...what makes a load follower...design, size, location...please give some examples...
Nuclear plants as a whole are not load followers... We all supply power to our section of the grid, which is a chunk of the US electrical power distribution network. There are many supplies to every part of the grid, all hooked up in parallel, and loads attached to the grid... As you can imagine, depending upon time of day, and time of year, the load demand placed upon the grid varies greatly. A balance must be maintained between supply and demand, and as demand increases or comes off, system ops has to control the supply to meet demand. Commercial nuclear plants generally are not used to follow the load.. they're the backbone, steady state power suppliers, and we use coal plants, windfarms, gas turbines to adjust upwards and downwards to ensure the the grid is stable and supplying the desired load. This is for several reasons.
First, Nuclear plants are on an 18 month schedule (or 12, or 24) for refueling. When we shutdown, we have access to containment, and can do lots of maintenance and modifications that can't be done at any other time. The planning and coordination to accomplish all we have to in a month of outage is considerable... Then factor in all the outside help that is required, HP's, vendors of every type, and that those outside folks are working a schedule going from outage to outage with other plants... So, outages are on a fixed schedule, and to begin one early always causes many problems. But, the fuel we buy, and install, is engineered for 18 months. (or 12, or 24)... So, if your plant runs at 80% capacity for it's 18 months between outages, then you've wasted a lot of fuel, (Fuel is $$$$), without getting the income from your MW output. Not good economics.
So, when you hear some idea from Cali about running Nukes as a backup only when the wind energy is maxed out, it doesn't make very good sense from the utilities standpoint.
Next, Commercial power plants don't like rapid power changes. I've heard comparisons that navy plants are Ferraris, while commercial plants are dump trucks. Takes a while to get up to speed, and takes a while to stop. That's a simple comparison, but from my limited simulator time here, it is a pretty big deal to take power down 20%... Lots of coordination between the BOP, RO, boration... It's not nearly as easy as shutting the throttles a couple of turns used to be.
I'm sure there are other reasons... I don't know of any nuke plants that are load followers, but I'm sure there are some out there.
Mvars are Mega-Vars, which is the unit of reactive power, or power which isn't really used for doing real work, but rather is stored in inductive and capacitave components and returned to the circuit. The 3 types of power are real (Watts) reactive (Vars) and Apparent (VA's). Apparent is the total of voltage and current output, and is the vector sum of the other 2, but that gets a little hard to discuss without drawing power triangles. (Google power triangle)
Oops, out of time for now... Hope that helps,
Bill