Investigation of RBMK-1500 Spent Nuclear Fuel and Storage Casks Performance during Very Long Term Storage (IAEA No. 17275)

The present spent nuclear fuel (SNF) management concept in the Lithuania foresees dry storage of SNF for 50 years. During this time the final SNF management concept shall be developed. However due to various uncertainties in future, it is possible that final management options can be not implemented in due time, therefore elongation of the SNF storage for a period over 50 years shall be also considered. The performance of spent fuel rod/assembly and performance of storage cask components are the most important subjects in case of SNF very long term storage. At the moment there are some investigations on spent RBMK fuel performance during wet storage in the pools, however, investigations on spent fuel performance during very long term storage inside the dry storage casks are not performed.

The scope of project is to initiate the researches related to very long term storage of spent RBMK-1500 fuel and to perform modelling of RBMK-1500 spent nuclear fuel (with different initial U-235 enrichments) characteristics for very long term periods, investigate of RBMK-1500 spent nuclear fuel performance and evaluate the dose rate variations on the surface of the casks and at some distance during very long term storage, perform modelling of neutron transport in storage casks and analyse neutron activation of storage cask components.

LEI has provided the overview of the existing investigations on RBMK spent nuclear fuel performance during the storage and has performed the modelling of spent RBMK-1500 nuclear fuel (with initial U-235 enrichments of 2.0%, 2.4%, 2.6%, 2.8% and without/with Erbium burnable absorber) characteristics for very long term storage period. Also numerical models were prepared, and shielding characteristics of RBMK-1500 storage containers were evaluated, as well as neutron activation of the components forming the storage container during long-term storage was analysed.