Chernobyl was the result of some design decisions that were significantly less than ideal, along with the indispensable addition of a person in authority who was an arrogant fool. As bad as that person was he would have been stopped if the jackass in question had not operated in the authoritarian soviet culture.
Take a mediocre technology and operate it with superior people who are conscientious and you will have a good result.
Take a mediocre technology and operate it with mediocrities and if you are unlucky something very bad will happen.
So what is mediocre technology?
Sometimes it is amazing engineering, which has not been critiqued.
In the case of Fukushima you had what was very well engineered reactor with ancillary equipment that was not up to the stresses that were placed on it.
The current generation of Westinghouse Electric (AP1000) reactors are generation III+ designs with passive safety features.
Third generation designs improve on early designs by incorporating passive or inherent safety features which require no active controls or (human) operational intervention to avoid accidents in the event of malfunction, and may rely on pressure differentials, gravity, natural convection, or the natural response of materials to high temperatures.
What this means is that in the event of malfunction no operator intervention is required. One feature of the Westinghouse design is that in the event of a shut down combined with a loss of auxiliary power (which was needed at Fukushima to power coolant circulation) the reactor is designed in such a manner that it would cool off without any power or operator control in such a manner that no damage to the plant would occur.
The degree of safety for such designs is awe inspiring.
On March 27, 2008, South Carolina Electric & Gas applied to the Nuclear Regulatory Commission (NRC) for a Combined Construction and Operating License (COL) to build two 1,100 MW AP1000 pressurized water reactors at the site. On May 27, 2008, SCE&G and Santee Cooper announced an engineering, procurement and construction (EPC) contract had been reached with Westinghouse. Costs were estimated to be approximately $9.8 billion for both AP1000 units, plus transmission facility and financing costs.
Unfortunately Westinghouse as run by its current owners Toshiba is quite bad when it comes to accounting. They underbid their South Carolina project. As general contractor they are fully responsible for cost overruns. And there have been massive cost overruns. As a result they have declared bankruptcy.
Edited 8/25/2017 13:48:36