We can see how useful it is by comparing the 1970s accident and death rate with todays. Doing that we'll find that we're spending over a billion dollars per life saved from radiation poisoning. Which is ludicrously inefficient.
"a paper [..] provides some empirical evidence that safety changes have contributed to the cost of building new nuclear reactors. But the study also makes clear that they're only one of a number of factors, accounting for only a third of the soaring costs. The study also finds that, contrary to what those in the industry seem to expect, focusing on standardized designs doesn't really help matters, as costs continued to grow as more of a given reactor design was built."