July-August 2019 NPJ

Nuclear Plant Journal, July-August 2019 NuclearPlantJournal.com 19 Research & Development VR Program EPRI’s Nuclear Maintenance Applications Center has introduced a virtual reality (VR) program to train nuclear plant workers on maintenance tasks for Terry Turbines. The objective is to provide training that is safer, more engaging, and more efficient than traditional hands-on component training—which involves setting up and maintaining hardware and mockups and sometimes transporting equipment to training sites. Wearing a headset, the technician enters a virtual environment and uses two handheld controllers to manipulate tools and disassemble and reassemble the turbine. Four modes are available:  Free-hand: The technician removes parts from the turbine in any order.  Show-me: The program uses animations to demonstrate the steps of turbine disassembly and reassembly.  Practice: The technician completes the steps, with key parts highlighted by the program.  Test: The technician completes the steps with no help from the program other than text descriptions of the steps. According to EPRI Principal Technical Leader Tom Walker, the program is easier to administer than hands-on training. Its requirements—a headset and a computer with sufficient graphics capabilities—are relatively low-cost and low-maintenance. It can be set up in any room, and there is no need to purchase and maintain spare plant components. EPRI demonstrated the program for its utility members, and the response has been positive. “Trainees really enjoyed using the program. They moved parts around, explored all areas of the turbine, and practiced the various steps. In some cases, it was difficult to get them to remove the headset,” Walker said. The initial response at Dominion Energy was “overwhelmingly positive,” according to Mark Quesenberry, Dominion’s nuclear maintenance performance improvement consultant. Participants enjoyed the experience and recommended expanding the technology’s use. Dominion was so impressed with the program that it installed VR rooms at its three nuclear plants. Quesenberry said that VR provides training that is safer, easier, and more engaging and cost- effective than traditional methods. Based on the success of the demonstrations, EPRI is working on a VR application for valve disassembly, repairs, and reassembly. “Our vision for VR is a virtual showroom with many components. The user would select a component, such as a circuit breaker or an emergency diesel generator, and enter a training room for that component,” said Walker. “Our members are already asking us to add specific components to the virtual showroom.” VR can help attract the next generation of nuclear plant technicians. “VR is a powerful training tool that can help the industry maintain worker proficiency, especially as the workforce transitions as a result of retirement and other turnover in the next 5 to 10 years,” said Walker. Contact: Tom Walker, EPRI, email: techexpert@eprijournal.com . SPV Tool In a nuclear power plant, a single point vulnerability (SPV) is a component or subcomponent that, if failure occurs, can cause a reactor or turbine to trip and the plant to go offline. Among plants built in the 20th century, about 1% of components are SPVs, with most in the turbine-generator side (not the reactor side) of the plant. For example, if the setpoint of a relay in the main power system drifts too low, the generator could trip, which in turn could cause the turbine to trip. While many SPVs are known to plant operators, others are unrecognized or inadequately mitigated. To minimize the risk of an SPV failure, operators may enhance operational procedures or conduct additional inspections, testing, and preventive maintenance. Preventing SPV-related shutdowns and eliminating SPVs are vital to safe, reliable plant operations. Shutdowns as a result of equipment failure can be costly. Repair of an easy-to-fix component may require a three-day shutdown at a cost of about $3 million in lost generation revenue. To prevent unnecessary shutdowns, utilities are using EPRI’s new Single Point Vulnerability Analysis Tool to identify SPVs in their plants along with actions to eliminate or mitigate them. The tool draws on a database of SPV data provided by the industry—including identified vulnerabilities, mitigation designs and costs, and successful elimination strategies. Users can compare SPVs in their facilities with SPVs in other plants and learn how those plants mitigated them. The tool enables users to organize and plot data by plant system, plant design, and component type. It alerts EPRI technical staff to newly identified component vulnerabilities, which prompts research to address them. Because engineers at different plants often use different names for the same components and systems, EPRI incorporated a common information model that helps users find relevant SPVs. SPV comparisons on the reactor side are most beneficial when made between plants with similar designs—and the tool enables such comparisons. On the turbine/generator side, plant operators and engineers can compare across different designs and still gain insights about their facilities. For example, consider nuclear plants A and B with similar designs. If plant A shares all its information on SPVs and successful mitigations in the database, plant B can verify that it has identified the same SPVs and that it is using the best mitigation strategies. If plant B has listed an SPV that plant A has not listed, Plant A may have already eliminated that SPV, and plant B may want to consider plant A’s elimination strategy. (Continued on page 20)