Applied study on optimizing the final disposal of Loviisa NPP spent fuel assemblies

Tuukka Lahtinen, Jaakko Kuopanportti (Fortum)

28th Symposium of AER on VVER Reactor Physics and Reactor Safety (2018, Olomouc, Czechia)
Spent fuel disposal and actinide transmutation


In this paper, the optimization of the assignment of spent fuel assemblies into final disposal canisters is considered. This application is of essential importance because the final disposal canisters are expansive and there is a limit for canister-wise total heat load, which must not be exceeded.

The study utilizes mathematical optimization algorithms that have been developed by Timo Ranta is his D.Sc thesis (Tampere University of Technology, 2012). In the used formulation, the target of the optimization is to minimize the maximum canister-wise decay heat load at the time of the encapsulation.

The optimization algorithms were implemented using the Python programming language. The paper demonstrates results and findings of a work, where the algorithms were utilized for analyzing some arbitrary final disposal scenarios for present and expected future spent fuel assemblies of Loviisa NPP.

Paper concludes that, despite a huge amount of degrees of freedom, the algorithms are capable of finding practically a global optimum for the problem. The outcome of the work is a software tool, which can be used for further final disposal analyses according to various needs This is considered very beneficial as the final disposal costs play an important role in overall economics of the fuel utilization.

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