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  1. Rod, even if the GEBWRs were not design with power up rates in mind, it still would in all likelihood be possible to safety up rate their existing design. Reactors are designed with sufficient tolerance to easily handle the added heat and pressure. The limitations of their heat exchange systems, which would not be a problem for a BWR, and of their turbines, which would be a problem, come into play, before safety considerations would.

  2. Many plants were built that way. TMI-I was also, as we called back then “turbine limited.” Rancho Seco (The B&W portion of Rancho Seco and TMI-II are essentially identical other than some last minute AEC/NRC “ratchets”), and to some extent TMI-II were also turbine limited. Only the HP turbine needed replaced, along with the uprate review package. All was lost/forgotten after TMI-II. The info is readily apparent on the heat balance drawings for these plants if you know what you are looking at.
    This “hidden” capacity caused problems during initial startup at those plants as they had steam driven feed-water pumps. The FWP Turbine was sized for the full MWT (megawatt thermal) capacity. That extra 20 percent of FWP capacity made for a very difficult control loop. And worse yet, there was a start-up FW control valve, Main FW control valve and then the variable speed FWP Turbine. Take a FWP designed for a ~1,000 MWE plant and put it in a ~800 MWE plant. Now try and control a flow at 20% through a eight inch control valve, with the turbine at half speed (that is all the slower the manufacture would let it go.) I spent several days tuning those loops.
    Did you know Oyster Creek only cost (about) $60 Million.

    1. Rich – thank you for the detailed information. It is always nice to hear from professionals with experience.
      It really is amazing to think about the moderate cost of the initial plants and their small or non-existent cost and schedule overruns. One of the biggest numbers driving the total cost of some of the later plants was interest on the loans taken out to finance construction. In an era where the prime lending rate approached 20% (late 1970s early 1980s) delays were incredibly expensive. That fact led to other cost increasing processes – like keeping specialized welders on site for weeks just so there would be no delay when their services were needed. (I had a friend who built a tidy nest egg during that time. He collected a lot of per diem, read a lot of books in his hotel rooms, and ate some very nice meals. When I knew him, he owned a jewelry shop in Tarpon Springs where he put to use some of the skills that he learned welding in nuclear power plants.)
      The vendors also had a lot of negotiation power with their customers about component pricing. Labor leaders also took advantage of the looming expenses of delays to keep work rules and wages higher than they would have been under normal circumstances.
      For a while, the utilities did not mind too much. They knew they would get the costs back in the rate cases. The party ended when the PUC’s stepped in with “prudency” hearings and questioned the expenses and delays and did not allow full cost recovery.
      Truly a mess that we all need to understand so that we can avoid a repeat. There will be no third chance to get it right if we do what we did in the 1970s and 1980s. The failure to control costs handed the opposition their biggest stick with which to beat us down. Customers would have been far more supportive of nuclear plant construction if they had not seen rate increases every time a new nuclear plant got completed. They would have been our biggest allies if they had seen even moderate rate decreases.
      Since EVERYONE is an electricity customer, we need to understand that we have a great tool for building support – simply keep cost under control. We can afford to sell power at a lower cost than the competition. It is a well proven way to win friends and influence people.

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