NuScale Power LLC was formed in 2007 to commercialize an SMR design that had been initially developed during 2000-2003 by a research team at Oregon State University and the Idaho National Laboratory. Fluor joined NuScale Power in 2011 as its major investor and strategic partner. Each NuScale Power Module produces 50 MWe (gross) from a simplified integral system configuration that uses natural circulation of the primary coolant. The core is composed of 37 half-height 17 X 17 pin array fuel assemblies and is controlled using 16 control rods and soluble boron within the primary coolant. Superheated steam is produced in two co-mingled helical coil steam generators that surround the central hot leg riser. A NuScale plant can be scaled to accommodate up to 12 modules, which can be installed incrementally to best match a desired investment or demand profile.

The reactor pressure vessel is contained within a compact, high-pressure, steel containment vessel, which is immersed in a below-grade pool shared by all modules. The shared pool is the ultimate heat sink for residual heat removal. A fail-safe emergency core cooling system can provide an unlimited post-accident grace period with no operator action, no AC or DC power, and no make-up water. Each module has an independent skid-mounted turbine-generator set for power conversion and

Figure 2.11 NuScale (United States) — NuScale Power, LLC (Fluor) © NuScale Power.

can continue to operate while other modules are being refueled. The modules, including the reactor and containment vessels, can be shipped to the site by truck, rail or barge.

A scaled integral test facility was built in 2003 as part of the original design development project and has been used throughout the design refinement process to inform design modifications and validate its safety performance. A 12-module control room simulator was commissioned in 2012 to evaluate operator performance for multi-module control rooms. A first plant is being pursued by a consortium of utilities in the western United States to be potentially sited in Idaho. Key parameters and a representative graphic for the NuScale design are given in Figure 2.11. [9]