of both long-lived and short-lived radionuclides. For most radionuclides, including longer-lived radionuclides such as Ra-226, post-closure safety places no limit on the radionuclide inventory that could be disposed of using the borehole disposal concept. Even for radionuclides such as Pu-238, Pu-239 and Am-241 with exceedingly long daughters (i.e. half-lives in excess of 100,000 years), the concept has the potential to dispose around 1TBq in a single borehole.
AMBER has also been used in the IAEA study of the application of the graded approach to the post-closure safety assessment for the disposal of disused sealed radioactive sources in boreholes, and the assessment of the concept’s implementation in countries such as Brazil, Ghana and Malaysia.
Lead image courtesy of NECSA.