California’s Historical Nuclear Meltdown

"The accident, which occurred in 1959, is claimed to have released more radiation than Three Mile Island...Fortunately, this reactor was only 1/100 the size of the Three Mile Island reactor. However, it’s been reported to have released up to 240 times more radiation than the 1979 disaster. How can this be? The answer: the experimental reactor did not have a concrete containment structure. Thus, any radiation that escaped the venting system entered the atmosphere...When the Department of Energy came out in 1989 with the statement that the SSFL site was still contaminated, community concern began to grow. A study showing increased levels of bladder cancernearby the site showed up. Then there was the follow up report by UCLA that SRE plant workers who had been exposed to the highest levels of radiation had triple the amount of cancer death rates then those not exposed."

https://ww2.kqed.org/quest/2011/03/20/californias-historical-nuclear-meltdown/