Engineering Analysis And Design

FuelSolutionsÔ Fuel Storage System

The FuelSolutionsÔ dry fuel storage system consists of a concrete storage cask, a water shielded transfer cask, a transportation cask, and a variety of spent nuclear fuel canisters.  Q‑Metrics had the lead responsibility for the thermal design of the FuelSolutionsÔ system.  The design goal of the system is to provide a modular design that is qualified for on-site storage and transfer operations, off-site transportation, and, potentially, ultimate disposal in a national repository without the need for re-packaging the spent nuclear fuel into separate systems.

 Q-Metrics’ was responsible for establishing the thermal properties for the various materials of fabrication, selecting the analysis approach, developing the thermal models, and documenting the thermal analysis in design documents and safety analysis reports (SARs).  A variety of canister assemblies are offered to handle a wide range of PWR and BWR fuel types, burnup levels, and enrichment levels.  To avoid having to explicitly model each unique combination of fuel and canister type, Q‑Metrics developed a methodology of characterizing the fuel type by bounding global and localized heat loading parameters.  This characterization methodology allows the using plant authority to quickly thermally qualify their fuel assemblies for loading within a given canister based on enrichment and burnup level, and cooling time since discharge from the reactor. 

Due to the unique design features of the canister fuel baskets, internal convection played an important factor in the overall thermal performance of the system.  Q-Metrics provided the research establishing the basis for numerically analyzing the convection gas flow regime within the canisters, developed the software coding for subroutines to compute the convection flow as a function of gas pressure, temperature differences, and constituents making up the fill gas and analyzed four canister designs and two transportation cask designs for normal and accident conditions.  Since the NRC had never before granted a license for a design the explicitly relied on internal convection as a major heat transfer mode, Q-Metrics was required to rigorously document and verify the level of convection expected.  In addition,  Q-Metrics was required to numerically predict the behavior of the system with the potential release of fission gases from the spent fuel rods.  The release of fission gases would create a trinary gas mixture of helium, xenon, and krypton within the canisters.  An independent analysis commissioned by the NRC subsequently validated the level of convection heat transfer predicted by the Q-Metrics’ analysis. 

The FuelSolutionsÔ system was granted a certificate of compliance (CofC) by the NRC in January of 2001.

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Last modified: September 06, 2002