Time-dependent variations in the radiological health impact of an interim spent fuel storage facility

Radiation shielding calculations on spent fuel casks are an inherent part of the nuclear analyses performed for the site safety report (SSR) when siting an interim spent fuel storage facility (ISFSF). The basis for this is a legislative requirement that the licensee must demonstrate to the nuclear regulator that no member of the public will be exposed to a radiation health risk as result of the operation of the ISFSF. Because of the enormous number of isotopes that are generated as result of the operation of a nuclear reactor, shielding calculations have to perform the following analyses which are the objectives of this research paper: (a) identify a group/set of nuclides that are important in radiation shielding with a view to ensuring that the shielding material/strategy adopted envelops the radiation emissions of all nuclides so as to prevent a deficiency in the radiation protection measures adopted (i.e. optimisation of protective measures); (b) determine the mathematical expression that links the behaviour (i. e. growth or decay) as a function of time within a stipulated time frame (i.e. the boundary conditions); (c) develop a mechanism for ranking nuclide importance in shielding; (d) determine whether there is a relationship between taking credit for burnup or not (Leotlela et al., 2015; Leotlela et al., 2020) and the resulting effective dose; and (e) determine whether there is a relationship between the effective dose and the duration of cask storage in the ISFSF.

Automated summary

Radiation shielding calculations on spent fuel casks are essential in nuclear analyses for siting an interim spent fuel storage facility. The objectives include identifying important nuclides for shielding, determining mathematical expressions related to behavior over time, developing a ranking mechanism, and exploring relationships between burnup credit, effective dose, and cask storage duration in the ISFSF.