The NuScale integrated reactor pressure vessel contains the nuclear core, the HCSG, and a pressurizer. The HCSG consists of two independent sets of tube bundles with separate feedwater inlet and steam outlet lines. Feedwater is pumped into the tubes where it boils to generate superheated steam. A set of pressurizer heaters is located in the upper head of the vessel to provide pressure control. The entire Nuclear Steam Supply System (NSSS) is enclosed in a steel containment that is 24.6 m (80 ft) long by 4.6 m (15 ft) in diameter.

NuScale HCSG. Source: NuScale. Click to enlarge.

The NRC inspection team concluded that NuScale’s and SIET’s QA policies and procedures complied with the applicable requirements, and that SIET’s personnel were implementing these policies and procedures effectively in support of NuScale’s HCSG testing activities.

NuScale is currently developing and testing computer code design analysis software to support the NRC design certification of their advanced light water reactor design. The NuScale design includes a first-of-a-kind HCSG for conversion of nuclear heat into process steam.

NuScale contracted the services of SIET for the full-scale testing of the HCSG performance over the expected range of reactor operating conditions. SIET has extensive experience with similar heat exchanger test bundle fabrication and testing for other reactor vendors.

NuScale’s test aimed to:

• Design and test a steam generator stabilization system so that stable steam generator operation is assured;

• Provide ample data covering the full range of operation to benchmark NuScale HCSG computer codes and models; and

• Measure steam generator outlet conditions as a function of primary and secondary system conditions and tube geometry.

In December 2013, NuScale Power was selected as the sole winner of the second round of the US Department of Energy’s (DOE) competitively-bid, cost-sharing program to develop nuclear Small Modular Reactor (SMR) technology. As part of the award, NuScale will receive funding that will support the accelerated development of its NuScale Power Module SMR technology. NuScale and DOE are currently negotiating a cooperative agreement that formalizes the public-private relationship and establishes milestones for the five-year funding program. (Earlier post.)

As the only US-based company established solely for the commercialization of its SMR, NuScale Power has developed a novel and proprietary technology for an innovative, simple, safe, economic and scalable small modular reactor. Natural forces of physics—gravity, convection, and conduction—are used for normal operations and safe shutdown. This eliminates many of the large and complex systems (e.g., reactor coolant pumps, motors, valves, large-diameter reactor coolant system piping) found in today’s nuclear power plants and other SMR designs. As a result, the plant is safe, simpler, and less expensive to build and operate, according to the company. At 45 megawatts per module, a NuScale power plant can include as many as 12 NuScale Power Modules to produce as much as 540 MW.

The NuScale design was initially developed in 2000 and has been demonstrated and in testing programs since 2003 in a fully-instrumented one-third scale electrically-heated test facility in Corvallis, OR. In addition, NuScale commissioned a full-scale multi-module control-room simulator in May of 2012. Both facilities were US SMR industry firsts.