July-August 2018 NPJ

44 NuclearPlantJournal.com Nuclear Plant Journal, July-August 2018 with flat screen monitors. In contrast, in the control room for a typical operating nuclear power plant, there are around 1000 to 1400 different traditional control switches. In the AP1000 plant’s main control room, there are only about 70 control switches, and they are only for the critical safety functions. Everything else is a modern work environment to control plant operation with soft computer-based controls. One example I always find interesting to discuss is how the computerized procedure system (CPS) works. The former generations of plants’ procedures have evolved from procedures on paper that are consulted by the operators. In the AP1000 plant and the Westinghouse digital architecture, the CPS is actually embedded in the overall I&C architecture. It’s effectively a compendium of potential events and issues and response approaches an operator would take. It’s not just documents on a computer; it’s actually more than just static files of the respective procedures. What the CPS does is integrate procedures with the I&C architecture of the plant. The CPS evaluates the status of the plant at each step of the procedure. It provides recommendations on transitions to the next appropriate procedure, executes necessary parallel information, alerts the operator to needed actions and links each step of the procedure to the appropriate soft display and associated soft controls. It’s actually designed to provide online information and help to the plant operator. 7. What are lessons learned with the AP1000 which can be applied to the existing plants with modifications? The advanced digital control system, including the cyber security aspect, is an example for existing plants’ digital upgrades. Some of the AP1000 plant’s coping and mitigating strategies for extreme events have already informed key products and services that Westinghouse developed in support of the FLEX requirements for operating plants. Another example is its risk-informed design. The AP1000 probabilistic risk assessment developed by Westinghouse was used very early as a design tool for the AP1000 plant. As we developed that technology, it has influenced many modern products and services in terms of risk-informed applications. Another aspect, from a U.S. technology point of view, is that the AP1000 plant was the first to actually exercise much of the more modern nuclear construction and design codes. This helps ensure the development and alignment of licensing requirements for those new codes. For example, the American Concrete Institute’s (ACI) “Code Requirements for Nuclear Safety Related Concrete Structures (ACI 349- 01)” provides a standard for modern structural construction, and the Institute of Electrical and Electronics Engineers’ (IEEE) “IEEE 384-2008 IEEE Standard Criteria for Independence of Class 1E Equipment and Circuits,” establishes standards for electrical separation requirements. In terms of other engineering services, such as security, the AP1000 plant was the first nuclear power plant design to comply with and be licensed addressing post-9/11 requirements, in multiple countries. This includes physical security, aircraft crash protection and cyber security, from which our experience in developing and testing different approaches to compliance with these new regulations on the AP1000 plant created a model for the operating plants today. 8. How does AP1000 meet the cyber security challenge? We always want to consider two aspects to security: cyber and physical. Both have been key features of the development of the AP1000 plant. In layman’s terms, for physical security, this is the first nuclear power plant that really fully incorporates and addresses all the new requirements in a post-9/11 regulatory environment. Specific to cyber security, the units that are being deployed at the Vogtle site in Georgia implement the requirements of Title 10 of the Code of Federal Regulations and its article 73.54, “Protection of Digital Computer and Communication Systems and Networks,” including the detailed specification of critical digital assets, implementation of secure configurations for critical digital equipment or assets, and the design and delivery of an instrumentation and control approach for the security monitoring system. Again, one of the key aspects of the design is the concept of a layered, defense-in- depth approach to safety, which provides unique strengths in term of security. This includes the diverse and hardwired backup system that enables actuation of the critical safety features I mentioned earlier, but also the minimization and robustness of key assets to defend. 9. What are the major innovations which have been undertaken in AP1000? It is the first nuclear power plant to rely on passive safety systems to respond to all of the plant events. The other innovation that I would mention is the extensive use of structural modules within the nuclear island. That’s really a concept that is still maturing in its application, but it extrapolates a lot of the lessons learned from the U.S. nuclear industry, and military and civil applications in terms of maximizing the benefits of off-site construction and manufacturing. The AP1000 plant is also the first commercial plant for which the reactor cooling system implements the canned motor reactor coolant pump design for PWRs. This not only greatly reduces maintenance, but it also eliminates the need for a large number of support systems, and most importantly, it eliminates the need to inject water to maintain the integrity of the pumps’ seals. The extensive use of the soft controls, that is, the touchscreens and large digital displays, and the advanced main control room design we discussed lessen operator burden. Another key innovation for the plant is the main control room habitability I discussed earlier, which does not require AC power but relies on passive filtration and stored air for long-term habitability and operator protection. This is a very exciting time for us because really the AP1000 plant does not introduce only one plant, but demonstrates an entire new technology for power generation with new passive safety technology – Generation III+ nuclear power technology. Contact: Donna Ruff, Westinghouse Electric Company, telephone: (412) 374- 4705, email: ruffdl@westinghouse.com. Passively Safe... ( Continued from page 24)