We are pleased to announce the successful commissioning of the sheltered dry fuel storage system at Slovenia’s Krško Nuclear Power Plant. Holtec delivered this project on a turnkey basis with able support from the plant operator Nuklearna elektarna Krško (NEK). As shown in the photos in this issue, Holtec’s HI-STORM FW casks are stored in an anchored configuration inside the earthquake-hardened and flood-proof Fuel Storage Building. Another unique feature of the Krško Fuel Storage Building is its compliance with the extremely low dose accretion limit mandated by Slovenia’s national regulations. Each HI-STORM FW cask, bolstered by its steel-concrete-steel construction (METCONTM) is designed to withstand a severe commercial and military aircraft impact according to IAEA criteria for nuclear installations.
The overarching characteristic of the Krško dry storage installation is its extreme ruggedness. The health and safety of the plant’s host community is protected by a series of robust protective structures starting with the reinforced concrete Fuel Storage Building, which is designed to serve as protection against most damaging loadings such as a crashing aircraft.
The second barrier against release of radioactivity under an impactive strike on the Fuel Storage Building is the HI-STORM FW cask itself, whose uniquely double wall buttressed steel structure has been accepted by America’s Atomic Safety and Licensing Board (2005) as structurally invincible to an incident missile, such as a crashing aircraft. In addition, the Multi-Purpose Canister (MPC) used in Holtec’s storage systems has been qualified to withstand free fall from 18 feet elevation without rupturing, serving as the third robust barrier against radiation release. Finally, the tubular enclosure of the fuel pellets, known as the fuel cladding, provides the fourth barrier against release of radiation to the environment. Working conjunctively, the above-mentioned barriers make the probability of radiation leakage from Krško’s fuel storage system under the most severe postulated accident events non-credible. Holtec’s dry storage installations that are deployed at 149 nuclear units worldwide have similar multi-layer protective barriers that guard the health and safety of their local communities.