Training NuScale SMR operators

Above: NuScale Control Room simulator

NUSCALE POWER IS ON A mission to provide scalable advanced nuclear technology for the production of electricity, heat and water that will improve the quality of life for people around the world. In August 2020, the Oregon-based company became the first to receive US Nuclear Regulatory Commission (NRC) approval for a small modular reactor (SMR) design.

A NuScale Power Module can generate 250MWt of heat in the form of superheated steam, or generate 77MWe. It is 65 feet (19.8m) tall and 9 feet (2.7m) in diameter and it sits within a containment vessel 76 feet (23.1m) tall and 15 feet (4.5m) in diameter. Modules are located below grade in a pool of water, which provides passive containment cooling and decay heat removal.

NuScale’s flagship 12-module NuScale power plant provides a total output of 924MWe. Smaller four module (308MWe) and six module (462MWe) plant solutions are also offered. The first commercial NuScale module is planned for construction at Idaho National Laboratory for Utah Associated Municipal Power Systems (UAMPS) and is due to begin initial operation in mid-2029.

History

NuScale’s SMR design dates back to the Multi-Application Small Light Water Reactor (MASLWR) programme, which was funded by the US Department of Energy in 2000. The Idaho National Environment & Engineering Laboratory (INEEL) led this three-year research project with support from an Oregon State University (OSU) team led by Dr. Jose´ Reyes, head of the Department of Nuclear Engineering and Radiation Health Physics.

During this time Reyes and his OSU team began to build a one-third scale electrically heated version of what would become the NuScale Power ModuleTM, which is at the heart of NuScale’s design. In 2007, NuScale Power was formed when OSU granted the company exclusive rights to the Power Module design. Reyes went on to become the company’s co-founder and chief technology officer.

Operations experience

Reyes is an internationally recognised expert on passive safety system design, testing and operations for nuclear power plants. He was the OSU principal investigator for the AP600 and AP1000 design certification test programmes sponsored by the US NRC, the US DOE and Westinghouse. Prior to joining the faculty at OSU in 1987, Reyes worked nearly ten years as a thermal hydraulics research engineer in the Reactor Safety Division of the US NRC.

Reyes also needed someone with plant operating experience to drive development. Ross Snuggerud, a former nuclear engineering student of Reyes at OSU had already had a 15-year career in the nuclear industry, including earning a senior reactor operator (SRO) licence in 2001. In 2008, Snuggerud became NuScale employee number eight at the company’s Corvallis, Oregon office.

After joining NuScale, he was charged with developing the main control room staffing solution and defining the concept of operations. Snuggerud quickly recognised that a simulator would be needed to determine, and then justify, the licensed operator staffing requirements for the US NRC.

NuScale 12-unit Main Control Room Simulator

In its design certification application to the NRC, NuScale included an alternative licensed operator staffing and control room solution to that which is prescribed in the code of federal regulations (10 CFR 50.54(m)).

Previously, the US NRC had determined that the maximum number of reactors that could be operated from a single control room was two. But a NuScale SMR power plant has design approval to operate 12 reactors from a single control room with a staff of six licensed operators.

US-based GSE Solutions was chosen to develop a simulator for the NuScale power plant. GSE used the Idaho National Laboratory’s RELAP5-3D code in an interactive, real-time simulation environment, Studvik’s S3R reactor core model and GSE’s JADETM Simulation toolset to create an accurate model of the new reactor design.

The first single-unit simulator was up and running by 2010. By May 2012, NuScale commissioned the world’s first SMR control room at its Corvallis facility. The simulator comprised 12 independent workstations — each dedicated to simulating the operation of a NuScale SMR and its turbine generator. It served as a model control room, allowing NuScale to evaluate different approaches to the design and operation of a power plant.

Over the next several years, a team of operators, human factors engineers and software engineers developed an unique human-system interface. This interface provided operators with indications, alarms, controls, procedures and automations to allow a small team of operators to monitor and control 12 reactors from a single control room safely, reliably and efficiently.

Testing, testing, testing

NuScale used the simulator to validate its staffing plan with the NRC and provide the technical justification for the concept of operating 12 reactors from a single control room using only six licensed operators.

NuScale developed three challenging simulator scenarios that included events with the highest workload, the most potential to impact safety and the highest risk significance. These scenarios covered events including design basis, beyond design basis and multi-module transients. Two operating crews independently completed each of the three scenarios while being closely monitored by an examination team of licensed operators and human factors engineers. The exams were conducted over two weeks in August 2016 and one week was audited by the NRC.

An integrated system validation (ISV) followed the staffing plan validation two years later, in 2018. The ISV was a comprehensive suite of performance-based tests to ensure that the integrated system design components (hardware, software, procedures and personnel elements) work together to support safe operation of the plant. This process was similar to staffing validation, but was four times larger, with a focus on integrated system operation rather than staffing.

NuScale hired 22 ISV operators with varying degrees of experience, including recent college graduates, ex-Navy nuclear plant operators and ex-commercial nuclear plant operators. It trained these operators in the classroom and in the simulator for five and a half months. This was followed by two more months of testing under the watchful eye of the test team, who collected data and made observations during each exam.

The data was collected, analysed and distilled into a test report. The report provided objective evidence demonstrating that the training, procedures, human-system interface and crew all functioned together to safely and effectively operate the 12 reactors.

Report results were submitted to the NRC in March 2019 as the last human factors engineering deliverable required for NuScale’s design certification application.

Simulator multiplication

In May 2017, NuScale commissioned a second small modular reactor control room simulator at its Richland, Washington office.

Like the first simulator in Corvallis, the Richland simulator is used to train future plant operators as well as develop plant operating procedures and engaging training materials. The two simulators are a useful communication tool to demonstrate the innovative features of NuScale plant operations and safety systems to the media and the general public, potential investors and customers, regulators, legislators and NuScale staff. The ability to conduct live simulator demonstrations of the unique features of NuScale’s SMR technology, such as its load following capability or island mode operation, is much more effective than a PowerPoint presentation. NuScale is proud to have provided hundreds of demonstrations over the years at both simulator locations.

In late 2018 and early 2019, NuScale began to use a remote-hosted simulator at meetings and conferences. During these events, proprietary computer codes could be run from a secure location to protect intellectual property and assure export control compliance, all while allowing NuScale to take its simulator demonstrations ‘on the road’.

Later in 2019, the Richland simulator was converted into a ‘remote simulator’ using a similar approach. The software for the simulator was moved to a secure, remote server in the NuScale Portland office and a user-friendly interface was developed to run the simulator. This remote simulator served as a prototype for future remote simulator events.

In 2020, the NuScale Energy Exploration Center (E2 Center), was installed at OSU. It is the first of three planned installations of NuScale power plant control room simulators at US universities. These initial E2 Centers are funded by a 2019 US Department of Energy grant to broaden the understanding of advanced nuclear technology in a control room setting while also providing students, researchers, operators, and the general public opportunities to engage in science, technology, engineering and maths research and education.

Licensed operators

NuScale is laying the groundwork to license operators in support of commercial operation.

The goal is to have operators complete their first licensing class at least three years prior to first plant operation.

NuScale is working with the NRC and the Institute of Nuclear Power Operations to clearly define a training and licensing process that is commensurate with the safety and simplicity of the NuScale SMR design.

The initial licence class is anticipated to take nearly half the time of an existing commercial plant class. The simulator that will be used to train operators will also be a fraction of the cost of existing commercial simulators, and NuScale intends to make these cost-competitive simulators widely available.

Innovating the future

NuScale’s simulators are highly capable, cost effective training tools that can be remote-hosted for enhanced security, export control compliance and maintainability while providing the capability for easy and seamless updates and top-notch customer support.

Beyond the simulator, NuScale has built other facilities that serve as research and learning tools and help communicate to diverse audiences the unique features and functionality of its technology.

NuScale’s SMR technology truly stands out through the cutting edge testing it performs at state-of-the-art facilities worldwide. Information from these tests is used to validate the thermal-hydraulic and design computer models for predicting the thermal efficiency, performance and safety of NuScale’s SMR. Data are also used to validate the reactor design and to gain manufacturing, assembly, and material handling insights.

Most importantly, these facilities reinforce NuScale’s testing-related work to ensure that the first licensed SMR is a safe and resilient power plant.