Foster Wheeler Environmental Corporation is located in Clinton, New Jersey and it has designed and installed two specialized dry cask storage systems in the U.S.  Known as a modular vault dry store (MVDS) system, the MVDS is a vault-type structure that houses a matrix of 83 pressurized water reactor (PWR) spent nuclear fuel (SNF) assemblies or 150 boiling water reactor (BWR) SNF assemblies in separate storage locations within the vault structure.  Each storage location holds one SNF assembly in a fuel storage container.

Unlike other dry cask storage systems, the MVDS is housed within a reinforced concrete and steel building.  In addition, rather than simply placing concrete and steel casks inside the building, individual SNF is placed within a steel fuel storage container (FSC) that is then vertically inserted into a “charge face structure” that forms a shielded cover over the vault modules (see the accompanying photo).  Ambient air flows into the vault modules through an inlet duct and passes around the outside of the FSCs. The air exits through a reinforced concrete exhaust stack, which projects above the MVDS and is covered by a steel canopy.

The MVDS is being used at the Idaho National Engineering Laboratory and at Fort St. Vrain for DOE-owned SNF.