Zaporozhye NPP is completely disconnected from the Ukrainian power grid and has been feeding itself from the only operating generator for more than a day. This was reported on the IAEA website.
After the connection of the station with the last remaining operating 750 kV line was disconnected on September 2, a backup 330 kV line was used to supply electricity from the ZNPP to the grid. It was turned off on September 5 to extinguish the fire, the line itself was not damaged.
On September 6, the capacity of the sixth power unit was reduced to 150 MW. A source at the station told The Insider that the reduction in power output is bad for the turbine.
“The reactor plant can operate at any power level, the problem is in the turbine. At such low loads, the thermal and mechanical parameters of the turbine are low, vibration may appear, and protection will work later. It is good for a turbine to work at rated power, then the steam parameters (its quantity and temperature) allow keeping the thermal mechanics of the turbine plant in the conditions for which it was designed. When the steam parameters decrease, a steam-water mixture begins to appear at the individual (final) stages of the turbine, since the parameters are low, erosion occurs or, even worse, water hammer, vibration, etc. Even at a power of 500 MW, the turbine is no longer very good, at a power of 150-200 it is super hard for it, it works on the verge of its capabilities and, as you understand, some serious defects may appear on it in this mode. Therefore, now they are trying to load themselves to the maximum possible in order to somehow make her life easier.
According to the source, even the approximate timing of how long the turbine will last is unknown, since "it has never worked like this, and no one has done it." The interlocutor also specified that now the station produces exactly as much as it spends.
“More than 150 MW cannot be produced, because there is nowhere to dump it. The ability to load the block will be when / if one of the lines is restored. In the meantime, they will work in this mode, which is dangerous for the turbine.”
