July-August 2018 NPJ

Nuclear Plant Journal, July-August 2018 NuclearPlantJournal.com 23 owner to collect and disseminate all of the actionable information into the hands of operation and maintenance staff efficiently. The AP1000 plant not only adds the additional sensor capabilities, it also adds the infrastructure to enable the distribution of the right data to the right place at the right time. 3. Is the data available from the existing plants? Could we extrapolate it for AP1000? Yes. The vast majority of the components of the AP1000 plant rely on decades of experience. For example, the steam generators of the AP1000 plant have the same design concept as what we have used on a number of our plants in a number of different applications. The reactor fuel, reactor vessel, the reactor internals, the fatigue monitoring system, piping, all those basic components – are similar, if not identical, to the most modern designs we have already deployed in operating plants. There is a limited number of first-of-a-kind components for which we have had to develop appropriate data through extensive testing programs. Another advantage of the AP1000 plant is how the information is organized hierarchically and in a standard approach that is applied to all AP1000 units. This approach will make it easier for different operators of different AP1000 plants in the world to share information, as well as for Westinghouse to develop solutions and options with fleet applicability. For example, if you look at the nuclear island piping design inside containment, there’s very little difference between the AP1000 units in China and the ones being built at Vogtle, in the United States. The data, the documents, the tag ID numbers, everything is exactly identical to facilitate that sharing of information. You pointed out an important point with this question because one of the reasons we did that is when we considered bringing a new fleet to the market, we wanted to maximize the speed at which we, and plant owners, can generate data and lessons learned that can be shared. 4. What are the post-Fukushima modifications? As discussed in a previous question, since the inception of the design, one of the key objectives of the AP1000 plant’s safety concept was to maximize the capability of the plant to deal with what you would call extreme environmental events. When we were in the earlier stages of design, a key event that we were considering was Hurricane Andrew in 1992. We were considering those types of catastrophic natural events that could seriously compromise the entire infrastructure that surrounds the plant, which means the accessibility, power, water supply, etc. To address this, the concept that matured was a plant that really could be as self-sufficient and as autonomous as possible, thus requiring nothing in terms of power or off-site intervention for at least three days, and even after those three days, needing only very minimal support. Post-Fukushima, and after, the FLEXNRC regulation, there wasn’t really any significant modification that was made to the AP1000 plant, as those very concepts were already embedded in the design. In fact, some of the FLEX requirements were informed by some of the experience of the NRC’s review of the passive plant designs in the ‘90s. A unique aspect of the AP1000 plant is that it is designed with a complete station blackout as a design basis event, not as a beyond design basis event. On loss of AC electrical power, even if you postulate a catastrophic event that loses not only the grid connection but the backup connections, as well as all on-site backup diesel generator systems, as I was saying previously, the AP1000 reactor simply shuts itself down and the plant moves to a safe state that it can sustain without any intervention or any AC power for at least 72 hours. Even after three days, the key difference from the prior generation of plants is that the AP1000 plant is designed to require only approximately 28 kW of power for long- termsupport, compared to several hundred kW for a comparably sized nuclear plant. The reason it was so important for us to make that power requirement very small is that once the power need is reduced, then you can have very small ancillary diesel generators that you can literally transport even by helicopter if you have lost all site access. They are very easy to supply from the existing emergency event infrastructure. 5. What major systems are safety- related, on the equipment side and also on the instrument side? Without being able to discuss every plant safety feature in the space we have, I can cover a few. First, you have the I&C – the instrumentation and control safety system. The safety I&C system is the digital protection and monitoring system (PMS), which is built around a two-out- (Continued on page 24) Haiyang: © Shangdong Nuclear Power Company Limited (SDNPC) . Haiyang Nuclear Power Plant. Used with permission. All rights reserved.