Strategic directions at the shelter object after putting into operation new safe confinement

Since 1993, Ukraine jointly with international community takes measures (actions) to the Shelter object tran s- formation into an ecologically safe system. At the end of 2016, the New Safe Confinement t ( NSC) was installed into design position at the Chornobyl NPP. During 2017 – 2018 , works on putting into operation of the NSC are under way. Construction of the NSC allowed reduce significantly the risk of potential radioactive contamination of the territory as the consequence of the collapse of unstable building structures of the Shelter object due to its isolation from the environment. However, construction of the NSC is just an intermediate stage. It is needed to take many scientific and technical measures for the Shelter object transformation into an ecologically safe system. The ultimate goal is to transfer the fuel containing materials into controlled state. There are some views, that after the NSC construction the problem of the Shelter object transformation is fully resolved. However, guaranteed term of the NSC operation is only 100 years and half - life of nuclear materials contained in the NSC are much longer. In this regard, the hazard to the environment will exist for thousands of years. Therefore t his problem is needed to be solved otherwise its solution will be transferred to the future generations and the term of the NSC operation is not so big. The article focuses on scientific and technical problems that needed to be solved for achieving the ultimate goal – the Shelter object transformation into an ecologically safe system. Pros and cons of the strategies of the Shelter object transformation into an ecologically safe system are considered, main of them are: in - place disposal by filling with concrete or other mixes and stage - by - stage fuel containing materials retrieval with further the Shelter object decommissioning. The Shelter object transformation works are considered to be done stage - by - stage during the NSC lifetime. Strategies of works at the Shelter object after putting into operation the NSC are defined. It is shown that fuel containing materials retrieval is key condition on the way of the Shelter object transformation into an ecologically safe system. Transition to the decommissioning can b e done only when fuel containing materials are transformed into radioactively safe state and placed for controllable storage or transferred to disposal. Therefore, the variant "stage - by - stage fuel - containing materials retrieval with further the Shelter object decommissioning" is considered as the key to the Shelter object transformation into an ecologically safe system. According to existing national experience of projects realization at the Chornobyl NPP site, it is clear that Ukraine alone cannot manage the problem. Therefore, the necessity to apply to the international society for the help concerning infrastructure building and acquiring appropriate up - to - date technologies exists. (author)