Protective barriers for radioactivity isolation:
- I barrier – fuel cladding
- II barrier – multi sealed basket – internal steel container filled by helium
- Ventilated concrete cask (mechanical and biological protection, vertical stability of MSB during transportation and storage)
- Concrete storage site (structural and seismic stability)
Safety of storage in ventilated concrete casks is based on the following physical processes and is ensured by the structural decisions accepted in the design:
Thus, SFDS protective functions listed above ensure safety of spent fuel storage in ventilated concrete casks not worse – and in part of some parameters even better – than the level of spent fuel storage in the spent fuel ponds at the power units. Besides, risk of emergencies during transportation of VCC to SFDS on the plant size is not commensurable with risk of similar emergencies during transportation of TK-13 containers via railway. For 50 years of intermediate storage at the plant the potential risk will even be reduced and accordingly the risks during spent fuel transportation to the locations of their constant disposal or processing will be significantly reduced.