Each NuScale Power Plant is self contained and each module operates independent of the other in a multi-module configuration. However, all are managed from a single control room.
The reactor pressure vessel (1) measures 45 x 9. It sits within a containment vessel (2). The integrated Reactor and Containment Vessel operate inside a water-filled pool (3) that is built below grade.
The NuScale reactor operates using the principles of natural circulation. No pumps are needed to circulate water through the reactor Instead, the system uses a convection process. Water is heated as it passes over the fuel or core (4).
As it is heated the water rises within the interior of the vessel. Once the heated water reaches the top of the riser (5), it is drawn downward by water that is cooled passing through the steam generators (6). The cooler water has a higher density. It is pulled by gravity back down to the bottom of the reactor where it is again drawn over the core.
Water in the reactor system and the Steam Generator system are kept separate. As the hot water in the reactor system passes over the hundreds of tubes in the Steam Generators, heat is transferred through the tube walls.
Water inside the tubes turns to steam. The steam turns turbines (7) which are attached by a single shaft to the electrical generator.
After passing through the turbines, the steam losses its energy. It is cooled back into liquid form in the condenser (9) then pumped by the feed water pump (10) back to the steam generator (6), where it begins the cycle again.
The Regulatory Approval Process and NuScale Systems
The NuScale design is fully prepared to meet NRC licensing requirements with two distinct advantages. First, it relies on proven light water (LWR) technology. Second, it utilizes a test facility that replicates the entire system and is fully capable of meeting all NRC requirements for plant certification.
The LWR technology used in the NuScale design is not new to the NRC, which offers huge advantages over less established technologies. For example, non-light water cooled designs pose issues for licensing such as the need to develop approved computer codes that will serve as appropriate licensing tools and the need to identify approved codes and standards necessary to permit NRC approval of the design.
In contrast, the NuScale design draws upon a vast depth of experimental data based on billions of dollars of research and development that has already been conducted on light water cooled systems. The NRC licensing staff is familiar with light water designs like NuScale’s and the existing licensing structure is based upon light water cooled systems.
Additionally, the NRC developed the necessary analytical tools and experimental correlations for the analysis of natural circulation flows in passive safety systems through its certification of the Westinghouse AP-600 and AP-1000 designs. Several of the tests were conducted in facilities designed and built at Oregon State University by Dr. Jose Reyes, NuScale’s chief technical officer. The tests confirmed the ability to model and analyze natural circulation flow and heat transfer in light-water cooled systems.
NuScale will use this test facility at OSU as the basis for a Design Certification program to benchmark vendor and NRC safety evaluation models, which should accelerate the review and certification process.
The Nuclear Energy Institute has published an excellent fact sheet about this process. You can download their PDF here.
NuScale Status in the Regulatory Process
NuScale notified the Nuclear Regulatory Commission (NRC) in January 2008 of its intent to begin the Pre-Application Review process. This process guides the preparation of the Design Certification request and the combined Construction & Operating License application (COL).
NuScale met with the NRC in July 2008, November 2008, April 2009 and September 2009. NuScale forecasts it will be prepared to file for Design Certification in 2012. The NRC review process is expected to take approximately three years. NRC regulations permit an applicant to file a COL while the Design Certification process is underway, so the design and review processes will proceed on parallel paths.
The design ultimately certified by the NRC will be incorporated in the COL. NuScale anticipates a COL filing in advance of final Design Certification in preparation of building the first NuScale facility. A benefit of the NuScale design is that it incorporates off-the-shelf components and all equipment will manufactured domestically. This will help shorten the lead-time for production dramatically.
Depending upon the amount of time the NRC requires to review the DC and COL applications, NuScale expects the first nuclear facility will be operational sometime in 2018.
Presentations by NuScale Power
NuScale is presenting its technology and research findings at international conferences and to private and public organizations. Following are PDF files for some of those presentations.
NuScale Power Company Overview & Product HistoryIntroduction to NuScale DesignLicensing Approach with the Nuclear Regulatory CommissionIdentification of Pre-Application TopicsLegal Issues for Pre-Application to the NRC