As to area, nobody lives in the ocean and houses next to an exclusion zone also have huge drops in property values. So, yes some sort of decreasing metric, as a sanity check the property value drop from being within sight of a nuclear power plant is going to be more than 300$. Further, actual exclusion zones may depend on wind so risk really does extend out to 40 miles.
Edit: As an upside, if you included these costs then there would be a push to place reactors in the middle of nowhere to lower costs which IMO is a very good thing.
PS: As a sanity check fukushima is estimated to cost tax payers ~188 billion$ and many people are worse off after the disaster so real costs are higher than that. If the odds are 0.2% that's ~400 million vs your estimate of 300 * 100,0000 = 30 million.
Add in the fact that the worst disaster (Chernobyl) has an exclusion zone of 1004 miles^2 (equivalent to a 17 mile circle, rather than your 40 miles) and we discover that my initial estimate was about 25x too pessimistic.
I'm beginning to think your concerns about cost are FUD. Out of curiosity, since cost is such a big concern for you, do you hold similar concerns about our bloated infrastructure costs? For example, given the bloated costs of the 2nd ave subway in NYC (1 mile of track there costs as much as the entire Delhi Metro), should we also curtail this project? Or is cost only an issue for nuclear energy?