All property insurance excludes the risk of loss of value due to a nuclear incident or contamination by radioactivity. A quick look at any householders insurance policy will confirm this.
So if there is some incident, such as a large leak of radiation, it is likely that many people will either be forced to evacuate their home, or choose to move out of the area due to the increased risk of cancer, particularly amongst women and children. This was have a predictable effect on property values. For serious accidents, property close to Koeberg would become unsellable, as no- one would want to move into an uninhabitable area. For property further away, or in the case of a less major incident, the value is likely to drop significantly. In the case of guest houses, restaurants and other places reliant on tourism, it is likely that few tourists will want to visit a radioactive region. This means revenue will drop, and the businesses would not longer be viable.
In these cases, the owner has recourse by suing the operator of the nuclear plant, in this case Eskom. However, in terms of the National Nuclear Regulator Act of 1999, there is a limit on the liability of Eskom, which at the moment stands at about R3 billion. While this sounds like a lot at first glance, once one considers that the cost of clean up of radioactive contamination, compensation for health effects, etc. then it is questionable if there will be anything left for the less crucial property value compensation. In Japan, the cost of clean up and compensation appears to be exceeding R100 billion. If, for the sake of argument, we assume there are no clean up or other compensations paid out and all the R3.5 billion is spent on property value loss compensation and that Eskom actually pays out, even then it will not go very far. About one third of the properties in Melkbos would be covered, and as has been seen from Fukushima and Chernobyl, the extent of the contamination could spread far further than that.
In all cases however, any mortgage would have to continue being paid. The bank has an agreement with you which is independent of the ‘market fluctuations’ of the value of your house. This means that many would need to sequestrate themselves, and so lose any savings or other investments. Also, any person or trust which stood surety on the loan would be required to fulfil the obligations in terms of that surety.
Why is this limit on liablity in place? The answer is simple – nuclear power stations could not afford the premiums for full cover. This is especially true as nuclear stations get older. While the chances of a large accident are relatively low, the consequences are massive. For example, if the chances of an accident are one in 10 000 years, the statistical chance of one occurring in the first year are the same as it occurring in the 1000th year. Since the lifetime of the plant is always less than 100 years, this means that the 10 000 years of premiums would need to compressed into less than 100 years. For those interested in some academic research into this see this paper: Calculation of a risk-adjusted insurance premium to cover the liability risks resulting from the operation of nuclear plants. It concludes that a nuclear plant may need to charge over R600/kWh to cover the full insurance premiums (current price around R1/kWh).